JP5665909B2 - Relay station and wireless communication relay method - Google Patents

Description

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

  In recent years, wireless communication terminals typified by mobile phones and PHS (Personal Handy phone System) terminals 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 system such as WiMAX uses a high-frequency band of 2.5 GHz or higher, the 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 whole area. 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 that relays between the base station device and the wireless communication terminal, it communicates with the base station regardless of the service area due to shadowing effects caused by obstruction by obstacles such as buildings. A technique capable of reducing the range incapable of being disclosed is disclosed (for example, Patent Document 1). In addition, a technique is also disclosed in which a plurality of transmission windows are defined in the transmission frequency band, and a transition point from reception to transmission is effectively controlled by a relay station (for example, Patent Document 2).

  In addition, the relay station is not limited to a fixed installation in a building or a tower, but can be installed in a moving body on which a person can get on and off, such as a bus or a train. Since the relay station installed in the mobile body can maintain the relative positional relationship with the wireless communication terminal, stable communication of the wireless communication terminal can be ensured.

JP 2006-74325 A JP 2008-136201 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

  The relay station functions as a wireless communication terminal for communication with the base station, functions as a base station for communication with the wireless communication terminal, and maintains real-time communication data transmission. That is, when the terminal communication unit of the relay station that performs communication with the wireless communication terminal receives communication data (downlink) from the base station, the base station communication unit of the relay station that performs communication with the base station is the wireless communication terminal Communication data (downlink) is transmitted at the same timing. Similarly, when the base station communication unit receives communication data (uplink) from the wireless communication terminal, the terminal communication unit transmits communication data (uplink) to the base station.

  Usually, since the relay station is housed in an integrally formed casing, the terminal communication unit and the base station communication unit described above are often not separated from each other by a sufficient distance. Under such circumstances, if the frequency band used for communication with the base station is close to the frequency band used for communication with the wireless communication terminal, the leakage power of transmission data on the transmission side Wraps around the receiving side and interferes with the received data, which may cause the receiving side to be unable to receive the received data correctly.

  Here, radio communication between the base station and the relay station is intermittently performed, and interference is avoided by executing communication between the relay station and the radio communication terminal during a period in which the base station and the relay station are not communicating. It is also possible. However, in order to realize such a protocol, not only the relay station but also the base station and the wireless communication terminal are modified.

  In addition, since the relay station performs wireless communication with the base station as if it were a wireless communication terminal, the base station determines whether the wireless communication terminal that has performed communication with the base station is a wireless communication terminal, It is difficult to identify whether the relay station functions as a communication terminal. Therefore, if wireless communication is intermittently executed mainly by the base station, intermittent communication is forced even to wireless communication terminals that originally do not require such intermittent communication, and effective use of resources is impaired. Even if the base station can discriminate between the relay station and the wireless communication terminal, a special process is started each time, resulting in an increase in processing load and cost.

  Furthermore, when intermittent communication is performed independently between the base station and the relay station and between the relay station and the wireless communication terminal, a control packet such as a data control packet is lost, and the packet is frequently retransmitted. Wireless resources can be wasted.

  In view of such a problem, the present invention controls interference with a base station or a radio communication terminal mainly by the relay station without modifying the base station or the radio communication terminal, thereby reducing interference in the relay station. An object of the present invention is to provide a relay station and a wireless communication relay method capable of avoiding and performing stable wireless communication.

In order to solve the above problems, a typical configuration of the present invention is a relay station capable of relaying wireless communication between a wireless communication terminal and a base station, and performs wireless communication with one or a plurality of wireless communication terminals. A base station communication unit, a terminal communication unit that performs wireless communication with the base station, a sleep transmission unit that transmits a sleep request command that repeats communication and non-communication every predetermined frame to the base station through the terminal communication unit, and Based on the sleep request command, when the terminal communication unit and the base station are not communicating, the base station communication unit and the wireless communication terminal are communicated, and when the terminal communication unit and the base station are communicating, the base station It includes a communication switching unit that performs intermittent communication of the communication unit and the radio communication terminal to a non-communication, and a response including a second sleep schedule first sleep schedule has been changed to be included in the sleep request command When end communication section receives from the base station, the communication switching unit is characterized Rukoto performing intermittent communication based on the second sleep schedule.

  In the present invention, an existing sleep request command is used to request the base station to intermittently disable communication (sleep) with the relay station. Then, communication between the relay station and the wireless communication terminal is executed at the timing of sleep. In this way, it is possible to avoid interference in the relay station by controlling the communication with the base station and the wireless communication terminal by the relay station without modifying the base station and the wireless communication terminal. In addition, since intermittent communication is performed mainly by the relay station, packet loss and retransmission can be suppressed, and stable wireless communication can be performed.

  The base station communication unit may realize non-communication by not assigning communication data to a channel map in the OFDMA scheme.

  Since the base station communication unit can operate as a base station, the OFDMA channel map can be freely changed. Accordingly, a non-communication state can be realized by not allocating the communication data for each channel map without stopping communication. In this way, intermittent communication between the base station communication unit and the wireless communication terminal can be easily realized without any modification of the wireless communication terminal.

Another exemplary configuration of the present invention is a wireless communication relay method of a relay station that relays wireless communication between a wireless communication terminal and a base station, and performs wireless communication with one or a plurality of wireless communication terminals. run the wireless communication station Prefecture, transmits a communication and non-communication with a sleep request command to repeat every predetermined frame, the base station for controlling wireless communication with the relay station, based on a sleep request command, the base If during the stations Metropolitan of non-communicating, communicates with the radio communication terminal and is communicating with the base station performs intermittent communication to non-communication between the wireless communication terminal, included in the sleep request command When a response including the second sleep schedule in which the first sleep schedule is changed is received from the base station, intermittent communication based on the second sleep schedule is performed .

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

  As described above, according to the present invention, it is possible to reduce interference within a relay station by controlling communication with the base station and the radio communication terminal mainly by the relay station, without modifying the base station or the radio communication terminal. It is possible to avoid and perform stable wireless communication.

1 is a block diagram illustrating 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 in the first embodiment. It is the perspective view which showed the external appearance of the radio | wireless communication terminal in 1st Embodiment. It is the block diagram which showed the schematic structure of the base station in 1st Embodiment. FIG. 3 is a block diagram showing a schematic configuration of a relay station in the first embodiment. It is explanatory drawing which showed the communication state of the base station and relay station when sleep in 1st Embodiment was performed. It is explanatory drawing which showed switching of communication with the base station and terminal communication part in 1st Embodiment, and a base station communication part and a radio | wireless communication terminal. It is the sequence diagram which showed the specific process of the radio | wireless communication relay method in 1st Embodiment. It is the block diagram which showed the schematic structure of the relay station in 2nd Embodiment. It is explanatory drawing which showed the communication state of the base station and relay station at the time of the scan of the adjacent cell in 2nd Embodiment being performed. It is explanatory drawing which showed switching of communication with the base station and terminal communication part in 2nd Embodiment, and a base station communication part and a radio | wireless communication terminal. It is the sequence diagram which showed the specific process of the radio | wireless communication relay method in 2nd Embodiment.

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.
(First embodiment)
Wireless communication terminals such as mobile phones and PHS terminals construct a broadband wireless communication system with a plurality of distributed base stations, and communicate with other wireless communication terminals and servers on the communication network through this wireless communication system. Run. Furthermore, in next-generation high-speed wireless communication systems such as WiMAX, in order to avoid a reduction in the communication range (coverage), a mobile object having a poor radio wave condition, a place where buildings are densely populated, or a radio wave condition changes significantly. In addition, a relay station functioning as a base station can be provided to take part of the wireless communication system.

Here, in order to facilitate understanding of the present embodiment, first, a schematic configuration of the entire wireless communication system including the relay station will be described, and then a specific operation of each device configuring the wireless communication system will be described. .
(Wireless communication system 100)
FIG. 1 is a block diagram illustrating a schematic configuration of a wireless communication system 100. The radio communication system 100 includes radio communication terminals 110 (110A and 110B), base stations 120 (120A and 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.

  Here, as the wireless communication terminal 110, wireless communication such as a mobile phone, a PHS terminal 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 also be used.

  In the wireless communication system 100 described above, when a user performs communication from his / her own wireless communication terminal 110A to another wireless communication terminal 110B, the wireless communication terminal 110A makes a wireless connection request to the base station 120A within the communicable range. I do. 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 via the communication network 140, and the relay server 150 refers to the location registration information of the other wireless communication terminal 110B, The base station 120B within the radio communication range of the other radio communication terminal 110B is extracted to secure a communication path between the base station 120A and the base station 120B, and communication between the radio communication terminal 110A and the radio communication terminal 110B is executed (established). )

  Here, when the user gets on, for example, a train as the moving body 170, the wireless communication terminal 110A switches to communication via the relay station 130 instead of directly with the base station 120A. The relay station 130 is fixed to the moving body 170 and moves together with the moving body 170 to play a role of extending the coverage to the moving body. The moving body 170 may be various vehicles on which people can get on and off, such as automobiles, buses, trains (trains), ships, and airplanes.

  The wireless communication terminal 110A and the relay station 130 possessed by the user who has entered the moving body move together without any change in the positional relationship unless an operation such as searching for a vacant seat occurs, and also shields between the two. Since there is no barrier to this, stable wireless communication can be ensured. Accordingly, the wireless communication terminal 110A can stably maintain communication with the other wireless communication terminal 110B via the relay station 130 regardless of the movement of the moving body 170.

Hereinafter, the wireless communication terminal 110, the base station 120, and the relay station 130 that configure the wireless communication system 100 will be described individually.
(Wireless communication terminal 110)
FIG. 2 is a functional block diagram showing a hardware configuration of the wireless communication terminal 110, and FIG. 3 is a perspective view showing an appearance of the wireless communication terminal 110. As shown in FIG. 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 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. The terminal wireless communication unit 222 includes an OFDMA, TDMA (Time Division Multiple Access) in addition to OFDMA such as WiMAX, ARIB (Association of Radio Industries and Businesses) STD T95, PHS MoU (Memorandum of Understanding). Various wireless communication methods such as a method can be applied.
(Base station 120)
FIG. 4 is a block diagram illustrating a schematic configuration of the base station 120. The base station 120 includes a base station control unit 250, a base station memory 252, a base station wireless communication unit 254, and a base station wired communication unit 256.

  The base station control unit 250 manages and controls the entire base station 120 using a semiconductor integrated circuit including a central processing unit (CPU). The base station memory 252 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 250.

The base station wireless communication unit 254 performs wireless communication with the wireless communication terminal 110 or the relay station 130 using, for example, the OFDMA method, and adaptively performs QoS according to the communication state with the wireless communication terminal 110 or the relay station 130. It can also be changed (adaptive modulation). The base station wired communication unit 256 can communicate with various servers including the relay server 150 via the communication network 140.
(Relay station 130)
FIG. 5 is a block diagram showing a schematic configuration of relay station 130. The relay station 130 includes a relay station control unit 310, a relay station memory 312, and a relay station wireless communication unit 314. Such a relay station 130 is not limited to the mobile body 170 described above, and can be fixedly installed in a building or tower.

  The relay station control unit 310 manages and controls the entire relay station 130 by a semiconductor integrated circuit including a central processing unit (CPU). The relay 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 relay station control unit 310. The relay station wireless communication unit 314 performs wireless communication between the wireless communication terminal 110 and the base station 120 and relays between the wireless communication terminal 110 and the base station 120. The relay station radio communication unit 314 functions as a base station communication unit 350, a connection control unit 352, a terminal communication unit 354, a sleep transmission unit 356, and a communication switching unit 358.

  The base station communication unit 350 functions as the base station 120 for communication with the wireless communication terminal 110 and is responsible for the physical layer (layer 1) and the data link layer (layer 2) in the OSI reference model. As shown in FIG. 5, only one base station communication unit 350 is provided for one relay station in this embodiment. Moreover, when it applies to a space large to some extent, such as a ship and an aircraft, it can also comprise in multiple. With this base station communication unit 350, even if the wireless communication terminal 110 performs wireless communication with the relay station 130 instead of the base station 120, it operates as if it is performing wireless communication with the base station 120.

  When a plurality of wireless communication terminals 110 are connected to the base station communication unit 350, the connection control unit 352 performs channel control (MAC tracer function), and when the OFDMA method is employed as in this embodiment The communication data is assigned to a channel map in which subchannels, which are the minimum transmission unit of communication data, are arranged in the time and frequency directions. Further, the connection control unit 352 can adaptively change the QoS according to the communication state between the base station communication unit 350 and the wireless communication terminal 110 that is performing wireless communication (adaptive modulation).

  The terminal communication unit 354 functions as the wireless communication terminal 110 for communication with the base station 120 and serves as a physical layer and a data link layer in the OSI reference model. In the present embodiment, a configuration in which only one terminal communication unit 354 is provided based on the OFDMA method is described. However, the present invention is not limited to this, and a plurality of terminal communication units 354 are provided in the OFDMA method and in other communication methods. It is also possible to provide it. When a plurality of terminal communication units 354 are provided as described above, communication can be independently performed by different base stations 120.

  Since the relay station 130 is housed in an integrally formed casing, the base station communication unit 350 and the terminal communication unit 354 described above are often not separated from each other by a sufficient distance. Under such circumstances, if the frequency band used for communication with the base station 120 and the frequency band used for communication with the wireless communication terminal 110 are close, transmission data on the transmission side Leakage power wraps around the receiving side and interferes with the received data, which may cause the receiving side to be unable to receive the received data correctly.

  For example, in the case of OFDMA systems such as WiMAX, ARIB STD T95, and PHS MoU, the transmission power of the terminal communication unit 354 and the base station communication unit 350 is about 23 dBm at maximum, and the adjacent leakage power is equivalent to 4 to -4 dBm. Interference wave to base station communication unit 350 when terminal communication unit 354 transmits communication data to base station 120, and to terminal communication unit 354 when communication data is transmitted from base station communication unit 350 to radio communication terminal 110 Both of the interference waves are about -10 to -20 dBm. On the other hand, the received power from the base station 120 and the wireless communication terminal 110 that the terminal communication unit 354 and the base station communication unit 350 originally desire to receive is about −40 to −80 dBm, and the power of the interference wave is higher than the received power. It can be understood that the received data is highly likely to be affected by the interference wave. Such an interference wave causes deterioration of reception quality. The power value (dBm) described above is an example, and it goes without saying that the present embodiment is not limited to such a numerical value.

  Here, wireless communication between the base station 120 and the relay station 130 is intermittently performed, and communication between the relay station 130 and the wireless communication terminal 110 is executed during a period in which the base station 120 and the relay station 130 are not communicating. To avoid interference. However, if the intermittent communication is simply executed, not only the relay station 130 but also the base station 120 and the wireless communication terminal 110 are modified. In addition, when intermittent communication is performed independently between the base station 120 and the relay station 130 or between the relay station 130 and the wireless communication terminal 110, a control packet such as a data control packet is lost, and the packet is retransmitted. It frequently occurs and wastes radio resources.

  In the present embodiment, the base station 120 and the radio communication terminal are mainly configured by the relay station 130, particularly a sleep transmission unit 356 and a communication switching unit 358 described later, without modifying the base station 120 and the radio communication terminal 110. By controlling communication with 110, it is an object to avoid interference in the relay station and perform stable wireless communication.

  The sleep transmission unit 356 transmits a sleep request command for repeating communication and non-communication every predetermined frame to the base station 120 through the terminal communication unit 354. Normally, the wireless communication terminal 110 can cause the base station 120 to repeat communication and non-communication with such a sleep request command. Therefore, the terminal communication unit 354 functioning as the wireless communication terminal 110 with respect to data transmission / reception can also repeat communication and non-communication by the sleep request command.

  FIG. 6 is an explanatory diagram showing a communication state between the base station 120 and the relay station 130 when sleep is executed. The sleep transmission unit 356 can include, as a parameter, how to repeat communication and non-communication in the sleep request command. Here, the repeat unit can be specified in units of frames. For example, FIG. 6 shows a case where two frames are designated. The reason why two frames are used here is that the base station 120 requires a processing period of a maximum of two frames for such a control command of the wireless communication terminal 110. Here, the frame unit to be repeated is two frames, but the number of frames is not limited to this, and an arbitrary number of 1 or more can be selected.

  The base station 120 performs communication with the terminal communication unit 354 as indicated by hatching in FIG. 6 and sleeps the frame specified by the sleep request command, and during that time, allocates a channel map for reception and transmission. Not performed.

  The communication switching unit 358 operates the base station communication unit 350 based on the content of the permission response according to the sleep request command received by the terminal communication unit 354 from the base station 120, and the terminal communication unit 354, the base station 120, Is not communicating (stopped), the base station communication unit 350 and the wireless communication terminal 110 are communicated, and when the terminal communication unit 354 and the base station 120 are communicating, the base station communication unit 350 and the wireless communication terminal 110 are wireless. The communication terminal 110 is not in communication. While communication with the wireless communication terminal 110 is in a non-communication state, the connection control unit 352 does not assign a channel map to the wireless communication terminal 110 for reception and transmission.

  FIG. 7 is an explanatory diagram showing switching of communication between the base station 120 and the terminal communication unit 354 and between the base station communication unit 350 and the wireless communication terminal 110.

  The base station communication unit 350 maintains the non-communication state without assigning the channel map of the wireless communication terminal 110 as shown in (2) in the figure at the time point (1) when the communication request from the wireless communication terminal 110 is received. To do. When the sleep transmission unit 356 transmits a sleep request command including two frames that are sleep repetition cycles (3), the base station 120 returns a permission response to the sleep request command (4). The permission response includes whether sleep is permitted, a sleep schedule (how many frames are communicated and how many frames are sleeped), and a start timing when permission is permitted. However, when the base station 120 changes the sleep schedule and permits sleep, the changed sleep schedule is shown.

  When the start timing indicated in the permission response from the base station 120 is reached (5), the base station 120 starts intermittent communication with the terminal communication unit 354. When the terminal communication unit 354 is communicating with the base station 120 in accordance with a command from the communication switching unit 358, the base station communication unit 350 does not perform communication with the radio communication terminal 110, and does not perform communication with the terminal communication unit 354 and the base station. When communication with the station 120 is stopped, communication with the wireless communication terminal 110 is executed.

  In the present embodiment, an existing sleep request command is used to request the base station 120 to stop (sleep) communication with the relay station 130 intermittently. During this time, since communication with the base station 120 is interrupted, the RF of the terminal communication unit 354 can be stopped. Then, communication between the relay station 130 and the wireless communication terminal 110 is executed at the timing of sleep. Thus, it is possible to avoid interference in the relay station by controlling the communication with the base station 120 and the radio communication terminal 110 by the relay station 130 without modifying the base station 120 and the radio communication terminal 110. Further, since relay station 130 performs alternately with base station 120 and radio communication terminal 110, it is not necessary to shift the synchronization with base station 120.

  Here, the base station communication unit 350 realizes non-communication with the wireless communication terminal 110 by not allowing the connection control unit 352 to allocate communication data to the channel map.

  Since the base station communication unit 350 can operate as the base station 120, the channel map can be freely changed through the connection control unit 352. Therefore, a non-communication state can be realized by not allocating the communication data for each channel map without stopping (disconnecting) the communication. In this way, intermittent communication between the base station communication unit 350 and the wireless communication terminal 110 can be easily realized without refurbishing the wireless communication terminal 110.

As described above, the intermittent communication characteristic of the present embodiment is performed mainly by the relay station 130, so that the packet transmission / reception can be performed at the specified timing, and the presence / absence of the transmission / reception data by the channel mapping. Can be reliably transmitted, so that packet loss and retransmission can be suppressed, and stable wireless communication can be performed.
(Wireless communication relay method)
Next, a wireless communication relay 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. 8 is a sequence diagram showing specific processing of the wireless communication relay method. First, the terminal communication unit 354 of the relay station 130 starts wireless communication with the wireless communication system 100 through the base station 120, and the base station communication unit 350 registers with the wireless communication system 100 so as to be recognized as the base station 120 ( S400). The terminal communication unit 354 receives the fact that the registration of the base station communication unit 350 is completed (S402), and keeps the non-communication state (idle state) until the wireless communication terminal 110 that requests communication connection appears. Maintain (S404).

  If a communication establishment request is made by the wireless communication terminal 110 (S406), the base station communication unit 350 transfers the terminal registration information acquired from the wireless communication terminal 110 to the terminal communication unit 354 (S408), and the terminal communication unit 354 performs registration processing of the wireless communication terminal 110 that has made a communication establishment request using the terminal registration information (S410). At this time, the base station communication unit 350 still maintains a non-communication state by not assigning a channel map to the wireless communication terminal 110.

  Subsequently, the sleep transmission unit 356 transmits a sleep request command to the base station 120 through the terminal communication unit 354 (S412), and the base station 120 returns a permission response to the terminal communication unit 354 in response to the sleep request command. (S414). The terminal communication unit 354 transfers the sleep schedule and start timing necessary for intermittent communication from the permission response to the base station communication unit 350 (S416), and when the start timing is reached, the base station 120 and the terminal communication unit 354 and the base station Intermittent communication is started between the station communication unit 350 and the wireless communication terminal 110 (S418).

  In such intermittent communication, the communication speed is expected to be halved, but the base station 120 performs spatial multiplexing to widen the communication band allocated to the wireless communication terminal 110 in order to secure a predetermined communication amount. It can respond.

Even in such a wireless communication relay method, even if the base station 120 and the wireless communication terminal 110 are not modified, the relay station 130 mainly controls the communication with the base station 120 and the wireless communication terminal 110 to perform the relay. It is possible to avoid in-station interference and perform stable wireless communication.
(Second Embodiment)
In the first embodiment, intermittent communication is realized through an existing sleep request command. However, the means for performing intermittent communication mainly by the relay station 130 is not limited to this, and can be realized by, for example, a scan request command. In the second embodiment, intermittent communication using a scan request command will be described.

  FIG. 9 is a block diagram showing a schematic configuration of the relay station 530 in the second embodiment. The relay station 530 includes a relay station control unit 310, a relay station memory 312, and a relay station wireless communication unit 514. The relay station radio communication unit 514 functions as a base station communication unit 350, a connection control unit 352, a terminal communication unit 354, a scan transmission unit 556, and a communication switching unit 558. The relay station control unit 310, the relay station memory 312, the base station communication unit 350, the connection control unit 352, and the terminal communication unit 354 that have already been described as the constituent elements in the first embodiment are substantially functional. Since the description is the same, repeated description is omitted, and here, the scan transmission unit 556 and the communication switching unit 558 having different configurations will be mainly described.

  The scan transmission unit 556 transmits a scan request command for repeating communication and adjacent cell scan every predetermined frame to the base station 120 through the terminal communication unit 354.

  FIG. 10 is an explanatory diagram showing a communication state between the base station 120 and the relay station 530 when scanning of adjacent cells is executed. The scan transmission unit 556 can include, as a parameter, how to repeat scanning in the scan request command. Here, the repeat unit can be specified in units of frames. For example, FIG. 10 shows a case in which a scan of 2 frames is designated in a 4-frame cycle.

  The base station 120 performs communication with the terminal communication unit 354 as indicated by hatching in FIG. In addition, the base station 120 performs a scan of adjacent cells in the frame specified by the scan request command, and does not allocate a channel map for reception and transmission with the relay station 530 while performing the adjacent scan. .

  Further, the scan transmission unit 556 may transmit a scan request command every predetermined time. Unlike the sleep request command in the first embodiment, the scan request command automatically stops scanning when a predetermined time (for example, several seconds) elapses, and returns to a normal state in which communication is performed in all frames. In this embodiment, the relay station 530 avoids interference by repeatedly transmitting a scan request command to the base station 120 every predetermined time in anticipation of the time at which the cell scan is completed, and allowing the base station 120 to maintain intermittent communication. Thus, it is possible to continuously perform stable wireless communication.

  When the base station 120 permits the scan request command, the communication switching unit 558 determines that when the terminal communication unit 354 and the base station 120 are not in communication based on the scan request command, the base station communication unit 350 and the wireless communication terminal 110 When the terminal communication unit 354 and the base station 120 are communicating, the base station communication unit 350 and the wireless communication terminal 110 are made non-communication.

  FIG. 11 is an explanatory diagram showing switching of communication between the base station 120 and the terminal communication unit 354 and between the base station communication unit 350 and the wireless communication terminal 110.

  The base station communication unit 350 maintains the non-communication state without assigning the channel map of the wireless communication terminal 110 as shown in (2) in the figure at the time point (1) when the communication request from the wireless communication terminal 110 is received. To do. When the scan transmission unit 556 transmits a scan request command (3), the base station 120 returns a permission response to the scan request command (4). The permission response includes whether or not scanning can be performed, a scan schedule (how many frames are communicated and how many frames are scanned), and a start timing when permission is permitted.

  When the start timing indicated in the permission response from the base station 120 is reached (5), the base station 120 starts intermittent communication with the terminal communication unit 354 by scanning adjacent cells. When the terminal communication unit 354 is communicating with the base station 120 in accordance with a command from the communication switching unit 558, the base station communication unit 350 does not execute communication with the wireless communication terminal 110, and the terminal communication unit 354 When communication with the station 120 is stopped, communication with the wireless communication terminal 110 is executed.

  Here, in the scan request command, as described above, when a predetermined time (for example, several seconds) elapses, scanning (intermittent communication) is automatically completed and the normal state is restored. Therefore, the scan transmission unit 556 repeatedly transmits the scan request command every predetermined time in anticipation of the time when the adjacent cell scan is completed (3), (4), (5), and maintains the intermittent communication.

As described above, in the present embodiment, the adjacent cell is intermittently scanned using the existing scan request command instead of the sleep request command. Since the base station 120 temporarily stops communication during scanning of adjacent cells, communication between the relay station 530 and the wireless communication terminal 110 is executed at the scanning timing. Thus, like the sleep request command, the relay station 530 can control the communication with the base station and the wireless communication terminal without revising the base station 120 and the wireless communication terminal 110, thereby avoiding interference in the relay station. It becomes.
(Wireless communication relay method)
Next, a wireless communication relay 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. 12 is a sequence diagram illustrating specific processing of the wireless communication relay method according to the second embodiment. Here, since the processing (S400 to S418) described with reference to FIG. 8 in the first embodiment is substantially the same, description thereof is omitted by attaching the same reference numerals.

  The terminal communication unit 354 performs registration processing of the wireless communication terminal 110 that has requested communication establishment using the terminal registration information (S410). At this time, the base station communication unit 350 maintains a non-communication state by not assigning a channel map to the wireless communication terminal 110.

  After the terminal communication unit 354 performs registration processing of the wireless communication terminal 110 that has requested communication establishment using the terminal registration information (S410), the scan transmission unit 556 sends a scan request command to the base station 120 through the terminal communication unit 354. (S600), the base station 120 returns a permission response to the terminal communication unit 354 in response to the scan request command (S414). Thus, when the start timing arrives, intermittent communication is started between the base station 120 and the terminal communication unit 354 and between the base station communication unit 350 and the wireless communication terminal 110 (S418).

  However, the scan request command automatically ends intermittent communication after a predetermined time (S602). Accordingly, the scan transmission unit 556 periodically repeats the scan request command (S604) and maintains intermittent communication.

  In such a wireless communication relay method, the relay station 130 mainly controls the communication with the base station 120 and the wireless communication terminal 110 without modifying the base station 120 and the wireless communication terminal 110, so Interference can be avoided and stable wireless communication can be performed.

  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.

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

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

110 ... wireless communication terminal 120 ... base station 130, 530 ... relay station 350 ... base station communication unit 352 ... connection control unit 354 ... terminal communication unit 356 ... sleep transmission unit 358, 558 ... communication switching unit 556 ... scan transmission unit

Claims (2)

A relay station capable of relaying wireless communication between a wireless communication terminal and a base station,
A base station communication unit that performs wireless communication with one or more of the wireless communication terminals;
A terminal communication unit for performing wireless communication with the base station;
A sleep transmission unit for transmitting a sleep request command for repeating communication and non-communication every predetermined frame to the base station through the terminal communication unit;
Based on the sleep request command, when the terminal communication unit and the base station are not communicating, the base station communication unit and the wireless communication terminal are communicated, and the terminal communication unit and the base station communicate with each other. A communication switching unit that performs intermittent communication for non-communication between the base station communication unit and the wireless communication terminal ,
When the terminal communication unit receives a response including the second sleep schedule in which the first sleep schedule included in the sleep request command is changed from the base station, the communication switching unit adds the second sleep schedule to the second sleep schedule. A relay station that performs the intermittent communication based on the relay station. A wireless communication relay method of a relay station that relays wireless communication between a wireless communication terminal and a base station,
Performing wireless communication with one or more of the wireless communication terminals;
Performing wireless communication with the base station;
A sleep request command for repeating communication and non-communication every predetermined frame is transmitted to the base station;
Based on the sleep request command, between the base station if the non-communication, communication with the wireless communication terminal and is communicating with the base station, to a non-communication between the wireless communication terminal Intermittent communication,
When a response including a second sleep schedule in which the first sleep schedule included in the sleep request command is changed is received from the base station, the intermittent communication based on the second sleep schedule is performed. Wireless communication relay method.

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