JP2014165750A - Radio communication system, radio communication method, base station information management device, and base station information management method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve radio communication efficiency while suppressing the influence of radio wave interference between base station devices, even if the transmission time of a base station device is restricted.SOLUTION: A radio communication system includes: an acquisition unit for collecting, from another base station device, base station information, including a frequency used in the other base station device and transmission timing of the other base station device, for each base station device; a use frequency selection unit for selecting a frequency for use in the base station device on the basis of the base station information transmitted from the base station device; a transmission timing selection unit for selecting transmission timing different from the transmission timing of the other base station device using the selected frequency, as the transmission timing of the base station device; and a setting unit for setting a use frequency and the transmission timing of the self-device, for each base station device and on the basis of the frequency and the transmission timing selected by the transmission timing selection unit.

Description

  The present invention relates to a technique for controlling a base station apparatus that performs wireless communication.

Conventionally, a private wireless system using an unlicensed band such as a 2.4 GHz band or a 920 MHz band that has not been licensed has attracted attention. In a 2.4 GHz band wireless communication system, a wireless local area network (LAN) is mainly used in many homes and businesses to connect a PC (Personal Computer), a smartphone, etc. via the optical line to the Internet. .
The 920 MHz band wireless communication system is attracting attention as an M2M wireless access system that performs M2M (Machine-to-Machine) communication connected to meters, home appliances, sensors, and the like typified by smart grids. In the wireless communication system of the 920 MHz band, wireless systems other than the wireless LAN such as ZigBee (registered trademark) and specific low power wireless are particularly used.

  In such a private wireless system, in order to avoid collision of user data transmitted by base station devices or wireless terminals existing in the same area with the same frequency channel, or to allow coexistence with other wireless systems, It is obliged to carry out career sense. As a result, collision of user data with other base station apparatuses or wireless terminals can be avoided. However, while another base station apparatus, a wireless terminal, or another system is using a communication path, the own terminal or the own system cannot communicate. Therefore, the throughput of the own terminal or the own system is reduced.

  In view of this, a method is used in which the usage state of surrounding frequencies is measured and the least used frequency is selected before the base station apparatus is installed in the system and the frequency is set. However, in recent wireless LAN standards such as IEEE802.11n and 11ac, the available frequency bandwidth is gradually increased, and the possibility of radio wave interference between neighboring base station apparatuses is further increased. . On the other hand, a technique for avoiding radio wave interference by using a plurality of antennas to direct antenna directivity nulls toward other base station apparatuses between base station apparatuses that may interfere with each other has been developed.

  However, a wireless LAN using the 2.4 GHz band uses a relatively high frequency and is often used indoors, so the number of interfering base station apparatuses is not so large. On the other hand, in the 920 MHz band, as defined in the ARIB (registered trademark) standard (see Non-Patent Document 1), the frequency band is low, the bandwidth per channel is as narrow as 200 kHz, and further utilization Since the environment is assumed to be outdoors as well as indoors, there is a problem that the number of base station apparatuses subject to interference greatly increases.

  In addition, there are a plurality of wireless systems using the 920 MHz band, such as a system using IEEE802.5.4 / 4g + Zigbee (registered trademark) IP, which is currently being studied, and a specific low power wireless system that is already commercially available as an original system. It is necessary to assume coexistence with different wireless systems. In order to avoid interference from different wireless systems in the same frequency band, it is necessary to divide the frequencies to be used. As a result, the number of frequency channels that can be used in the own system is reduced.

ARIB Standard ARIB STD-T108 Version 1.0

In the ARIB (registered trademark) standard described in Non-Patent Document 1, the transmission time of one base station apparatus and wireless terminal is limited to a maximum of 360 seconds (duty 10%) per hour. Therefore, the downlink user data transmission of the base station apparatus is limited to 10%. Therefore, the remaining 90% is allocated to uplink user data transmission from the wireless terminal. If the uplink user data transmission is an application having a higher communication frequency than the downlink user data transmission, the influence of such a limitation on the transmission time is small. However, when there is no difference in communication frequency compared with uplink user data transmission and downlink user data transmission, there is a problem that the communication efficiency of wireless communication is lowered due to the influence of the transmission time restriction of the base station. .
In addition, in the ARIB (registered trademark) standard, an upper limit value of transmission power that can be transmitted is determined for each frequency channel that can be used in a 920 MHz band wireless system. The number of frequency channels that can be used is 29 channels from 922.4 MHz to 928.0 MHz. Among them, there are only 6 frequency channels from 922.4 MHz to 923.4 MHz that can be transmitted up to 250 mW as transmission power, so that it is necessary to operate with fewer frequency channels when trying to realize a wider range of operations. There is.

  A setting example of transmission timing of a conventional base station apparatus is shown in FIG. FIG. 8 shows a transmission timing setting example using five base station apparatuses. In the example shown in FIG. 8, the base station devices 1 to 3 use the same frequency (f1 in FIG. 8), the base station device 4 uses the frequency f2, and the base station device 5 uses the frequency f3. Yes. The horizontal axis t represents time. Further, the transmission cycle T represents a time interval at which transmission / reception of uplink user data and downlink user data of the base station apparatus is performed. As shown in FIG. 8, in wireless communication using the 920 MHz band, a small number of frequency channels are shared among a plurality of base station apparatuses. Therefore, even when the base station apparatus 1 tries to transmit downlink user data to the wireless terminal, the downlink user data of the base station apparatus 2 is transmitted while the base station apparatus 2 is transmitting downlink user data to the wireless terminal. The base station apparatus 1 cannot transmit downlink user data to the wireless terminal due to the influence of the above.

  As shown in FIG. 8, when the downlink user data transmission timing of the base station apparatus 3 and the reception timing of the uplink user data from the wireless terminal to the base station apparatus 1 overlap, the downlink user data of the base station apparatus 3 It becomes an interference wave. For this reason, the reception performance of the uplink user data deteriorates due to the influence of the downlink user data of the base station apparatus 3, and the base station apparatus 1 cannot receive the uplink user data.

  The base station device 4 and the base station device 5 each use a frequency channel different from that of the base station devices 1 to 3. Therefore, the base station device 4 and the base station device 5 are not affected by the interference of other base station devices. However, in wireless communication using the 920 MHz band, the transmission time of the base station apparatus is limited by the ARIB (registered trademark) standard. On the other hand, the wireless terminals connected to the base station apparatus are limited to 10% each, but there is no limitation on the transmission time for the entire system. It is possible to share the wireless terminals and transmit the uplink user data. However, in the case of a usage mode in which there is no difference between the downlink user data transmitted by the base station device and the uplink user data communication volume transmitted by the wireless terminal, the transmission time of the wireless terminal is affected by the transmission time limitation of the base station device. Will be limited. As a result, areas that are not used by the base station apparatus 4 and the base station apparatus 5 and the connected wireless terminals become free areas. The vacant area represents the time until the base station device 4 and the base station device 5 can next transmit downlink user data. Even when there are no base station apparatuses that interfere with each other like the base station apparatus 4 and the base station apparatus 5, a free area is generated due to the transmission time limitation. As a result, the frequency per base station device cannot be effectively used. Therefore, there exists a problem that communication efficiency will fall between a base station apparatus and a radio | wireless terminal.

  As described above, in wireless communication using the 920 MHz band, there is a problem that throughput decreases due to radio wave interference between base station apparatuses due to a small number of frequency channels, and communication efficiency decreases due to transmission time of the base station apparatus.

  In view of the above circumstances, the present invention is a technique for improving the efficiency of wireless communication while suppressing the influence of radio wave interference between base station apparatuses even when the transmission time of base station apparatuses is limited. The purpose is to provide.

  One aspect of the present invention collects, for each base station device, base station information including the frequency used by the other base station device and the transmission timing of the other base station device from another base station device. An acquisition unit; a use frequency selection unit that selects a frequency used by the base station device based on the base station information transmitted from the base station device; and the other that uses the selected frequency. Based on the transmission timing selection unit that selects transmission timing different from the transmission timing of the base station device as the transmission timing of the base station device, and the frequency and transmission timing selected by the transmission timing selection unit, And a setting unit that sets the frequency used for the transmission and the transmission timing of the device itself.

  One aspect of the present invention is the above-described wireless communication system, wherein the use frequency selection unit selects a frequency with the smallest number of the other base station devices from frequencies available to the base station device. Select a frequency to be used by the base station apparatus.

  One aspect of the present invention is the above-described wireless communication system, wherein the transmission timing selection unit acquires the transmission timing of the other base station apparatus that uses the selected frequency, and acquires the acquired transmission timing. The number of base station apparatuses to be used is calculated from the base station apparatus, the number of base station apparatuses that can be transmitted within a transmission period is calculated from a preset transmission time, and the other base station apparatus using the selected frequency is used. Is less than the number of transmittable base station devices, a transmission timing different from the transmission timing of the other base station device is selected as the transmission timing of the base station device, and the selected frequency is used. When the number of the other base station devices is equal to or greater than the number of base station devices capable of transmission, the transmission timing of the other base station device having the smallest received power among the other base station devices The same transmission timing as to select the transmission timing of the base station apparatus.

  One aspect of the present invention is the above-described wireless communication system, wherein the acquisition unit further acquires reception power of a signal transmitted from the other base station device as the base station information, and the transmission timing selection unit If the other base station apparatus having a value of the received power equal to or greater than a threshold is present in the other base station apparatus using the selected frequency, the other base station apparatus If the other base station apparatus whose reception power value is equal to or greater than a threshold does not exist, the same transmission timing as that of the other base station apparatus is selected. Select the transmission timing.

  One aspect of the present invention collects, for each base station device, base station information including the frequency used by the other base station device and the transmission timing of the other base station device from another base station device. An acquisition step, a use frequency selection step of selecting a frequency to be used by the base station device based on the base station information transmitted from the base station device, and the other using the selected frequency. Based on the transmission timing selection step of selecting a transmission timing different from the transmission timing of the base station device as the transmission timing of the base station device, and the frequency and transmission timing selected by the transmission timing selection step, A setting step for setting the frequency used for the transmission and the transmission timing of the own device.

  One aspect of the present invention collects, for each base station device, base station information including the frequency used by the other base station device and the transmission timing of the other base station device from another base station device. The base station device obtains the base station information, and based on the base station information, selects a frequency to be used by the base station device, and the other that uses the selected frequency. A transmission timing selection unit that selects a transmission timing different from the transmission timing of the base station device as the transmission timing of the base station device, and the base station device based on the frequency and transmission timing selected by the transmission timing selection unit A base station information management device comprising: a notification unit that notifies a frequency to be used and a transmission timing each time.

  One aspect of the present invention collects, for each base station device, base station information including the frequency used by the other base station device and the transmission timing of the other base station device from another base station device. Obtaining the base station information from the base station apparatus, and selecting a frequency to be used by the base station apparatus based on the base station information, and the other using the selected frequency Based on the transmission timing selection step for selecting the transmission timing different from the transmission timing of the base station device as the transmission timing of the base station device, and the frequency and transmission timing selected by the transmission timing selection step, the base station device And a notification step of notifying the frequency and transmission timing used every time.

  According to the present invention, it is possible to improve the efficiency of radio communication while suppressing the influence of radio wave interference between base station apparatuses even when the transmission time of the base station apparatus is limited.

It is a figure which shows the system configuration | structure of the radio | wireless communications system in this embodiment. 3 is a schematic block diagram illustrating functional configurations of a base station information management device 10 and a base station device 20. FIG. It is a figure which shows the specific example of a management information database. It is a figure showing the example of a setting of transmission timing. It is a sequence diagram which shows the specific example of the operation | movement of the process in this embodiment. It is a figure showing the example of a setting of the transmission timing at the time of making reception power into a reference | standard. It is a sequence diagram which shows the specific example of the operation | movement of the process in a modification. It is a figure showing the example of a setting of the conventional transmission timing.

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 in the present embodiment. The wireless communication system of the present embodiment includes a base station information management device 10, one or a plurality of base station devices 20-1 to 20-5, and a network 30. An interference source 40 exists in the vicinity of the wireless communication system. In FIG. 1, the number of interference sources 40 existing in the vicinity of the wireless communication system is one, but a plurality of interference sources 40 may be provided.
Moreover, the range which a radio wave reaches from each base station apparatus 20-1 to 20-5 is represented as cells 21-1 to 21-5, respectively. Further, a range where radio waves reach from the interference source 40 is represented as a cell 41-1. In the following description, the base station devices 20-1 to 20-5 are referred to as the base station device 20 unless otherwise distinguished. In FIG. 1, the number of base station apparatuses 20 is five, but the number of base station apparatuses 20 may be six or more, and the number of base station apparatuses 20 is four or less. Also good.

The base station information management device 10 is configured using an information processing device, and is connected to the base station device 20 via the network 30 so as to be communicable. The base station information management device 10 controls the operation of the base station device 20.
The base station apparatus 20 communicates with a terminal apparatus (not shown) connected to the base station apparatus 20. The base station device 20 communicates with a terminal device (not shown) according to control by the base station information management device 10.

The network 30 may be a network configured in any way. For example, the network 30 may be configured using the Internet.
The interference source 40 is a device that outputs a signal that interferes with a radio signal transmitted and received between the base station device 20 and a terminal device (not shown). The interference source 40 is not controlled by the base station information management apparatus 10.

  FIG. 2 is a schematic block diagram illustrating functional configurations of the base station information management device 10 and the base station device 20. First, the functional configuration of the base station information management apparatus 10 will be described. The base station information management device 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 executing the control program, the base station information management device 10 functions as a device including the communication unit 101, the base station information storage unit 102, the management information storage unit 103, the use frequency selection unit 104, and the transmission timing selection unit 105. Note that all or a part of each function of the base station information management apparatus 10 is realized by using hardware such as an application specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable gate array (FPGA). Also good. 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 the computer system. Further, the control program may be transmitted / received via a telecommunication line.

  The communication unit 101 communicates with the base station device 20. The communication unit 101 also receives base station information and other system information transmitted from the base station apparatus 20. The base station information represents information related to other base station devices 20 existing around the own device (base station device 20) collected by the base station device 20. The base station information includes, for example, a base station ID, a use frequency, reception power, transmission timing, and the like. Further, the information on the other system represents, for example, information on the interference source 40 that cannot be controlled by the base station information management apparatus 10. The information of the other system includes, for example, received power and a frequency used by the interference source 40. Base station ID represents the identification number for identifying the base station apparatus 20 which the base station information management apparatus 10 controls. The used frequency represents a frequency used by the base station apparatus 20. The received power represents the power of the received signal when the base station apparatus 20 receives a beacon transmitted from another base station apparatus 20. The transmission timing represents a timing at which the base station apparatus 20 starts transmission of a downlink signal such as a beacon. In addition, the communication unit 101 transmits the frequency channel used by the base station apparatus 20 and the transmission timing of the base station apparatus 20 to the base station apparatus 20.

The base station information storage unit 102 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The base station information storage unit 102 stores base station information received by the communication unit 101.
The management information storage unit 103 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The management information storage unit 103 stores a management information database. Information regarding the base station apparatus 20 is stored in the management information database. The management information database stores, for example, each value of use frequency, transmission power, transmission timing, and peripheral base station apparatus information for each base station ID of the base station apparatus 20.

  Based on the base station information stored in the base station information storage unit 102, the use frequency selection unit 104 is a frequency channel (hereinafter referred to as “use frequency”) used by the base station apparatus 20 that has transmitted the base station information. Select. Hereinafter, a specific example of processing of the use frequency selection unit 104 will be described. First, the use frequency selection unit 104 refers to the base station information and the information of other systems, and generates a base station map based on the frequencies and received powers of the other base station devices 20 and the interference sources 40. The base station map is the distance between the base station device 20 based on the received power and the frequency map used by the other base station devices 20 and the interference sources 40 around the base station device 20. It is a distance map to represent. The frequency map includes the number of base station devices that use the frequency for each frequency and information on whether or not other systems are used.

  Next, the use frequency selection unit 104 refers to the frequency map to determine whether there is a frequency used by another system among frequencies that can be used by the base station apparatus 20 (hereinafter referred to as “selection candidates”). Determine whether or not. When there is a frequency used by another system, the used frequency selection unit 104 excludes the frequency used by the other system from the selection candidates. Thereafter, the use frequency selection unit 104 selects a frequency with the smallest number of other base station apparatuses 20 using the frequency as a frequency to be used by the base station apparatus 20 from the selection candidates.

  On the other hand, when there is no frequency used by another system, the use frequency selection unit 104 uses the frequency with the smallest number of other base station devices 20 being used from among the selection candidates. Select the frequency to be used.

In addition, when there are a plurality of frequencies with the smallest number of other base station devices 20 being used among the selection candidates, the use frequency selection unit 104 determines the distance between the base station device 20 and the other base station devices 20. You may select the frequency which the base station apparatus 20 utilizes based on a map. Further, a more accurate distance map may be created using the value of transmission power in the management information database. Specifically, first, the use frequency selection unit 104 acquires the value of transmission power from the management information database for each base station ID stored in the base station information storage unit 102. Next, based on the difference between the acquired transmission power value for each base station ID and the received power value for each base station ID, the use frequency selection unit 104 determines whether the other base station apparatus 20 and the base station apparatus 20 The distance is calculated. And the utilization frequency selection part 104 selects the frequency which the base station apparatus 20 utilizes based on the calculated distance. For example, the use frequency selection unit 104 selects a frequency used by another base station device 20 that is the farthest from the base station device 20 as a frequency used by the base station device 20.
Above, description of the process of the utilization frequency selection part 104 is complete | finished.

  The transmission timing selection unit 105 selects the transmission timing of the base station apparatus 20 based on the frequency selected by the use frequency selection unit 104. Hereinafter, a specific example of processing of the transmission timing selection unit 105 will be described. First, the transmission timing selection unit 105 acquires from the base station information storage unit 102 the transmission timing value of another base station device 20 that uses the selected frequency (hereinafter referred to as “use base station device”). The number of used base station apparatuses is calculated from the acquired transmission timing value. Next, the transmission timing selection unit 105 calculates the number of base station apparatuses that can transmit within the transmission cycle, using the transmission time limit value defined in the ARIB (registered trademark) standard. Thereafter, the transmission timing selection unit 105 compares the number of used base station devices with the number of base station devices that can transmit within the transmission cycle (hereinafter referred to as “the number of transmittable base stations”).

When the number of base station apparatuses to be used is smaller than the number of base stations that can be transmitted, the transmission timing selection unit 105 sets the transmission timing that is not used among the transmission timings of the frequencies selected by the use frequency selection unit 104 to the base station apparatus. 20 transmission timings are selected.
On the other hand, when the number of use base station devices is larger than the number of transmittable base stations, the use frequency selection unit 104 uses the use base station device with the smallest received power among the use base station devices that have already been assigned transmission timing. Select. Thereafter, the use frequency selection unit 104 selects the same transmission timing as the transmission timing of the other selected base station apparatus 20 as the transmission timing of the base station apparatus 20.

Thereafter, the transmission timing selection unit 105 outputs each value of the use frequency and the transmission timing to the communication unit 101. Further, the transmission timing selection unit 105 records each value of the use frequency and the transmission timing in the management information database in association with the base station ID.
Above, description of the process of the transmission timing selection part 105 is complete | finished.

  Next, the functional configuration of the base station apparatus 20 will be described. The base station device 20 includes a CPU, a memory, an auxiliary storage device, and the like connected by a bus, and executes a base station program. By executing the base station program, the base station device 20 functions as a device including a communication unit 201, a base station information acquisition unit 202, a transmission timing calculation unit 203, a clock unit 204, a setting unit 205, and a wireless communication unit 206. Note that all or part of the functions of the base station device 20 may be realized using hardware such as an ASIC, PLD, or FPGA. Further, the 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 the computer system. The base station program may be transmitted / received via a telecommunication line.

The communication unit 201 communicates with the base station information management apparatus 10. In addition, the communication unit 201 transmits base station information and information on other systems to the base station information management apparatus 10. Further, the communication unit 201 receives the frequency channel and transmission timing transmitted from the base station information management apparatus 10.
The radio communication unit 206 receives beacons periodically transmitted from other base station apparatuses 20 for all frequency channels set in advance in the base station apparatus 20 as selection candidates. The wireless communication unit 206 outputs the received beacon signal and the received frequency channel information to the base station information acquisition unit 202.
The base station information acquisition unit 202 acquires the base station ID stored in the received beacon using the frequency channel information received from the beacon as the use frequency of the other base station apparatus 20 that is the transmission source of the beacon. . Moreover, the base station information acquisition unit 202 acquires the value of the received power of the transmitted beacon. In addition, the base station information acquisition unit 202 may use frequency information stored in the received beacon as a use frequency of another base station apparatus 20.

  When the predetermined timing arrives, the transmission timing calculation unit 203 calculates the transmission timing for each base station device 20 based on the base station ID acquired by the base station information acquisition unit 202. For example, when a predetermined timing arrives, the transmission timing calculation unit 203 calculates a reception interval of beacons received within a predetermined period for each base station ID. Thereafter, the transmission timing calculation unit 203 calculates the reception interval calculated for each base station ID as the transmission timing. A difference from the reference timing transmitted from the clock unit 204 may be used as the transmission timing. The predetermined timing may be, for example, a timing at which a predetermined period (for example, 10 seconds, 1 minute, 1 hour) has elapsed, a timing at which an instruction is given from the user, or other It may be timing. The transmission timing calculation unit 203 outputs the calculated transmission timing to the communication unit 201 in association with the base station ID.

The clock unit 204 outputs a reference timing. The reference timing may be set by receiving a GPS signal. The reference timing may be set by the user.
The setting unit 205 sets the frequency received by the communication unit 201 to a frequency used by the own device (base station device 20). The setting unit 205 refers to the reference timing output from the clock unit 204 and sets the transmission timing received by the communication unit 201.

  FIG. 3 is a diagram illustrating a specific example of the management information database. The management information database includes a plurality of records 50 representing information related to the base station device 20. The record 50 has each value of base station ID, use frequency, transmission power, transmission timing, and neighboring base station apparatus information. The value of the base station ID represents an identification number that identifies the base station device 20 represented by the record 50. The value of the use frequency represents the frequency selected for each base station device 20 represented by the record 50. In the specific example of FIG. 3, “MHz (megahertz)” is set as the unit of the use frequency.

  The value of the transmission power represents the power allocated by the base station information management apparatus for each base station apparatus 20 represented by the record 50. In the specific example of FIG. 3, “mW (milliwatt)” is set as a unit of transmission power. The value of the transmission timing represents the transmission timing selected for each base station apparatus 20 represented by the record 50. The value of the transmission timing represents the transmission timing selected for each base station apparatus 20 represented by the record 50. The value of the neighboring base station apparatus information represents information of another base station apparatus 20 from which the base station apparatus 20 represented by the record 50 has collected the base station apparatus information. Specific examples of the peripheral base station apparatus information include base station IDs and received power of other base station apparatuses 20.

  In the example shown in FIG. 3, there are four base station IDs in the management information database. These four base station IDs are “AAAA”, “BBBB”, “CCCC”, and “DDDD”. In FIG. 3, the top row of the management information database shows that the base station ID value is “AAAA”, the use frequency value is “f1”, the transmission power value is “250”, and the transmission timing value is “0”. The base station ID values of the other base station apparatuses 20 are “BBBB”, “CCCC”, “DDDD”, and the received power values are “−80”, “−90”, and “−110”. That is, the base station device 20 identified by the base station ID “AAAA” uses the frequency “f1”, the transmission power “250 mW”, and transmits the downlink signal from the transmission cycle “0”. The base station IDs of the other base station devices 20 from which the base station device 20 identified by the base station ID “AAAA” has collected base station information are “BBBB”, “CCCC”, “DDDD”, It is shown that the received power for each of the other base station apparatuses 20 corresponding to the base station ID of the other base station apparatus 20 is “−80”, “−90”, and “−110”.

  In FIG. 3, the second row of the management information database has a base station ID value of “BBBB”, a use frequency value of “f1”, a transmission power value of “250”, and a transmission timing value of “50,000”, the base station ID values of the other base station apparatuses 20 are “CCCC” and “DDDD”, and the received power values are “−80” and “−100”. That is, the base station device 20 identified by the base station ID “BBBB” uses the frequency “f1”, the transmission power “250 mW”, and the transmission timing from the transmission cycle “50,000”. The base station IDs of the other base station devices 20 from which the base station device 20 identified by the base station ID “BBBB” has collected base station information are “CCCC” and “DDDD” The received power for each of the other base station apparatuses 20 corresponding to the base station ID of the base station apparatus 20 is “−80” and “−100”.

FIG. 4 is a diagram illustrating a setting example of transmission timing. In the example shown in FIG. 4, the base station devices 20-1 to 20-4 use the same frequency (f1 in FIG. 4), and the base station device 20-5 uses the frequency f2. The horizontal axis t represents time. The time interval from “t0” to “t3” is the transmission cycle T, which represents one cycle. Signals are transmitted and received between the base station apparatus and the wireless terminal at this transmission cycle T.
FIG. 4 shows an example in which the number of transmittable base stations is “3”. Since the number of base stations that can be transmitted is “3”, the transmission timing selection unit 105 assigns the transmission cycle T to the three base station devices 20-1 to 20-3 at different transmission timings. In the example shown in FIG. 4, the time interval from “t0” to “t1” is the usage range of the base station apparatus 1, and the time interval from “t1” to “t2” is the usage range of the base station apparatus 20-2. , “T2” to “t3” are allocated to the use range of the base station apparatus 20-3.

Furthermore, the same transmission timing as that of the already assigned base station device is assigned to the fourth and subsequent base station devices assigned to the frequency f1. For example, like the base station apparatus 20-4, the base station apparatus that is assigned fourth to the frequency f1 is set to the same transmission timing as the base station apparatus 20-1. The transmission timing setting parameters are the transmission start timing and the transmittable range of the base station apparatus. The base station apparatus 20 sets the timing for starting transmission of the downlink signal from the beginning of the time interval allocated to the own apparatus. With this configuration, it is possible to reduce the possibility of congestion or interference occurring between base station apparatuses to which the same transmission timing is assigned.
The transmittable range is a range in which the base station apparatus can preferentially acquire uplink user data from the terminal apparatus. Further, when it is necessary for the terminal device to transmit uplink data beyond the transmittable range, the uplink user data may be transmitted to the uplink region of the transmittable range of another base station device.

FIG. 5 is a sequence diagram showing a specific example of the processing operation in the present embodiment. Note that transmission of signals from the base station apparatus 20 to the base station information management apparatus 10 and transmission of signals from the base station information management apparatus 10 to the base station apparatus 20 are indicated by broken lines.
The radio communication unit 206 of the base station device 20 receives a beacon periodically transmitted from another base station device 20 (step S101). The base station information acquisition unit 202 determines whether or not the base station ID has been acquired from the received beacon (step S102).

  When the base station ID can be acquired (step S102-YES), the base station information acquisition unit 202 acquires each value of the base station ID, the used frequency, and the received power of the other base station device 20 that transmitted the beacon (step S102). S103-1). On the other hand, when the base station ID cannot be acquired in the process of step S102 (step S102-NO), the base station information acquisition unit 202 receives each of the received power and the frequency used by the other system from the beacon transmitted from the other system. A value is acquired (step S103-2).

  The transmission timing calculation unit 203 determines whether or not a predetermined timing has elapsed (step S104). When the predetermined timing has passed (step S104—YES), the transmission timing calculation unit 203 calculates the transmission timing for each base station ID (step S105). For example, the transmission timing calculation unit 203 calculates the transmission timing for each base station ID based on the reception interval of beacons received within a predetermined period. On the other hand, when the predetermined timing has not elapsed in the process of step S104 (step S104-NO), the processes after step S101 are repeatedly executed.

  Thereafter, the communication unit 201 of the base station device 20 transmits the base station information and information of other systems to the base station information management device 10 (step S106). The communication unit 101 of the base station information management device 10 receives the base station information and information on other systems transmitted from the base station device 20 (step S107). The communication unit 101 records the received base station information in the base station information storage unit 102. In addition, the communication unit 101 transfers the received other system information to the use frequency selection unit 104. Thereafter, the use frequency selection unit 104 generates a base station map based on the use frequency and reception power of the other base station device 20 and the use frequency of other systems stored in the base station information storage unit 102 (step S108). ).

The use frequency selection unit 104 refers to the base station map and determines whether or not there is a frequency used by another system around the base station device 20 (step S109). When there is a frequency used by another system (step S109-YES), the used frequency selection unit 104 excludes the frequency used by the other system from the selection candidates (step S110).
When there is no frequency used by another system (step S109-NO), or after the process of step S110, the use frequency selection unit 104 uses the least number of other base station apparatuses 20 among the selection candidates. A frequency is selected as a use frequency of the base station apparatus 20 (step S111).

  The transmission timing selection unit 105 acquires, from the base station information storage unit 102, the value of the transmission timing of another base station apparatus 20 that uses the selected frequency. The transmission timing selection unit 105 calculates the number of base station apparatuses to be used from the acquired transmission timing information, and calculates the number of base stations that can be transmitted from the transmission time determined by the ARIB (registered trademark) standard (step S112). ).

  Thereafter, the transmission timing selection unit 105 determines whether or not the number of used base station devices is less than the number of base stations that can be transmitted (step S113). When the number of use base station apparatuses is less than the number of transmittable base stations (step S113—YES), the transmission timing selection unit 105 sets unused transmission timings that are not used in the transmission timing in the transmission cycle of the selected frequency. It selects as transmission timing of the base station apparatus 20 (step S114).

  On the other hand, in the process of step S113, when the number of base stations used is equal to or greater than the number of base stations that can be transmitted (NO in step S113), the transmission timing selector 105 uses the lowest received power among the base stations used. Select a base station device. The transmission timing selection unit 105 selects the same transmission timing as the transmission timing of the selected use base station apparatus as the transmission timing of the base station apparatus 20 (step S118).

  The communication unit 101 transmits each value of the selected frequency and transmission timing to the base station apparatus 20 (step S115). The communication unit 201 of the base station apparatus 20 receives each value of the frequency and transmission timing transmitted from the base station information management apparatus 10 (step S116). The setting unit 205 sets the received frequency to a frequency used by the own device. The setting unit 205 sets the received transmission timing based on the reference timing output from the clock unit 204 (step S117). Thereafter, the process of FIG. 5 ends.

  According to the wireless communication system configured as described above, the frequency and transmission timing used by the base station device 20 based on the base station information collected from other base station devices 20 existing around the base station device 20 are the same. Selected. Therefore, the base station information management device 10 reduces the influence of radio wave interference between the base station devices by selecting the frequency with the least number of other base station devices 20 used as the frequency used by the base station device 20. can do. Further, the base station information management apparatus 10 uses a single frequency shared by a plurality of base station apparatuses 20 by setting different transmission timings for a plurality of base station apparatuses 20 that use the same frequency. . As a result, even when one frequency is used by a plurality of base station apparatuses 20, there is no possibility that the communication efficiency of the wireless communication is reduced. Therefore, even when the transmission time of the base station device is limited, it is possible to improve the efficiency of wireless communication while suppressing the influence of radio wave interference between the base station devices.

<Modification>
The processes in steps S108 to S111 described above may be performed by a device other than the base station information management apparatus 10. For example, the base station apparatus 20 generates a base station map centered on the base station apparatus based on beacons received from the other base station apparatuses 20 and the interference sources 40, and refers to the generated base station map. The frequency to be used may be selected. In this case, the base station apparatus 20 transmits various information including the selected frequency, the collected base station information, and other system information to the base station information management apparatus 10. Thereafter, the base station information management device 10 selects the transmission timing of the base station device 20 based on the received various information.
One base station device 20 among the plurality of base station devices 20 may be configured to function as the base station information management device 10.

The transmission timing setting method need not be limited to the method described above. For example, the transmission timing of the base station apparatus 20 may be set based on the received power of the other base station apparatus 20.
In this case, first, the transmission timing selection unit 105 acquires the value of the received power of the other base station apparatus 20 that uses the frequency selected by the use frequency selection unit 104 from the base station information storage unit 102. Next, the transmission timing selection unit 105 determines whether there is another base station apparatus 20 whose reception power value is equal to or greater than a threshold value. Then, when there is another base station apparatus 20 whose received power value is equal to or greater than the threshold, the transmission timing selection unit 105 selects a transmission timing different from that of the other base station apparatus 20 as the transmission timing of the base station apparatus 20.
On the other hand, when there is no other base station apparatus 20 whose reception power value is equal to or greater than the threshold, the transmission timing selection unit 105 selects the same transmission timing as the other base station apparatus 20 as the transmission timing of the base station apparatus 20.

  FIG. 6 is a diagram illustrating a setting example of transmission timing when reception power is used as a reference. In the example shown in FIG. 6, the base station apparatuses 20-1 to 20-4 use the same frequency (f1 in FIG. 6). Further, the base station device 20-5 uses the frequency f2. The setting example of the transmission timing shown in FIG. 6 is set when there is no other base station apparatus whose reception power is equal to or greater than the threshold. In this case, even if the base station apparatuses 20-1 to 20-4 have the same frequency, it is assumed that the distance between the base station apparatuses is far from each other. Therefore, even when the base station devices 20-1 to 20-4 transmit downlink signals at the same timing, it is possible to reduce a decrease in communication efficiency due to radio wave interference between the base station devices.

FIG. 7 is a sequence diagram showing a specific example of the processing operation in the modification. Note that transmission of signals from the base station apparatus 20 to the base station information management apparatus 10 and transmission of signals from the base station information management apparatus 10 to the base station apparatus 20 are indicated by broken lines. Also, the same processing as in FIG. 5 will be described with the same reference numerals as in FIG.
When the process of step S111 in FIG. 5 is completed, the transmission timing selection unit 105 includes another base station apparatus 20 whose reception power is greater than or equal to the threshold among the other base station apparatuses 20 using the selected frequency. Whether or not (step S201).

When there is another base station apparatus 20 whose reception power is equal to or greater than the threshold (step S201—YES), the transmission timing selection unit 105 selects a transmission timing different from the use base station apparatus as the transmission timing of the base station apparatus 20 (step S201). S202). Thereafter, the processing after step S115 is performed.
On the other hand, in the process of step S201, when there is no other base station apparatus 20 whose reception power is equal to or higher than the threshold (step S201-NO), the same transmission timing as the other base station apparatus 20 is used as the transmission timing of the base station apparatus 20. Select (step S203). Thereafter, the processing after step S115 is performed.

  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 designs and the like that do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Base station information management apparatus, 20 (20-1-20-5) ... Base station apparatus, 30 ... Network, 40 ... Interference source, 101 ... Communication part, 102 ... Base station information storage part, 103 ... Management information storage , 104 ... Utilization frequency selection part, 105 ... Transmission timing selection part, 201 ... Communication part, 202 ... Base station information acquisition part (acquisition part), 203 ... Transmission timing calculation part, 204 ... Clock part, 205 ... Setting part, 206: Wireless communication unit

Claims (7)

For each base station device, from another base station device, an acquisition unit that collects base station information including the frequency used by the other base station device and the transmission timing of the other base station device;
Based on the base station information transmitted from the base station device, a use frequency selection unit that selects a frequency used by the base station device;
A transmission timing selection unit that selects a transmission timing different from the transmission timing of the other base station device using the selected frequency as the transmission timing of the base station device;
Based on the frequency and transmission timing selected by the transmission timing selection unit, a setting unit for setting the frequency used for each base station device and the transmission timing of the own device,
A wireless communication system comprising:   The said use frequency selection part selects the frequency with the fewest number of said other base station apparatuses from the frequency which the said base station apparatus can use as the frequency which the said base station apparatus uses. Wireless communication system.   The transmission timing selection unit acquires the transmission timing of the other base station device that uses the selected frequency, calculates the number of base station devices to be used from the acquired transmission timing, and is set in advance. When the number of base station apparatuses that can transmit within the transmission period is calculated from the transmission time, and the number of the other base station apparatuses that use the selected frequency is less than the number of base station apparatuses that can transmit The base station apparatus selects a transmission timing different from the transmission timing of the other base station apparatus as the transmission timing of the base station apparatus, and the number of the other base station apparatuses using the selected frequency is the base that can be transmitted. If the number of station devices is equal to or greater than the number of station devices, the transmission timing of the base station device is set to the same transmission timing as the transmission timing of the other base station device having the smallest received power among the other base station devices. The wireless communication system according to claim 1 or 2 to select the grayed. The acquisition unit further acquires the received power of a signal transmitted from the other base station device as the base station information,
The transmission timing selection unit, when there is the other base station apparatus having a value of the received power equal to or higher than a threshold value among the other base station apparatuses using the selected frequency, When a transmission timing different from that of the other base station apparatus is selected as the transmission timing of the own apparatus, and there is no other base station apparatus whose received power value is equal to or greater than a threshold value, the same as the other base station apparatus The wireless communication system according to claim 1, wherein the transmission timing is selected as the transmission timing of the own device. For each base station device, from another base station device, an acquisition step of collecting base station information including the frequency used by the other base station device and the transmission timing of the other base station device;
Based on the base station information transmitted from the base station device, a use frequency selection step for selecting a frequency used by the base station device;
A transmission timing selection step of selecting, as the transmission timing of the base station device, a transmission timing different from the transmission timing of the other base station device using the selected frequency;
Based on the frequency and transmission timing selected in the transmission timing selection step, a setting step for setting the frequency used for each base station apparatus and the transmission timing of the own apparatus,
A wireless communication method. For each base station apparatus, from the base station apparatus that collects base station information including the frequency used by the other base station apparatus and the transmission timing of the other base station apparatus from the other base station apparatus, Station information is acquired, and based on the base station information, a use frequency selection unit that selects a frequency used by the base station device;
A transmission timing selection unit that selects a transmission timing different from the transmission timing of the other base station device using the selected frequency as the transmission timing of the base station device;
Based on the frequency and transmission timing selected by the transmission timing selection unit, a notification unit for notifying the frequency and transmission timing used for each base station device,
A base station information management device comprising: For each base station apparatus, from the base station apparatus that collects base station information including the frequency used by the other base station apparatus and the transmission timing of the other base station apparatus from the other base station apparatus, A station frequency is obtained by acquiring station information and, based on the base station information, selecting a frequency to be used by the base station device;
A transmission timing selection step of selecting, as the transmission timing of the base station device, a transmission timing different from the transmission timing of the other base station device using the selected frequency;
Based on the frequency and transmission timing selected in the transmission timing selection step, a notification step for notifying the frequency and transmission timing used for each base station device;
A base station information management method comprising:

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