JP4913784B2 - Relay station, base station, radio communication system, and radio communication method - Google Patents

Description

  The present invention relates to a relay station, a base station, a wireless communication system, and a wireless communication method capable of relaying communication between a wireless communication terminal and a base station.

  In recent years, wireless communication terminals represented by PHS (Personal Handy phone System) terminals and mobile phones have become widespread, making it possible to make calls and obtain information regardless of location or time. Especially in recent years, the amount of available information has been increasing, and high-speed and high-quality wireless communication systems have been introduced to download large amounts of data.

  As one of such high-speed digital wireless communication systems, there are OFDMA (Orthogonal Frequency Division Multiplex Access) systems represented by IEEE 802.11 and WiMAX (for example, Non-Patent Document 1). The OFDMA method is classified as one of data multiplexing methods, uses a large number of carriers on the unit time axis, and sets the carrier band so that the phase of the signal wave to be modulated is orthogonal between adjacent carriers. This is a method of effectively using the frequency band by overlapping a part. In addition, the OFDMA system, in which OFDM (Orthogonal Frequency Division Multiplexing) system in which subchannels are allocated in time division for each individual user, a plurality of users share all subchannels, Is characterized by allocating a subchannel with the highest transmission efficiency.

  When the next-generation high-speed wireless communication method such as WiMAX uses a high-frequency band of 2.5 GHz or higher, a communication range (coverage) for one base station in an area where the radio wave condition is bad such as many obstacles. ) Becomes smaller and a large number of base stations must be installed to cover the entire surroundings. In addition, since the wraparound of radio waves is suppressed, there is a high possibility of being out of service indoors.

Therefore, by installing a relay station device that relays between the base station device and the wireless terminal device, it communicates with the base station device regardless of the service area due to the influence of shadowing caused by shielding by obstacles such as buildings. A technique for reducing the range in which the operation cannot be performed is disclosed (for example, Patent Document 1).
JP 2006-74325 A "Mobile WiMAX-Part I: A Technical Overview and Performance Evaluation" Prepared on Behalf of the WiMAX Forum, February 21, 2006, http://www.intel.com/netcomms/technologies/wimax/WiMAX_Overview_v2.pdf

  However, there are both the wireless communication terminal A communicating with the relay station and the wireless communication terminal B communicating directly with the base station in the vicinity of the above-described relay station, and the distance between them is very close. In such a case, interference may occur in either or both of the communication between the relay station and the wireless communication terminal A or the communication between the base station and the wireless communication terminal B (between the wireless communication terminals).

  FIG. 13 is an explanatory diagram for explaining interference that occurs between wireless communication terminals. For example, when the wireless communication terminal A communicating with the relay station and the wireless communication terminal B directly communicating with the base station are in the vicinity of the relay station, the radio wave conditions between the wireless communication terminal A and the relay station are It is expected that the wireless communication terminal A is good, and the wireless communication terminal A can communicate with the relay station with a small transmission power 10. On the other hand, since the vicinity of the relay station is generally assumed to be far from the base station or difficult to receive radio waves from the base station, the fact that the wireless communication terminal B is located near the relay station is located far from the base station. Will be. Accordingly, the wireless communication terminal B communicates with the base station with a transmission power 12 that is significantly higher than that of the wireless communication terminal A. In this case, if the frequency of the carrier used by the wireless communication terminal A and the relay station and the frequency of the carrier used by the wireless communication terminal B and the base station are equal or adjacent to each other, There is a possibility that the radio communication terminal B with high power gives interference (indicated by hatching in FIG. 13) across the frequency direction to the radio communication terminal A with low transmission power.

  In view of such a problem, the present invention can suppress interference in communication between a relay station and a wireless communication terminal by performing a proper communication connection by handover of the wireless communication terminal causing the interference. An object of the present invention is to provide a possible relay station, base station, radio communication system and radio communication method.

  In order to solve the above problems, a typical configuration of the present invention is a relay station capable of relaying communication between a wireless communication terminal and a base station, and relays communication between the wireless communication terminal and the base station. A communication quality acquisition unit that acquires communication quality in communication between the local station and the wireless communication terminal, and whether communication between the local station and the wireless communication terminal is interfered based on the acquired communication quality. An interference determination unit that determines whether the interference is received in order to prompt the wireless communication terminal that is communicating with the base station to perform handover when determining that the interference is received. And an interference notification unit for notifying to each other.

  With this configuration, when it is determined that the communication between the local station (relay station) and the wireless communication terminal is subject to interference, handover is established to the other wireless communication terminal to be interfered with to establish communication with the local station. Can be urged. Thereby, it becomes possible for the radio communication terminal receiving interference and another radio communication terminal (interference target) causing the interference to communicate with the same relay station. Therefore, no carrier wave having the same frequency is assigned, and interference can be avoided.

  Also, when the wireless communication terminal is in the vicinity of the relay station and other wireless communication terminals that are directly communicating with the base station are also in the vicinity of the relay station, the communication between the relay station and the wireless communication terminal is more interfered. There is a high possibility of receiving. When the wireless communication terminal and the relay station are at a short distance, the radio wave condition is good, so that the wireless communication terminal can reduce power consumption, and can communicate with the relay station with low transmission power. On the other hand, when another wireless communication terminal that is directly communicating with the base station is also in the vicinity of the relay station, it is located at a location far from the base station or difficult to receive radio waves from the base station. Therefore, other radio communication terminals communicate with the base station with a significantly higher transmission power than radio communication terminals communicating with the relay station. In this case, when the frequency of the carrier used by the wireless communication terminal and the relay station and the frequency of the carrier used by the other wireless communication terminal and the base station are adjacent, the other wireless communication terminal There is a risk of causing interference over the frequency direction to the wireless communication terminal.

  However, if the present invention is applied, other radio communication terminals that are causing interference, that is, other radio communication terminals that are subject to interference can be handed over to nearby relay stations, so that there is a high possibility of obtaining a good communication environment and power consumption Can be suppressed. Therefore, even if the frequency of the carrier wave used by another wireless communication terminal and the wireless communication terminal is adjacent to each other, both terminals will communicate with less transmission power, thus reducing the possibility of mutual interference Can be made.

  The communication quality acquired by the communication quality acquisition unit of the relay station may be RSSI, SINR, or CINR.

  By using RSSI (Received Signal Strength Indicator) and SINR (Signal to Interference and Noise Ratio) or CINR (Carrier to Interference and Noise Ratio), It is possible to appropriately grasp the communication quality.

  The interference determination unit of the relay station determines that communication between the local station and the wireless communication terminal is interfered when the relationship between SINR and RSSI or the relationship between CINR and RSSI satisfies a predetermined condition. Good.

  RSSI is the radio field intensity of all received radio waves, SINR is the ratio between the desired signal and noise including interference, and CINR is the ratio between the desired carrier and noise including interference. Therefore, if the relationship between SINR and RSSI or the relationship between SINR and RSSI satisfies a predetermined condition, it can be reliably determined whether or not there is interference.

  The interference notification unit of the relay station may notify the base station by including either or both of the carrier frequency and / or the time slot used in communication between the wireless communication terminal and the own station in the interference information.

  With this configuration, other wireless communication terminals that use a frequency that is substantially the same as or adjacent to the carrier frequency of the wireless communication terminal that is communicating with the relay station are handed over to the local station (relay station). The base station can be notified. As a result, only other wireless communication terminals that are likely to interfere with communication between the local station (relay station) and the wireless communication terminal can be urged to hand over to the local station (relay station) efficiently. Interference can be avoided.

  In addition, the base station can be handed over to the local station (relay station) another wireless communication terminal using the same or adjacent time slot as the time slot used by the wireless communication terminal communicating with the relay station. You can be notified.

  The relay station further includes a relay power acquisition unit that intermittently acquires transmission power information including the transmission power of the wireless communication terminal that is communicating with the local station, and a communication connection from a wireless communication terminal that is not communicating with the local station. When there is a request, the call number determination unit determines whether or not the number of calls in communication with the local station exceeds the predetermined number, and the relay power acquisition unit acquires when it is determined that the predetermined number is exceeded A terminal extraction unit that extracts a wireless communication terminal based on transmission power information, and an instruction notification unit that notifies the base station of instruction information that prompts the extracted wireless communication terminal to perform handover.

  With this configuration, when the relay station is communicating with a call exceeding a predetermined number, it is possible to estimate that the distance from the relay station is long, that is, the distance from other base stations is short, and the effect of handover can be easily obtained. By preferentially handing over the communication terminal, it is possible to establish appropriate wireless communication, and it is possible to suppress interference to communication between the relay station and the wireless communication terminal. Here, the call is, for example, a channel, a PRU (Physical Resource Unit) in WiMAX, or the like.

  The relay station may further include a base station communication unit that communicates with the base station and a terminal communication unit that communicates with the wireless communication terminal.

  With this configuration, the relay station functions as a wireless communication terminal when communicating with the base station, and can handle the relay station like the wireless communication terminal.

  In order to solve the above problems, another exemplary configuration of the present invention is a relay station capable of relaying communication between a wireless communication terminal and a base station, and relays communication between the wireless communication terminal and the base station. The communication quality acquisition unit for acquiring communication quality in communication between the local station and the wireless communication terminal, and whether the communication between the local station and the wireless communication terminal is interfered based on the acquired communication quality. An interference determination unit that determines whether or not, in order to prompt the handover to the wireless communication terminal that is communicating with the base station when it is determined that interference is received, interference information including that interference is received, An interference notification unit that notifies a base station and other base stations adjacent to the base station.

  When it is determined that the communication between the local station (relay station) and the wireless communication terminal is interfered, the interference information including the interference is communicated with the other wireless communication terminal to be interfered. In order to notify not only the current base station, but also other base stations adjacent to the base station, it is urged to make sure to establish a communication with the local station by handing over to another radio communication terminal subject to interference. Can do. Thereby, it becomes possible for the radio communication terminal receiving interference and another radio communication terminal (interference target) causing the interference to communicate with the same relay station. Therefore, no carrier wave having the same frequency is assigned, and interference can be avoided.

  In order to solve the above problems, another typical configuration of the present invention is a relay station capable of relaying communication between its own station and a wireless communication terminal and a base station that communicates with another wireless communication terminal, An interference receiving unit that receives interference information indicating that communication between the relay station and the wireless communication terminal is interfered, and another wireless communication terminal that is communicating with the local station when the interference information is received to the relay station A handover information transmission unit for transmitting handover information for instructing a handover of the mobile station, and a handover execution unit for executing a handover from the local station to the relay station in response to a handover request from another wireless communication terminal. It is characterized by.

  With this configuration, another radio communication terminal (interference target) that is causing interference can be handed over to a relay station that is communicating with the radio communication terminal receiving the interference. Therefore, no carrier wave having the same frequency is assigned, and interference can be avoided. In addition, after handover, communication with the relay station is performed with low transmission power, so even if the frequency of the carrier wave used by the other wireless communication terminal and the wireless communication terminal is adjacent, it interferes with each other It is possible to reduce the possibility.

  When the base station receives interference information, the base station extracts another wireless communication terminal that is communicating with the local station using a carrier having the same frequency as or near to the frequency of the carrier included in the interference information. The information processing apparatus may further include an extraction unit, and the handover information transmission unit may transmit the handover information to another wireless communication terminal extracted by the carrier terminal extraction unit.

  With such a configuration, it is possible to limit the radio communication terminals that are to be handed over by frequency, thereby reducing the load on the handover information transmitting unit and suppressing unnecessary handover.

  The base station further includes a base station power acquisition unit that intermittently acquires transmission power information including transmission power of other wireless communication terminals communicating with the own station, and the handover information transmission unit acquires the acquired transmission power information. Based on the above, handover information may be transmitted to other wireless communication terminals.

  The neighborhood of the relay station can be regarded as having a long distance from the base station. Therefore, there is a high possibility that a radio communication terminal that is far from the base station, that is, has a large transmission power, causes interference. In the present invention, it is possible to limit the wireless communication terminals targeted for handover by transmission power, and it is possible to reduce the load on the handover information transmission unit and suppress unnecessary handover.

  The base station further communicates with its own station using an antenna having an adaptive array function, a relay direction obtaining unit that obtains relay station direction information indicating the direction of the relay station using the adaptive array function, and an adaptive array function. A terminal direction acquisition unit that acquires terminal direction information indicating the direction of other wireless communication terminals in the handover information transmitting unit, the handover information transmission unit is handed over to other wireless communication terminals in a direction substantially equal to the direction of the relay station May be sent.

  With this configuration, it is possible to limit the wireless communication terminals that are to be handed over in the direction from the base station, thereby reducing the load on the handover information transmitting unit and suppressing unnecessary handover.

  In order to solve the above-described problem, another exemplary configuration of the present invention includes a wireless communication terminal, a base station capable of wireless communication with the wireless communication terminal, and relay communication between the wireless communication terminal and the base station. A wireless communication system including a relay station capable of relaying communication quality between the local station and the wireless communication terminal when the relay station relays communication between the wireless communication terminal and the base station. When it is determined that the communication quality acquisition unit to be acquired, the interference determination unit that determines whether or not the communication between the local station and the wireless communication terminal receives interference based on the acquired communication quality, and interference In addition, an interference notification unit that notifies the base station of interference information including interference is received in order to prompt the wireless communication terminal that is communicating with the base station to perform handover. Interference receiving unit that receives and interference information received In response to a handover request from another wireless communication terminal, a handover information transmitting unit for transmitting handover information for instructing another wireless communication terminal communicating with the local station to perform handover to the relay station. A handover execution unit that executes a handover from the station to the relay station.

  In order to solve the above problems, another exemplary configuration of the present invention is capable of relaying communication between a wireless communication terminal, a base station capable of wireless communication with the wireless communication terminal, and communication between the wireless communication terminal and the base station. A wireless communication method using a relay station, and when the relay station relays communication between the wireless communication terminal and the base station, the relay station acquires communication quality in communication between the local station and the wireless communication terminal. Based on the acquired communication quality, it is determined whether the communication between the own station and the wireless communication terminal is subject to interference, and when it is determined that the interference is received, the wireless communication communicating with the base station In order to prompt the terminal to perform handover, the base station is notified of interference information including that it is receiving interference, and when the base station receives the interference information, the base station notifies other wireless communication terminals that are communicating with the local station. Handover information for instructing handover to the relay station And Shin, in response to the handover request from another wireless communication terminal, and executes the handover to the relay station from the own station.

  The above-described components based on the technical idea of the relay station and the description thereof can be applied to the base station, the wireless communication system, and the wireless communication method.

  As described above, according to the relay station of the present invention, interference with the radio communication terminal that communicates with the relay station can be achieved by performing handover and handover of the radio communication terminal that causes interference. It becomes possible to suppress.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  A wireless communication terminal represented by a PHS terminal, a mobile phone, or the like constructs a broadband wireless communication system with a plurality of base stations arranged at a predetermined interval, and communicates with other wireless communication terminals and communication through this wireless communication system. Communicate with servers on the network.

  Here, in order to facilitate understanding of the following embodiments, a schematic configuration of a wireless communication system will be described first, and then specific operations of a wireless communication terminal, a base station, and a relay station will be described. Here, wireless communication such as a mobile phone, a PHS terminal, a notebook personal computer, a PDA (Personal Digital Assistant), a digital camera, a music player, a car navigation system, a portable TV, a game device, a DVD player, a remote controller, etc. Various possible electronic devices can be used.

(First embodiment: wireless communication system 100)
FIG. 1 is a block diagram showing a schematic configuration of a wireless communication system according to the present embodiment. The wireless communication system 100 includes a wireless communication terminal 110 (110A, 110B, 110C), a base station 120 (120A, 120B), a relay station 130, an ISDN (Integrated Services Digital Network) line, the Internet, a dedicated line, and the like. The communication network 140 and the relay server 150 are configured.

  In such a wireless communication system 100, when a user connects a communication line from his / her own wireless communication terminal 110A to another wireless communication terminal 110B, the wireless communication terminal 110A wirelessly connects to a base station 120A within a communicable range. Make a request. The base station 120A that has received the wireless connection request requests the relay server 150 to establish a communication connection with the communication partner (the wireless communication terminal 110B) via the communication network 140, and the relay server 150 determines the position of the other wireless communication terminal 110B. With reference to the registration information, the base station 120B within the radio communication range of the other radio communication terminal 110B is selected to secure a communication path between the base station 120A and the base station 120B, and the radio communication terminal 110A and the radio communication terminal 110B Establish communication.

  At this time, when a high-frequency band of 2.5 GHz or higher in a next-generation high-speed wireless communication system such as WiMAX is used as the wireless communication system, the wraparound of radio waves is suppressed. The possibility of being out of service is increased when it is located in the building 160, that is, indoors. Therefore, in the present embodiment, the wireless communication terminal 110 is located indoors by fixing the relay station 130 that relays the base station 120 and the wireless communication terminal 110 to the boundary between the indoor and the outdoor such as the window of the building 160. Even in this case, communication with the base station 120 can be performed stably. That is, the wireless communication terminal 110 according to the present embodiment can communicate with both the relay station 130 and the base station 120.

  However, there are both a wireless communication terminal 110A communicating with the relay station 130 and a wireless communication terminal 110C directly communicating with the base station 120 in the vicinity of the relay station 130, both (110A and 110C). May be interfered with either or both of communication between the relay station 130 and the wireless communication terminal 110A and / or communication between the base station 120 and the wireless communication terminal 110C.

  Here, it is assumed that the wireless communication terminal 110 </ b> A communicating with the relay station 130 and the wireless communication terminal 110 </ b> C directly communicating with the base station 120 are in the vicinity of the relay station 130. Under such circumstances, radio wave conditions between the wireless communication terminal 110A and the relay station 130 are expected to be good, and thus the wireless communication terminal 110A can communicate with the relay station 130 with a small transmission power. On the other hand, the location where the relay station 130 is installed is often difficult to receive radio waves from the base station 120, such as being far away from the base station 120, and the wireless communication terminal 110C is located in the vicinity of the relay station 130. That is, it is located in a place where the radio wave environment is bad such as a place far from the base station 120.

  Therefore, the wireless communication terminal 110C communicates with the base station 120 with significantly higher transmission power than the wireless communication terminal 110A. In this case, when the frequencies of the carrier wave used by the wireless communication terminal 110A and the relay station 130 and the carrier wave used by the wireless communication terminal 110C and the base station 120 are equal or adjacent to each other, the transmission power There is a possibility that the wireless communication terminal 110C having a high frequency may cause interference across the frequency direction to the wireless communication terminal 110A having a low transmission power.

  Therefore, in the present embodiment, by interfering with the radio communication terminal 110C that causes interference and performing an appropriate communication connection, it is possible to suppress interference with the radio communication terminal 110A that communicates with the relay station 130. Hereinafter, the wireless communication terminal 110, the base station 120, and the relay station 130 that are components of the wireless communication system 100 will be described individually.

(Wireless communication terminal 110)
FIG. 2 is a functional block diagram illustrating a hardware configuration of the wireless communication terminal according to the present embodiment, and FIG. 3 is a perspective view illustrating an appearance of the wireless communication terminal. The wireless communication terminal 110 includes a terminal control unit 210, a terminal memory 212, a display unit 214, an operation unit 216, a voice input unit 218, a voice output unit 220, and a terminal wireless communication unit 222. The

  The terminal control unit 210 manages and controls the entire wireless communication terminal 110 using a semiconductor integrated circuit including a central processing unit (CPU). The terminal control unit 210 also performs a call function, a mail transmission / reception function, an imaging function, a music playback function, and a TV viewing function using the program in the terminal memory 212. The terminal control unit 210 also functions as a handover request unit 230 that requests a handover in accordance with a handover instruction from the base station 120. The terminal memory 212 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores a program processed by the terminal control unit 210, audio data, and the like.

  The display unit 214 includes a liquid crystal display, an EL (Electro Luminescence) display, etc., and is stored in the terminal memory 212 or provided from an application relay server (not shown) via the communication network 140, An application GUI (Graphical User Interface) can be displayed. The operation unit 216 includes switches such as a keyboard, a cross key, and a joystick, and receives a user operation input.

  The voice input unit 218 includes voice recognition means such as a microphone, and converts a user voice input during a call or the like into an electrical signal that can be processed in the wireless communication terminal 110. The audio output unit 220 includes a speaker, and converts the audio signal of the other party received by the wireless communication terminal 110 into audio and outputs it. The voice output unit 220 can also output a ringtone, an operation sound of the operation unit 216, an alarm sound, and the like.

  The terminal wireless communication unit 222 performs wireless communication with the base station 120 or the relay station 130 in the communication network 140. Various wireless communication methods such as OFDM and OFDMA can be applied to the terminal wireless communication unit 222.

(Base station 120)
FIG. 4 is a block diagram showing a schematic configuration of the base station according to the present embodiment. The base station 120 includes a base station control unit 310, a base station memory 312, a base station wireless communication unit 314, a base station wired communication unit 316, and a plurality of antennas 318 for performing an adaptive array function. Is done.

  The base station control unit 310 manages and controls the entire base station 120 using a semiconductor integrated circuit including a central processing unit (CPU). The base station memory 312 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores a program processed by the base station control unit 310.

  The base station wireless communication unit 314 establishes wireless communication with the wireless communication terminal 110 or the relay station 130 using, for example, the OFDMA method, and adapts the modulation method according to the communication state with the wireless communication terminal 110 or the relay station 130. (Adaptive modulation). In addition, the base station radio communication unit 314 executes handover between the own station (base station 120) and the relay station 130 in response to a handover request from the radio communication terminal 110. The base station wired communication unit 316 can be connected to various servers including the relay server 150 via the communication network 140.

  In this embodiment, the base station control unit 310 includes an interference reception unit 320, a carrier terminal extraction unit 322, a handover information transmission unit 324, a base station power acquisition unit 326, a relay direction acquisition unit 328, a terminal direction acquisition unit 330, a handover It also functions as the execution unit 332.

  The interference receiving unit 320 receives, via the base station wireless communication unit 314, interference information transmitted from the relay station 130 to the effect that the communication between the relay station 130 and the wireless communication terminal 110 has received interference.

  When the interference reception unit 320 receives the interference information transmitted by the relay station 130, the carrier terminal extraction unit 322 uses the carrier of the same frequency as or near to the frequency of the carrier included in the interference information. The other wireless communication terminal 110 in communication with the base station 120) is extracted.

  When the interference receiving unit 320 receives interference information from the relay station 130, the handover information transmitting unit 324 performs handover to the relay station 130 to another wireless communication terminal 110 that is communicating with the own station (base station 120). Handover information for instructing is transmitted. At this time, the handover information transmitting unit 324 can also transmit the handover information only to the other wireless communication terminal 110 extracted by the carrier terminal extracting unit 322.

  The configuration in which the handover information transmission unit 324 transmits the handover information to the other radio communication terminals 110 extracted by the carrier terminal extraction unit 322 can limit the radio communication terminals 110 that are to be handed over by frequency. It is possible to reduce the load on the transmission unit 324 and suppress unnecessary handover.

  The base station power acquisition unit 326 acquires transmission power information including the transmission power of the other wireless communication terminal 110 communicating with the own station (base station 120) from the relay station 130 intermittently, that is, every predetermined time.

  Further, in the present embodiment, the handover information transmission unit 324 includes other wireless communication terminals 110 whose transmission power acquired by the base station power acquisition unit 326 exceeds a predetermined value among the other wireless communication terminals 110 extracted by the carrier terminal extraction unit 322. It is also possible to send handover information to the communication terminal 110.

  The vicinity of the relay station 130 can be regarded as having a long distance from the base station 120. Therefore, there is a high possibility that the radio communication terminal 110 that is far from the base station 120, that is, has a large transmission power, causes interference. In the present embodiment, it is possible to limit the radio communication terminal 110 that is a target of handover by transmission power, and it is possible to reduce the load on the handover information transmission unit 324 and suppress unnecessary handover.

  The relay direction acquisition unit 328 acquires relay station direction information indicating the direction of the relay station 130 using an adaptive array function performed using a plurality of antennas 318.

  The terminal direction acquisition unit 330 acquires terminal direction information indicating the direction of another wireless communication terminal 110 in communication with the local station (base station 120) using an adaptive array function performed using a plurality of antennas 318. .

  In this embodiment, the handover information transmission unit 324 is another wireless communication terminal whose transmission power acquired by the base station power acquisition unit 326 exceeds a predetermined value among the other wireless communication terminals 110 extracted by the carrier terminal extraction unit 322. 110, and another wireless communication terminal in a direction substantially equal to the direction of the relay station 130 based on the relay station direction information acquired by the relay direction acquisition unit 328 and the terminal direction information acquired by the terminal direction acquisition unit 330 The handover information may be transmitted to 110.

  With this configuration, it is possible to limit the wireless communication terminals 110 that are to be handed over in the direction from the base station 120, thereby reducing the load on the handover information transmitting unit 324 and suppressing unnecessary handovers. .

  In this embodiment, the handover information transmission unit 324 transmits other handover information based on the information acquired by the carrier terminal extraction unit 322, the base station power acquisition unit 326, the relay direction acquisition unit 328, and the terminal direction acquisition unit 330. Although the wireless communication terminal 110 has been determined, the present invention is not limited to this, and any one or a combination of the carrier terminal extraction unit 322, the base station power acquisition unit 326, the relay direction acquisition unit 328, and the terminal direction acquisition unit 330 is used. You can also

  For example, when determining another radio communication terminal 110 based on information acquired by the carrier terminal extraction unit 322 and the base station power acquisition unit 326, the handover information transmission unit 324 transmits the transmission power acquired by the base station power acquisition unit 326. The handover information may be transmitted to the wireless communication terminal 110 having the maximum transmission power or to the wireless communication terminals 110 having the maximum transmission power up to a predetermined number.

  In response to a handover request from another radio communication terminal 110, the handover execution unit 332 executes a handover from the own station (base station 120) to the relay station 130.

  As described above, according to the base station 120 according to the present embodiment, the radio communication terminal 110 receiving the interference is communicating with another radio communication terminal 110 (interference target) that is causing the interference. The relay station 130 can be handed over. Therefore, no carrier wave having the same frequency is assigned, and interference can be avoided. Further, after the handover, communication with the relay station 130 is performed with a small transmission power, so that the transmission powers of the radio communication terminal 110 and the other radio communication terminals 110 are substantially equal. Therefore, even if the frequencies of the carrier waves used by the other wireless communication terminals 110 and the wireless communication terminals 110 communicating with the relay station 130 are adjacent to each other, the possibility of mutual interference can be reduced. It becomes possible.

(Relay station 130)
FIG. 5 is a block diagram showing a schematic configuration of the relay station according to the present embodiment. The relay station 130 includes a relay station control unit 410, a relay station memory 412, and a relay station wireless communication unit 414.

  The relay station control unit 410 manages and controls the entire relay station 130 by a semiconductor integrated circuit including a central processing unit (CPU). The relay station memory 412 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores a program processed by the relay station control unit 410. The relay station radio communication unit 414 includes a terminal communication unit 416 that communicates with the radio communication terminal 110, and a base station communication unit 418 that communicates with the base station 120, and the radio communication terminal 110, the base station 120, and the like. Relay. Accordingly, the relay station 130 functions as a wireless communication terminal when communicating with the base station 120, and the base station 120 can handle the relay station 130 in the same manner as the wireless communication terminal. The terminal communication unit 416 can also adaptively change the modulation scheme according to the communication state with the wireless communication terminal 110 (adaptive modulation).

  In this embodiment, the relay station control unit 410 includes a communication quality acquisition unit 420, an interference determination unit 422, an interference notification unit 424, a relay power acquisition unit 426, a call number determination unit 428, a terminal extraction unit 430, and an instruction notification unit 432. Also works.

  When the communication between the wireless communication terminal 110 and the base station 120 is relayed, the communication quality acquisition unit 420 acquires the communication quality in the communication between the own station (relay station 130) and the wireless communication terminal 110. For example, in this embodiment, the communication quality in communication with the wireless communication terminal 110A is acquired.

  In this embodiment, the communication quality acquisition unit 420 acquires RSSI and CINR as communication quality. By using RSSI and CINR, it is possible to appropriately grasp the communication quality. Here, although the communication quality acquisition unit 420 acquires RSSI and CINR as communication quality, the communication quality can be properly grasped even if RSSI and SINR are acquired.

  The interference determination unit 422 determines whether communication between the local station (the relay station 130) and the wireless communication terminal 110 is interfered based on the RSSI and CINR as the communication quality acquired by the communication quality acquisition unit 420. To do. In the present embodiment, the interference determination unit 422, when SINR / RSSI as a relationship between SINR and RSSI, or CINR / RSSI as a relationship between CINR and RSSI satisfies a predetermined condition, for example, below a predetermined value, It is determined that the communication between the own station (relay station 130) and the wireless communication terminal 110 is subject to interference. Specifically, the interference determination unit 422 according to the present embodiment determines that communication between the own station (relay station 130) and the wireless communication terminal 110 is receiving interference when CINR / RSSI is equal to or less than a predetermined value. . For example, in the present embodiment, it is determined whether or not communication with the wireless communication terminal 110A is subject to interference.

  RSSI is the radio field intensity of all received radio waves, and CINR is the ratio between the desired carrier and noise including interference. Therefore, if CINR / RSSI is equal to or less than a predetermined value, it can be reliably determined whether or not interference has occurred.

  When the communication quality acquisition unit 420 acquires RSSI and SINR as communication quality, the interference determination unit 422 determines that the local station (relay station 130) and the wireless communication terminal when the SINR / RSSI is equal to or less than a predetermined value. It is determined that the communication with 110 is receiving interference. Since SINR is a ratio between a desired signal and noise including interference, it is determined whether or not communication with the wireless communication terminal 110 is receiving interference in the same manner as in the case where the presence / absence of interference is determined using CINR / RSSI. It becomes possible.

  When the interference determination unit 422 determines that the communication with the wireless communication terminal 110 has received interference, the interference notification unit 424 notifies the wireless communication terminal 110 that is communicating with the base station 120 of the own station (relay station 130). In order to facilitate handover to the base station 120, the base station 120 is notified of interference information including the fact that interference has been received via the base station communication unit 418. For example, in the present embodiment, when the interference determination unit 422 determines that the communication with the wireless communication terminal 110A has received interference, the wireless communication terminal 110C communicating with the base station 120 communicates with its own station (relay station 130). The base station 120 is notified of interference information including the fact that it is receiving interference via the base station communication unit 418.

  In the present embodiment, the interference notification unit 424 notifies the base station 120 of the interference information including the frequency and time slot of the carrier wave used for communication between the wireless communication terminal 110 and the own station (relay station 130).

  As a result, another wireless communication terminal 110 that uses a frequency that is substantially the same as or adjacent to (or in the vicinity of) the carrier wave of the wireless communication terminal 110 that is communicating with the relay station 130 is used as the local station (relay). The base station 120 can be notified to be handed over to the station 130). Therefore, it is possible to prompt only another wireless communication terminal 110 that is highly likely to cause interference to the wireless communication terminal 110 to be handed over to the own station (relay station 130), and to efficiently avoid interference. Become.

  Further, another wireless communication terminal 110 using a time slot that is the same as or adjacent to the time slot used by the wireless communication terminal 110 communicating with the relay station 130 is handed over to the own station (relay station 130). To the base station 120. Therefore, in the case of a wireless communication method using the TDMA method, a handover to the own station (relay station 130) is preferably performed only to another wireless communication terminal 110 that is likely to be interfering with the wireless communication terminal 110. It is possible to prompt.

  The relay power acquisition unit 426 acquires transmission power information including the transmission power of the wireless communication terminal 110 in communication with the own station (relay station 130). For example, in this embodiment, transmission power information including the transmission power of the wireless communication terminals 110A and 110C is acquired.

  The call number determination unit 428 exceeds a predetermined number of calls in communication with the local station (relay station 130) when there is a communication connection request from the wireless communication terminal 110 that is not communicating with the local station (relay station 130). It is determined whether or not. Here, the call is, for example, a channel, a PRU (Physical Resource Unit) in WiMAX, or the like.

  The terminal extraction unit 430 selects a predetermined wireless communication terminal 110 based on the transmission power information acquired by the relay power acquisition unit 426 when the call number determination unit 428 determines that the number of calls in communication exceeds the predetermined number. Extract. For example, in this embodiment, the wireless communication terminal 110C is extracted.

  The instruction notification unit 432 notifies the base station 120 via the base station communication unit 418 of the instruction information that prompts the wireless communication terminal 110 extracted by the terminal extraction unit 430 to perform a handover. Here, the instruction notifying unit 432 transmits to the base station 120 a command that prompts the wireless communication terminal 110 extracted by the terminal extracting unit 430 to perform a handover.

  When the relay station 130 is communicating with a call exceeding a predetermined number by the configuration including the relay power acquisition unit 426, the call number determination unit 428, the terminal extraction unit 430, and the instruction notification unit 432 described above, the relay station 130 It is possible to establish appropriate wireless communication by preferentially handing over the wireless communication terminal 110 that can be estimated that the distance to the other base station is long, that is, the distance to other base stations is short and the effect of handover is easy to obtain. Thus, interference with the wireless communication terminal 110 that communicates with the relay station 130 can be suppressed.

  As described above, according to the relay station 130 according to the present embodiment, when it is determined that the wireless communication terminal 110 communicating with the local station (relay station 130) is receiving interference, the relay station 130 is subject to interference. It is possible to prompt the other wireless communication terminal 110 to perform handover and establish communication with the own station (relay station 130). As a result, the radio communication terminal 110 that is receiving interference and the other radio communication terminal 110 (interference target) that is causing the interference can communicate with the same relay station 130. Therefore, no carrier wave having the same frequency is assigned, and interference can be avoided.

  Furthermore, since the other wireless communication terminal 110 (interference target) that is causing interference can be handed over to a nearby relay station 130 as compared with the base station 120 that is performing communication, a favorable communication environment can be obtained. Therefore, power consumption can be suppressed. Therefore, even if the carrier frequencies used by the other wireless communication terminals 110 and 110 are adjacent to each other, the other wireless communication terminals 110 and the wireless communication terminals 110 communicate with each other with substantially the same transmission power. Therefore, the possibility of mutual interference can be reduced.

(Wireless communication method)
Next, a wireless communication method for performing wireless communication using the wireless communication terminal 110, the base station 120, and the relay station 130 will be described in detail.

  FIG. 6 is a sequence diagram showing processing of the wireless communication method according to the present embodiment. For example, in the present embodiment, description will be given by taking the wireless communication terminal 110A communicating with the relay station 130 and another wireless communication terminal 110C communicating with the base station 120.

  Another wireless communication terminal 110C located in the vicinity of relay station 130 is communicating with base station 120 (S500: communication step), and relay station 130 relays communication between wireless communication terminal 110A and base station 120. In the case of (S502: communication relay step), the communication quality acquisition unit 420 of the relay station 130 acquires the communication quality in communication between the local station (relay station 130) and the wireless communication terminal 110A (S504: communication quality acquisition step). .

  Based on the communication quality acquired in the communication quality acquisition step S504, the interference determination unit 422 of the relay station 130 determines whether the communication between the local station (relay station 130) and the wireless communication terminal 110A is subject to interference. (S506: Interference determination step) When it is determined that interference is received, interference information including interference is received in order to prompt other wireless communication terminals 110C communicating with the base station 120 to perform handover. To the base station 120 (S508: interference information notification step).

  When the interference receiving unit 320 of the base station 120 receives the interference information (S510: interference information receiving step), the handover information transmitting unit 324 among other wireless communication terminals 110 that are communicating with the own station (base station 120) Based on the information acquired by the carrier terminal extraction unit 322, the base station power acquisition unit 326, the relay direction acquisition unit 328, and the terminal direction acquisition unit 330, the other wireless communication terminal 110C that transmits the handover information is selected (S512: transmission). First selection step).

  Handover information for instructing handover to the relay station 130 is transmitted to the other radio communication terminal 110C selected in the transmission destination selection step S512 (S514: handover information transmission step).

  When the other wireless communication terminal 110C communicating with the base station 120 receives the handover information (S516: handover information receiving step), the handover request unit 230 of the other wireless communication terminal 110C transmits a handover request to the base station 120 ( S518: Handover request step).

  The handover execution unit 332 of the base station 120 executes a handover from the own station (base station 120) to the relay station 130 in response to a handover request from another radio communication terminal 110C (S520: handover process execution step). Communication establishment between the relay station 130 and the other wireless communication terminal 110C is performed (S522: communication establishment step).

  As described above, also in the wireless communication method according to the present embodiment, when it is determined that the communication between the relay station 130 and the wireless communication terminal 110 has received interference, the other wireless communication terminal 110 to be interfered with is determined. To establish a communication with the relay station 130. As a result, the radio communication terminal 110 that is receiving interference and the other radio communication terminal 110 (interference target) that is causing the interference can communicate with the same relay station 130. Therefore, after the handover, communication with the relay station 130 is performed with a small transmission power, so that the transmission powers of the radio communication terminal 110 and the other radio communication terminals 110 are substantially equal. As a result, even if the frequencies of the carrier waves used by the other wireless communication terminal 110 and the wireless communication terminal 110 are adjacent to each other, it is possible to reduce the possibility of mutual interference.

(Second Embodiment)
In the first embodiment described above, interference with the wireless communication terminal 110 that communicates with the relay station 130 is suppressed by handing over another wireless communication terminal 110 that causes interference and performing an appropriate communication connection. The wireless communication system 100, the base station 120, the relay station 130, and the wireless communication method that can be used have been described.

  However, since the relay station 130 assists the communication between the radio communication terminal 110 and the base station 120, compared to the base station 120, the relay station 130 or the call The number is limited. Therefore, when the relay station 130 actively performs communication with another wireless communication terminal 110 that is an interference target, communication with the wireless communication terminal 110 located in a predetermined area to which the relay station 130 should originally be connected is limited. It might be. For example, in the present embodiment, communication with the wireless communication terminal 110 located indoors where the relay station 130 is installed may be restricted.

  In addition, the relay station 130 generally moves in the mobile body or in the building in order to efficiently relay communication between the wireless communication terminal 110 located in the mobile body or in the building and the base station 120. It is often installed at the boundary between the outside of the body or the outside of the building (such as near the window of the building 160). When the relay station 130 is installed near the window, the line of sight is often good, so another wireless communication terminal 110 located outside the moving body or outside the building is connected, and again in the moving body or inside the building. Communication with the other wireless communication terminal 110 is restricted.

  Therefore, in this embodiment, it is determined whether or not a wireless communication terminal requesting establishment of communication with a relay station is in a predetermined area, and a wireless communication terminal located in the predetermined area is preferentially connected to perform relaying. A relay station and a wireless communication method capable of reliably accomplishing the original purpose of the station will be described.

(Relay station 600)
FIG. 7 is a block diagram showing a schematic configuration of the relay station according to the present embodiment. Components that are substantially the same as those of the relay station 130 described above are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 7, the relay station 600 includes a relay station control unit 610, a relay station memory 612, a relay station wireless communication unit 614, and a plurality of antennas 616 for performing an adaptive array function. The relay station wireless communication unit 614 includes a terminal communication unit 620 that communicates with the wireless communication terminal 110 and a base station communication unit 622 that communicates with the base station 120, as in the first embodiment described above. The wireless communication terminal 110 and the base station 120 are relayed.

  In this embodiment, the relay station memory 612 that functions as a plurality of antennas 616 and a direction holding unit 630 to be described later is provided integrally, but is not limited thereto, and may be provided separately.

  The relay station control unit 610 manages and controls the entire relay station 600 using a semiconductor integrated circuit including a central processing unit (CPU). The relay station memory 612 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores a program processed by the relay station control unit 610. In the present embodiment, the relay station memory 612 also functions as the direction holding unit 630. The direction holding unit 630 holds in advance information for specifying the direction indicating the direction of the predetermined area and the direction indicating the outside of the predetermined area. For example, in the present embodiment, the direction holding unit 630 includes a direction indicating a direction in a building where the relay station 600 is installed or a mobile body where the relay station 600 is installed as a predetermined area. Information for specifying a direction indicating the outside of the building where the relay station 600 is installed outside the predetermined area or the outside of the moving body where the relay station 600 is installed is stored in advance.

  In the present embodiment, the relay station control unit 610 includes a communication quality acquisition unit 420, an interference determination unit 422, an interference notification unit 424, a relay power acquisition unit 426, a terminal extraction unit 430, an instruction notification unit 432, an inside / outside determination unit 632, a call It also functions as the number determination unit 634.

  When there is a communication connection request from the wireless communication terminal 110, the inside / outside determination unit 632 causes the wireless communication terminal 110 that has made the communication connection request to be located in a predetermined area, that is, in the building where the relay station 600 is installed. It is determined whether or not there is. The inside / outside determination unit 632 also determines whether or not there is a wireless communication terminal 110 located outdoors (outside a predetermined area) among the wireless communication terminals 110 in which communication is established.

  In the present embodiment, the inside / outside determination unit 632 holds the direction of the wireless communication terminal 110 having a communication connection request derived by the adaptive array function performed using the plurality of antennas 616 held in the direction holding unit 630. Wireless communication for which there was a communication connection request depending on whether or not it is included in a direction indicating a predetermined area (indoor) based on information specifying a direction indicating a predetermined area (indoor) and a direction indicating a predetermined area (outdoor) It is determined whether or not the terminal 110 is located in a predetermined area (indoor).

  By using the adaptive array function using the plurality of antennas 616, the inside / outside determination unit 632 can accurately derive the direction of the wireless communication terminal 110. The relay station 600 simply compares the direction derived by the adaptive array function with the direction indicating the predetermined area (indoor) held in advance and the direction indicating the predetermined area (outdoor). It is possible to easily and reliably determine whether the area is indoor (indoor).

  Further, the relay station 600 relays communication between the radio communication terminal 110 and the base station 120 located in a place where it is difficult to directly communicate with the base station 120 such as in a mobile body or indoors of a building. It is often installed near the window of a building 160 or the like, that is, at the boundary between indoor and outdoor. Accordingly, if the installation location of the relay station 600, the direction indicating the indoor and the direction indicating the outdoor with respect to the installation location are held in advance, even if the distance from the relay station 600 to the wireless communication terminal 110 is unknown, If the direction of the communication terminal 110 can be derived, it can be easily determined whether it is indoor.

  For example, the terminal communication unit 620 described above in the present embodiment gives priority to establishment of communication with the wireless communication terminal 110D that the inside / outside determination unit 632 determines to be in a predetermined area (indoor).

  When there is a communication connection request from the wireless communication terminal 110, the call number determination unit 634 determines whether or not the number of calls in communication with the own station (relay station 600) exceeds the first predetermined number.

  In this embodiment, the terminal communication unit 620 determines that the number of calls that the call number determination unit 634 is communicating with the local station (relay station 600) is the first predetermined number, for example, 70% of the allowable number of calls of the wireless communication terminal 110. When it is determined that the number of the wireless communication terminal 110 exceeds the wireless communication terminal 110, the internal / external determination unit 632 rejects establishment of communication with the wireless communication terminal 110 determined not to be in the predetermined area (indoor). For example, in the present embodiment, establishment of communication with the wireless communication terminal 110E is rejected.

  Thereby, when communicating with the number of calls exceeding the first predetermined number, it is possible to reject establishment of communication of the wireless communication terminal 110D that is not in the predetermined area (indoor), that is, outside the predetermined area (outdoor). . In other words, when communicating with a number of calls exceeding the first predetermined number, it is possible to permit communication only with the wireless communication terminal 110C located in a predetermined area (indoor). Therefore, it is possible to prevent the number of wireless communication terminals 110 that can communicate in relay station 600 from being limited by wireless communication terminals 110 located outside a predetermined area (outdoors).

  In the present embodiment, the call number determination unit 634 further includes a second predetermined number of calls in communication with the own station (relay station 600) that is larger than the first predetermined number, for example, 95% of the allowable number of calls of the wireless communication terminal 110. It is also determined whether or not it exceeds.

  When the number-of-calls determination unit 634 determines that the number of calls in communication with the local station (relay station 600) exceeds the second predetermined number, the terminal communication unit 620 uses the internal / external determination unit 632 to determine a predetermined area ( The wireless communication terminal 110 that is determined not to be indoors is urged to perform handover with another base station.

  As a result, in the case where communication with the number of calls exceeding the second predetermined number that is larger than the first predetermined number is being established (during communication), the wireless communication terminal 110 that is in the middle of communication is out of a predetermined area (outdoor). Communication between the communication terminal 110 and the relay station 600 can be excluded. Therefore, the relay station 600 can secure the number of calls that can be communicated by the number of calls outside the predetermined area (outdoor) that has been disconnected, and assign this to the wireless communication terminals 110 in the predetermined area (indoor). be able to.

  As described above, according to the relay station 600 according to the present embodiment, it is determined whether or not the wireless communication terminal 110 requesting establishment of communication with the own station (relay station 600) is in a predetermined area (indoor). In addition, the wireless communication terminal 110 located in a predetermined area (indoor) is preferentially connected, so that the original purpose of the relay station can be reliably achieved.

(Wireless communication method)
Next, a wireless communication method for performing wireless communication using the wireless communication terminal 110, the base station 120, and the relay station 600 will be described in detail.

  FIG. 8 is a flowchart showing processing of the wireless communication method according to the present embodiment.

  When there is a communication connection request from the wireless communication terminal 110 (YES in S700: communication connection reception step), the number of calls in communication with the local station (relay station 600) by the call number determination unit 634 is the allowable call of the relay station 600. It is determined whether the number is equal to or less than the number (S702: allowable call number determination step). If the number is equal to or less than the allowable number of calls (YES in S702), the number-of-calls determination unit 634 further determines that the number of calls in communication with the own station (relay station 600) is equal to or greater than the first predetermined number. It is determined whether or not the wireless communication terminal 110 attempting to establish the communication is outside a predetermined area (outside the building where the relay station is installed) (S704: inside / outside determination step).

  On the other hand, if the number of calls in communication with the own station (relay station 600) is the allowable number of calls of the relay station 600 in the allowable call number determination step S702, the communication establishment of the wireless communication terminal 110 attempting to establish the communication is established. Reject (S706: communication rejection step).

  In the inside / outside determination step S704, the number of calls in communication with the own station (relay station 600) is equal to or greater than the first predetermined number, and the wireless communication terminal 110 that the inside / outside determination unit 632 tries to establish the communication is in a predetermined area ( If it is not determined to be located indoors (NO in S704), communication is established (S708: communication establishment step).

  Furthermore, the call number determination unit 634 determines whether or not the number of calls in communication with the own station (relay station 600) exceeds the second predetermined number (S710: second predetermined number determination step), and the second predetermined number If the number is greater than or equal to the number (YES in S710), the terminal communication unit 620 is communicating with the own station (relay station 600) and performs a handover with another base station to the wireless communication terminal 110 outside the predetermined area (outdoors). The handover information to be urged is instructed (S712: handover instruction step).

  In the inside / outside determination step S704, the number of calls in communication with the own station (relay station 600) is equal to or more than the first predetermined number, and the wireless communication terminal 110 that the inside / outside determination unit 632 tries to establish the communication is in a predetermined area. If it is determined that it is located outside (outdoor) (YES in S704), communication is rejected (S714: communication rejection step).

  As described above, according to the wireless communication method according to the present embodiment, communication can be preferentially established with the wireless communication terminal 110 located in a predetermined area (indoor). Therefore, the relay station 600 is occupied by the wireless communication terminal 110 located outside the predetermined area (outdoors), and serves as a device that relays communication between the wireless communication terminal 110 and the base station 120 in the predetermined area (indoors). It is possible to avoid a situation where the original purpose of the relay station cannot be achieved.

(Other embodiments)
In the second embodiment described above, the direction of the wireless communication terminal 110 for which there was a communication connection request derived by the adaptive array function performed using the plurality of antennas 616 is a predetermined area held in the direction holding unit 630. Whether or not the wireless communication terminal 110 for which a communication connection request has been made is located in the predetermined area depending on whether it is included in the direction indicating the predetermined area based on the information specifying the direction indicating the direction and the direction indicating the outside of the predetermined area The configuration for determining whether or not is described.

  Here, a configuration is described in which it is possible to determine whether or not the wireless communication terminal 110 that has requested communication connection is located in a predetermined area (indoor) without a plurality of antennas 616 capable of performing the adaptive array function. To do.

(Relay station 800)
FIG. 9 is a block diagram for explaining another configuration of the relay station. Constituent elements that are substantially the same as those of the relay stations 130 and 600 described above are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 9, the relay station 800 includes a relay station control unit 610, a relay station memory 812 functioning as an area holding unit 822, and a relay station radio communication unit 814. 814 includes a terminal communication unit 820 that communicates with the wireless communication terminal 110 and a base station communication unit 622 that communicates with the base station 120, as in the first and second embodiments described above. The wireless communication terminal 110 and the base station 120 are relayed.

  The area holding unit 822 holds predetermined area information as a range of a predetermined area (inside the building where the relay station 800 is installed). For example, in the present embodiment, the relay station 800 is fixedly attached to the boundary between the indoor and outdoor areas such as the window of the building 160, so that the area holding unit 822 holds predetermined area information as an indoor range in advance. .

  FIG. 10 is an explanatory diagram for explaining an indoor range as a range of a predetermined region. As shown in FIG. 10A, when the relay station 800 is installed near a window, the indoor range may be a substantially semicircular range indicated by hatching in FIG. On the other hand, when the relay station 800 is installed at a substantially corner of the building 160, a hatched range in FIG. 10B can be an indoor range.

  At this time, the absolute position of the own station (relay station 800) may be obtained from GPS satellites by acquiring the position information of the own station (relay station 800). Register location information.

  In the present embodiment, the terminal communication unit 820 also functions as the position information receiving unit 824. The position information receiving unit 824 receives position information from the GPS satellite 830 acquired by the wireless communication terminal 110.

  In this embodiment, the inside / outside determination unit 632 stores the position of the wireless communication terminal 110 based on the position information of the wireless communication terminal 110 that has received the communication connection request received by the position information reception unit 824 in the area holding unit 822 in advance. It is determined whether the predetermined area information is within the indoor range.

  Thereby, it is determined whether or not the wireless communication terminal 110 is in a predetermined area (indoor) depending on whether or not the wireless communication terminal 110 is located in the range of the predetermined area (indoor) targeted by the own station (relay station 800). Can do.

  In addition, when the wireless communication terminal 110 is indoors, the position information from the GPS satellite 830 cannot be obtained, so the inside / outside determination unit 632 has received the position information by the position information receiving unit 824 before a predetermined time. It can also be determined whether or not the user is outdoors depending on whether or not.

  In relay station 850, inside / outside determination unit 632 is a predetermined area information in which the position of wireless communication terminal 110 based on the position information of wireless communication terminal 110 for which a communication connection request has been made is held in area holding unit 822 in advance. The wireless communication terminal 110 and the local station (relay) are obtained from the positional information received from the wireless communication terminal 110 and the positional information of the local station (relay station 800). When the distance to the station 800) is equal to or greater than a predetermined value, it can be determined that the vehicle is outdoors. At this time, the distance from the position of the relay station 850 to the outside of the building where the own station (relay station 800) is installed may be set as a predetermined value.

  As a result, depending on the distance between the relay station 800 (the local station) and the wireless communication terminal 110, it can be understood that the wireless communication terminal 110 cannot exist in a predetermined area (indoor), and can be determined easily and quickly. It is possible to determine whether the area is indoor (indoor).

(Relay station 850)
FIG. 11 is a block diagram for explaining still another configuration of the relay station. Constituent elements that are substantially the same as those of the relay stations 130, 600, and 800 described above are denoted by the same reference numerals and description thereof is omitted.

  The relay station 850 is configured to include two relay station GPS receivers 852 in addition to the components of the relay station 800. Here, the relay station 850 is installed in a mobile body including a vehicle on which a person can get on and off, such as an automobile, a bus, a train (train), a ship, and an aircraft.

  The relay station GPS receiving unit 852 receives position information from the GPS satellite 830. The predetermined area information held by the area holding unit 822 in the relay station 850 is determined based on the relative position with respect to the two relay station GPS receiving units 852.

  FIG. 12 is an explanatory diagram for explaining determination of predetermined area information based on a relative position with the relay station GPS receiver.

  As shown in FIG. 12, the relay station GPS receiver 852 (indicated by 852a and 852b in FIG. 12) of the relay station 850 includes a predetermined area (in the moving body) and a predetermined area (outside the moving body). Are installed on a substantially boundary line (indicated by a solid line in FIG. 12). For example, when the left side in FIG. 12 is a predetermined area (in the moving body) and the right side is outside the predetermined area (outside the moving body), the area holding unit 822 uses the two relay stations GPS as the predetermined area information. The position on the left side of the relay station GPS receiver 852a as viewed from the position relative to the receiver 852, that is, the position of the relay station GPS receiver 852b, is a predetermined area (in the moving body), and the right position is outside the predetermined area. The information that is (outside the moving body) is held.

  In this case, when the position information of the wireless communication terminal 110 received by the position information receiving unit 824 is the point 860, the inside / outside determination unit 632 indicates that the point 860 is the relay station GPS receiving unit as viewed from the position of the relay station GPS receiving unit 852b. Since it is located on the left side of 852a, it is determined to be a predetermined area (in the moving body). On the other hand, when the position information of the wireless communication terminal 110 received by the position information receiving unit 824 is the point 862, the point 860 is positioned on the right side of the relay station GPS receiving unit 852a as viewed from the position of the relay station GPS receiving unit 852b. Therefore, it is determined that it is outside the predetermined area (outside the moving body).

  Based on the relative position with respect to the two or more relay station GPS receivers 852 of the own station (relay station 850), the range of the predetermined area (in the moving body) targeted by the own station (relay station 850) described above. Therefore, the relay station 850 is installed in a moving body including a vehicle on which a person can get on and off such as an automobile, a bus, a train (train), a ship, an airplane, etc., and the absolute position in the moving body is constantly changing. Even in the case of a change, the range of the predetermined area (in the moving body) can be easily and reliably defined.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, it is possible to construct this wireless communication system by high-speed digital wireless communication (for example, WiMAX, next-generation PHS, etc.) using the OFDM method or OFDMA method. In this case, the wireless communication terminal or relay station uses the OFDM method. And a communication function corresponding to the OFDMA system.

  In the above-described embodiment, the relay station is fixed in the building, but is not limited thereto, and may be installed in a moving body. Here, the moving body refers to a vehicle on which a person can get on and off, such as an automobile, a bus, a train (train), a ship, an aircraft, and the like, and the predetermined area is the moving body.

  Further, in the above-described embodiment, it is a relay station that determines whether or not the wireless communication terminal is subject to interference, but the base station acquires communication quality from the relay station and the wireless communication terminal is subject to interference. It may be determined whether or not there is.

  In the above-described embodiment, when it is determined that the communication between the local station (relay station) and the wireless communication terminal is subject to interference, the other wireless communication terminal (interference target) that causes the interference is determined. Interference information is notified only to the base station that is communicating with the base station, but the interference information is notified to the base station that is communicating with other wireless communication terminals (interference targets), and further adjacent to the base station. The interference information may be notified to the other base station via the base station.

  Note that each step in the wireless communication method of the present specification does not necessarily have to be processed in time series in the order described in either or both of the sequence diagram and the flowchart, and may include processing in parallel or by a subroutine. Good.

  The present invention can be used for a relay station, a base station, a wireless communication system, and a wireless communication method capable of relaying communication between a wireless communication terminal and a base station.

1 is a block diagram showing a schematic configuration of a wireless communication system according to a first embodiment. It is a functional block diagram showing the hardware configuration of the wireless communication terminal according to the first embodiment. It is the perspective view which showed the external appearance of the radio | wireless communication terminal concerning 1st Embodiment. It is the block diagram which showed the schematic structure of the base station concerning 1st Embodiment. It is the block diagram which showed schematic structure of the relay station concerning 1st Embodiment. It is the sequence diagram which showed the process of the radio | wireless communication method concerning 1st Embodiment. It is the block diagram which showed schematic structure of the relay station concerning 2nd Embodiment. It is the flowchart which showed the process of the radio | wireless communication method concerning 2nd Embodiment. It is a block diagram for demonstrating the other structure of a relay station. It is explanatory drawing for demonstrating the indoor range as a range of a predetermined area | region. It is a block diagram for demonstrating other structure of a relay station. It is explanatory drawing for demonstrating the determination of the predetermined area information based on a relative position with a relay station GPS receiving part. It is explanatory drawing for demonstrating the interference which arises between radio | wireless communication terminals.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Wireless communication system, 110 ... Wireless communication terminal, 120 ... Base station, 130, 600, 800, 850 ... Relay station, 140 ... Communication network, 150 ... Relay server, 160 ... Building, 210 ... Terminal control part, 212 ... Terminal memory, 214 ... display unit, 216 ... operation unit, 218 ... voice input unit, 220 ... voice output unit, 222 ... terminal radio communication unit, 230 ... handover request unit, 310 ... base station control unit, 312 ... base station memory 314 ... base station wireless communication unit, 316 ... base station wired communication unit, 318 ... antenna, 320 ... interference reception unit, 322 ... carrier terminal extraction unit, 324 ... handover information transmission unit, 326 ... base station power acquisition unit, 328 ... Relay direction acquisition unit, 330 ... Terminal direction acquisition unit, 332 ... Handover execution unit, 410, 610 Relay station control unit, 412, 612, 812 ... relay station memory, 414, 614, 814 ... relay station radio communication unit, 416, 620, 820 ... terminal communication unit, 418, 622 ... base station communication unit, 420 ... communication quality Acquisition unit, 422 ... interference determination unit, 424 ... interference notification unit, 426 ... relay power acquisition unit, 428, 634 ... call number determination unit, 430 ... terminal extraction unit, 432 ... instruction notification unit, 616 ... antenna, 630 ... direction Holding unit, 632 ... Inside / outside determination unit, 822 ... Area holding unit, 824 ... Position information receiving unit, 830 ... GPS satellite, 852 ... Relay station GPS receiving unit

Claims (13)

A relay station capable of relaying communication between a wireless communication terminal and a base station,
When relaying communication between the wireless communication terminal and the base station, a communication quality acquisition unit that acquires communication quality in communication between the local station and the wireless communication terminal;
Based on the acquired communication quality, an interference determination unit that determines whether communication between the local station and the wireless communication terminal is receiving interference,
An interference notification for notifying the base station of interference information including interference in order to prompt a radio communication terminal communicating with the base station to perform handover when it is determined that the interference is received. And
A relay station comprising:   The relay station according to claim 1, wherein the communication quality acquired by the communication quality acquisition unit is RSSI and either SINR or CINR.   The interference determination unit determines that communication between the local station and the wireless communication terminal is subject to interference when a relationship between SINR and RSSI or a relationship between CINR and RSSI satisfies a predetermined condition. The relay station according to claim 2.   The interference notification unit notifies the base station of either or both of a carrier frequency and / or a time slot used for communication between the wireless communication terminal and the own station in the interference information. The relay station according to any one of 1 to 3. The relay station further
A relay power acquisition unit that intermittently acquires transmission power information including transmission power of a wireless communication terminal in communication with the local station;
A call number determination unit for determining whether or not the number of calls in communication with the local station exceeds a predetermined number when there is a communication connection request from a wireless communication terminal not communicating with the local station;
A terminal extraction unit that extracts a wireless communication terminal based on transmission power information acquired by the relay power acquisition unit when it is determined that the predetermined number is exceeded;
An instruction notifying unit that notifies the base station of instruction information for prompting the extracted wireless communication terminal to perform a handover;
The relay station according to any one of claims 1 to 4, further comprising: The relay station further
A base station communication unit for communicating with the base station;
A terminal communication unit for communicating with the wireless communication terminal;
6. The relay station according to claim 1, comprising: A relay station capable of relaying communication between a wireless communication terminal and a base station,
When relaying communication between the wireless communication terminal and the base station, a communication quality acquisition unit that acquires communication quality in communication between the local station and the wireless communication terminal;
Based on the acquired communication quality, an interference determination unit that determines whether communication between the local station and the wireless communication terminal is receiving interference,
When it is determined that the wireless communication terminal is receiving the interference, in order to prompt the wireless communication terminal that is communicating with the base station to perform a handover, the interference information including the interference is transmitted to the base station and the base station. An interference notification unit for notifying other adjacent base stations;
A relay station comprising: A relay station capable of relaying communication between its own station and a wireless communication terminal and a base station that communicates with another wireless communication terminal,
An interference receiver that receives interference information indicating that communication between the relay station and the wireless communication terminal is interfered;
A handover information transmitting unit for transmitting handover information for instructing handover to the relay station to another wireless communication terminal communicating with the local station when the interference information is received;
In response to a handover request from the other radio communication terminal, a handover execution unit that executes a handover from the local station to the relay station;
A base station comprising: A carrier terminal extraction unit that extracts another wireless communication terminal that is communicating with the local station using a carrier having a frequency that is the same as or close to the frequency of the carrier included in the interference information when the interference information is received; Prepared,
The base station according to claim 8, wherein the handover information transmitting unit transmits the handover information to another radio communication terminal extracted by the carrier terminal extracting unit. A base station power acquisition unit that intermittently acquires transmission power information including transmission power of other wireless communication terminals that are communicating with the own station;
The base station according to claim 8 or 9, wherein the handover information transmitting unit transmits the handover information to another wireless communication terminal based on the acquired transmission power information. The base station further
An antenna having an adaptive array function;
A relay direction acquisition unit that acquires relay station direction information indicating the direction of the relay station using the adaptive array function;
A terminal direction acquisition unit that acquires terminal direction information indicating a direction of another wireless communication terminal communicating with the local station using the adaptive array function;
With
The base station according to any one of claims 8 to 10, wherein the handover information transmitting unit transmits the handover information to another radio communication terminal in a direction substantially equal to the direction of the relay station. . A wireless communication system comprising a wireless communication terminal, a base station capable of wireless communication with the wireless communication terminal, and a relay station capable of relaying communication between the wireless communication terminal and the base station,
The relay station is
When relaying communication between the wireless communication terminal and the base station, a communication quality acquisition unit that acquires communication quality in communication between the local station and the wireless communication terminal;
Based on the acquired communication quality, an interference determination unit that determines whether communication between the local station and the wireless communication terminal is receiving interference,
An interference notification for notifying the base station of interference information including interference in order to prompt a radio communication terminal communicating with the base station to perform handover when it is determined that the interference is received. And
With
The base station
An interference receiver for receiving the interference information;
A handover information transmitting unit for transmitting handover information for instructing handover to the relay station to another wireless communication terminal communicating with the local station when the interference information is received;
In response to a handover request from the other radio communication terminal, a handover execution unit that executes a handover from the local station to the relay station;
A wireless communication system comprising: A wireless communication method using a wireless communication terminal, a base station capable of wireless communication with the wireless communication terminal, and a relay station capable of relaying communication between the wireless communication terminal and the base station,
The relay station is
When relaying communication between the wireless communication terminal and the base station, obtain communication quality in communication between the local station and the wireless communication terminal,
Based on the acquired communication quality, determine whether communication between the own station and the wireless communication terminal is receiving interference,
If it is determined that the interference is received, in order to prompt the handover to the wireless communication terminal that is communicating with the base station, to notify the base station of interference information including the interference,
The base station
When the interference information is received, it transmits handover information for instructing handover to the relay station to another wireless communication terminal that is communicating with the own station,
A wireless communication method comprising: performing handover from a local station to the relay station in response to a handover request from the other wireless communication terminal.

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