JP4217665B2 - Wireless communication system, wireless communication method, wireless terminal, and wireless base station - Google Patents

Description

  The present invention relates to a wireless communication system, a wireless communication method, a wireless terminal, and a wireless base station.

  In the IEEE802.11 wireless LAN infrastructure mode in which multiple wireless terminals belong to one wireless base station, wireless terminals cannot communicate directly with other wireless terminals in the same cell. IEEE802.11e, which is currently being developed as an extended specification, enables communication between wireless terminals (DLP: Direct Link Protocol) (see IEEE802.11e).

  For example, in IEEE802.11e, a wireless base station transmits a frame (QoS Cf-Poll frame) that grants a transmission right with a transmittable period written to a wireless terminal, and grants the wireless terminal a transmission right for a certain period. The wireless base station can centrally control the wireless space (HCCA: HFC controlled channel access) (see IEEE802.11e).

  However, in a wireless communication system that performs wireless communication using the CSMA / CA method adopted by the wireless LAN communication standard represented by IEEE802.11, each wireless terminal uses the same communication channel in the same cell (BSS). And communicate. Therefore, in the same cell (BSS), it was not possible to perform communication between multiple terminals at the same time.

In Patent Document 1 below, when a carrier signal arriving from a mobile station in a base station service area is always searched for with a group of directional antennas of a base station and a carrier signal is detected, a packet is transmitted using the directional antenna. Receive. While the packet is being received, the flag portion included in the packet is monitored, the omnidirectional carrier search is restarted by detecting the end flag, and the reception of the packet for which the reception start flag has not been detected by the lapse of a certain time after the start of reception is performed. Absent. Also, in a system employing the CSMA scheme, the beam width of the directional antenna of the base station is made smaller than the carrier sense area of the mobile station.
JP-A-9-247187

  An object of the present invention is to provide a wireless communication system, a wireless communication method, a wireless terminal, and a wireless base station that can solve the above-described problems and can simultaneously perform communication between a plurality of terminals in the same cell. .

A wireless communication system as one aspect of the present invention includes:
A wireless communication system comprising first, second, third, and fourth wireless terminals and a wireless base station,
The first to fourth wireless terminals are respectively
First transmission means for transmitting an inter-terminal communication request frame requesting to perform inter-terminal communication with another radio terminal among the first to fourth radio terminals, to the radio base station;
A receiving antenna for receiving radio waves,
Inspection means for inspecting the reception status of radio waves;
Have
The radio base station is
First receiving means for receiving the inter-terminal communication request frame;
A first inter-terminal communication request frame for requesting to perform inter-terminal communication between the first and second radio terminals from the first radio terminal; and the third and fourth from the third radio terminal. When a second inter-terminal communication request frame requesting that inter-terminal communication is performed between the wireless terminals of
The reception status of the radio wave is inspected during inter-terminal communication between the first and second wireless terminals.
Transmitting a first inspection instruction frame instructing to perform to the third and fourth wireless terminals;
The reception status of the radio wave is inspected during inter-terminal communication between the third and fourth wireless terminals.
Second transmitting means for transmitting a second inspection instruction frame instructing to the first and second wireless terminals;
Second receiving means for receiving radio wave reception status information indicating a radio wave reception status from the first to fourth radio terminals;
Inter-terminal communication between the first and second wireless terminals and inter-terminal communication between the third and fourth wireless terminals based on the radio wave reception status information received from the first to fourth wireless terminals Determination means for determining whether or not can be executed simultaneously;
A third transmission means for transmitting a communication permission frame to each of the first and third wireless terminals when it is determined that the communication between the terminals can be performed simultaneously;
It is provided with.

A radio base station as one aspect of the present invention is:
A wireless base station that performs wireless communication with a plurality of wireless terminals,
A first inter-terminal communication request frame requesting to perform inter-terminal communication between the first and second radio terminals is received from the first radio terminal, and the third and fourth radio terminals are received from the third radio terminal. First receiving means for receiving a second inter-terminal communication request frame for requesting inter-terminal communication between terminals;
When the first and second inter-terminal communication request frames are received, a first inspection instructing to inspect radio wave reception status during inter-terminal communication between the first and second wireless terminals A second inspection instruction that transmits an instruction frame to the third and fourth wireless terminals and instructs to inspect the reception status of the radio wave during inter-terminal communication between the third and fourth wireless terminals. First transmission means for transmitting a frame to the first and second wireless terminals;
Second receiving means for receiving radio wave reception status information indicating a radio wave reception status from the first to fourth radio terminals;
Based on the radio wave reception status information received from the first to fourth wireless terminals, communication between terminals between the first and second wireless terminals and communication between terminals between the third and fourth wireless terminals, Determining means for determining whether or not can be executed simultaneously;
When it is determined that inter-terminal communication between the first and second radio terminals and inter-terminal communication between the third and fourth radio terminals can be performed simultaneously, the first and third radio terminals A second transmission means for transmitting communication permission data to the terminal;
It is provided with.

  The wireless communication method of the present invention is a wireless communication method in which a plurality of wireless terminals perform inter-terminal communication within a communication area by a wireless base station, wherein the first wireless terminal is a terminal between the first and second wireless terminals. A first transmission step of transmitting a first inter-terminal communication request frame requesting to perform inter-communication to the radio base station, and inter-terminal communication between the third and fourth radio terminals by the third radio terminal A second transmission step of transmitting a second inter-terminal communication request frame requesting to be performed to the radio base station, and when the radio base station receives the first and second inter-terminal communication request frames The first and second test instruction frames for instructing the radio base station to inspect the reception status of radio waves while performing inter-terminal communication between the first and second radio terminals. Third transmission step for transmitting to the wireless terminal The second and second inspection instruction frames instructing the wireless base station to inspect the reception status of the radio wave during inter-terminal communication between the third and fourth wireless terminals. A fourth transmitting step for transmitting to a wireless terminal; a receiving step for receiving, from the first to fourth wireless terminals, radio wave reception status information indicating a radio wave reception status from the first to fourth radio terminals; and Based on the radio wave reception status information, inter-terminal communication between the first and second wireless terminals and inter-terminal communication between the third and fourth wireless terminals for the first to fourth wireless terminals. A determination step of determining whether or not the wireless base station can be executed simultaneously, and the wireless base station performs inter-terminal communication between the first and second wireless terminals and the third and the third wireless terminals with respect to the first to fourth wireless terminals. Inter-terminal communication between fourth wireless terminals can be performed simultaneously If it is determined that includes, a fifth transmission step of transmitting the communication permission data to the first and third wireless terminals.

  According to the present invention, it is possible to simultaneously perform communication between a plurality of terminals in the same cell.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiment of the present invention will be described using IEEE 802.11, which is one of wireless communication standards, as an example. The wireless LAN communication system based on IEEE802.11 is one of the wireless communication systems to which the present invention can be preferably applied, but the application target of the present invention is not limited to IEEE802.11, and the present invention is applicable to all wireless communication systems. Is possible.

(First embodiment)
FIG. 1 is a diagram showing a basic configuration of a radio communication system according to an embodiment of the present invention.

  Four terminals (STA) 102 to 105 belong to the access point (AP) 101 to form one wireless cell (BSS). These four terminals 102 to 105 and the access point 101 are connected to the wireless space centralized control (HCCA: HFC controlled channel access) and inter-terminal communication (DLP: Direct Link Protocol) defined in IEEE802.11e. The transmission power control specified in .11h is executed. This transmission power control is as follows. That is, in order for the terminal to control the transmission power, the terminal transmits a control frame in which the transmission power value is written to the access point (wireless base station), and the access point that receives the control frame checks the power at the time of reception. And return the received power value. The terminal controls transmission power based on the difference between the transmitted power value and the received power value (see IEEE802.11h).

  Control frames (ADDTS.requset, ADDTS.response, DLP request, TPC request, TPC) necessary to execute the above three functions, centralized control of radio space (HCCA), communication between terminals (DLP), and transmission power control report) has been exchanged. Inter-terminal communication (DLP) is performed between the terminal 102 and the terminal 103 and between the terminal 104 and the terminal 105. In the present embodiment, it is assumed that terminal 102 and terminal 104 are transmitting terminals.

  FIG. 2 is a block diagram illustrating the configuration of the terminal 102 to the terminal 105.

  The transmission / reception unit 11 includes an omnidirectional transmission / reception antenna 11a and transmits / receives data. The transmission power control unit 12 controls transmission power. The radio wave reception state inspection unit 13 inspects the reception state of radio waves. The control unit 14 controls the entire terminal.

  FIG. 3 is a block diagram showing the configuration of the access point 101.

  The transmission / reception unit 21 includes a non-directional transmission / reception antenna 21a, and transmits / receives data. The inspection instruction unit 22 generates an inspection instruction signal that instructs the terminal to inspect the reception state of the radio wave for a certain period. The transmission right granting unit 23 generates a QoS CF-Poll frame (hereinafter referred to as a transmission right granting frame) that is a frame for granting a transmission right to a terminal for a certain period (TXOP). The control unit 24 controls the entire access point.

  FIG. 4 is a flowchart for explaining the operation of the wireless communication system of FIG.

The terminal-to-terminal communication (DLP) setting has been completed between the terminal 102 and the terminal 103, and the ADDTS frame in the TSPEC in which the direction from the terminal 102 is Direct link and the Access Policy is HCCA or Both controlled and contention-based channel access. When the HCCA setup is performed by the access point 101, the access point 101 calculates a period (TXOP) and a transmission cycle necessary to satisfy TSPEC, and periodically transmits a transmission right grant frame to the terminal 102. 102 is granted a transmission right for a certain period (TXOP period), and the terminal 102 and the terminal 103 perform inter-terminal communication by HCCA (step S1).
The terminal-to-terminal communication (DLP) setting has been completed between the terminal 104 and the terminal 105, and the access point 101 has a Direct link from the terminal 104 and an Access Policy of HCCA or Both controlled and contention-based channel access. Receive an ADDTS.requset frame using TSPEC. (Step S2)
The access point 101 transmits an inspection instruction signal to the terminal 104 and the terminal 105 to inspect for how long a radio wave is detected in each of the terminals 104 and 105 for a certain period (step S3).

  On the other hand, as shown in FIG. 7, the access point 101 transmits a transmission right grant frame to the terminal 102, and performs communication by DLP (hereinafter referred to as DLP communication) between the terminal 102 and the terminal 103 for a certain period (step S4). .

  After completing the DLP communication between the terminal 102 and the terminal 103, the access point 101 receives a test result report from the terminal 104 and the terminal 105 (step S5). That is, the access point 101 determines whether or not radio waves are detected in the terminal 104 and the terminal 105 during the DLP communication between the terminal 102 and the terminal 103, and if so, reports how much the terminal 104 and Receive from terminal 105.

  From the reported result, the access point 101, when performing DLP communication between the terminal 102 and the terminal 103, indicates that the radio waves that interfere with the DLP communication simultaneously between the terminal 104 and the terminal 105 are transmitted to the terminal 104 and the terminal 105. It is determined whether or not it has been detected in at least one of the terminals 105 (step S6).

  If such a radio wave is not detected (NO in step S6), that is, if no radio wave is detected, or if it is weak, it does not affect the DLP communication between the terminal 104 and the terminal 105, The access point 101 determines that the DLP communication between the terminal 102 and the terminal 103 does not affect the carrier sense between the terminal 104 and the terminal 105. Similarly, the access point 101 performs DLP communication between the terminal 104 and the terminal 105, and inspects how much radio waves are detected in the terminal 102 and the terminal 103 during that time (step S7).

  When performing DLP communication between the terminal 104 and the terminal 105, radio waves that hinder simultaneous DLP communication between the terminal 102 and the terminal 103 were not detected in at least one of the terminal 102 and the terminal 103. In this case (NO in step S8), the access point 101 determines that the DLP communication between the terminal 102 and the terminal 103 and the DLP communication between the terminal 104 and the terminal 105 do not affect each other (step S9). That is, the access point 101 determines that the DLP communication between the terminal 102 and the terminal 103 and the DLP communication between the terminal 104 and the terminal 105 can be executed at the same time.

  In step S6 or step S8, when a radio wave that hinders the DLP communication is detected in any of the terminal 102 to the terminal 105, this process ends.

  When the number of DLP communications performed in the same cell has increased to two or more, the process of checking the reception status of radio waves while other DLP communications are being performed It is possible to confirm whether or not a plurality of DLP communications can be performed at the same time.

  As described above, according to the present embodiment, two or more DLP communications can be simultaneously executed in a cell, so that the throughput of the entire cell can be improved.

(Second Embodiment)
FIG. 5 is a block diagram showing a configuration of terminal 202 to terminal 205 according to the present embodiment.

  The transmission / reception unit 31 includes an omnidirectional transmission antenna 31a and a reception antenna 31b having variable directivity, and transmits / receives data. The transmission power control unit 32 controls transmission power. The directional antenna control unit 33 controls the reception directivity of the reception antenna 31b and directs the directional beam toward the terminal that is the transmission destination of the radio wave. As the omnidirectional transmitting antenna, the same antenna as the directional receiving antenna may be used, and this antenna may be used for omnidirectional transmission. The radio wave reception state inspection unit 34 inspects the reception state of radio waves. The control unit 35 controls the entire terminal. Terminal 202 to terminal 205 correspond to terminal 101 to terminal 105 in the first embodiment.

  The configuration of the access point according to this embodiment is the same as that of the first embodiment (see FIG. 3).

  FIG. 6 is a flowchart for explaining the operation of the radio communication system according to this embodiment.

  The access point 101 transmits an inspection instruction signal to the terminal 204 and the terminal 205 to inspect for a certain period whether or not radio waves are detected (step S11).

  As shown in FIG. 7, the access point 101 transmits a transmission right grant frame to the terminal 202 to perform DLP communication between the terminal 202 and the terminal 203 for a certain period (step S12).

  After completing the DLP communication between the terminal 202 and the terminal 203, the access point 101 receives a test result report from the terminal 204 and the terminal 205 (step S13). That is, the access point 101 receives from the terminal 204 and the terminal 205 a report of how much radio wave has been detected while performing DLP communication between the terminals 202 and 203.

  From the reported result, the access point 101, when performing DLP communication between the terminal 202 and the terminal 203, indicates that the radio waves that hinder simultaneous DLP communication between the terminal 204 and the terminal 205 are transmitted to the terminal 204 and the terminal 205. It is determined whether or not it has been detected by the terminal 205 (step S14).

  When such a radio wave is not detected (NO in step S14), the access point 101 determines that the DLP communication between the terminal 202 and the terminal 203 does not affect the carrier sense between the terminal 204 and the terminal 205. Similarly, the access point 101 performs DLP communication between the terminal 204 and the terminal 205, and inspects how much radio waves are detected in the terminal 202 and the terminal 203 during that time (step S15).

  When DLP communication is performed between the terminal 204 and the terminal 205, a radio wave that hinders simultaneous DLP communication between the terminal 202 and the terminal 203 is not detected in the terminal 202 and the terminal 203 (step S16: NO), the access point 101 determines that the DLP communication between the terminal 202 and the terminal 203 and the DLP communication between the terminal 204 and the terminal 205 do not affect each other (step S17). That is, the access point 101 determines that the DLP communication between the terminal 202 and the terminal 203 and the DLP communication between the terminal 204 and the terminal 205 can be executed at the same time.

  In step S14 or step S16, when a radio wave that interferes with DLP communication is detected in at least one of terminal 202 to terminal 205, access point 101 transmits a transmission power control instruction signal to the terminal that performs DLP communication. Is transmitted to lower the output of the radio wave (step S18). For example, when a strong radio wave is detected at the terminal 205, the output of the radio wave is lowered by at least one of the terminal 202 and the terminal 203. In addition, a directivity control instruction signal is transmitted to the terminal in which strong radio waves are detected, and null is directed toward the terminal performing DLP communication (step S18). Or both of these are performed (step S18). Thereafter, the access point 101 performs the same inspection (steps S11 to S17).

  When the number of DLP communications performed in the same cell has increased to two or more, the process of checking the reception status of radio waves while other DLP communications are being performed It is possible to confirm whether or not a plurality of DLP communications can be performed at the same time.

  As described above, according to the present embodiment, since the terminal is provided with the variable directivity receiving antenna and the directional antenna control unit, and when radio waves that cannot be used for DLP communication are detected, Since the transmission power is reduced, the possibility of simultaneously executing a plurality of DLP communications in one cell can be increased.

(Third embodiment)
In this embodiment, first, the access point 101 can execute the DLP communication between the terminal 102 and the terminal 103 and the DLP communication between the terminal 104 and the terminal 105 at the same time using the second embodiment. Confirm that there is. The first embodiment may be used. Thereafter, the access point 101 transmits a transmission right grant frame to a terminal that is a transmission side of each DLP communication in order to start each DLP communication. Hereinafter, a transmission method of the transmission right grant frame will be described.

  FIG. 8 is a flowchart illustrating a transmission right grant frame transmission method.

  Assume that the terminal 202 is the transmission side in the DLP communication between the terminal 202 and the terminal 203, and the terminal 204 is the transmission side in the DLP communication between the terminal 204 and the terminal 205. In this case, the access point 101 grants a transmission right for performing DLP communication between the terminal 202 and the terminal 203 to the terminal 202, and grants a transmission right for performing DLP communication between the terminal 204 and the terminal 205 to the terminal 204. To do. The access point 101 creates a multicast address for simultaneously granting transmission rights to the terminal 202 and the terminal 204 (step S20). If the set of terminals to be transmitted is different, another multicast address is created.

The access point 101 notifies the terminal 202 and the terminal 204 that the created multicast address is a multicast address addressed to the terminal 202 and the terminal 204. (Step S21)
The access point 101 generates a transmission right grant frame (QoS CF-Poll frame) including the created multicast address and a DLP communication period (TXOP period: Transmission Opportunity period), and the generated transmission right grant frame is shown in FIG. It transmits as shown (step S22). As a result, a transmission right is simultaneously given to each terminal 202 and terminal 204.

  After transmitting the transmission right grant frame, the access point 101 confirms whether carrier sense busy is detected within PIFS (step S23).

  If it is detected (YES in step S23), the access point 101 determines that the transmission right grant frame has reached at least one of the terminal 202 and the terminal 204. The terminal 202 and the terminal 204 to which the transmission right is given start DLP communication with the terminal 203 and the terminal 205, respectively (step S24). This improves the throughput of the entire cell.

  On the other hand, when carrier sense busy is not detected within PIFS (NO in step S23), the access point 101 determines that transmission of the transmission right grant frame has failed, and transmits again (step S25).

  As described above, according to the present embodiment, since a transmission right grant frame is transmitted using a multicast address, a transmission right can be simultaneously given to each terminal, and thus a plurality of DLP communications can be started simultaneously or substantially simultaneously.

(Fourth embodiment)
In the third embodiment, a transmission right is simultaneously granted using a multicast address. In this embodiment, another method for simultaneously granting a transmission right will be described.

  FIG. 10 is a block diagram showing the configuration of the access point 201 according to the present embodiment.

  The transmission / reception unit 41 includes a directional variable transmission antenna 41a and an omnidirectional reception antenna 41b. The directional antenna control unit 43 controls the transmission directivity of the transmission antenna 41a to form a directional beam for a terminal that is a radio wave transmission destination. As the omnidirectional receiving antenna, the same antenna as the transmitting antenna having directivity may be used and used for omnidirectional reception. The inspection instruction unit 42, the transmission right grant unit 44, and the control unit 45 are the same as those in FIG.

  The configuration of the terminal according to this embodiment is the same as that of the second embodiment (see FIG. 5).

  FIG. 11 is a flowchart illustrating a transmission right grant frame transmission method according to the present embodiment.

  When the access point 201 confirms that the DLP communication between the terminal 202 and the terminal 203 and the DLP communication between the terminal 204 and the terminal 205 can be performed at the same time using the second embodiment, (TXOP period) Two transmission right grant frames for granting transmission right are generated. One transmission right grant frame includes the unicast address of the terminal 202, and the other transmission right grant frame includes the unicast address of the terminal 204.

  The access point 201 controls the transmission directivity of the transmission antenna 41a, and simultaneously transmits the two generated transmission right grant frames to the counterpart terminal (step S31).

  After transmitting the transmission right grant frame, the access point 201 confirms whether carrier sense busy is detected within PIFS (step S32).

  If it is detected (YES in step S32), the access point 201 determines that the transmission right grant frame has reached the terminal 202 and the terminal 204. The terminal 202 and the terminal 204 that have received the transmission right grant frame start DLP communication with the receiving side terminal 203 and the terminal 205, respectively (step S33).

  On the other hand, if not detected (NO in step S32), the access point 201 determines that transmission of the transmission right grant frame has failed, and transmits again (step S34).

  As described above, according to the present embodiment, since the transmission point and the directional antenna control unit having variable directivity are provided in the access point, it is possible to simultaneously transmit a plurality of transmission right grant frames and thereby perform a plurality of DLP communication. Can be started simultaneously or substantially simultaneously.

(Fifth embodiment)
FIG. 12 is a block diagram showing the configuration of terminal 302 to terminal 305 according to the present embodiment.

  The transmission / reception unit 51 includes a transmission antenna 51a having variable directivity and a non-directional reception antenna 51b, and transmits and receives data. The transmission power control unit 52 controls transmission power. The directional antenna control unit 53 controls the transmission directivity of the transmission antenna 51a to form a directional beam for a terminal that is a radio wave transmission destination. As the omnidirectional transmitting antenna, the same antenna as the directional receiving antenna may be used and used for omnidirectional transmission. The radio wave reception state inspection unit 54 inspects the reception state of radio waves. The control unit 55 controls the entire terminal.

  The access point in the present embodiment is the same as that in the fourth embodiment, and the directivity of the transmission antenna can be controlled (see FIG. 10).

  FIG. 13 is a flowchart for explaining the operation of the radio communication system according to the present embodiment.

  The access point 201 transmits an inspection instruction signal to the terminal 304 and the terminal 305 to inspect for how long a radio wave is detected for a certain period (step S41).

  As shown in FIG. 14, the access point 201 grants a transmission right for a certain period to the terminal 302 and causes the terminal 302 and the terminal 303 to start DLP communication (step S42).

  However, the terminal 302 controls the transmission directivity and transmission power of the transmission antenna 51a so that the first frame to be transmitted after receiving the transmission right is received by both the access point 201 and the terminal 303. (Step S43). This is to make the access point 201 confirm that the transmission right has been given to the terminal 302. After transmitting the first frame, DLP communication is performed by controlling the directivity and transmission power of the transmission antenna 51a so that data can be transmitted and received only between the terminal 302 and the terminal 303.

  After completing the DLP communication between the terminal 302 and the terminal 303, the access point 201 receives a test result report from the terminal 304 and the terminal 305 (step S44). That is, the access point 201 receives from the terminal 304 and the terminal 305 a report of how much radio wave has been detected while performing DLP communication between the terminal 302 and the terminal 303.

  From the reported result, the access point 201 indicates that when DLP communication is performed between the terminal 302 and the terminal 303, radio waves that hinder simultaneous DLP communication between the terminal 304 and the terminal 305 are transmitted to the terminal 304 and the terminal 303. It is determined whether or not it has been detected at the terminal 305 (step S45).

  When it is determined that such a radio wave has not been detected (NO in step S45), the access point 201 determines that the DLP communication between the terminal 302 and the terminal 303 does not affect the carrier sense between the terminal 304 and the terminal 305. To do. Similarly, the access point 201 performs DLP communication between the terminal 304 and the terminal 305, and causes the terminal 302 and the terminal 303 to check how much radio waves have been detected during that time (step S46).

  When it is determined that radio waves that interfere with DLP communication at the same time between the terminal 302 and the terminal 303 are not detected at the terminal 302 and the terminal 303 during the DLP communication between the terminal 304 and the terminal 305. (NO in step S47), the access point 201 determines that the DLP communication between the terminal 302 and the terminal 303 and the DLP communication between the terminal 304 and the terminal 305 do not affect each other (step S48). That is, the access point 201 determines that the DLP communication between the terminal 302 and the terminal 303 and the DLP communication between the terminal 304 and the terminal 305 can be executed at the same time. The access point 201 uses the third embodiment to generate a transmission right grant frame with multicast addresses addressed to the terminal 302 and the terminal 304, and the access point 201, as shown in FIG. A transmission right granting frame by the addressed multicast address is transmitted, and the transmission right is simultaneously given to the terminal 302 and the terminal 304. Alternatively, the transmission right granting frames addressed to the terminal 302 and the terminal 304 are respectively generated using the fourth embodiment. Then, as shown in FIG. 15, the access point 201 controls the transmission directivity of the transmission antenna 41a and transmits the generated two transmission right grant frames to the terminal 302 and the terminal 304. A transmission right is given to the terminal 304 at the same time.

  If it is determined in step S45 or step S47 that a radio wave that hinders DLP communication has been inspected, the access point 201 controls transmission power to the terminal that performs DLP communication when such radio wave is detected. An instruction signal is transmitted to reduce the output of radio waves, or data transmission / reception is performed using a reception directional antenna (step S49). Thereafter, the access point 201 performs the same investigation (steps S41 to S48).

  When the number of DLP communications performed in the same cell has increased to two or more, the process of checking the reception status of radio waves while performing communications by one DLP is performed for the number of DLP communications. It is possible to confirm whether or not a plurality of DLP communications can be performed at the same time.

  As described above, according to the present embodiment, since the terminal is provided with the transmission antenna and the directional antenna control unit having variable directivity, it is possible to increase the possibility that a plurality of DLP communications can be simultaneously executed in one cell. I can do it.

(Sixth embodiment)
FIG. 16 is a block diagram showing the configuration of terminal 402 to terminal 405 according to the present embodiment.

  The transmitting / receiving unit 61 includes a transmitting / receiving antenna 61a with variable directivity, and transmits / receives data by forming a beam using directivity. The transmission power control unit 62 controls transmission power. The directivity antenna control unit 63 controls the directivity of transmission and reception of the transmission / reception antenna 61a. The radio wave reception state inspection unit 64 inspects the reception state of radio waves. The control unit 65 controls the entire terminal.

The access point in this embodiment is the same as that in the fourth embodiment, and the directivity of the transmission antenna can be controlled (see FIG. 10).
FIG. 17 is a flowchart for explaining the operation of the radio communication system according to the present embodiment.

  The access point 201 transmits an inspection instruction signal to the terminals 404 and 405 to inspect for a certain period whether or not radio waves are detected (step S51).

  As shown in FIG. 14, the access point 201 grants a transmission right to the terminal 402 for a certain period, and causes the terminal 402 and the terminal 403 to start DLP communication (step S52).

  However, after the terminal 402 is granted the transmission right, the transmission directivity of the transmission / reception antenna 61a and the transmission power are set so that the first frame to be transmitted is received by both the access point 201 and the terminal 403. Control (step S53). This is to make the access point 201 confirm that the transmission right is granted to the terminal 402. After transmitting the first frame, DLP communication is performed by controlling the directivity and transmission power of transmission / reception antenna 61a so that data can be transmitted / received only between terminal 402 and terminal 403.

  After completing the DLP communication between the terminal 402 and the terminal 403, the access point 201 receives a test result report from the terminal 404 and the terminal 405 (step S54). That is, the access point 201 receives from the terminal 404 and the terminal 405 a report of how much radio wave has been detected while performing DLP communication between the terminal 402 and the terminal 403.

  From the reported result, the access point 201 indicates that when DLP communication is performed between the terminal 402 and the terminal 403, radio waves that hinder simultaneous DLP communication between the terminal 404 and the terminal 405 are transmitted to the terminal 404 and the terminal 405. It is determined whether or not it has been detected at the terminal 405 (step S55).

  If it is determined that such a radio wave has not been detected (NO in step S55), the access point 201 determines that the DLP communication between the terminal 402 and the terminal 403 does not affect the carrier sense between the terminal 404 and the terminal 405. To do. Similarly, the access point 201 performs DLP communication between the terminal 404 and the terminal 405, and causes the terminal 402 and the terminal 403 to check how much radio waves have been detected during that time (step S56).

  When DLP communication is performed between the terminal 404 and the terminal 405, when it is determined that a radio wave that hinders simultaneous DLP communication is not detected between the terminal 402 and the terminal 403 (NO in step S57) The access point 201 determines that the DLP communication between the terminal 402 and the terminal 403 and the DLP communication between the terminal 404 and the terminal 405 do not affect each other (step S58). That is, the access point 201 determines that the DLP communication between the terminal 402 and the terminal 403 and the DLP communication between the terminal 404 and the terminal 405 can be executed at the same time. The access point 201 uses the third embodiment to generate a transmission right granting frame based on the multicast address addressed to the terminal 402 and the terminal 404, and the access point 201 transmits the transmission right based on the multicast address addressed to the terminal 402 and the terminal 404. The grant frame is transmitted (see FIG. 15), and the transmission right is granted to the terminal 402 and the terminal 404 simultaneously. Alternatively, the transmission right granting frames addressed to the terminal 402 and the terminal 404 are respectively generated using the fourth embodiment. Then, the access point 201 controls the transmission directivity of the transmission / reception antenna 61a to be transmitted to the terminal 402 and the terminal 404, and simultaneously transmits to the terminal 302 and the terminal 304. Grant rights.

  If it is determined in step S55 or step S57 that a radio wave that hinders DLP communication has been detected, the access point 201 controls transmission power to the terminal that performs DLP communication when such radio wave is detected. An instruction signal is transmitted to reduce the output of radio waves, or data transmission / reception is performed using directivity using a transmission / reception directional antenna (step S59). Alternatively, a directivity control instruction signal is transmitted to the terminal that has detected such radio waves, and null is directed toward the terminal that is performing DLP communication (step S59). Or both of these are performed (step S59). Thereafter, the access point 201 performs the same investigation (steps S51 to S58).

  When the number of DLP communications performed in the same cell has increased to two or more, the process of checking the reception status of radio waves while performing communications by one DLP is performed for the number of DLP communications. It is possible to confirm whether or not a plurality of DLP communications can be performed at the same time.

  As described above, according to the present embodiment, since the terminal is provided with the receiving antenna and the transmitting antenna with variable directivity, and the directivity antenna control unit, there is a possibility that a plurality of DLP communications can be executed simultaneously in one cell. Can be dramatically improved.

(Seventh embodiment)
In this embodiment, when the communication quality deteriorates, the directivity of the directional antenna (the receiving antenna having variable directivity and / or the transmitting antenna having variable directivity or both) is recalculated to reduce the communication quality. A method of improving is described. Hereinafter, this embodiment will be described by taking as an example a wireless communication system using terminals 402 to 405 (see FIG. 16) and an access point 201 (see FIG. 10) used in the sixth embodiment.

  FIG. 18 is a flowchart for explaining a method of performing directivity recalculation when communication quality deteriorates.

  While DLP communication is being performed between the terminal 402 and the terminal 403 and between the terminal 404 and the terminal 405 (step S61), after the terminal 402 and the terminal 404 transmit data (step S62), data delivery When an ACK frame for confirmation cannot be obtained (step S63), the number of times of reception failure is counted (step S64).

  When the counted number of ACK frame reception failures is less than a certain number, the terminal 402 and the terminal 404 continue to use the directivity information as before. When the number of ACK frame reception failures has become a certain number or more (a certain number of steps S64 or more), the terminal 402 and the terminal 404 determine that the communication quality has deteriorated, and recalculate the transmission directivity (step S65). The terminal 402 and the terminal 404 communicate with the receiving terminal 403 and the terminal 405 according to the calculated directivity. The communication according to the method of the present invention may be terminated without recalculating the transmission directivity (step S65).

  In the middle of the communication (step S61), if the received power of the frame received by the terminal 403 and the terminal 405 becomes equal to or less than a certain power (less than the certain power in steps S66, S67, and S68), the terminal 403 The terminal 405 determines that the communication quality has deteriorated, and recalculates the reception directivity (step S65). The terminal 403 and the terminal 405 communicate with the transmitting side terminal 402 and the terminal 404 by the reception directivity after the calculation. The communication of the method according to the present invention may be terminated without recalculating the reception directivity (step S65).

  Further, during the communication (step S61), the number of CRC errors in the frames received by the terminal 403 and the terminal 405 is counted (step S69), and when the number of CRC errors exceeds a certain number. It is determined that the communication quality has deteriorated (at a predetermined number of times in step S70), and the reception directivity is recalculated (step S65). The terminal 403 and the terminal 405 communicate with the transmitting side terminal 402 and the terminal 404 by the reception directivity after the calculation. The communication of the method according to the present invention may be terminated without recalculating the reception directivity (step S65).

  However, as a result of changing the directivity, the directivity angle of the access point 201 with respect to at least one of the terminal 402, the terminal 403, the terminal 404, and the terminal 405 changes significantly, and the directivity with respect to the terminal 402 and the terminal 403 and the terminal 404 and the terminal are changed. If it is determined that the directivity with respect to 405 is approaching, the access point 201 uses the method of any one of the first and fourth to sixth embodiments described above to again execute two DLP communications simultaneously. Investigate.

  In the above description, the directivity is recalculated when it is determined that the communication quality has deteriorated. However, the directivity may be recalculated every time the receiving terminal receives a frame.

  As described above, according to the present embodiment, the quality of communication is checked after a plurality of DLP communications are started, and the directivity is recalculated when the quality deteriorates. Can be executed.

(Eighth embodiment)
In the first to seventh embodiments described above, the frequency bands used in the two DLP communications are the same, but the present invention is applicable even when the frequency bands used in the respective DLP communications are different. Is applicable.

  For example, when the frequency bands used in each DLP communication are adjacent to each other, there is a possibility that the DLP communications interfere with each other and cannot communicate. Thus, the interference state of the two DLP communications is inspected using the first to seventh embodiments described above, and if it is confirmed that there is no interference due to the adjacent channel, the DLP communication on the adjacent radio channel is started.

  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.

It is a figure which shows the basic composition of the radio | wireless communications system concerning embodiment of this invention. It is a block diagram which shows the structure of the terminal of FIG. It is a block diagram which shows the structure of the access point of FIG. 2 is a flowchart for explaining the operation of the wireless communication system of FIG. It is a block diagram which shows the structure of the terminal concerning the 2nd Embodiment of this invention. It is a flowchart explaining the operation | movement by the radio | wireless communications system concerning the 2nd Embodiment of this invention. It is a figure which shows the state in which an access point transmits a transmission right grant frame. It is a flowchart explaining the transmission method of a transmission right grant frame. It is a figure which shows the state which transmits the transmission right grant frame by a multicast address. It is a block diagram which shows the structure of the access point concerning the 4th Embodiment of this invention. It is a flowchart explaining the transmission method of the transmission right grant frame in the 4th Embodiment of this invention. It is a block diagram which shows the structure of the terminal concerning the 5th Embodiment of this invention. It is a flowchart explaining operation | movement of the radio | wireless communications system concerning the 5th Embodiment of this invention. It is a figure which shows the state which an access point gives a transmission right for a fixed period. It is a figure which shows the state in which an access point transmits two transmission right grant frames simultaneously. It is a block diagram which shows the structure of the terminal concerning the 6th Embodiment of this invention. It is a flowchart explaining operation | movement of the radio | wireless communications system concerning this Embodiment. It is a flowchart for demonstrating the method of performing recalculation of directivity when communication quality deteriorates.

Explanation of symbols

101,201: Access point (wireless base station)
102 to 105, 202 to 205, 302 to 305, 402 to 405: Wireless terminal
11, 21, 31, 41, 61: Transmitter / receiver
11a, 21a: Omnidirectional antenna for transmission and reception
31a: Omnidirectional transmit antenna
41b, 51b: Omnidirectional receiving antenna
12, 32, 52, 62: Transmission power control unit
13,34,54,64: Radio wave reception state inspection section
14,24,35,45,55,65: Control unit
22,42: Inspection instruction section
23,44: Transmission right grant section
31b: Directional variable receiving antenna
33,43,53,63: Directional antenna controller
41a, 51a: Directional variable transmission antenna
61a: Variable directivity antenna

Claims (8)

A wireless communication system comprising first, second, third, and fourth wireless terminals and a wireless base station,
The first to fourth wireless terminals are respectively
First transmission means for transmitting an inter-terminal communication request frame requesting to perform inter-terminal communication with another radio terminal among the first to fourth radio terminals, to the radio base station;
A receiving antenna for receiving radio waves,
Inspection means for inspecting the reception status of radio waves;
Have
The radio base station is
First receiving means for receiving the inter-terminal communication request frame;
A first inter-terminal communication request frame for requesting to perform inter-terminal communication between the first and second radio terminals from the first radio terminal; and the third and fourth from the third radio terminal. When a second inter-terminal communication request frame requesting that inter-terminal communication is performed between the wireless terminals of
The reception status of the radio wave is inspected during inter-terminal communication between the first and second wireless terminals.
Transmitting a first inspection instruction frame instructing to perform to the third and fourth wireless terminals;
The reception status of the radio wave is inspected during inter-terminal communication between the third and fourth wireless terminals.
Second transmitting means for transmitting a second inspection instruction frame instructing to the first and second wireless terminals;
Second receiving means for receiving radio wave reception status information indicating a radio wave reception status from the first to fourth radio terminals;
Inter-terminal communication between the first and second wireless terminals and inter-terminal communication between the third and fourth wireless terminals based on the radio wave reception status information received from the first to fourth wireless terminals Determination means for determining whether or not can be executed simultaneously;
A third transmission means for transmitting a communication permission frame to each of the first and third wireless terminals when it is determined that the communication between the terminals can be performed simultaneously;
A wireless communication system. The first to fourth wireless terminals have a variable directivity receiving antenna as the receiving antenna, and further have directivity control means for controlling the directivity of the receiving antenna,
If it is determined by the determining means that the inter-terminal communication is not executable in at least one of the first to fourth wireless terminals, the wireless base station sends a null to the arrival direction of the radio wave to the wireless terminal. fifth wireless communication system according to claim 1, further comprising a transmission means for transmitting a null formation instruction frame for forming a. At least the first and second radio terminals have a transmission antenna with variable directivity, and a transmission directivity control means for controlling the directivity of the transmission antenna, between the first and second radio terminals. 2. A beam communication is performed with a counterpart wireless terminal in the inter-terminal communication of claim 1.
Or the radio | wireless communications system of 2. At least the first and second wireless terminals include transmission power control means for controlling transmission power,
The radio base station, when it is judged by the judging means that at least one of the third and fourth radio terminals cannot execute the inter-terminal communication, the radio base station instructs to lower the transmission power 4. The wireless communication system according to claim 1 , further comprising sixth transmission means for transmitting a control instruction frame to at least one of the first and second wireless terminals. The third transmission means transmits the communication permission frame whose destination is a multicast address commonly assigned to the first and third wireless terminals, thereby allowing the communication permission to the first and third wireless terminals. The wireless communication system according to claim 1 , wherein a frame is transmitted. The radio base station has a transmission antenna with variable directivity, and transmission directivity control means for controlling the directivity of the transmission antenna,
The third transmission means beam-transmits a communication permission frame whose destination is the address of the first wireless terminal and a communication permission frame whose destination is the address of the third wireless terminal. The wireless communication system according to any one of claims 1 to 4 . A wireless base station that performs wireless communication with a plurality of wireless terminals,
A first inter-terminal communication request frame requesting to perform inter-terminal communication between the first and second radio terminals is received from the first radio terminal, and the third and fourth radio terminals are received from the third radio terminal. First receiving means for receiving a second inter-terminal communication request frame for requesting inter-terminal communication between terminals;
When the first and second inter-terminal communication request frames are received, a first inspection instructing to inspect radio wave reception status during inter-terminal communication between the first and second wireless terminals A second inspection instruction that transmits an instruction frame to the third and fourth wireless terminals and instructs to inspect the reception status of the radio wave during inter-terminal communication between the third and fourth wireless terminals. First transmission means for transmitting a frame to the first and second wireless terminals;
Second receiving means for receiving radio wave reception status information indicating a radio wave reception status from the first to fourth radio terminals;
Based on the radio wave reception status information received from the first to fourth wireless terminals, communication between terminals between the first and second wireless terminals and communication between terminals between the third and fourth wireless terminals, Determining means for determining whether or not can be executed simultaneously;
When it is determined that inter-terminal communication between the first and second radio terminals and inter-terminal communication between the third and fourth radio terminals can be performed simultaneously, the first and third radio terminals A second transmission means for transmitting communication permission data to the terminal;
Wireless base station with A wireless communication method in which a plurality of wireless terminals perform inter-terminal communication within a communication area by a wireless base station,
A first transmission step of transmitting a first inter-terminal communication request frame requesting that the first radio terminal performs inter-terminal communication between the first and second radio terminals to the radio base station;
A second transmission step of transmitting a second inter-terminal communication request frame requesting that the third radio terminal performs inter-terminal communication between the third and fourth radio terminals to the radio base station;
When the radio base station receives the first and second inter-terminal communication request frames, the radio base station receives radio waves during inter-terminal communication between the first and second radio terminals. A third transmission step of transmitting to the third and fourth wireless terminals a first inspection instruction frame instructing to inspect
The wireless base station transmits a second inspection instruction frame for instructing to inspect the reception status of the radio wave during inter-terminal communication between the third and fourth wireless terminals. A fourth transmission step for transmitting to the terminal;
A receiving step in which the radio base station receives radio wave reception status information indicating a radio wave reception status from the first to fourth radio terminals;
Based on the radio wave reception status information, the wireless base station communicates between the first and second wireless terminals and between the third and fourth wireless terminals for the first to fourth wireless terminals. A determination step of determining whether or not inter-terminal communication can be performed simultaneously;
The radio base station can simultaneously execute inter-terminal communication between the first and second radio terminals and inter-terminal communication between the third and fourth radio terminals for the first to fourth radio terminals. A fifth transmission step of transmitting communication permission data to the first and third wireless terminals,
A wireless communication method comprising:

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