JP5261254B2 - Radio apparatus and method - Google Patents

Description

  The present invention relates to wireless communication.

  A technology has been proposed in which a terminal that detects interference from another logical network becomes a base station of a logical network that integrates a logical network to which the terminal itself is connected and another logical network, and expands a communication area (for example, a patent). Reference 1). However, in the technique disclosed in Patent Document 1, it is complicated to set which terminal is to be a base station of the logical network after integration, and a function in which each terminal connected to each logical network can be a base station. Must have.

  In addition, there is a technology in which a terminal that has moved out of the wireless communication area of the wireless base station relays data from the base station to other terminals that are within the wireless communication area, thereby substantially expanding the communication area. Proposed. However, the technique disclosed in Patent Document 2 does not consider the case where the terminal to be relayed is in the power save mode, the directionality is directed to the base station, and the like. In addition, the setting of the base station and the relay terminal becomes complicated.

JP 2006-135943 A JP 2008-271523 A

  The present invention has been made in view of the above, and an object of the present invention is to provide a radio apparatus and method capable of easily expanding an area connectable to a network.

In order to achieve the above object, a radio apparatus according to an embodiment of the present invention is a radio apparatus connected to a first radio base station, and receiving means for receiving a synchronization signal from the first radio base station; Transmission means for transmitting the synchronization signal to a second area including at least other than the first area capable of receiving the synchronization signal from the first radio base station, and after transmitting the synchronization signal. Then, for a period designated by the first radio base station, the receiving means waits for reception of a connection request frame requesting connection with the first radio base station, and receives the connection request frame from another radio apparatus. In this case, the transmission means transmits a frame requesting accommodation to the first radio base station.

  According to the present invention, the area connectable to the network can be easily expanded.

1 is a diagram showing a wireless system according to a first embodiment of the present invention. 1 is a block diagram showing a configuration of a wireless device according to a first embodiment of the present invention. The figure which shows the transmission timing of a synchronizing signal. The sequence diagram which shows operation | movement of the radio | wireless system which concerns on the 1st Embodiment of this invention. The figure which shows the radio | wireless system which concerns on the modification 5 of the 1st Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described. The wireless LAN standard IEEE802.11 will be described as an example. However, the wireless LAN standard is not limited to the IEEE802.11 standard wireless communication system, and can be applied to all wireless communication systems. The MAC layer access control method will be described by taking a polling method, which is a centralized control method, as an example. However, the MAC layer access control method can be applied to other general wireless communication methods such as a typical CSMA / CA method. A wireless base station (access point) is referred to as AP, and a wireless device and a wireless terminal are referred to as STA.

(First embodiment)
FIG. 1 is a diagram illustrating a wireless system according to the first embodiment. A dotted circle indicates an area (hereinafter referred to as a communication area) in which radio waves transmitted by a wireless device existing at the center of the circle can be received. In the example of FIG. 1, each radio apparatus has radio wave directivity in all directions, but may be in a specific direction.

  The wireless system includes a parent AP1, STA1, STA2, STA3, child AP1, STAa, STAb, and STAx. The parent AP1, STA1 to STA3, child AP1, and STAa, b constitute one network (for example, BSS: Basic Service Set). The parent AP1 is directly connected to the STA1 to STA3 and the child AP1. The STAs 1 to 3 communicate with each other via the parent AP1. The child AP1 is directly connected to the STAa and b. The STAa and b communicate with each other via the child AP1. The STAa, b communicates with the STAs 1 to 3 via the child AP1 and the parent AP1. STAx does not belong to any network. The radio waves transmitted by the STAx can be received only by the STA1, and the parent AP1 cannot.

  FIG. 2 is a block diagram showing a configuration of the radio apparatus STA1 according to the first embodiment. The configurations of STA2, STA3, and child AP1 are the same.

  The STA 1 includes a transmission / reception unit 10, a communication control unit 20, a mode switching unit 30, a child AP function unit 40, and a synchronization signal storage unit 50.

  The transmission / reception unit 10 transmits and receives wireless signals. The transmission / reception unit 10 controls directivity when transmitting and receiving a radio signal. The transceiver 10 transmits radio waves in a specific direction or all directions. The transmission / reception unit 10 receives radio waves from a specific direction or all directions.

  The communication control unit 20 controls the overall communication, for example, the transmission / reception unit 10.

  The child AP function unit 40 performs processing related to the function of the child AP. A child AP refers to a wireless device that operates as an AP of a certain terminal (for example, STAx) and operates as an STA of a certain base station (for example, parent AP1). The parent AP has a function of accommodating the child AP as described above as an STA, and has a function of controlling all terminals connected to the STA and subordinates of the child AP.

  The synchronization signal storage unit 50 stores information described in the synchronization signal from the parent AP1. The synchronization signal is a signal (for example, a Beacon signal) that is periodically transmitted by an access point (for example, the parent AP1) for synchronization.

  The mode switching unit 30 switches whether to operate in a mode of a terminal connected to an access point (parent AP1 or the like) or a child AP that accommodates a station (STAx or the like).

  The configuration of the parent AP1 is the same as that of the STA1 except that the parent AP function unit 40 is provided instead of the child AP function unit 40. The parent AP function unit performs processing related to the function of the parent AP. The parent AP function unit performs allocation processing of information on a number of connected STAs including STAs under the control of the child AP and a scheduling period for each STA, holds and manages the allocated information, and transmits and receives based on the scheduling information Instructions etc. are performed.

  FIG. 3 is a diagram illustrating an example of the operation of the wireless system according to the first embodiment. FIG. 4 is a sequence diagram illustrating an operation of the wireless system according to the first embodiment. In the method shown in FIG. 4, the STAx is connected to the STA1 and is accommodated in the network of the parent AP1.

  First, the parent AP 1 and the STAs 1 to 3 configure the same network and are in a state where they can communicate with each other. The parent AP 1 selects a terminal (hereinafter, cell edge terminal) located at the end of the communication area of the parent AP 1 among the STAs 1 to 3 and the child AP 1 that are directly connected. The parent AP 1 selects a terminal whose radio wave reception intensity is equal to or less than a threshold value as a cell edge terminal. The parent AP1 notifies the cell edge terminal (STA1) that it has been selected as a cell edge terminal, and transmits a cell edge notification signal instructing to perform a synchronization signal transfer process.

  The parent AP 1 periodically transmits a synchronization signal. The parent AP1 includes, in the synchronization signal, a flag indicating that transfer processing is required for the cell edge terminal (hereinafter referred to as a transfer flag), a period for transferring the synchronization signal (hereinafter referred to as a transfer period), and a connection to the parent AP1. A period of waiting for a connection request signal for requesting (for example, Association Request) is described. The parent AP1 transmits a synchronization signal into the network (step S101). Since the parent AP 1 cannot communicate at least during the “transfer period” and the “standby period”, it enters a power save mode (at least a mode in which power supply to the transmission / reception unit 10 is stopped), thereby reducing power consumption. . During the “waiting period”, when the parent AP 1 also waits for reception of a connection request signal, it may be activated.

  The STAs 1 to 3 receive the synchronization signal from the parent AP 1 (step S102). Since the STAs 2 and 3 are not cell edge terminals, the synchronization signal transfer process is not performed. The STA1 performs a synchronization signal transfer process. Note that the STA1 does not have to transfer the synchronization signal when the remaining battery level is equal to or less than the threshold value. At this time, the STA1 may notify the parent AP1 that the transfer of the synchronization signal is rejected.

  When the transfer flag is described in the synchronization signal, the communication control unit 20 of the STA1 stores the information described in the synchronization signal in the synchronization signal storage unit 50 and creates a synchronization signal that describes the MAC address of the STA1. .

  Next, the communication control unit 20 of the STA1 transmits a synchronization signal during the “transfer period” (step S103). The communication control unit 20 of the STA1 transmits a synchronization signal to an area including at least the communication area of the parent AP1. The communication control unit 20 of the STA1 transmits radio waves in all directions (omni) when transmitting the synchronization signal. The communication control unit 20 of the STA1 may direct the radio wave directivity in a direction different from the direction of the parent AP1. Then, after transferring the synchronization signal, the communication control unit 20 of the STA 1 waits for reception of the connection request signal during the “waiting period”. If the connection request signal is not received during the “waiting period”, the STA1 directs transmission / reception directivity to the parent AP1 again and returns to the normal communication state. However, the directivity of transmission / reception does not necessarily have to be directed to the parent AP1.

  The STAx starts scanning for a synchronization signal to connect to the AP, such as when the power is turned on (step S104). When STA1 transfers a synchronization signal during the period when STAx is scanning, STAx receives the synchronization signal (step S105). The STAx grasps from the information described in the synchronization signal that the synchronization signal from the parent AP1 is transferred by the STA1.

  Next, the STAx determines whether or not to request accommodation of the parent AP1 by the network based on the information described in the synchronization signal (step S106). If the list of addresses of terminals that are connected to the parent AP1 network is described in the synchronization signal, the STAx depends on whether the address of the terminal that is desired to be connected is included in the list or not. It may be determined whether or not accommodation is requested. STAx determines whether or not to request accommodation by the parent AP1 network according to the presence / absence of connection to the external network when the synchronization signal includes the presence / absence of connection to the external network such as the Internet. May be. The STAx may determine whether to request accommodation of the parent AP1 by the network based on whether or not the reception power of the synchronization signal is equal to or greater than a threshold value.

  If it is determined to connect to the parent AP1 network, the STAx transmits a connection request signal to the STA1 during the “waiting period” described in the synchronization signal (step S107). In the connection request frame, information such as the number of applications executed by the STAx and the bandwidth amount requested by the applications may be described together.

  The STA1 receives a connection request signal from the STAx (step S108). When the communication control unit 20 of the STA1 receives a connection request signal from the STAx during the “waiting period”, the communication control unit 20 determines whether to permit the connection of the STAx (step S109). The communication control unit 20 of the STA1 may permit the connection if the remaining bandwidth amount allocated from the parent AP1 is greater than or equal to the bandwidth amount necessary for the STAx (application executed by the STAx). The communication control unit 20 of the STA1 may determine whether or not to permit connection of the STAx depending on whether or not the remaining battery level is equal to or greater than a threshold value. The communication control unit 20 of the STA1 may take a form in which the STA1 itself uses the bandwidth amount allocated from the parent AP1 and newly requests the parent AP1 for the bandwidth amount necessary for the STAx.

  If it is determined that the STAx connection is permitted, the communication control unit 20 of the STA1 acquires a transmission right by a poll frame or the like from the parent AP1, and the switching signal for notifying that the STA1 becomes a child AP and connects to the STAx, and the STAx Is sent to the parent AP 1 (step S110). The parent AP 1 is in the power save mode during the “transfer period” and the “waiting period”, but after the “waiting period”, it becomes the normal mode and grants a transmission right to the STA 1 to cause the STA 1 to transmit the accommodation request signal. .

  The parent AP1 receives the switching signal and the accommodation request signal from the STA1 (Step S111). The parent AP1 determines whether or not to accommodate the STAx (whether or not the STA1 is switched to the child AP and connected to the STAx) (step S112). The parent AP 1 may determine whether or not to accommodate the STAx according to the remaining number of connectable terminals from the number of connected terminals in the current network. Based on the bandwidth amount allocated to the connected terminal, the parent AP 1 may further determine whether or not to accommodate the STAx by comparing the allocatable bandwidth amount with the bandwidth amount requested by the STAx. . When it is determined that the STAx is accommodated, the parent AP 1 transmits an accommodation permission signal for accommodating the STAx to the STA 1 (step S113).

  The STA1 receives the accommodation permission signal from the parent AP1 (step S114). When receiving the accommodation permission signal, the mode switching unit 30 of the STA1 switches from the terminal mode to the child AP mode (step S115). The mode switching unit 30 of the STA1 activates the child AP function unit 40 and starts processing for the function of the child AP. After starting the process for the function of the child AP, the communication control unit 20 of the STA1 transmits a connection permission signal to the STAx (step S116). The STAx receives a connection permission signal from the child AP (STA1) (step S117). The STAx knows from the connection permission signal that the STA1 has changed to the child AP mode and that it has connected to the STA1. Thereafter, the STAx can communicate with the STAs 1 to 3 and the like via the child AP (STA1) and the parent AP1.

  Through the above operation, a terminal located outside the communication area of the parent AP1 can be accommodated in the parent AP1 network, and the area connectable to the parent AP1 network can be easily expanded. By making a cell edge terminal a candidate for a child AP, an STA suitable for expanding the area connectable to the network of the parent AP 1 can be easily selected. By determining whether or not the cell edge terminal becomes a child AP depending on whether the remaining battery level of the cell edge terminal is equal to or greater than the threshold, it is possible to connect to the network of the parent AP1 based on a period during which communication can be continued. The area can be enlarged.

  In FIG. 4, the parent AP 1 selects and designates the cell edge terminal before transferring the synchronization signal. However, a field (hereinafter referred to as a cell edge field) in which the address of the cell edge terminal is described in the synchronization signal. The MAC address of the cell edge terminal may be described in the synchronization signal (step S101) provided by the parent AP1. The parent AP1 may transmit the synchronization signal by sequentially describing the addresses of the terminals connected to the parent AP1 in the cell edge field. In addition, all terminals transmit a synchronization signal without providing a cell edge field, and by providing a transfer request bit in the synchronization signal and setting the corresponding bit when transmitting the synchronization signal to be transferred, the synchronization signal is transmitted to all terminals. You may take the method of instructing transfer. By doing so, it is possible to expand the area connectable to the network of the parent AP 1 while omitting the process of selecting the cell edge terminal.

Next, details of the operation of STAx in steps S104 and S105 will be described.
The STAx is turned on and activated by a user or a timer of the device. After starting, the STAx is input by a user or read from a memory or the like, and SSID and security key information are set.

  Next, the STAx scans (searches) for a network having an SSID that matches the set SSID (step S104). When a synchronization signal in which an SSID that matches the set SSID is received from the AP, the STAx performs a connection process with the AP that is the transmission source of the synchronization signal. When the synchronization signal is not received from the AP but the synchronization signal transferred by the STA1 is received (step S105), the STAx transmits a connection request to the STA1 and requests whether the parent AP1 is accommodated by the network. Is determined (step S106). Note that if the synchronization signal cannot be received at all even after a predetermined number of scans, the STAx becomes an AP and starts the network.

Next, details of the operation of STA1 in steps S102 and S103 will be described.
First, the transmission / reception unit 10 of the STA1 receives a cell edge notification signal from the parent AP1. When the communication control unit 20 of the STA1 receives the cell edge notification signal, the communication control unit 20 enables the function as a cell edge terminal (a function of transferring a synchronization signal and a function of storing information on the synchronization signal in the synchronization signal storage unit 50).

  Next, the transceiver 10 of the STA1 receives a synchronization signal from the parent AP1 (step S102). The communication control unit 20 of the STA1 confirms that the transfer flag is described in the synchronization signal, and writes the information described in the synchronization signal in the synchronization signal storage unit 50. The communication control unit 20 of the STA1 acquires information indicating the “transfer period” and the “standby period” described in the synchronization signal. The “transfer period” and the “waiting period” are specified by a relative value from the time when reception of the synchronization signal is completed, or an absolute value of time information for performing synchronization processing with the parent AP 1 using the synchronization signal. The communication control unit 20 of the STA1 starts a timer from the time when reception of the synchronization signal is completed.

  At the timing when the “transfer period” starts, the communication control unit 20 of the STA1 sends a synchronization signal that describes the information stored in the synchronization signal storage unit 50 and the address of the STA1 to all directions in which the STA1 can transmit. The transmission of the synchronization signal is started (for example, omni) (step S103).

  At the timing when the “waiting period” starts, the communication control unit 20 of the STA1 sets the direction (directivity) to receive radio waves as all directions (for example, omni) that the STA1 can receive from the direction of the parent AP1. Start waiting for a connection request signal.

  When the “waiting period” has ended but the connection request signal has not been received, the communication control unit 20 of the STA1 changes the direction (directivity) to receive radio waves from all directions in which the STA1 can receive signals. Change in the direction of AP1. Note that the communication control unit 20 of the STA1 may continue the omni transmission / reception.

(Modification 1)
In the first embodiment, the only terminal that can communicate with the STAx is the STA1. However, there may be a plurality of terminals (here, STA1 and STA2 as an example) that can communicate with the STAx, such as when the STAx is located slightly above the position shown in FIG. Here, it is assumed that the parent AP1 selects STA1 and STA2 as cell edge terminals and transmits a cell edge notification signal to STA1 and STA2.

  When the transfer flag is described in the synchronization signal, the parent AP1 transmits, in addition to the “waiting period”, the “transfer period for STA1”, which is the period during which STA1 transmits the synchronization signal, and STA2 transmits the synchronization signal. The “transfer period for STA2”, which is a period to be performed, is described. Note that the “transfer period for STA1” and the “transfer period for STA2” do not overlap.

  By doing so, STA1 transmits a synchronization signal in which the address of STA1 is described in the “transfer period for STA1”, and STA2 transmits a synchronization signal in which the address of STA2 is described in the “transfer period for STA2”. As a result, collisions with each other can be avoided.

  In addition, when transmission of the synchronization signal from STA1 and STA2 can be separated in space in consideration of directional transmission or terminal arrangement, the “transfer period for STA1” and the “transfer period for STA2” are the same. It may be.

  The STAx receives from the STA1 and STA2 a synchronization signal in which each address is described (step S105). The STAx transmits a connection request signal to the higher reception power of the synchronization signal (step S107). Note that the STAx may inquire of the STA1 and STA2 about the remaining battery level and connect to the battery with the higher remaining battery level. In addition, when the synchronization signals transmitted from a plurality of terminals are each equal to or greater than the threshold value, the STAx may inquire about the remaining battery power of the plurality of terminals and connect to the battery with the larger remaining battery capacity.

  In this way, a terminal having a communication quality with a STAx newly connected to the network of the parent AP1 that is higher than a certain level and having a large remaining battery capacity and a period of time during which communication can be continued can be designated as a child AP. Can be selected as a terminal.

(Modification 2)
In Modification 1 of the first embodiment, when there are a plurality of terminals (here, STA1 and STA2 as examples) that can communicate with STAx, STA1 and STA2 assign their addresses to the synchronization signal. The synchronization signal is transmitted (transferred) as described (step S103).

  However, in the first modification of the first embodiment, the STA1 and the STA2 can transmit (transfer) exactly the same synchronization signal (for example, the synchronization signal itself received from the parent AP1) (step S103).

  When describing the transfer flag in the synchronization signal, the parent AP1 describes “transfer timing”, which is the timing at which the STA1 and STA2 transmit the synchronization signal, in addition to the “waiting period”.

  When the plurality of cell edge terminals (STA1, STA2) receive the synchronization signal in which the transfer flag is described, they simultaneously transmit the synchronization signal itself received from the parent AP1 at the “transfer timing” (step S103).

  When STAx receives synchronization signals from a plurality of cell edge terminals (STA1, STA2) at the same time, the synchronization signal transmitted from STA1 and the synchronization signal transmitted from STA2 are exactly the same. The reception characteristic can be improved by the diversity effect in which the signals strengthen each other.

  When the STAx requests connection to the network of the parent AP1, the STAx transmits a connection request signal with the parent AP1 as the destination (step S107). The STA1 and STA2 receive the connection request signal transmitted from the STAx to the parent AP1 although the destination address is not their own address (step S108).

  Then, STA1 and STA2 individually determine whether or not to accommodate STAx (step S109). If only one side determines to accommodate the STAx, then the same processing as in the first embodiment is performed. When STA1 and STA2 determine to accommodate STAx, one of STA1 and STA2 that has acquired the transmission right earlier transmits a switching signal and an accommodation request signal to parent AP1 (step S110). The other of the STA1 and STA2 that has acquired the transmission right earlier interrupts the STAx accommodation process (the process after step S110) when the STA1 transmits the switching signal and the accommodation request signal to the parent AP1.

  In this way, the synchronization signal from the parent AP1 can be transmitted over a wider range using the diversity effect, and the tolerance against errors in the synchronization signal can be improved.

(Modification 3)
In the second modification of the first embodiment, only the terminal designated as the cell edge terminal for the parent AP1 transmits (transfers) the synchronization signal (step S103).

  However, in the second modification of the first embodiment, all of the terminals (STA1 to 3 and child AP1) that are connected to the parent AP1 and directly receive the synchronization signal from the parent AP1 (hereinafter, all terminals) Exactly the same synchronization signal (for example, the synchronization signal itself received from the parent AP1) can be transmitted (transferred) (step S103). Note that all terminals connected to the parent AP1 may be determined in advance to transfer the synchronization signal, or the parent AP1 may transmit a cell edge notification signal in which all terminals are cell edge terminals.

  When describing the transfer flag in the synchronization signal, the parent AP1 describes “transfer timing”, which is the timing at which all terminals transmit the synchronization signal, in addition to the “waiting period”.

  When all the terminals have received the synchronization signal in which the transfer flag is described, they simultaneously transmit the synchronization signal itself received from the parent AP 1 at “transfer timing” (step S103). Note that the STAx can receive the synchronization signal transmitted from the STA1 and STA2 among all the terminals. The STAx cannot receive the synchronization signal transmitted from the STA3 and the child AP1 among all the terminals.

  In the case of STAx, when synchronization signals are simultaneously received from a plurality of terminals (STA1, STA2) among all terminals, the synchronization signal transmitted from STA1 and the synchronization signal transmitted from STA2 are exactly the same. The reception characteristic can be improved by the diversity effect in which both synchronization signals strengthen each other.

  The STAx receives the synchronization signal whose transmission source is the parent AP1 from the STA1 and STA2 (step S105). When the STAx requests connection of the parent AP1 to the network (step S106), the STAx transmits a connection request signal to the parent AP1.

  All terminals (here, STA1 and STA2 in particular) try to receive (observe) a connection request signal destined for the parent AP1 and its delivery confirmation signal (for example, Ack). All terminals can grasp that the parent AP1 has accepted the connection request when the connection request signal addressed to the parent AP1 and the delivery confirmation signal thereof can be received. On the other hand, when all terminals can receive a connection request signal destined for the parent AP1 a plurality of times and cannot receive the delivery confirmation signal at all, and when the number of retransmissions of the connection request signal exceeds a threshold value Changes to the parent AP1 and transmits a delivery confirmation signal for the connection request signal destined for the parent AP1 to the STAx. Thereafter, as in the second modification of the first embodiment, the STA1 proceeds with processing (steps S109, S110, etc.).

  In this way, even if the parent AP1 does not select a cell edge terminal, a terminal located outside the communication area of the parent AP1 can be accommodated in the parent AP1 network, and an area that can be connected to the parent AP1 network is established. Can be easily expanded.

(Modification 4)
In the first embodiment, when the cell edge terminal (STA1) transmits (transfers) the synchronization signal (step S103), it is assumed that the STAx is being scanned (step S104). However, there are cases where the STAx is not yet powered on and has not started scanning.

  In this case, the STA1 transmits a synchronization signal (step S103), and then does not receive a connection request signal from the STAx even if it waits for a “waiting period” and a connection request signal.

  However, it is assumed that a predetermined period has passed and STA1 has received a search signal (Probe Request) for searching for an AP connected from STAx. In this case, the communication control unit 20 of the STA1 uses the information stored in the synchronization signal storage unit 50 to create a synchronization signal previously received from the parent AP1, and transmits it to the STAx when the STA1 acquires the transmission right. . Thereafter, processing similar to that of the first embodiment (step S109 and subsequent steps) is performed.

  By doing so, even if the STAx is not scanning during the “transfer period”, the area that can be connected to the network of the parent AP 1 can be easily expanded by transmitting the search signal.

(Modification 5)
In the first embodiment, an example has been described in which the parent AP1, STA1, STA2, and STAx can transmit (omni) radio waves in all directions. However, the parent AP1, STA1, STA2, and STAx may not be able to transmit (omni) radio waves in all directions or receive (omni) radio waves from all directions.

  FIG. 5 is a diagram illustrating an arrangement of the parent AP1, STA1, STA2, and STAx.

  The parent AP1, STA1, and STA2 receive radio waves from a specific direction and transmit radio waves in the specific direction. The parent AP1, STA1, and STA2 can narrow the directivity of transmission and reception radio waves with respect to at least one of areas (sectors) obtained by dividing a specific direction into four. When the parent AP1 directs directivity to the first sector, if the STA2 directs directivity to the fourth sector, communication can be performed between the parent AP1 and the STA2. However, when the parent AP1 directs directivity to the first sector, if the STA2 directs directivity to the first to third sectors, communication cannot be performed between the parent AP1 and the STA2. When the parent AP1 directs directivity toward the fourth sector, if the STA1 directs directivity toward the first sector, communication can be performed between the parent AP1 and the STA2. However, when the parent AP1 directs directivity to the fourth sector, if the STA1 directs directivity to the second to fourth sectors, communication cannot be performed between the parent AP1 and the STA1. When the parent AP1 directs directivity to the second and third sectors, it cannot communicate with the STA1 and STA2. If STA1 transmits radio waves with directivity directed to at least the third sector, STAx can receive radio waves.

  As shown in FIG. 5, even if the parent AP1, STA1, STA2, and STAx are arranged and the transmission and reception range is limited, the method described in the first embodiment and the first to third modifications of the first embodiment is used. The area connectable to the parent AP1 network can be easily expanded.

  The parent AP1 selects the wireless terminals (STA1, STA2) that communicate with the end sectors (1, 4th sector) among the 1st to 4th sectors as cell edge terminals. The parent AP 1 selects, as a cell edge terminal, a terminal whose received signal power is equal to or less than a threshold value, even if it is a wireless terminal that communicates in the central sector (second and third sectors) among the first to fourth sectors. . Note that the communication control unit 20 of the parent AP1 manages each terminal and its directivity information, uses the fourth sector for transmission / reception with the STA1, and uses the first sector for communication with the STA2. I manage things.

  STA1 and STA2 can determine whether they are cell edge terminals without receiving a cell edge notification signal from parent AP1. The AP periodically transmits synchronization signals while sequentially directing the directivity of radio waves to the first to fourth sectors that can be transmitted. This synchronization signal describes the number of wireless directional sectors of the parent AP 1 and the sector number used for transmission. Therefore, if the STA1 and the STA2 receive the synchronization signal from the parent AP1, the STA1 and the STA2 can grasp the number of wireless directional sectors of the connected parent AP1 and the number of sectors that can be received by the STA1 and STA2. STA1 and STA2 determine that they are cell edge terminals when they are located in the end sector of the parent AP1 sectors.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

STA1, STA2, STA3, STAx ... wireless device AP1 ... wireless base station 10 ... transmission / reception unit 20 ... communication control unit 30 ... mode switching unit 40 ... child AP function unit 50 ...・ Sync signal storage

Claims (10)

A wireless device connected to the first wireless base station,
Receiving means for receiving a synchronization signal from the first radio base station;
Transmission means for transmitting the synchronization signal to a second region including at least other than the first region capable of receiving the synchronization signal from the first radio base station;
After receiving the synchronization signal, for a period specified by the first radio base station, the receiving unit waits for reception of a connection request frame for requesting connection with the first radio base station,
When the connection request frame is received from another radio apparatus, the transmission means transmits a frame requesting accommodation to the first radio base station. A connection means for connecting to the other wireless device that has transmitted the connection request frame without being connected to the first wireless base station;
When connected to the other wireless device and receiving a first frame addressed to the other wireless device from the first wireless base station, the first frame is transmitted to the other wireless device;
Transmitting the second frame to the first radio base station when connected to the other radio device and receiving a second frame addressed to the first radio base station from the other radio device; The wireless device according to claim 1, characterized in that: When the remaining battery level is equal to or less than the threshold, the transmitting unit does not transmit the frame requesting accommodation to the first radio base station even when the receiving unit receives the connection request frame. The wireless device according to claim 1. The synchronization signal transmitted from the first radio base station is received not only by the radio device but also by the second radio device,
The time at which the wireless device transmits the synchronization signal is designated as the first time from the first wireless base station,
The time at which the second radio apparatus transmits the synchronization signal is designated as the second time from the first radio base station,
The first time and the second time are different,
The radio apparatus according to claim 1, wherein the transmission unit transmits the synchronization signal at the first time. The synchronization signal transmitted from the first radio base station is received not only by the radio device but also by the second radio device,
The time at which the wireless device transmits the synchronization signal is designated as the first time from the first wireless base station,
The time at which the second radio apparatus transmits the synchronization signal is designated as the second time from the first radio base station,
The first time and the second time are the same time,
The transmission means transmits the synchronization signal at the first time,
The source address of the synchronization signal transmitted by the transmission means and the synchronization signal transmitted by the second radio apparatus is set to the address of the first radio base station for both. The wireless device according to claim 1. When the receiving means receives the connection request frame from the other wireless device, the transmitting means sends a frame requesting the accommodation to the first wireless base station and the wireless device as a second Send a switch request frame to switch to the radio base station,
The wireless device according to claim 3, wherein the connection unit is connected to the other wireless device. When the number of retransmissions of the connection request frame addressed to the first radio base station by the other radio device exceeds a threshold, the transmission means transmits a frame requesting the accommodation to the first radio base station; A switch request frame for switching the wireless device to a second wireless base station,
The wireless device according to claim 3, wherein the connection unit is connected to the other wireless device. Even when it is determined that the connection with the other wireless device is to be performed, the second wireless device before the transmission means transmits the frame requesting accommodation and the switching request frame, The wireless device according to claim 6, wherein, when connected to a wireless device, the transmission unit does not transmit the frame requesting accommodation and the switching request frame. It further comprises control means for controlling the directivity of radio waves to be transmitted and received,
The radio apparatus according to claim 1, wherein when the reception unit waits for reception of the connection request frame, the control unit sets the directivity of the radio wave in all directions. A communication method of a wireless device connected to a first wireless base station,
Receiving a synchronization signal from the first radio base station;
Transmitting the synchronization signal to a second area including at least other than the first area capable of receiving the synchronization signal from the first radio base station;
Waiting for reception of a connection request frame for requesting connection with the first radio base station for a period designated by the first radio base station after transmitting the synchronization signal,
A wireless device communication method, comprising: transmitting a frame requesting accommodation to the first wireless base station when the connection request frame is received from another wireless device.

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