JP2015088994A - Communication system and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce interference in communication.SOLUTION: A communication system comprises: a plurality of radio base station devices which intercommunicate with the neighboring radio base station devices by different frequency bands; and a central control station device which is connected by wire with the radio base station devices and controls radio communication with the radio base station devices. A first radio base station device comprises a radio communication unit which receives a signal transmitted by using a frequency band at which a neighboring second radio base station device communicates. The central control station device comprises: a transmission determination unit which determines whether the signal received by the radio communication unit of the first radio base station device is transmitted by the second radio base station device; and an adjustment unit which controls radio communication by the second radio base station device on the basis of a determination result by the transmission determination unit.

Description

  The present invention relates to a communication system and a communication method.

  In recent years, wireless base station apparatuses (access points, APs) for wireless LANs are densely installed in response to demand for traffic offload and large-capacity communication. However, dense installation of APs facilitates interference between communication areas (cells) of APs, and lowers AP throughput. In order to reduce such inter-cell interference, for example, a centralized control station apparatus that collectively controls a plurality of APs is arranged, and the apparatus dynamically allocates a frequency band (channel) used by each AP. A method has been proposed (for example, Non-Patent Document 1).

P. Mahonen, J. Riihijarvi, and M. Petrova, “Automatic channel allocation for small wireless local area networks using graph coloring algorithm approach”, in 15th IEEE PIMRC, vol. 1, Sep. 2004, pp.536-539.

  However, the conventional technology cannot always reduce interference. For example, there are cases where it is not possible to cope with an unexpected interference wave transmitted from other than the AP configuring the wireless LAN system.

  The present invention has been made in view of the above points, and provides a communication system and a communication method capable of reducing interference.

  The present invention has been made to solve the above problems, and one aspect of the present invention is a wireless base station device in which a plurality of adjacent wireless base station devices communicate in different frequency bands, and a wireless base station device. And a centralized control station device that controls the wireless communication of the wireless base station device, wherein the first wireless base station device communicates with the adjacent second wireless base station device. A centralized control station device that receives a signal transmitted by a wireless communication unit of a first wireless base station device, and that receives a signal transmitted using a frequency band that is transmitted to a second wireless base station. A transmission determination unit that determines whether or not the signal is transmitted by the device; and an adjustment unit that controls radio communication by the second radio base station device based on a determination result of the transmission determination unit. It is a communication system.

  Further, according to one aspect of the present invention, in the communication system described above, the first radio base station apparatus determines the reception time of the signal when the power of the signal received by the radio communication unit exceeds a predetermined threshold. A transmission determining unit of the centralized control station device, wherein the transmission determination unit of the centralized control station device is configured to receive the first radio base station based on the reception time and the transmission time of the signal transmitted from the second radio base station device. It is characterized in that it is determined whether or not the signal received by the radio communication unit of the device is a signal transmitted by the second radio base station device.

  One embodiment of the present invention is characterized in that, in the communication system described above, the adjustment unit of the centralized control station device controls wireless communication by the second wireless base station device by changing a frequency band or transmission power. And

  One embodiment of the present invention is characterized in that, in the communication system, the transmission determination unit of the centralized control station apparatus aggregates and determines determination results for a plurality of received signals by logical operation. .

  One embodiment of the present invention is the communication system, wherein the communication system includes a terminal station device that performs wireless communication with the radio base station device, and the terminal station device connected to the first radio base station device includes: 2, a terminal-side communication unit that receives a signal in a frequency band with which the radio base station device communicates, and the transmission determination unit of the centralized control station device receives the second signal received by the terminal-side communication unit of the terminal station device. It is characterized by determining whether it is the signal transmitted by the wireless base station apparatus.

  One embodiment of the present invention is characterized in that, in the communication system described above, the adjustment unit of the centralized control station apparatus controls the wireless communication by causing the second wireless base station apparatus to perform null steering. To do.

  Further, according to one aspect of the present invention, in the communication system described above, the central control station device is based on an estimation unit that estimates a position and power of a transmission source of a received signal, and a position and power estimated by the estimation unit. An interference determination unit that determines whether or not the degree of interference due to the signal is significant, and the adjustment unit of the centralized control station apparatus uses the second radio base station apparatus based on the determination result of the interference determination unit It controls the wireless communication by.

  In addition, according to one embodiment of the present invention, a plurality of adjacent radio base station devices communicate with each other in different frequency bands, and are connected to the radio base station device with a wire to control radio communication of the radio base station device. And a centralized control station apparatus that communicates a signal transmitted by a first radio base station apparatus using a frequency band communicated by an adjacent second radio base station apparatus. A radio communication process to be received, a transmission determination process in which the central control station apparatus determines whether a signal received by the first radio base station apparatus is a signal transmitted by the second radio base station apparatus, The control station apparatus includes an adjustment process for controlling wireless communication by the second radio base station apparatus based on a determination result in the transmission determination process.

  According to the present invention, interference can be reduced.

It is a conceptual diagram which shows an example of the communication system which concerns on this embodiment. It is a figure which shows an example of a function structure of the radio base station apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of a function structure of the centralized control station apparatus which concerns on this embodiment. It is a figure which shows an example of the process by the wireless base station apparatus which concerns on this embodiment. It is a figure which shows an example of the process by the centralized control station apparatus which concerns on this embodiment. It is a conceptual diagram which shows an example of the communication system which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of a function structure of the centralized control station apparatus which concerns on this embodiment. It is a figure which shows an example of a function structure of the terminal station apparatus which concerns on this embodiment. It is a figure which shows an example of the process by the terminal station apparatus which concerns on the 3rd Embodiment of this invention. It is a conceptual diagram which shows an example of the communication system which concerns on a prior art.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram illustrating an example of a communication system 1 according to the present embodiment. The communication system 1 according to the present embodiment includes five radio base station apparatuses 10-1 to 10-5, five terminal station apparatuses 20-1 to 20-5, a core network 30, and a central control station apparatus. 40 and a server device 50.

  Each of the five APs 10-1 to 10-5 can perform wireless communication with a plurality of terminal station devices 20 located in the cell. The AP 10-1 communicates with the terminal station device 20-1. The AP 10-2 communicates with the terminal station devices 20-2 and 20-3. The AP 10-4 communicates with the terminal station device 20-4. The AP 10-5 communicates with the terminal station device 20-5. The channels used by the APs 10-1 to 10-5 for communication with the terminal station device 20 are different. In this example, APs 10-1 to 10-5 perform communication using channels CH0 to CH4, respectively. Channel information is notified from each of the APs 10-1 to 10-5 to each of the terminal station apparatuses 20-1 to 20-5 by a beacon signal. The terminal station apparatuses 20-1 to 20-5 select a channel based on the received beacon signal and establish communication with the APs 10-1 to 10-5.

  The cells 60-1 to 60-5 of the APs 10-1 to 10-5 are set so as not to overlap each other. For example, in the example of FIG. 1, the AP 10-1 cell includes AP 10-2, AP 10-3, AP 10-4, and AP 10-5 cells included in the range indicated by reference numeral 70. In these adjacent cells of AP 10-1, a signal transmitted from AP 10-1 is detected only with power less than a predetermined threshold. In addition, in the AP 10-1 cell, radio waves transmitted from adjacent AP 10-2, AP 10-3, AP 10-4, and AP 10-5 are detected only with power less than a predetermined threshold. Similarly, for the APs other than the AP 10-1, signals transmitted from the respective APs are detected only with power equal to or lower than the threshold in the cell of the adjacent AP. Hereinafter, each of the cells set such that the radio wave use boundaries do not intersect between APs may be referred to as a radio wave closed space.

  Each of the five APs 10-1 to 10-5 is connected to the centralized control station device 40 via the core network 30. The core network 30 is formed of an optical fiber and can perform high-speed and large-capacity communication. The centralized control station device 40 collectively controls communication of each of the five APs 10-1 to 10-5. For example, each of the APs 10-1 to 10-5 communicates with the terminal station devices 20-1 to 20-5, and each of the APs 10-1 to 10-5 performs A / D conversion and D / A conversion of transmission / reception signals. The central control station apparatus 40 performs arithmetic processing such as modulation, demodulation, encoding, and decoding. The centralized control station apparatus 40 estimates the amount of interference (the amount of interference) that each of the APs 10-1 to 10-5 gives to the other APs 10-1 to 10-5 based on the radio wave power distribution map. The centralized control station apparatus 40 controls the channels used by the APs 10-1 to 10-5, the transmission power at the time of signal transmission, the antenna directivity, and the like. Therefore, the centralized control station device 40 can generate the radio wave closed space as described above by controlling the APs 10-1 to 10-5.

  A server device 50 is connected to the core network 30. The server device 50 includes a database that stores data of signals received by the APs 10-1 to 10-5. In the database, received signal data is stored as a radio wave power distribution map, and long-term radio wave fluctuations can be stored. This radio wave power distribution map is generated and stored based on reception radio wave data, transmission radio wave data, and position information of the APs 10-1 to 10-5 transmitted from the centralized control station device 40 described later. In addition, the database includes, for example, radio wave power distribution based on signal data received by each of the other APs 10-1 to 10-5 when a signal is transmitted from each of the APs 10-1 to 10-5 with a predetermined power. Store test data such as maps. The centralized control station device 40 generates a radio wave closed space based on the radio wave power distribution map stored in the database.

  As long as the communication system 1 operates normally, the radio wave closed space generated in this way does not leak a signal having a power higher than the threshold to the adjacent radio wave closed space. Therefore, in the communication system 1, when a signal of a channel used by a certain AP is detected with power equal to or higher than a threshold in the radio wave closed space of the adjacent AP, it is considered that an abnormality has occurred in the communication system 1. There are two possible causes for the detected abnormality. As a first possibility, it is assumed that the radio waves of adjacent APs that should not have reached originally have arrived due to changes in the propagation environment of radio waves. As a second possibility, as shown in FIG. 1, a device (interference source) 80 other than the communication system constituting the radio wave closed space transmits a signal (interference wave) 90 of a channel used in the radio wave closed space. It is assumed that For example, in a so-called secondary usage radio system that shares a radio frequency used by an existing radio communication system, the components of the secondary use radio system in the existing radio communication system may be an interference source depending on the frequency band to be used. Can be observed as

  The centralized control station device 40 collectively manages signal transmission / reception by each of the APs 10-1 to 10-5, so that the signal received by the AP 10 can be compared with the transmitted signal. The centralized control station device 40 receives the reception time of the signal indicating the abnormality of the communication system 1 detected by the AP 10 and the transmission time of the signal transmitted from the AP 10 that performs communication using the channel that interferes with the signal. A comparison is made to determine whether the signal is leaked from the adjacent AP. Further, in order to improve the detection accuracy, the transmission signal of the communication system 1 may be temporarily held in the central control station, and the correlation with the detected signal may be obtained and determined. When the received signal is leaked from the adjacent AP 10, the centralized control station device 40 controls the signal transmission power and the antenna directivity, and resets the boundary of the radio wave closed space. If the received signal is not leaked from the adjacent AP, the cause of the abnormality of the communication system 1 is considered to be due to the second possibility. Therefore, the centralized control station device 40 changes the channel to be used for the AP 10 that performs communication using the channel that interferes with the interference wave.

  For example, in the radio wave closed space of APs 10-2 to 10-5 adjacent to AP 10-1, when the signal of channel CH0 used by AP 10-1 is received with power equal to or higher than a threshold, centralized control station apparatus 40 It is determined whether this is due to an abnormality in the radio wave closed space of the AP 10-1 or due to the arrival of an interference wave on the channel CH0. When it is determined that the cause of reception is due to an abnormality in the radio wave closed space, the centralized control station device 40 controls the transmission power of the AP 10-1 to reset the radio wave closed space. When it is determined that the cause of reception is due to the arrival of the interference wave 90, the central control station apparatus 40 changes the channel used in the radio wave closed space of the AP 10-1 that is affected by the interference wave 90. Thus, the communication system 1 can detect and reduce interference.

  Next, the configuration of the AP 10 will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a functional configuration of the radio base station apparatus according to the present embodiment. The AP 10 includes a wireless communication unit 100, a wired communication unit 110, a storage unit 120, a wireless communication control unit 130, an abnormality detection unit 140, a wired communication control unit 150, a frequency information update unit 160, and a power information update. Unit 170.

  The wireless communication unit 100 includes an antenna and a switch, and transmits and receives signals. The wireless communication unit 100 transmits a signal input from the wireless communication control unit 130 via an antenna. When receiving the signal, the wireless communication unit 100 outputs the received signal to the wireless communication control unit 130.

  The wired communication unit 110 includes a network interface 111. The network interface 111 is connected to the core network 30 via an optical fiber. The wired communication unit 110 transmits and receives communication signals with the centralized control station device 40 on the core network 30 via the network interface 111.

  The storage unit 120 includes, for example, an HDD (Hard Disc Drive), an SSD (Solid State Drive), an EEPROM (Electrically Erasable Programmable Read Only Memory), and a ROM (Read Only Memory). ) Or RAM (Random Access Memory), etc., and stores various programs (firmware, application programs, etc.) executed by the processor included in the AP 10 and various processing results performed by the processor. The wireless communication control unit 130, the abnormality detection unit 140, the wired communication control unit 150, the frequency information update unit 160, and the power information update unit 170 function, for example, when the processor executes a program stored in the storage unit 120.

  The storage unit 120 includes a threshold information storage unit 121, a frequency information storage unit 122, and a power information storage unit 123. The threshold information storage unit 121 stores threshold information indicating a threshold used for processing performed by the abnormality detection unit 140. The frequency information storage unit 122 is channel information indicating a channel used by the own device for communication with the terminal station device 20 and a channel used by the AP adjacent to the own device for communication with the terminal station device 20. Is stored. The power information storage unit 123 stores power information indicating the power of the signal transmitted by the own device.

  The wireless communication control unit 130 performs level adjustment, frequency conversion, waveform shaping, A / D conversion, and the like on the signal received by the wireless communication unit 100, and outputs the converted data to the wired communication control unit 150. The wireless communication control unit 130 refers to the power information storage unit 123 and acquires transmission power. The wireless communication control unit 130 performs D / A conversion, frequency conversion, band limitation, level adjustment, and the like on the data input from the wired communication control unit 150 based on the acquired transmission power. The radio communication control unit 130 controls the radio communication unit 100 and transmits the converted signal to the terminal station device 20.

  The radio communication control unit 130 monitors the radio communication unit 100 and determines whether or not the communication with the terminal station device 20 is in an idle state. When it is determined that the own apparatus is in the idle state, the wireless communication control unit 130 refers to the frequency information storage unit 122 and acquires channel information. Based on the acquired channel information, the wireless communication control unit 130 performs carrier sense on the channel used by the own device and the channel used by the AP adjacent to the own device. Here, the carrier sense refers to receiving a signal and observing the received power (spectrum) of the signal in a specific channel by FFT (Fast Fourier Transform), band limitation, square detection, or the like. The wireless communication control unit 130 outputs spectrum information indicating the spectrum observed by carrier sense to the abnormality detection unit 140.

  When receiving the notification of channel information update from the frequency information update unit 160, the wireless communication control unit 130 refers to the frequency information storage unit 122 and acquires the channel information of the own device. The wireless communication control unit 130 generates a beacon signal based on the channel information. The wireless communication control unit 130 controls the wireless communication unit 100 and transmits the generated beacon signal to the terminal station device 20.

  When acquiring the spectrum information from the wireless communication control unit 130, the abnormality detection unit 140 refers to the threshold information storage unit 121 and acquires threshold information. The abnormality detection unit 140 determines whether or not there is a channel indicating reception power exceeding the threshold indicated by the threshold information among the reception power of the signals for each channel indicated by the spectrum information. When the radio wave closed space is maintained normally, a signal transmitted from an adjacent AP should not be detected with power exceeding the threshold. Therefore, if there is a channel with reception power exceeding the threshold, the communication system 1 An error has occurred. When a channel indicating reception power exceeding the threshold is detected, the abnormality detection unit 140 outputs a data set including the channel, signal power, and signal waveform data to the wired communication control unit 150.

  The wired communication control unit 150 outputs the data received by the wired communication unit 110 from the centralized control station device 40 to the wireless communication control unit 130. The wired communication control unit 150 controls the wired communication unit 110, and for the data input from the wireless communication control unit 130 and the data set input from the abnormality detection unit 140, the reception time of the signal by the wireless communication unit 100 and A header portion including identification information of the device itself, CRC (Cyclic Redundancy Check), and the like are added to form a frame, which is transmitted to the centralized control station device 40 via the core network 30.

  When the wired communication unit 110 receives the channel information from the centralized control station device 40, the wired communication control unit 150 outputs the channel information to the frequency information update unit 160. When the wired communication unit 110 receives power information from the centralized control station device 40, the wired communication control unit 150 outputs the power information to the power information update unit 170.

The frequency information update unit 160 updates the channel information stored in the frequency information storage unit 122 based on the channel information input from the wired communication control unit 150. The frequency information update unit 160 notifies the wireless communication control unit 130 that the channel information has been updated.
The power information update unit 170 updates the power information stored in the power information storage unit 123 based on the power information input from the wired communication control unit 150.

  Next, the configuration of the centralized control station device 40 will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of a functional configuration of the central control station apparatus according to the present embodiment. The centralized control station device 40 includes a control device side communication unit 400, a storage unit 410, a communication control unit 420, and an analysis unit 430.

  The control device side communication unit 400 includes a network interface 401. The network interface 111 is connected to the core network 30 via an optical fiber. The control device side communication unit 400 transmits and receives signals to and from each of the APs 10-1 to 10-5 on the core network 30 via the network interface 401.

  The storage unit 410 includes, for example, an HDD, SSD, EEPROM, ROM, or RAM, and various programs (firmware, application programs, etc.) executed by the processor included in the central control station device 40 and various processing results performed by the processor. Etc. are stored. The communication control unit 420 and the analysis unit 430 function, for example, when the processor executes a program stored in the storage unit 410.

  The storage unit 410 includes a reception radio wave data storage unit 411, a transmission radio wave data storage unit 412, an aggregate frequency information storage unit 413, an aggregate power information storage unit 414, and an AP position information storage unit 415. The received radio wave data storage unit 411 stores data of signals received by the AP 10 and transmitted from other APs 10 in time series based on the reception time at the AP 10. The received radio wave data stored includes, for example, a channel (reception channel) that indicates power higher than a threshold in the abnormality detection unit 140 of the AP 10, signal power in the channel, AP 10 identification information (reception AP identification information), Waveform data (received waveform data) and reception time.

  The transmission radio wave data storage unit 412 stores the data of the signal transmitted from the central control station device 40 via the AP 10 in time series based on the transmission time from the central control station device 40. The stored transmission radio wave data includes, for example, identification information of the transmission source AP 10 (transmission AP identification information), a use channel (transmission channel) of the AP 10, transmission power of the AP 10, and waveform data of transmission signals (transmission waveform data). Is the transmission time.

The aggregate frequency information storage unit 413 stores information on the channels that the APs 10-1 to 10-5 controlled by the central control station device 40 use for communication with the terminal station device 20 and each of the APs 10-1 to 10-5. The identification information is stored in association with each other.
The aggregated power information storage unit 414 associates the transmission power set for signal transmission by each of the APs 10-1 to 10-5 controlled by the centralized control station device 40 with the identification information of each of the APs 10-1 to 10-5. Store.

  The AP position information storage unit 415 includes identification information of each of the APs 10-1 to 10-5 controlled by the central control station device 40, position information indicating the positions of the APs 10-1 to 10-5, and APs 10-1 to 10-5. The adjacent relationship information indicating each of the APs 10-1 to 10-5 adjacent to each other is stored in association with each other.

The communication control unit 420 includes a modulation unit 421, a demodulation unit 422, and an upper layer 423, and controls communication via the control device side communication unit 400.
The modulation unit 421 performs modulation, frequency conversion, waveform shaping, and the like on the data input from the upper layer 423. The communication control unit 420 controls the control device side communication unit 400, adds a header part, CRC, and the like to the data, frames it, and transmits it to the AP 10.
The demodulation unit 422 demodulates the data received from the AP 10 by the control device side communication unit 400 and outputs the demodulated data to the upper layer 423.

  The upper layer 423 uses the identification information of the transmission source AP 10, the channel used by the AP 10, the transmission power of the AP 10, and the waveform data of the transmission signal as transmission radio wave data for transmission data in a time series based on the transmission time. The data is stored in the data storage unit 412. The upper layer 423 acquires the time when the transmission data is transmitted from the transmission source AP 10 to the terminal station apparatus 20, and stores it as the transmission time. When receiving a data set including a channel, signal power, reception time, identification information of the AP 10 of the reception source, and signal waveform data from the demodulation unit 422, the communication control unit 420 sets the reception data based on the reception time. The received radio wave data storage unit 411 is stored in series.

  The upper layer 423 refers to the reception radio wave data storage unit 411, the transmission radio wave data storage unit 412, and the AP position information storage unit 415 periodically or when data is updated, and receives radio wave data and transmission radio wave data. The position information of AP10 is acquired. The upper layer 423 transmits the acquired reception radio wave data, transmission radio wave data, and position information of the AP 10 to the server device 50 via the control device side communication unit 400.

  The upper layer 423 refers to the aggregated frequency information storage unit 413 to acquire channel information regularly or when receiving a notification that the channel used by the AP 10 has changed from the frequency adjustment unit 441. The upper layer 423 refers to the AP location information storage unit 415 and acquires identification information of APs adjacent to each of the APs 10-1 to 10-5. The upper layer 423 transmits each AP and channel information of an AP adjacent to each AP to each of the APs 10-1 to 10-5 via the control device side communication unit 400.

  When the upper layer 423 receives from the transmission power adjustment unit 442 that the transmission power of the AP 10 has been changed, the upper layer 423 refers to the aggregate power information storage unit 414 and acquires the power information of each of the APs 10-1 to 10-5. . The upper layer 423 transmits power information indicating each transmission power to the APs 10-1 to 10-5 via the control device side communication unit 400.

  The analysis unit 430 includes a transmission determination unit 431 and an adjustment unit 440. The transmission determination unit 431 monitors the transmission radio wave data storage unit 412 and acquires the latest transmission radio wave data when the transmission radio wave data is updated. The transmission determination unit 431 refers to the AP position information storage unit 415 and acquires identification information (adjacent AP identification information) of the AP 10 adjacent to the AP 10 indicated by the transmission AP identification information of the latest transmission radio wave data. The transmission determination unit 431 refers to the received radio wave data storage unit 411, the received AP identification information of the received radio wave data is the adjacent AP identification information acquired from the AP position information storage unit 415, and the reception time is determined from the transmitted radio wave data. It is determined whether there is received radio wave data within a predetermined time from the acquired transmission time. If the received radio wave data exists, the received radio wave data is extracted.

  The transmission determination unit 431 compares the extracted reception waveform data of the received radio wave data with the transmission waveform data of the latest transmission radio wave data. The transmission determining unit 431 performs, for example, frequency analysis such as FFT on the received waveform data, or correlation detection between the received waveform data and the transmitted waveform data. Based on the processing result, the transmission determination unit 431 determines whether or not the transmission signal from the AP indicated by the transmission AP identification information of the transmission radio wave data is included in the received waveform data in the frequency band of the transmission channel. .

  When a plurality of received radio wave data are extracted, the transmission determining unit 431 aggregates the determination results for the received radio wave data by a logical operation. If the received AP identification information is the same in a plurality of received radio wave data, for example, a logical product is calculated from each of the determination results for the received radio data at different reception times, and whether or not a transmission signal is included. Determine whether. Specifically, for example, when three reception radio wave data by the AP 10-2 are extracted by the transmission determination unit 431, two of the reception signals are determined as signals transmitted from the AP 10-1, and the remaining one is an interference wave. Is determined to be an interference wave.

  If the received AP identification information is different in a plurality of received radio wave data, for example, a logical sum is calculated from each of the determination results for the received data, and it is determined whether or not a transmission signal is included. Specifically, for example, when two reception radio wave data by AP 10-2 and AP 10-3 are extracted by transmission determination unit 431, one of the reception signals is determined as a signal transmitted from AP 10-1, and the remaining When it is determined that one is an interference wave, it is determined that the signal is transmitted from the AP 10-1.

  When it is determined that a transmission signal is included, the transmission determination unit 431 determines that the signal received by the AP 10 indicated by the reception AP identification information is a signal received by the AP 10 indicated by the transmission AP identification information. Since this indicates that an abnormality has occurred in the radio wave closed space, the transmission determination unit 431 notifies the transmission power adjustment unit 442 of the occurrence of an abnormality in the radio wave closed space.

  If it is determined that the transmission signal is not included, the transmission determination unit 431 determines that the signal received by the AP 10 indicated by the received AP identification information is an interference wave transmitted by an interference source outside the communication system 1. . The transmission determination unit 431 notifies the frequency adjustment unit 441 that an interference source has occurred, and outputs transmission AP identification information used for the determination.

  The adjustment unit 440 controls wireless communication by the AP 10 based on the determination result of the transmission determination unit 431. A frequency adjustment unit 441 and a transmission power adjustment unit 442 are provided. When receiving the notification of the generation of the interference source from the transmission determination unit 431, the frequency adjustment unit 441 outputs a database reference request of the server device 50 to the communication control unit 420. The frequency adjustment unit 441 selects a channel to be allocated to each AP from channels that do not interfere with the interference wave, based on the radio wave power distribution map acquired in response to the reference request. The frequency adjustment unit 441 associates the selected channel with the identification information of each of the APs 10-1 to 10-5 and stores them in the aggregate frequency information storage unit 413. The frequency adjustment unit 441 notifies the communication control unit 420 that the channel used by the AP 10 has been changed.

When the transmission power adjustment unit 442 receives a notification from the transmission determination unit 431 that an abnormality in the radio wave closed space has occurred, the transmission power adjustment unit 442 outputs a database reference request of the server device 50 to the communication control unit 420. Based on the radio wave power distribution map acquired in response to the reference request, the transmission power adjustment unit 442 calculates the propagation loss L _b [dB] at the cell boundary of the APs 10-1 to 10-5. The transmission power adjustment unit 442 calculates the transmission power P _tx [dBm] of each of the APs 10-1 to 10-5 according to the following equation (1) based on the predetermined allowable interference amount I _th [dBm]. .

P _tx = L _b −G _ANT + I _th (1)

In Formula (1), G _ANT [dB] is a transmission antenna gain. The transmission power adjustment unit 442 calculates transmission power that can cover a wider range while forming a radio wave closed space according to the antenna characteristics of each of the APs 10-1 to 10-5. The transmission power adjustment unit 442 associates the calculated transmission power with the identification information of each of the APs 10-1 to 10-5 and causes the aggregate power information storage unit 414 to store them. The transmission power adjustment unit 442 notifies the communication control unit 420 that the transmission power of the APs 10-1 to 10-5 has been changed.

  FIG. 4 is a diagram illustrating an example of processing performed by the AP 10. First, when the wired communication unit 110 receives channel information from the centralized control station device 40 (step S100), the wired communication control unit 150 outputs the channel information to the frequency information update unit 160. For example, in the case of the AP 10-1, the channel information is information on the channels of the AP 10-1 and the AP 10-2 to 10-5 adjacent to the AP 10-1. Next, the frequency information update unit 160 updates the channel information stored in the frequency information storage unit 122 based on the channel information input from the wired communication control unit 150. The frequency information update unit 160 notifies the wireless communication control unit 130 that the channel information has been updated.

  Next, when receiving the notification of channel information update from the frequency information update unit 160, the radio communication control unit 130 refers to the frequency information storage unit 122 and acquires the channel information of the own device. Next, the wireless communication control unit 130 generates a beacon signal based on the channel information. The wireless communication control unit 130 controls the wireless communication unit 100 and transmits the generated beacon signal to the terminal station device 20 (step S101).

  Next, the wireless communication control unit 130 determines whether or not the communication with the terminal station device 20 is in an idle state (step S102). When it is determined that the own apparatus is not in the idle state (step S102; NO), the process returns to step S102. When it is determined that the own apparatus is in an idle state (step S102; YES), the wireless communication control unit 130 refers to the frequency information storage unit 122 and acquires channel information. For example, in the case of the AP 10-1, the channel information is information on the channels of the AP 10-1 and the AP 10-2 to 10-5 adjacent to the AP 10-1. The wireless communication control unit 130 performs carrier sense based on the acquired channel information (step S103). Next, the wireless communication control unit 130 outputs spectrum information indicating the spectrum observed by carrier sense to the abnormality detection unit 140.

  Next, when acquiring the spectrum information from the wireless communication control unit 130, the abnormality detection unit 140 refers to the threshold information storage unit 121 and acquires threshold information. The abnormality detection unit 140 determines whether or not there is a channel indicating reception power exceeding the threshold indicated by the threshold information among the reception power of the signals for each channel indicated by the spectrum information (step S104). When a channel indicating received power exceeding the threshold is not detected (step S104; NO), the process returns to step S102. When a channel indicating reception power exceeding the threshold is detected (step S104; YES), the abnormality detection unit 140 outputs a data set including the channel, signal power, and signal waveform data to the wired communication control unit 150. . For example, in the signal received by the AP 10-2, when the power of the channel CH0 used by the AP 10-1 exceeds the threshold, the data set including the channel CH0, the average power in the channel CH0, and the waveform data of the signal is wired communication control. Is output to the unit 150.

  Next, the wired communication control unit 150 framing the data set input from the anomaly detection unit 140 by adding a header part or CRC including the signal reception time and identification information of the own device. The wired communication control unit 150 controls the wired communication unit 110 and transmits the framed data to the centralized control station device 40 via the core network 30 (step S105). Thereafter, the process returns to step S102.

  FIG. 5 is a diagram illustrating an example of processing performed by the central control station device 40. First, periodically, the upper layer 423 of the communication control unit 420 refers to the aggregate frequency information storage unit 413 and acquires channel information. The upper layer 423 refers to the AP position information storage unit 415 and acquires identification information of the AP 10 adjacent to each AP 10. The upper layer 423 transmits channel information on the channel of the AP 10 adjacent to the channel of each AP 10 to each AP 10 via the control device side communication unit 400 (step S200). For example, channel information about the channel of AP 10-1 and the channels of AP 10-2 to AP 10-5 adjacent to AP 10-1 is transmitted to AP 10-1.

  When the control device side communication unit 400 receives a data set including a channel, signal power, reception time, identification information of the AP 10 of the reception source, and waveform data of the signal for the signal received by the AP 10, the upper layer 423 The reception data is stored in the reception radio wave data storage unit 411 in time series based on the reception time (step S201). Next, the transmission determination unit 431 refers to the transmission radio wave data storage unit 412 and acquires the latest transmission radio wave data. The transmission determination unit 431 refers to the AP position information storage unit 415 and acquires adjacent AP identification information based on the AP 10 indicated by the transmission AP identification information of the latest transmission radio wave data. For example, when the transmission source AP 10 is AP 10-1, identification information of AP 10-2 to AP 10-5 adjacent to AP 10-1 is acquired.

  Next, the transmission determination unit 431 refers to the received radio wave data storage unit 411, the received AP identification information is the adjacent AP identification information acquired from the AP position information storage unit 415, and the reception time is acquired from the transmission radio wave data. It is determined whether there is received radio wave data that is within a predetermined time from the transmitted time (step S202). For example, when the transmission channel of transmission radio wave data is CH0 and the transmission AP identification information is AP10-1, the reception AP identification information is one of APs 10-2 to 10-5 that are APs adjacent to AP10-1, It is determined whether or not there is received radio wave data whose time is within several tens of milliseconds from the transmission time. If the received radio wave data does not exist (step S202; NO), the process ends. If the received radio wave data exists (step S202; YES), the received radio wave data is extracted. Next, the transmission determination unit 431 determines whether or not the transmission signal from the AP indicated by the transmission AP identification information of the transmission radio wave data is included in the received waveform data in the frequency band of the transmission channel (step S203). .

  When it is determined that a transmission signal is included (step S203; YES), the transmission determination unit 431 notifies the frequency adjustment unit 441 of the occurrence of an abnormality in the radio wave closed space. Next, when receiving the notification of the occurrence of the interference source from the transmission determination unit 431, the frequency adjustment unit 441 outputs a database reference request of the server device 50 to the communication control unit 420. The frequency adjustment unit 441 selects a channel to be allocated to each AP from channels that do not interfere with the interference wave, based on the radio wave power distribution map acquired in response to the reference request. For example, when the interference wave interferes with the channel CH0, a channel CH5 different from the channels CH1 to CH4 of the adjacent AP 10-2 to AP 10-5 is selected as the channel of the AP 10-1. Next, the frequency adjustment unit 441 associates the selected channel with the transmission AP identification information and causes the aggregate frequency information storage unit 413 to store the associated channel. Next, the frequency adjustment unit 441 notifies the communication control unit 420 that the use channels of the APs 10-1 to 10-5 have been changed. Next, the communication control unit 420 controls the control device-side communication unit 400 to transmit the updated channel information to each AP 10 (step S204). Thereafter, the process ends.

  When it is determined that the transmission signal is not included (step S203; NO), the transmission determination unit 431 notifies the frequency adjustment unit 441 of the occurrence of the interference source and outputs the transmission AP identification information used for the determination. Next, when the transmission power adjustment unit 442 receives a notification of the occurrence of an abnormality in the radio wave closed space from the transmission determination unit 431, the transmission power adjustment unit 442 refers to the database of the server device 50, and uses the AP 10-1 to 10-5 according to Expression (1). Each transmission power is calculated. Next, the transmission power adjustment unit 442 associates the calculated transmission power with the identification information of each of the APs 10-1 to 10-5 and stores it in the aggregate power information storage unit 414. Next, the communication control unit 420 controls the control device side communication unit 400 to transmit power information indicating each transmission power to each AP 10 (step S205). Thereafter, the process ends.

  FIG. 10 is a conceptual diagram illustrating an example of a communication system 2 according to a conventional technique. In FIG. 10, each of the cells 60-1 to 60-5 of each AP 10-1 to 10-5 overlaps each other and reaches the adjacent AP 10. In the conventional technology, in order to reduce interference, a beacon signal 95 is first transmitted and received between APs to measure a signal-to-interference plus noise ratio (SINR), and the measurement result is transmitted to a wireless LAN controller. The data is transmitted to the (centralized control station device) 40 via the network. Based on the measurement result at each AP, the wireless LAN controller grasps the number of APs adjacent to each AP and the SINR, and grasps the number of necessary channels so that the cells do not interfere with each other. In addition, when the number of channels is limited and the channels are partially overlapped, the SINR value is used as a determination of availability. As described above, the wireless LAN controller grasps the number of adjacent APs and the SINR of each AP and assigns a dynamic channel to avoid interference.

  However, as described above, in the conventional technique, in order to transmit and receive the beacon signal 95 in order to avoid interference, overlap and overreach of the cells 60 as shown in FIG. 10 are assumed. For this reason, it has been difficult to apply when limiting the use boundary of radio waves, such as in a closed radio wave space. Also, with the conventional technology, it has been difficult to cope with the unexpected arrival of interference waves from the outside of the communication system.

  However, as described above, the communication system 1 according to this embodiment includes the AP 10 in which a plurality of adjacent APs 10 communicate with each other in different frequency bands, and the centralized control station that controls the wireless communication of the AP 10 by being connected to the AP 10 by wire. Device 40. The AP 10-2 includes a wireless communication unit 100 that receives a signal in the frequency band CH0 that the adjacent AP 10-1 communicates with. The centralized control station device 40 includes a transmission determination unit 431 and an adjustment unit 440. The transmission determination unit 431 determines whether the signal received by the wireless communication unit 100 of the AP 10-2 is a signal transmitted by the AP 10-1. The adjustment unit 440 controls wireless communication by the AP 10-1 based on the determination result of the transmission determination unit 431. Accordingly, the communication system 1 determines the origin of the received radio wave, thereby determining whether the cause of the abnormality that has occurred in the communication system 1 is an abnormality in the radio wave closed space or the arrival of an interference wave from the outside of the communication system 1. Can be determined. Therefore, based on the determination result, the wireless communication of the AP 10 can be controlled to reduce interference. In addition, since the radio communication of the AP 10 can be controlled and the radio wave closed space can be normalized based on the determination result, the function of continuously reducing interference can be maintained.

  In addition, the AP 10-2 includes a wired communication unit 110 that transmits the reception time of the signal to the central control station apparatus when the power of the signal received by the wireless communication unit 100 exceeds a predetermined threshold. Based on the reception time and the transmission time of the signal transmitted from the AP 10-1, the transmission determination unit 431 of the centralized control station device 40 determines that the signal received by the wireless communication unit 100 of the AP 10-2 is the second wireless base station. It is determined whether or not the signal is transmitted by the station device. Thereby, the communication system 1 can determine the origin of the received signal correctly based on the transmission time and the reception time. Therefore, for example, even if the existing wireless system and the secondary usage wireless system are mixed, whether the signal received by the wireless base station device is from the existing wireless communication system or the secondary usage wireless system And the system can be controlled appropriately. As a result, the communication system 1 can effectively reduce interference.

  Further, the adjustment unit 440 controls wireless communication by the AP 10-2 by changing the frequency band or transmission power. As a result, the communication system 1 can normalize the radio wave closed space in order to readjust the transmission power from the AP when the cause of the communication system 1 is an abnormality in the radio wave closed space. Further, when the cause of the communication system 1 is the occurrence of an interference source, the communication system 1 effectively reduces interference because the channel used by each AP is changed to a frequency band different from the interference wave from the interference source. be able to.

  Further, the transmission determination unit 431 of the centralized control station apparatus 40 determines the determination results for a plurality of received signals by aggregating them with logical operations. As a result, the communication system 1 can integrate a plurality of determination results and specify the cause of the abnormality that has occurred in the communication system 1 with higher accuracy. Therefore, the communication system 1 can appropriately detect the occurrence of interference and reduce the interference.

<Second Embodiment>
The second embodiment of the present invention will be described below with reference to the drawings. The communication system according to the present embodiment is a system including a radio base station apparatus, a terminal station apparatus, and a centralized control station apparatus, similarly to the communication system according to the first embodiment. In the present embodiment, adjacent radio base station apparatuses are controlled by a plurality of centralized control station apparatuses. FIG. 6 is a conceptual diagram showing an example of the communication system 1a according to the present embodiment. Hereinafter, the same reference numerals are used for the same configurations as those in the first embodiment, and description thereof is omitted. In FIG. 6, the terminal station apparatus 20 is omitted. In this example, APs 10-1 to 10-9 are APs that can be adjacent to each other. The APs 10-1 to 10-5 are controlled by the centralized control station device 40a-1. The APs 10-6 to 10-9 are controlled by the centralized control station device 40a-2.

  FIG. 7 is a diagram illustrating an example of a functional configuration of the centralized control station device 40a. The centralized control station device 40a includes a control device side communication unit 400a, a storage unit 410a, a communication control unit 420a, and an analysis unit 430a. The control device side communication unit 400a includes a network interface 401a. The storage unit 410a includes a reception radio wave data storage unit 411a, a transmission radio wave data storage unit 412a, an aggregate frequency information storage unit 413a, an aggregate power information storage unit 414a, and an AP position information storage unit 415a. The communication control unit 420a includes a modulation unit 421a, a demodulation unit 422a, and an upper layer 423a. The analysis unit 430a includes a transmission determination unit 431a and an adjustment unit 440a. The adjustment unit 440a includes a frequency adjustment unit 441a and a transmission power adjustment unit 442a.

  Among the configurations of the centralized control station device 40a according to the present embodiment described above, the control device side communication unit 400a, the network interface 401a, the received radio wave data storage unit 411a, the transmission radio wave data storage unit 412a, the aggregate frequency information storage unit 413a, the aggregation The power information storage unit 414a, the modulation unit 421a, the demodulation unit 422a, the adjustment unit 440a, the frequency adjustment unit 441a, and the transmission power adjustment unit 442a are each a control device of the configuration of the centralized control station device 40 according to the first embodiment. Side communication unit 400, network interface 401, reception radio wave data storage unit 411, transmission radio wave data storage unit 412, aggregate frequency information storage unit 413, aggregate power information storage unit 414, modulation unit 421, demodulation unit 422, adjustment unit 440, frequency The same functional configuration as each of the adjustment unit 441 and the transmission power adjustment unit 442 is provided. Omitted because described, AP position information storage section 415a, which is a characteristic configuration according to the present embodiment, upper layer 423a of the communication control unit 420a, the transmission determination unit 431a will be described.

  The AP position information storage unit 415a includes identification information of each AP 10 controlled by the central control station device 40a of the communication system 1a, position information indicating the position of each AP 10, adjacency information indicating the AP 10 adjacent to each AP 10, The identification information (control device identification information) of the centralized control station device 40a that performs control is stored in association with each other. For example, in FIG. 6, the AP position information storage unit 415a of the central control station device 40a-1 includes APs 10-1 to 10-5 and the central control station device 40a-2 that are controlled by the central control station device 40a-1. Identification information of the APs 10-6 to 10-9 to be controlled, position information of each of the APs 10-1 to 10-9, and identification information of each of the APs 10-1 to 10-9 adjacent to each of the APs 10-1 to 10-9 And the identification information of the centralized control station device 40a-1 or the centralized control station device 40a-2 that controls each of the APs 10-1 to 10-9 are stored in association with each other.

  The upper layer 423a and the transmission determination unit 431a of the communication control unit 420a have functions described below in addition to the functions of the upper layer 423 and the transmission determination unit 431 of the communication control unit 420 according to the first embodiment, respectively. The transmission determination unit 431a monitors the transmission radio wave data storage unit 412a and acquires the latest transmission radio wave data when the transmission radio wave data is updated. The transmission determination unit 431a acquires transmission AP identification information, transmission time, and transmission channel of the transmission radio wave data. The transmission radio wave data storage unit 412a refers to the AP position information storage unit 415a and acquires adjacent AP identification information.

  The transmission determination unit 431a refers to the received radio wave data storage unit 411a, the received AP identification information of the received radio wave data is the adjacent AP identification information acquired from the AP position information storage unit 415a, and the reception time is determined from the transmitted radio wave data. It is determined whether there is received radio wave data within a predetermined time from the acquired transmission time. When the received radio wave data exists, the transmission determination unit 431a extracts the data and performs the same processing as the transmission determination unit 431 according to the first embodiment.

  If the received radio wave data does not exist, the other centralized control station device 40a is inquired about the presence or absence of the received radio wave data. For example, in the case of the central control station device 40a-1, the central control station device 40a-2 is inquired about the presence or absence of the received radio wave data. The transmission determination unit 431a refers to the AP position information storage unit 415a, and acquires control device identification information other than the own device among the control device identification information corresponding to the adjacent AP identification information. For example, in the case of the central control station device 40a-1, the identification information of the central control station device 40a-2 is acquired. The transmission determination unit 431a outputs transmission time information indicating the transmission time acquired from the acquired control device identification information and transmission radio wave data to the upper layer 423a.

  If the inquiry result input from the upper layer 423a according to the output indicates that the corresponding received radio wave data does not exist, the transmission determination unit 431a determines that no interference has occurred and ends the process. When received radio wave data is input as an inquiry result from the communication control unit 420a, the transmission determination unit 431a performs the same processing on the received data as the received radio wave data acquired from the received radio wave data storage unit 411a of its own device. By performing the process, it is determined whether or not interference has occurred. If interference has occurred, it is determined whether the cause of the interference is an abnormality in the radio wave closed space or an external interference source.

  Upon acquiring the control device identification information and the transmission time information from the transmission determination unit 431a of the own device, the upper layer 423a transmits the transmission time information to the centralized control station device 40a indicated by the control device identification information, and responds. Queries the presence of received radio wave data. For example, when the upper layer 423a acquires the identification information of the central control station device 40a-2 from the transmission determination unit 431a, the upper layer 423a determines whether or not the received radio wave data exists in the central control station device 40a-2 via the control device side communication unit 400a. Inquire.

  When the upper layer 423a receives the transmission time information from another central control station device 40a as an inquiry about the presence or absence of received radio wave data via the control device side communication unit 400a, the upper layer 423a refers to the received radio wave data storage unit 411a of the own device. Then, the reception radio wave data whose reception time is within a predetermined time from the time indicated by the transmission time information is searched. If the received radio wave data exists, the communication control unit 420a transmits the received radio wave data to the central control station apparatus 40a that is the inquiry source. If the received radio wave data does not exist, the fact that the received radio wave data does not exist is transmitted to the central control station apparatus 40a that is the inquiry source. For example, when receiving an inquiry from the central control station apparatus 40a-1, the upper layer 423a transmits the search result to the central control station apparatus 40a-1.

  As described above, according to the communication system 1a according to the second embodiment, adjacent APs 10-1 to 10-9 are controlled by the plurality of centralized control station devices 40a-1 and 40a-2. Also, the occurrence of interference and the cause of the interference can be correctly identified.

<Third Embodiment>
The third embodiment of the present invention will be described below with reference to the drawings. Similar to the communication system according to the first embodiment, the communication system 1b according to the present embodiment is a communication system including a radio base station device, a terminal station device, and a centralized control station device. In the present embodiment, the terminal station apparatus detects an abnormality that has occurred in the radio wave environment, like the radio base station apparatus according to the first embodiment. Hereinafter, the terminal-side communication unit 200b, which is a characteristic configuration according to the present embodiment, will be described, the same reference numerals are used for the same configurations as those in the first embodiment, and description thereof will be omitted. Each of the terminal station devices 20b-1 to 20b-5 is connected to the APs 10-1 to 10-5 in the same manner as each of the terminal station devices 20-1 to 20-5. However, the beacon signal transmitted by the AP 10 to the terminal station device 20b includes not only the channel used by the own device but also information on the channel used by the AP 10 adjacent to the own device.

FIG. 8 is a diagram illustrating an example of a functional configuration of the terminal station device 20b according to the present embodiment. The terminal station device 20b includes a terminal side communication unit 200b, a storage unit 210b, a wireless communication control unit 220b, a frequency information update unit 231b, and a terminal side detection unit 232b.
The terminal-side communication unit 200b includes an antenna and a switch, and transmits and receives signals to and from the AP 10.

  The storage unit 210b includes, for example, an HDD, an SSD, an EEPROM, a ROM, or a RAM, and various programs (firmware, application programs, etc.) executed by the processor included in the terminal station device 20b, various processing results performed by the processor, and the like. Is stored. The wireless communication control unit 220b, the frequency information update unit 231b, and the terminal side detection unit 232b function, for example, when the processor executes a program stored in the storage unit 210b.

  The storage unit 210b includes a frequency information storage unit 211b and a threshold information storage unit 212b. The frequency information storage unit 211b stores channel information indicating the channel used by the AP 10 to which the device is connected for communication and the channel used by the AP 10 adjacent to the AP 10 for communication. The threshold information storage unit 212b stores threshold information indicating a threshold used for processing performed by the terminal-side detection unit 232b.

The wireless communication control unit 220b includes a baseband signal processing unit 221b, a demodulation unit 222b, a modulation unit 223b, and an upper layer 224b.
The baseband signal processing unit 221b performs level adjustment, frequency conversion, and the like on the signal received by the terminal-side communication unit 200b, and outputs the converted signal to the wireless communication control unit 220b. The baseband signal processing unit 221b performs frequency conversion, band limitation, level adjustment, and the like on the baseband signal input from the wireless communication control unit 220b, and transmits from the antenna via the switch of the terminal side communication unit 200b. .

The demodulator 222b demodulates the signal input from the baseband signal processor 221b, such as guard interval removal, FFT, channel equalization, and error correction, and outputs the result to the upper layer 224b.
The modulation unit 223b performs modulation, IFFT (Inverse Fast Fourier Transform), guard interval addition, and the like on the signal input from the upper layer 224b, and outputs the result to the baseband signal processing unit 221b.

  The upper layer 224b monitors the terminal-side communication unit 200b and determines whether or not the state of the own apparatus is an idle state in which communication with the AP 10 is not performed. When it is determined that the own apparatus is in the idle state, the upper layer 224b refers to the frequency information storage unit 211b and acquires channel information. Based on the acquired channel information, the upper layer 224b performs carrier sense on the channel used by the AP 10 to which the own device is connected and the channel used by the AP 10 adjacent to the AP 10. The upper layer 224b outputs spectrum information indicating the spectrum observed by carrier sense to the terminal side detection unit 232b. When the upper layer 224b acquires the data set from the terminal side detection unit 232b, the upper layer 224b transmits the data set to the centralized control station device 40 via the terminal side communication unit 200b and the AP 10.

  The frequency information update unit 231b acquires the channel information of the AP 10 to which the device is connected and the neighboring AP 10 of the AP 10 from the beacon signal received by the terminal-side communication unit 200b and processed by the wireless communication control unit 220b. The frequency information update unit 231b stores the acquired channel information in the frequency information storage unit 211b.

  When acquiring the spectrum information from the upper layer 224b, the terminal-side detection unit 232b refers to the threshold information storage unit 212b and acquires the threshold information. The terminal-side detection unit 232b determines whether or not there is a channel indicating reception power exceeding the threshold indicated by the threshold information among the reception power of the signals for each channel indicated by the spectrum information. When a channel indicating received power exceeding the threshold is detected, it is assumed that an abnormality has occurred in the communication system 1b, and the terminal side detection unit 232b includes data including the channel, signal power, reception time, and signal waveform data. The set is generated in the wireless communication control unit 220b. The terminal side detection unit 232b outputs the generated data set to the upper layer 224b when the signal is observed for a predetermined time or more.

  FIG. 9 is a diagram illustrating an example of processing performed by the terminal station device 20b. First, the terminal-side communication unit 200b receives a beacon signal periodically transmitted from the AP 10 with an antenna and outputs the beacon signal to the baseband signal processing unit 221b of the wireless communication control unit 220b via a switch. The baseband signal processing unit 221b performs level adjustment, frequency conversion, and the like, and outputs the result to the demodulation unit 222b. The demodulator 222b performs guard interval removal, FFT, channel equalization, error correction, etc. on the beacon signal, converts it into a bit string, and outputs the bit string to the upper layer 224b. The upper layer 224b extracts information on the channel of the AP 10 to which the own apparatus is connected and information on the channel of the AP 10 adjacent to the AP 10 from the demodulated beacon signal. For example, when the own apparatus is the terminal station apparatus 20b-1, the channel information of the AP 10-1 to which the own apparatus is connected and the channel information of the APs 10-2 to AP10-5 adjacent to the AP 10-1 are extracted. Next, the frequency information update unit 231b stores the extracted channel information in the frequency information storage unit 211b (step S300).

  Next, the upper layer 224b monitors the terminal-side communication unit 200b and determines whether or not the state of the own device is an idle state in which communication with the AP 10 is not performed (step S301). When it is determined that the own apparatus is not in the idle state (step S301; NO), the process returns to step S301. When it is determined that the own device is in the idle state (step S301; YES), the wireless communication control unit 220b performs carrier sense on the channel used by the own device and the channel used in the adjacent radio closed space. Is performed (step S302). For example, in the case of the terminal station device 20b-2, carrier sense is performed for the channel CH1 of the AP 10-2 to which the own device is connected and the channel CH0 of the AP 10-1 adjacent to the AP 10-2. Next, the upper layer 224b outputs spectrum information indicating a spectrum observed by carrier sense to the terminal side detection unit 232b.

  Next, when acquiring the spectrum information from the wireless communication control unit 220b, the terminal-side detection unit 232b refers to the threshold information storage unit 212b and acquires the threshold information. The terminal-side detection unit 232b determines whether or not there is a channel indicating reception power exceeding the threshold indicated by the threshold information among the reception power of signals for each channel indicated by the spectrum information (step S303). When a channel indicating received power exceeding the threshold is not detected (step S303; NO), the process returns to step S301. When a channel indicating reception power exceeding the threshold is detected (step S303; YES), the terminal-side detection unit 232b generates a data set including the channel, signal power, reception time, and signal waveform data (step S303). S304). Next, the terminal side detection unit 232b determines whether or not the time exceeding the threshold is equal to or longer than the specified time (step S305). Here, in order to suppress erroneous determination and false alarm, the determination may be made only when a signal more than a specified number of times is observed within a specified time. When the time exceeding the threshold is less than the specified time (step S305; NO), the process returns to step S301.

  When the time exceeding the threshold is equal to or longer than the specified time (step S305; YES), the terminal side detection unit 232b outputs the data set to the upper layer 224b. For example, when the power of the signal received by the terminal station device 20b-2 exceeds the threshold for a specified time in the channel CH0, a data set including the power in the channel CH0, the channel CH0, the reception time, and the waveform data of the signal is output. Is done. Next, the upper layer 224b frames the input data set and outputs it to the modulation unit 223b. Next, the modulation unit 223b performs modulation, IFFT, guard interval addition, and the like on the input frame, converts the frame into a baseband signal, and outputs the baseband signal to the baseband signal processing unit 221b. Next, the baseband signal processing unit 221b performs frequency conversion, band limitation, level adjustment, and the like on the baseband signal, converts the signal into a radio frequency band signal, and transmits the signal from the antenna via the switch of the terminal side communication unit 200b. Transmit (step S306).

  The signal transmitted from the antenna is acquired by the central control station device 40 via the AP 10, and an abnormality is determined by the transmission determination unit 431 of the central control station device 40. For example, when the terminal station device 20b-2 receives the signal of the channel CH0 and the data is transmitted to the central control station device, the data is transmitted by the AP 10-1 that communicates using the channel CH0. It is determined whether the signal originates. Here, the transmission determination unit 431 of the centralized control station device 40 performs a logical sum or logic of the received radio wave data from a plurality of APs 10 in order to suppress an erroneous determination or false alarm regarding an abnormal determination of the radio wave closed space or the arrival of an interference wave. The determination may be made after performing a logical operation such as product.

  As described above, the communication system 1b according to the third embodiment includes the terminal station device 20b that performs wireless communication with the AP 10. The terminal station device 20b-2 includes a terminal-side communication unit 200b that receives a signal in a frequency band with which the AP 10-1 communicates. The transmission determination unit 431 of the centralized control station device 40 determines whether or not the signal received by the terminal side communication unit 200b of the terminal station device 20b-2 is a signal transmitted by the AP 10-1. Thereby, the terminal station apparatus 20b can detect that an abnormality has occurred in the communication system 1b, and can transmit the received signal to the centralized control station apparatus 40. Therefore, the centralized control station device 40 can determine the cause of the abnormality of the communication system 1b and can reduce interference.

  Note that the number of components of the communication system is not limited to those described above. For example, the communication system 1 according to the first embodiment may include four or less APs 10 or may include six or more APs. Further, there may be one or more terminal station apparatuses that communicate with each AP, or may be omitted. In the second embodiment, the communication system 1a may include three or more centralized control station devices 40a. Note that the communication system according to each embodiment may include a device having the functions of an AP and a centralized control station device.

  Note that the transmission determination units 431 and 431a may omit the process of acquiring the received radio wave data based on the adjacent AP identification information and the process of comparing the received waveform data and the transmitted waveform data. Further, for example, whether the reception channel of the reception radio wave data and the transmission channel of the transmission radio wave data coincide with each other may determine whether the radio wave closed space is abnormal or the interference source is generated. As described above, the transmission determination units 431 and 431a determine whether or not the received signal is transmitted by another AP 10 based on a combination of time, channel, signal power, waveform phase, or the like. You can do it.

  Note that each time a signal with power exceeding the threshold is received by the AP 10 or the terminal station device 20b, the transmission determination units 431 and 431a determine whether the reception signal is abnormal in the radio wave closed space and the occurrence of an interference source. Also good. For example, when a signal with power exceeding the threshold is received, the transmission determination units 431 and 431a extract the transmission radio wave data from the transmission radio wave data storage units 412 and 412a based on the reception time of the reception radio wave data. With respect to the extracted transmission radio wave data and reception radio wave data, the transmission determination units 431 and 431a may determine the abnormality of the radio wave closed space and the occurrence of the interference source by performing the processing described in each embodiment.

  Note that the transmission determination units 431 and 431a may determine that an interference source has occurred in the received radio wave data when there is received radio wave data that has not been determined after a predetermined time has elapsed since the reception time. As a result, even when the received radio wave data is extracted based on the transmission time, the cause of the abnormality of the communication system indicated by the received signal exceeding the observed threshold can be determined without omission and interference can be reduced.

  Note that the abnormality detection unit 140 and the terminal-side detection unit 232b may use a logical operation when detecting an abnormality in the communication system. For example, it may be determined that an abnormality in the communication system has been detected when a signal with power exceeding a threshold value is observed on a predetermined channel a plurality of times within a predetermined time. Further, the determination using the logical operation by the transmission determination unit 431 is not limited to the above. For example, the determination result by the logical operation may be reversed from that described above. Further, the determination result may be calculated by combining a plurality of logical operations.

  Note that the terminal station device 20b according to the third embodiment may detect an abnormality in the communication system 1b only when communication with the connection destination AP 10 is maintained. As a result, when the terminal station device 20b moves to the radio wave closed space of the AP 10 other than the AP 10 that has been connected so far, the abnormality of the communication system 1b is not detected, and thus erroneous detection can be prevented.

  The terminal station devices 20 and 20b may transmit the position information of the own device to the centralized control station device 40. Then, the centralized control station device 40 and the server device 50 may generate a more detailed radio wave power distribution map based on the position information and the power of signals received by the terminal station devices 20 and 20b. Thereby, the central control station apparatus 40 can calculate the transmission power of the signal transmitted from AP more appropriately.

  Note that the AP 10 according to each embodiment may reduce interference by so-called null steering. For example, the AP 10 includes a mechanism that controls antenna directivity. Then, the centralized control station device 40 analyzes the position of the interference source based on, for example, a radio wave power distribution map. Then, the adjustment unit 440 of the centralized control station device 40 may control the direction of the antenna so that a null with a low antenna gain is directed toward the analyzed position of the interference source. As described above, the adjustment unit 440 may control the wireless communication by causing the AP 10 to perform null steering to reduce interference.

  Note that the communication system according to each embodiment may predict the movement of the interference source and perform processing for reducing interference based on the prediction. For example, the centralized control station device 40 analyzes the position of the interference source as needed, and predicts the movement of the interference source. Whether or not the power at a specific channel of the interference wave transmitted from the interference source exceeds a predetermined threshold at the destination and affects communication in a radio wave closed space using the channel, that is, the degree of interference Determine if is critical. If it is determined that there is an influence, the centralized control station device 40 may change the channel used in the radio wave closed space. As described above, the central control station device uses the estimation unit that estimates the position and power of the transmission source of the signal received by the AP or the terminal station device, and the signal based on the position and power estimated by the estimation unit. An interference determination unit that determines whether or not the degree of interference is significant.

  Note that the search for empty channels by the frequency adjustment unit 441 and the calculation processing of the transmission power by the transmission power adjustment unit 442 may be performed by the server device 50 and the result may be transmitted to the central control station device 40.

  In addition, a part of the radio base station apparatus 10, the terminal station apparatuses 20, 20b, and the centralized control station apparatuses 40, 40a in the above-described embodiment, for example, the abnormality detection unit 140, the terminal side detection unit 232b, the transmission determination unit 431, 431a, frequency adjustment units 441 and 441a, and transmission power adjustment units 442 and 442a may be realized by a computer. In that case, the program for realizing the control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by the computer system and executed.

  Here, the “computer system” is a computer system built in the radio base station apparatus 10, the terminal station apparatuses 20, 20b, or the central control station apparatuses 40, 40a, and includes hardware such as an OS and peripheral devices. Wear. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In this case, a volatile memory inside a computer system that serves as a server or a client may be included that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  In addition, a part or all of the radio base station device 10, the terminal station devices 20, 20b, and the central control station devices 40, 40a in the above-described embodiment are realized as an integrated circuit such as an LSI (Large Scale Integration). Also good. Each functional block of the radio base station apparatus 10, the terminal station apparatuses 20, 20b, and the centralized control station apparatuses 40, 40a may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to the advancement of semiconductor technology, an integrated circuit based on the technology may be used.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

  DESCRIPTION OF SYMBOLS 1, 1a, 1b ... Communication system, 10 ... AP (radio base station apparatus), 20, 20b ... Terminal station apparatus, 30 ... Core network, 40 ... Centralized control station apparatus, 50 ... Server apparatus, 60 ... Cell, 70 ... AP10-1 adjacent area, 80 ... interference source, 90 ... interference wave, 100 ... wireless communication unit, 110 ... wired communication unit, 111 ... network interface, 120 ... storage unit, 121 ... threshold information storage unit, 122 ... frequency information Storage unit 123 ... Power information storage unit 130 ... Wireless communication control unit 140 ... Abnormality detection unit 150 ... Wired communication control unit 160 ... Frequency information update unit 170 ... Power information update unit 200b ... Terminal side communication unit , 220b ... wireless communication control unit, 221b ... baseband signal processing unit, 222b ... demodulation unit, 223b ... modulation unit, 224b ... upper layer, 210b ... storage unit, 2 DESCRIPTION OF SYMBOLS 1b ... Frequency information storage part, 212b ... Threshold information storage part, 231b ... Frequency information update part, 232b ... Terminal side detection part, 400 ... Control apparatus side communication part, 401 ... Network interface, 410 ... Storage part, 411 ... Received radio wave Data storage unit, 412 ... Transmission radio wave data storage unit, 413 ... Aggregated frequency information storage unit, 414 ... Aggregated power information storage unit, 415 ... AP position information storage unit, 420 ... Communication control unit, 421 ... Modulation unit, 422 ... Demodulation , 423 ... upper layer, 430 ... analysis unit, 431 ... transmission determination unit, 440 ... adjustment unit, 441 ... frequency adjustment unit, 442 ... transmission power adjustment unit

Claims (8)

A plurality of adjacent radio base station apparatuses that communicate with each other in different frequency bands, a centralized control station apparatus that is connected to the radio base station apparatus by wire and controls radio communication of the radio base station apparatus; A communication system comprising:
The first radio base station apparatus
A radio communication unit that receives a signal transmitted using a frequency band in which an adjacent second radio base station apparatus communicates;
With
The central control station device
A transmission determination unit that determines whether a signal received by the wireless communication unit of the first wireless base station device is a signal transmitted by the second wireless base station device;
Based on the determination result of the transmission determination unit, an adjustment unit that controls wireless communication by the second wireless base station device;
A communication system comprising: The first radio base station apparatus is
When the power of the signal received by the wireless communication unit exceeds a predetermined threshold, a wired communication unit that transmits the reception time of the signal to the centralized control station device,
With
The transmission determination unit of the centralized control station apparatus is configured such that the radio communication unit of the first radio base station apparatus is based on the reception time and the transmission time of a signal transmitted from the second radio base station apparatus. Determining whether the received signal is a signal transmitted by the second radio base station apparatus;
The communication system according to claim 1. The adjustment unit of the centralized control station apparatus controls radio communication by the second radio base station apparatus by changing a frequency band or transmission power.
The communication system according to claim 1 or 2. The transmission determination unit of the centralized control station device,
The determination results for the plurality of received signals are determined by aggregating by logical operation.
The communication system according to any one of claims 1 to 3, wherein: The communication system is:
A terminal station device that performs wireless communication with the wireless base station device,
The terminal station device connected to the first radio base station device is
A terminal-side communication unit that receives a signal in a frequency band with which the second radio base station apparatus communicates;
With
The transmission determination unit of the centralized control station apparatus determines whether the signal received by the terminal side communication unit of the terminal station apparatus is a signal transmitted by the second radio base station apparatus,
The communication system according to any one of claims 1 to 4, characterized in that: The adjustment unit of the centralized control station apparatus controls wireless communication by causing the second radio base station apparatus to perform null steering;
The communication system according to any one of claims 1 to 5, characterized in that: The central control station device
An estimation unit for estimating the position and power of the transmission source of the received signal;
Based on the position and power estimated by the estimation unit, an interference determination unit that determines whether the degree of interference by the signal is significant;
With
The adjustment unit of the centralized control station apparatus controls radio communication by the second radio base station apparatus based on a determination result of the interference determination unit.
The communication system according to any one of claims 1 to 6, characterized in that: A plurality of adjacent radio base station apparatuses that communicate with each other in different frequency bands, a centralized control station apparatus that is connected to the radio base station apparatus by wire and controls radio communication of the radio base station apparatus; A communication method in a communication system comprising:
A radio communication process in which a first radio base station apparatus receives a signal transmitted using a frequency band with which an adjacent second radio base station apparatus communicates;
A transmission determination process in which the central control station apparatus determines whether a signal received by the first radio base station apparatus is a signal transmitted by the second radio base station apparatus;
An adjustment process in which the centralized control station apparatus controls radio communication by the second radio base station apparatus based on a determination result in the transmission determination process;
A communication method characterized by comprising:

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