JP2017212714A - Radio communication system and communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high-speed realtime communication that does not impair the high-speed property of millimeter-wave radio communication while guaranteeing reliability of communication by performing multi-hop transfer using a terminal having a high-speed radio communication function like millimeter-wave radio communication in an environment in which conventional radio communication (such as wireless LAN using a microwave) cannot perform high-speed communication due to an impact of radio wave interference and congestion or the like.SOLUTION: A radio communication system 1 includes: one control terminal 10 having both of a wireless LAN communication function and a millimeter wave radio communication function; and a plurality of multi-hop terminals 20. In the radio communication system, communication route selection means 15 of the control terminal 10 selects a communication route on the basis of communication reliability information (RSSI) which terminal information search means 24 of each of the multi-hop terminals 20 searches for (scans) at a constant time interval, and each multi-hop terminal 20 forms a multi-hop network by starting millimeter wave radio communication on the basis of the communication route.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless communication system and a communication terminal.

  Recently, millimeter-wave wireless communication technology has attracted attention as a technology capable of high-speed wireless communication. In recent years, the activities of WGA (Wireless Gigabit Alliance) and WiFi Alliance (registered trademark) have been integrated, and the spread of millimeter-wave wireless communication is expected, and the feasibility is increasing. Although millimeter-wave wireless communication using the 60 GHz frequency band enables high-speed and large-capacity communication, it has a problem in that it has high directivity and a short communication distance.

  As one means for solving such a problem, hopping transfer between wireless communication terminals has been proposed. According to the hopping transfer, it is possible to search for a communication direction / route for avoiding an obstacle from the positions / directions of many terminals at the same time as increasing the communication distance of the millimeter wave wireless communication.

  As a hopping transfer technique between wireless communication terminals, a wireless communication ad hoc multi-hop technique called MANET (Mobile Ad hoc Network) has been studied. MANET uses multi-hop network path control using an ad hoc wireless communication terminal such as a wireless LAN, and a wireless communication terminal serving as a relay performs content transmission to the final destination terminal by hopping content data. It is. In IEEE 802.11s, a mesh network using a wireless LAN is also standardized.

  As described above, building a multi-hop network using millimeter-wave wireless communication technology may increase the number of scenes and use cases that use the wireless communication technology. There is a possibility that a different value from a wireless LAN that emits radio waves may be provided.

  However, communication characteristics differ greatly between millimeter wave wireless communication (IEEE802.11ad) and microwave wireless LAN (Wi-Fi, IEEE802.11a / b / g / n / ac), and the basic minimum cell (BSS) of the network. : Basic Service Set) is different, the ad hoc multi-hop wireless technology cannot be directly applied to the millimeter wave radio.

  Under such circumstances, various methods have been proposed to cover these two drawbacks of millimeter wave communication. For example, a communication system that provides high-speed data communication in a wider range by performing multi-hop communication as disclosed in Patent Document 1 can be considered.

  However, although the technology of Patent Document 1 assumes a multi-hop network that passes through a plurality of repeaters, communication is limited to communication in the downlink direction only. Further, in a communication system that performs millimeter-wave communication, communication is performed in a one-to-one network configuration or a star-type network configuration centered on one communication device, so the technique disclosed in Patent Document 1 is used. It is difficult to perform multi-hop communication.

  The present invention has been devised in view of the above points, and an object of the present invention is to allow all terminals to perform high-speed real-time communication even in a space where the density of wireless communication terminals is large, that is, the amount of wireless communication information is very large.

  A wireless communication system according to the present invention includes a plurality of millimeter wave wireless communication means, wireless LAN communication means, and beacon information transmission means for transmitting beacon information including its own terminal identification information by the millimeter wave wireless communication means. The plurality of terminals includes one control terminal serving as a personal basic service set control point (PCP) in millimeter wave wireless communication, the control terminal, and the control terminal The control terminal includes one or more multi-hop terminals that can communicate with each other by wireless LAN communication means, and the control terminal receives terminal specification information of the terminal in the PCP state and the PCP from each of the one or more multi-hop terminals. Communication reliability information between the terminal in the state and the multihop terminal is received by the wireless LAN communication means Terminal information receiving means, and based on the communication reliability information received by the terminal information receiving means, a predetermined number or less of the multi-hop terminals are selected as STAs as the next hop of the terminal in the PCP state, Communication path selection means for repeatedly executing a procedure for selecting the multihop terminal to be connected as the next hop by the millimeter wave wireless communication means as the PCP as the PCP, and the communication path selection means Communication that distributes communication path information including the multihop terminal selected as the STA and the multihop terminal selected as the PCP of the next hop of the selected multihop terminal by the wireless LAN communication means Route distribution means, and the multi-hop terminal is further provided by itself. Terminal information search means for constantly searching the terminal identification information and the communication reliability information of the other terminals in the PCP state that can be connected by the millimeter-wave wireless communication at regular time intervals by the millimeter-wave wireless communication; Terminal information transmitting means for transmitting the terminal identification information and the communication reliability information of the other terminal searched by the terminal information searching means to the control terminal by the wireless LAN communication means, and the communication path information. Communication path receiving means received by the wireless LAN communication means, and communication role switching means for switching the role in the millimeter-wave wireless communication based on the communication path information received by the communication path receiving means. It is characterized by that.

  According to an embodiment of the present invention, all terminals can perform real-time communication at high speed even in a space where the density of wireless communication terminals is large, that is, the amount of wireless communication information is very large.

It is a block block diagram which shows the radio | wireless communications system which concerns on one Embodiment of this invention, and is also a figure which shows an example of the initial state of a multihop network. It is a block block diagram which shows an example of the final state of the multilink network formed dynamically through the effect | action of the radio | wireless communications system which concerns on one Embodiment of this invention. FIG. 2 is a conceptual diagram illustrating an example of a process in which a multi-hop network is dynamically formed by a wireless communication system according to an embodiment of the present invention. It is a flowchart which shows an example of operation | movement of the control terminal in the formation process of a multihop network. It is a flowchart which shows an example of operation | movement of the multihop terminal in the formation process of a multihop network. It is a conceptual diagram of an example of the procedure which selects the PCP terminal which should be connected to a STA terminal. It is the schematic which shows an example of participation to the existing multihop network of a new terminal. It is a flowchart which shows an example of operation | movement of a control terminal and a multihop terminal when a new terminal participates in the existing multihop network. It is the schematic which shows an example in the state where the cutting | disconnection generate | occur | produced in a part of multihop network. It is a flowchart which shows an example of operation | movement in a control terminal and a multihop terminal when a cutting | disconnection generate | occur | produces in a part of multihop network. It is the schematic which shows an example of the scene where management by a group is performed. It is the schematic which shows an example of network formation which considered the group. It is a figure which shows the example of the hardware constitutions of the control terminal and multihop terminal which concern on one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In the description of the present embodiment, a radio communication system having high radio wave directivity and capable of high-speed radio communication, and capable of radiating radio waves in all directions, the communication distance is relatively long (10 m to 100 m) and stable. Assuming a communication network composed of wireless communication terminals that implement both wireless communication methods capable of wireless communication. For example, the former corresponds to millimeter wave wireless communication defined by IEEE802.11ad, and the latter corresponds to a wireless LAN using a microwave defined by IEEE802.11a / b / g / n / ac. Hereinafter, unless otherwise specified, the former wireless communication method is referred to as millimeter wave wireless communication, and the latter wireless communication method is referred to as microwave wireless communication, Wi-Fi, or wireless LAN, but is not limited thereto.

  First, the configuration will be described.

  FIG. 1 is a schematic diagram showing a configuration of a wireless communication system 1 according to the present embodiment, and at the same time, shows an initial state in the process of forming a multi-hop network to be described later.

  As shown in FIG. 1, there are two types of terminals included in the wireless communication system 1 according to the present embodiment: a control terminal 10 and a multihop terminal 20. There is only one control terminal 10 in the network, while there are one or more multi-hop terminals 20 (generic name of 20a, 20b, 20c,...).

  The wireless communication system 1 includes a millimeter-wave wireless communication unit 11, a wireless LAN communication unit 12, 22, and a beacon that constantly transmits beacon information including its own terminal identification information to the surroundings using the millimeter-wave wireless communication unit 11, 12. It comprises a plurality of terminals 10 and 20 provided with information transmission means 13 and 23. Here, the beacon information may include a BSSID (Basic Service Set ID) for specifying its own terminal.

  The control terminal 10 is always maintained in a PCP state that plays a role as a personal basic service set control point (PCP; PBSS Central Point) in millimeter-wave wireless communication. Here, the PCP is a coordinator device in millimeter-wave wireless communication, and refers to a device that forms and manages a network cell called PBSS (Personal Basic Service Set).

  On the other hand, the multi-hop terminal 20 includes a STA state serving as a radio station (STA) in millimeter-wave wireless communication, a PCP state serving as a PCP, and a STA / PCP state in which the role is undefined. , And is initialized to the STA / PCP state, and the role of the multi-hop terminal 20 is determined as either STA or PCP in the multi-hop network formation process. The multi-hop terminal 20 can communicate with the control terminal 10 and the wireless LAN communication means 12 and 22.

  Here, the millimeter-wave wireless communication performs communication using a millimeter-wave (60 GHz) band that has high straightness of radio waves and a relatively narrow communication range, and uses a wide band of 2.16 GHz per channel, thereby achieving high speed. Real data communication.

  In the millimeter wave band, radio wave propagation loss increases. Therefore, in millimeter wave wireless communication, in order to increase the antenna gain, a beam forming technique for transmitting and receiving radio waves while narrowing the beam direction of radio waves is used. Therefore, it is difficult for a control terminal for millimeter wave wireless communication to communicate simultaneously with a plurality of multi-hop terminals 20 around the control terminal.

  Therefore, in the millimeter wave wireless communication system, a TDMA (Time Division Multiple Access) communication protocol is used as a wireless multiplexing method instead of the CSMA / CA method used in the conventional wireless LAN (Local Area Network) system. It is done. A coordinator device called PCP forms a network cell (multihop network) called PBSS (Personal Basic Service Set), and performs time slot management in the TDMA protocol.

  The control terminal 10 includes a millimeter wave wireless communication unit 11, a wireless LAN communication unit 12, a beacon information transmission unit 13, a terminal information reception unit 14, a communication route selection unit 15, and a communication route distribution unit 16. Yes.

  The millimeter wave wireless communication means 11 can perform wireless communication with the multihop terminal 20 by millimeter wave wireless communication.

  The wireless LAN communication unit 12 can perform wireless communication with the multihop terminal 20 by wireless LAN communication (Wi-Fi).

  The beacon information transmitting unit 13 always transmits the beacon information of itself (the control terminal 10 including the beacon information transmitting unit 13) to the surroundings by the millimeter wave wireless communication unit 11.

  The terminal information receiving unit 14 receives the terminal identification information (BSSID) of the terminal in the PCP state and the communication reliability between the terminal in the PCP state and the multihop terminal 20 from each of the one or more multi-hop terminals 20. Information (RSSI) is received by the wireless LAN communication means 12 (Wi-Fi).

  Based on the communication reliability information (RSSI) of each of the one or more multi-hop terminals 20 received by the terminal information receiving means 14, the communication path selecting means 15 is a predetermined number or less as the next hop of the terminal in the PCP state. The multi-hop terminal 20 is selected as the STA, and the multi-hop terminal 20 selected as the STA repeatedly executes the procedure for selecting the multi-hop terminal 20 to be connected by the millimeter wave radio communication means 21 as the next hop as the PCP. To do.

  The communication path distribution unit 16 includes communication path information including the multihop terminal 20 selected as the STA by the communication path selection unit 15 and the multihop terminal selected as the PCP of the next hop of the selected multihop terminal 20. And distributed by the wireless LAN communication means 12 (Wi-Fi).

  The multihop terminal 20 includes a millimeter-wave wireless communication unit 21, a wireless LAN communication unit 22, a beacon information transmission unit 23, a terminal information search unit 24, a terminal information transmission unit 25, a communication path reception unit 26, a communication Role switching means 27.

  The millimeter wave wireless communication means 21 can perform wireless communication with other terminals 10 and 20 by millimeter wave wireless communication.

  The wireless LAN communication means 22 can perform wireless communication with the other terminals 10 and 20 by wireless LAN communication (Wi-Fi).

  The beacon information transmitting unit 23 always transmits the beacon information of itself (multi-hop terminal 20 including the beacon information transmitting unit 23) to the surroundings by the millimeter wave wireless communication unit 21.

  The terminal information search means 24 obtains terminal identification information and communication reliability information of other terminals in a PCP state to which the terminal (multi-hop terminal 20 including the terminal information search means 24) can be connected by the millimeter wave wireless communication means 21. The millimeter-wave wireless communication means 21 always searches at a constant time interval.

  The terminal information transmitting unit 25 transmits the terminal identification information and communication reliability information of other terminals searched by the terminal information searching unit 24 to the control terminal 10 by the wireless LAN communication unit 22 (Wi-Fi).

  The communication path receiving unit 26 receives the communication path information by the wireless LAN communication unit 22 (Wi-Fi).

  Based on the communication path information received by the communication path receiving unit 26, the communication role switching unit 27 switches the role of itself (the multihop terminal 20 including the communication role switching unit 27) in millimeter wave radio communication.

  With the above configuration, in the case where information exchange by wireless communication is performed in a space where the density of wireless communication terminals is large, that is, the amount of wireless communication information is very large, conventional wireless communication (such as wireless LAN) Even when high-speed communication is not possible due to the effect, high-speed performance of millimeter-wave wireless communication can be achieved by using multi-hop transmission using a high-speed wireless communication terminal having an antenna with very large directivity, such as millimeter-wave wireless communication. All terminals can perform high-speed real-time communication even in the above-described space by ensuring communication reliability without impairing communication.

  Further, the communication path selection unit 15 may be configured to select a larger number of the multi-hop terminals than to select based on only the communication reliability information.

  For example, the communication reliability information (RSSI value) is set as the first scale, and as a separate scale, “the number of other terminals connected to one terminal by millimeter wave wireless communication” is set as the second scale. By providing and selecting the multi-hop terminals 20 based on the first scale and the second scale, as a result, a larger number of multi-hop terminals 20 than selecting based on only the communication reliability information (RSSI value). May be selected.

  With this configuration, the depth (the number of hops) of the created multi-hop network can be suppressed, so that improvement in overall communication efficiency is expected when performing multi-hop data communication.

  Further, in the wireless communication system 1, the new terminal S / P 12 may be able to participate as the multihop terminal 20 as illustrated in FIG. 7. In this case, the new terminal S / P 12 searches for other terminals 10 and 20 in the PCP state in which the new terminal S / P 12 can be connected by the millimeter wave wireless communication means 21 at the beginning of participation.

  The new terminal S / P 12 transmits the terminal identification information (BSSID) and communication reliability information (RSSI) of the other terminals 10 and 20 to the control terminal 10 by the wireless LAN communication means 22 and receives the received control. The terminal 10 selects terminal identification information (BSSID) and communication reliability information (RSSI) of other terminals in the PCP state to which the new terminal S / P 12 is to be connected by the communication path selection means 15, and the wireless LAN communication means 12, the new terminal S / P 12 that has transmitted to and received the new terminal S / P 12 itself plays the role of STA.

  With this configuration, the new terminal S / P 12 can newly participate as a STA in the multi-hop network once created.

  On the other hand, in the control terminal 10, when the communication path selection unit 15 cannot find another terminal in the PCP state to which the new terminal S / P 12 should be connected, the new terminal S / P 12 Take a role.

  With this configuration, a new terminal can be newly joined as a PCP to a once created multi-hop network.

  Further, when the communication by the millimeter wave wireless communication means 21 between the multihop terminals 20 is disconnected, the multihop terminal 20 that has detected the disconnection notifies the control terminal 10 that the disconnection has occurred and selects a communication path. The means 15 may be configured to newly select a communication path.

  With this configuration, even if communication between multi-hop terminals is interrupted due to, for example, intrusion of an obstacle or movement of a user with a terminal, it is possible to perform communication on another route by reconfiguring the network. become.

  Further, the communication route selection means 15 is configured so that each multi-hop terminal 20 belongs to one of a plurality of groups, and when there are groups to which three or more multi-hop terminals 20 belong, The communication path may be selected so that the multi-hop terminals 20 that directly communicate with the group and the millimeter-wave wireless communication unit 21 include only two multi-hop terminals 20 having different roles.

  With this configuration, the overall communication efficiency can be improved by reducing communication with other groups.

  Further, the configuration may be such that the user can specify in advance the group to which each of the multi-hop terminals 20 belongs.

  With this configuration, a group can be created as intended by the user.

  Next, the operation will be described.

  As described above, the configuration of the wireless communication system 1 shown in FIG. 1 shows an initial state in the configuration process of the multihop network. FIG. 2 shows a final state where the formation of the multi-hop network is completed.

  In FIG. 2, the Wi-Fi communication is not changed from the initial network configuration shown in FIG. The control terminal 10 can communicate with a specific number of multi-hop terminals 20 by millimeter-wave wireless communication. The multihop terminal 20 can communicate with other specific number of multihop terminals 20 by millimeter waves. Note that there may be a multi-hop terminal 20 that cannot communicate with any terminal by millimeter-wave wireless communication. In this case, communication is performed by wireless LAN communication.

  However, a STA terminal in millimeter wave wireless communication can connect to only one PCP terminal at a time in each of the previous hop and the next hop. In order to connect to a plurality of PCP terminals, in a millimeter-wave wireless environment that employs a TDMA protocol for performing communication by time-sharing communication as a communication method, a time cost is required. It is assumed that the wave STA is connected only to a total of two PCPs, one previous hop and one next hop. The reason why the number of units is two is that the minimum number of connections is necessary to construct a multi-hop network.

  Hereinafter, the process from the initial state shown in FIG. 1 to the final state shown in FIG. 2 through the operation of the configuration of the wireless communication system according to the present embodiment will be described with reference to FIGS.

  FIG. 3 is a conceptual diagram showing step by step a process of forming a multi-hop network from the initial state shown in FIG. 1 to the final state shown in FIG. FIG. 4 is a flowchart showing the operation of the control terminal 10, and FIG. 5 is a flowchart showing the operation of the multihop terminal 20.

  (1) In the initial network state shown in FIG. 3A, the multi-hop terminal 20 is tentatively determined as STA or PCP, but temporarily operates as an STA. It is assumed that basic information (SSID, encryption key, etc.) essential for millimeter wave wireless communication is common to all terminals and distributed in advance by the control terminal 10 (2 ) Is started by the control terminal 10 through Wi-Fi communication (step S11 in FIG. 4, step S21 in FIG. 5).

  (2) All the multi-hop terminals 20 search for a PCP to be connected by millimeter-wave wireless communication by the terminal information search means 24 (step S22 in FIG. 5). In the initial state, since only the control terminal 10 is a PCP, the STA can discover only the control terminal 10 as a PCP. The multi-hop terminal 20 stores the BSSID (terminal identification information) and RSSI (communication reliability information) of the PCP discovered at this time, and the terminal information transmission means 25 causes the control terminal 10 to perform Wi-Fi communication, that is, wireless LAN communication means. 22 (step S22 in FIG. 5).

  The control terminal 10 receives the notified information by the terminal information receiving unit 14, and the communication path selecting unit 15 selects a communication path based on the notified information. Specifically, as shown in FIG. 3B, N terminals (3 terminals in the example) are selected in descending order of the RSSI value for each PCP, and are selected as STAs to be connected to the PCP (step S12 in FIG. 4). ). FIG. 3C shows that it has been determined that the three multi-hop terminals 20 indicated by the selected S1, S2, and S4 operate as STAs.

  (3) The control terminal 10 selects the STA terminal determined in the procedure (2) and the PCP terminal to which the STA terminal connects, that is, the communication path information, for the multi-hop terminal 20 whose role has not yet been determined, The selected communication path information is distributed by the communication path distribution means 16 by Wi-Fi communication, that is, by the wireless LAN communication means 12 (step S13 in FIG. 4).

  In the multihop terminal 20, the distributed communication path is received by the communication path receiving means 26 (step S23 in FIG. 5). Based on the received communication information, the communication role switching means 27 tentatively switches the communication role of the multihop terminal 20 to PCP when it is not selected as the STA, and the multihop terminal 20 continues to The processing is continued (steps S24 and S25 in FIG. 5).

  If the communication role switching means 27 is selected as the STA, the role is determined as the STA, and the multihop terminal 20 operates as the STA as it is (steps S28 and S29 in FIG. 5). As a result, the role of the multihop terminal 20 in the millimeter-wave wireless communication is determined as STA, and the network creation of the multihop terminal 20 is completed.

  The communication path selection means 15 of the control terminal 10 selects one PCP having a large RSSI value (communication reliability) for each STA, selects the PCP as the next hop to which the STA should be connected (step S14 in FIG. 4), The data is distributed to the multi-hop terminal 20 by the communication route distribution unit 16 by Wi-Fi communication, that is, by the wireless LAN communication unit 12. When the PCP is selected from a plurality of STAs, the STA having the larger RSSI value is selected. Here, the STA may not select the PCP. In FIG. 3 (d), P5 is selected as the PCT of the next hop of S1, the PCT of the next hop of S2 is not selected, and P3 is selected as the PCT of the next hop of S4. It is shown that.

  (4) The control terminal 10 transmits the PCP terminal determined in the above (3), that is, the communication path information to the Wi-Fi communication by the communication path distribution means 16 to the multi-hop terminal 20 whose role has not been determined yet. That is, distribution is performed by the wireless LAN communication means 22 (step S15 in FIG. 4).

  If the multi-hop terminal 20 is not selected as a PCP, the multi-hop terminal 20 performs scanning by switching the function temporarily switched to PCP in step S24 of FIG. 5 to STA (step S22 of FIG. 5).

  If the PCP is selected as a PCP, the role is determined and the PCP operates as it is (steps S26 and S27 in FIG. 5). As a result, the role of the multihop terminal 20 in the millimeter wave radio communication is determined to be PCP, and the network creation of the multihop terminal 20 is completed.

  Thereafter, the execution of (2)-(4) is repeated until the roles of all the multi-hop terminals 20 are determined, or until there are no multi-hop terminals whose roles are determined even after executing (2)-(4). continue. If the latter is used, a terminal that cannot communicate with millimeter waves is generated. By repeating (2)-(4), finally, as shown in FIG. 3 (e), all the multihop terminals 20 are connected by millimeter wave wireless communication, and the construction of the multihop network is completed. . As an exception, there are cases where millimeter waves do not reach some multi-hop terminals 20 from other terminals 10 and 20, and in this case, some of the multi-hop terminals 20 only communicate with Wi-Fi. Become.

  Through the above process, the initial state shown in FIG. 1 is reached and the final state shown in FIG. 2 is reached, and the construction of the multi-hop network by millimeter-wave wireless communication is completed.

  Further, in the above procedure (3), the communication path selection means 15 of the control terminal 10 selects one PCP having a large RSSI value (communication reliability) for each STA, and sets the next hop PCP to which the STA should be connected. When the PCP is selected from a plurality of STAs (step S14 in FIG. 4), the STA with the larger RSSI value is selected. However, other methods are used to connect to the STA terminal. An appropriate PCP terminal may be selected.

  That is, the communication path selection unit 15 may be configured to select a larger number of multi-hop terminals 20 than to select based on only the communication reliability information (RSSI value).

  FIG. 6 shows a conceptual diagram of an example of a procedure for selecting a PCP terminal to be connected to the STA terminal by such another method. Here, the communication path selection means 15 of the control terminal 10 is controlled so that the STA terminal and the PCP terminal are connected to as many other PCP terminals and STA terminals as possible by millimeter wave wireless communication.

  In determining the STA to which the PCP 3 is connected in the configuration example shown in FIG. 6, when viewed from the PCP 3, the RSSI value with the STA 1 is −50, and the RSSI value with the STA 2 is −55. Yes, the RSSI value with STA4 is −40. Here, as described above, in the step (3), when the PCP is selected from a plurality of STAs, the STA having the larger RSSI value is selected. In this case, the PCP3 is connected to the STA4 having the largest RSSI value, and the STA2 is not connected to any PCP.

  However, the result that the STA2 is not connected to any PCP is contrary to the control that “STA terminals and PCP terminals are connected to as many other PCP terminals and STA terminals as possible by millimeter wave radio communication”. Therefore, in such a case, the control is given priority over the magnitude of the RSSI value, and the PCP 3 is controlled to be connected to the STA 2.

  According to such a configuration, the number of hoppings can be suppressed, and the time cost for hopping of the entire network can be minimized.

  As shown in FIGS. 7 and 8, the wireless communication system 1 according to the present embodiment allows a new terminal to participate as a multihop terminal 20 in the multihop network constructed by the above procedures (1) to (4). It may be configured as follows.

  FIG. 7 is a schematic diagram showing participation of a new terminal in an existing network, and FIG. 8 is a flowchart showing operations of the control terminal 10 and the multihop terminal 20 when the new terminal joins the existing network. .

  When the new terminal S / P 12 joins an existing network as the multi-hop terminal 20, the multi-hop terminal 20 (new terminal S / P 12) first searches the terminal information search unit 24 for a PCP that can communicate by millimeter wave radio communication. The terminal identification information (BSSID) and the communication reliability information (RSSI) of the searched PCP are transmitted to the control terminal 10 by Wi-Fi communication by the terminal information transmitting means 25 (step S31 in FIG. 8). At this time, the new terminal S / P 12 is temporarily functioning as an STA, but the communication role is unconfirmed (STA / PCP state).

  The control terminal 10 receives the BSSID and RSSI value of the PCP (one or more of connection destination candidates) transmitted from the multihop terminal 20 (new terminal S / P12) by the terminal information receiving means 14, and selects a communication path. The PCP to which the multihop terminal 20 (new terminal S / P12) is to be connected is selected by means 15, and this is transferred to the multihop terminal 20 (new terminal S / P12) by Wi-Fi communication by the communication path distribution means 16. Transmit (step S35 in FIG. 8). In the selection, the PCP having the largest RSSI value is selected from among the PCTs having a sufficient number of STA connections.

  At this time, if there is no PCP that can be connected to the multi-hop terminal 20 (new terminal S / P12), for example, because there is no PCT with a sufficient number of STA connections, the control terminal 10 will Is transmitted to the multi-hop terminal 20 (new terminal S / P12) (step S35 in FIG. 8).

  In this case (when there is no PCP that can be connected), the fact is transmitted from the control terminal 10 to the multihop terminal 20 (new terminal S / P12), and the multihop terminal 20 (new terminal S / P12) This is received by the communication path receiving means 26 (step S32 in FIG. 8), and the multihop terminal 20 (new terminal S / P12) is switched to the role of PCP by the communication role switching means 27 and operates as a PCP (FIG. 8). 8 step S34).

  In this case (when there is no PCP that can be connected), the control terminal 10 further assumes that the multi-hop terminal 20 (new terminal S / P12) will eventually play the role of PCP (step S34 in FIG. 8). In order to discover STAs that can be connected to the multi-hop terminal 20 (new terminal S / P12) that will become the new PCP, all STAs are requested to scan and receive the results (step S36 in FIG. 8). ), When a STA that can be connected to the multihop terminal 20 (new terminal S / P12) is discovered by millimeter-wave wireless communication, the multihop terminal 20 (new terminal S) that becomes a new PCP with respect to the discovered STA. / P12) is instructed to connect (step S37 in FIG. 8).

  On the other hand, if there is a PCP that can be connected in step S35, the PCP to be connected is selected, and information on the connected PCP such as terminal identification information (BSSID) and communication reliability information (RSSI) of this PCP is the control terminal. 10 to the multihop terminal 20 (new terminal S / P12), and the multihop terminal 20 (new terminal S / P12) receives the information of the connection destination PCP by the communication path receiving means 26 (step S32 in FIG. 8). ), The multi-hop terminal 20 (new terminal S / P12) is switched to the role of STA by the communication role switching means 27 and connected to the connection destination PCP (step S33 in FIG. 8).

  In this way, the communication role of the multi-hop terminal 20 (new terminal S / P 12) is determined to be STA or PCP, thereby completing the procedure for the new terminal S / P 12 to join the multi-hop network.

  Also, as shown in FIG. 9 and FIG. 10, the wireless communication system 1 according to the present embodiment is a multi-hop network constructed by the procedures (1) to (4) described above, and between some terminals of the multi-hop network. The control terminal 10 may be configured to select a new communication path when the millimeter-wave wireless communication is disconnected.

  That is, when a disconnection occurs in the communication by the millimeter wave wireless communication means 21 between the multihop terminals 20, the multihop terminal 20 that detects the disconnection notifies the control terminal 10 that the disconnection has occurred, and selects a communication path. The means 15 may be configured to newly select a communication path.

  FIG. 9 is a schematic diagram illustrating a state in which a connection between some terminals of a multi-hop network is disconnected and a part of the network is isolated, and FIG. 10 illustrates a control terminal 10 and a multi-device when such a disconnection occurs. 4 is a flowchart showing an operation in the hop terminal 20.

  Here, the term “isolated” means a state in which communication by millimeter wave wireless communication with a short transmittable distance is disconnected, and communication by alpha wave wireless communication (Wi-Fi) having a longer transmittable distance. It does not mean that it has been disconnected. Accordingly, the multi-hop terminal 20 included in the isolated network in FIG. 9 is ensured to communicate with the control terminal 10 by the wireless LAN (Wi-Fi).

  As a case where the disconnection of the millimeter wave wireless communication occurs, for example, a person or an object that interferes with the millimeter wave wireless communication enters between the multihop terminals 20, or a user with the multihop terminal 20 moves. A case where an obstacle is interposed between the multi-hop terminals 20 can be assumed.

  FIG. 9 shows a state in which millimeter-wave wireless communication between the multihop terminal 20 in the PCP state and the multihop terminal 20 in the STA state is disconnected.

  As described above, the multihop terminal 20 uses the terminal information search unit 24 to obtain the terminal identification information (BSSID) and communication reliability information (RSSI) of the terminal in another PCP state that can be connected by millimeter wave wireless communication. Searches are made at regular time intervals by radio wave communication. Therefore, when the multi-hop terminal 20 in the STA state cannot retrieve the terminal identification information (BSSID) and the communication reliability information (RSSI) of the PCP terminal connected as the previous hop, the PCP terminal (connected to itself) It can be detected that a disconnection has occurred in the millimeter-wave wireless communication with the multi-hop terminal 20) in the PCP state.

  When the multi-hop terminal 20 in the STA state detects that a disconnection has occurred in the millimeter-wave wireless communication with the multi-hop terminal 20 in the PCP state, the wireless LAN communication (Wi-Fi) To notify the control terminal 10 (step S41 in FIG. 10).

  The control terminal 10 receives the notification (step S42 in FIG. 10), and can grasp all the multi-hop terminals 20 of the millimeter wave wireless communication network isolated by the disconnection.

  Next, the control terminal 10 requests all the multihop terminals 20 to search (scan) the terminal information by wireless LAN communication (Wi-Fi). By wireless LAN communication (Wi-Fi), the scan result by the multi-hop terminal 20, that is, the terminal identification information (BSSID) and communication reliability of the terminal in another PCP state in which each multi-hop terminal 20 can be connected by millimeter-wave wireless communication Sex information (RSSI) is received (step S43 in FIG. 10).

  The control terminal 10 can further eliminate the isolated route, that is, whether the multihop terminal 20 included in the isolated millimeter-wave wireless communication network can be connected to the non-isolated multihop terminal 20. Is calculated (step S44 in FIG. 10). That is, the communication path selection means 15 of the control terminal 10 selects a communication path including a communication role that the multi-hop terminal 20 included in the isolated millimeter-wave wireless communication network should newly play, a BSSID of the connection multi-hop terminal 20 and the like. To do.

  When the isolated route can be resolved, that is, when the above-described communication route can be selected, the control terminal 10 can play a role of communication to the multihop terminal 20 included in the isolated millimeter-wave wireless communication network, Communication path information including the BSSID of the connection destination multi-hop terminal 20 is transmitted by wireless LAN communication (Wi-Fi) (step S45 in FIG. 10).

  When the isolated route cannot be resolved, that is, when the above-described communication route cannot be selected, the control terminal 10 performs wireless LAN communication (Wi-Fi) in order to reconstruct the multi-hop network from scratch. Thus, all the multi-hop terminals 20 are notified of this, and a new multi-hop network is newly constructed according to the procedures (1) to (4) (step S46 in FIG. 10).

  As described above, according to the present embodiment, even if communication between terminals is interrupted due to, for example, an intrusion of an obstacle or movement of a user having a terminal, the network is reconfigured and another route is obtained. Will be able to communicate.

  11 and 12, the wireless communication system 1 according to the present embodiment includes a plurality of multi-hop networks that constitute the multi-hop network in the multi-hop network constructed by the procedures (1) to (4). It is good also as a structure which can divide the hop terminal 20 into several groups, and can manage for every group.

  FIG. 11 is a schematic diagram illustrating an example of a scene where management by a group is performed. FIG. 12 is a schematic diagram illustrating an example of network formation considering groups.

  As a scene where management by a group is performed, for example, an environment that is actually used in a meeting or training can be considered. In such an environment, it is assumed that communication is easy to some extent, that is, the multi-hop terminals 20 are gathered at a short distance.

  As shown in FIG. 11, when the multihop terminal 20 is placed in a straight line on a horizontally long table or the like, it can be assumed that the table is solid enough to fit a rectangular or circular table. At this time, communication between terminals in the same group is easy because a person does not block the communication path of millimeter-wave wireless communication. On the other hand, since the space between groups tends to be a “passage” for people to move, it is desirable to reduce communication between groups as much as possible. Because people move, even if they can communicate at a certain moment, they cannot always communicate at the next moment, and communication becomes unstable.

  Moreover, application software based on the group can be considered as an advanced form of management by the group.

  Even when groups are considered, the network formation method is basically the same, but the number of terminals that communicate with terminals of another group in one group may be limited to two in consideration of communication efficiency. This means one unit for reception from another group and one unit for transmission to another group. This is based on the assumption that it is difficult to communicate between the groups due to human bodies.

  In such a case, as shown in FIG. 12, the communication path selection means 15 of the control terminal 10 is such that each multihop terminal 20 belongs to one of a plurality of groups, and three or more multihop terminals 20 When there is a group to which the group belongs, the multi-hop terminals 20 that directly communicate with the other groups by millimeter wave wireless communication are only two multi-hop terminals 20 having different roles (STA or PCP). The communication path may be selected.

  With this configuration, the overall communication efficiency can be improved by reducing communication with other groups.

  Moreover, it is good also as a structure which a user can designate in advance the group to which each of the multihop terminal 20 belongs.

  Actually, as a method for specifying a group by the user, the user may select a group to which the terminal belongs.

  FIG. 13 is a diagram illustrating an example of a hardware configuration of a control device and a multihop terminal according to an embodiment of the present invention. In addition, since a control apparatus and a multihop terminal have the same hardware constitutions, it demonstrates as the communication apparatus 100 in FIG.

  The communication device 100 includes a general computer configuration. For example, a CPU (Central Processing Unit) 101, a RAM (Read Only Memory) 102, a ROM (Read Only Memory) 103, a storage device 104, a wireless LAN communication unit 105, A millimeter-wave wireless communication unit 106, a display input device 107, a bus 108, and the like are included.

  The CPU 101 is an arithmetic device that implements each function of the communication device 100 by reading a program or data stored in the ROM 103, the storage device 104, or the like onto the RAM 102 and executing processing. The functions of the control terminal 10 and the multihop terminal 20 in FIG. 1 are realized by the CPU 101 provided in each of the control terminal 10 and the multihop terminal 20. The RAM 102 is a volatile memory used as a work area for the CPU 101. The ROM 103 is a non-volatile memory that can retain programs and data even when the power is turned off.

  The storage device 104 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a flash ROM, and stores an OS (Operation System), application programs, various data, and the like.

  The wireless LAN communication unit 105 is a wireless communication unit for performing wireless LAN communication such as IEEE802.11a / b / g / n / ac, for example, and includes, for example, an antenna, a wireless unit, a MAC (Media Access Control) unit, And a communication control unit for wireless LAN communication. For example, the wireless LAN communication unit 105 of the control terminal 10 functions as an AP (access point) for wireless LAN communication by the wireless LAN communication unit 12 realized by a program executed by the CPU 101. The wireless LAN communication unit 105 of the multihop terminal 10 functions as a STA (station) for wireless LAN communication by the wireless LAN communication unit 22 realized by a program executed by the CPU 101.

  The millimeter-wave wireless communication unit 106 is a wireless communication unit for performing millimeter-wave wireless communication such as IEEE 802.11ad, for example, and includes, for example, an antenna, a wireless unit, a MAC unit, and a communication control unit for millimeter-wave wireless communication. Including. For example, the millimeter-wave wireless communication unit 106 of the control terminal functions as a PCP of the millimeter-wave wireless communication system by the millimeter-wave wireless communication means 21 realized by a program executed by the CPU 101, and the millimeter of the multihop terminal 10. The wave radio communication unit 106 functions as an STA of the millimeter wave radio communication system by the millimeter wave radio communication means 22 realized by a program executed by the CPU 101.

  The display input device 107 includes a display device that performs display, an input device that receives input, and the like. The bus 108 is connected to each of the above components, and transmits an address signal, a data signal, various control signals, and the like.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to one Embodiment mentioned above, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

  For example, the part that forms the multi-hop network of the wireless communication system 1 according to an embodiment includes a frequency band defined in IEEE 802.11ad, for example, a communication terminal that performs wireless communication in a millimeter wave frequency band of 30 to 300 GHz May be a member.

  In this case, the communication terminal selects a role as a control station that performs millimeter wave communication control for other member communication terminals and a role as a controlled station that performs millimeter wave communication under the control of the control station. It is desirable to have a configuration that can be switched automatically. Here, the control station plays a role equivalent to PCP in millimeter wave communication between the multihop terminals 20a to 20 of the wireless communication system 1 according to the above-described embodiment, and the controlled station plays a role equivalent to STA. .

  In short, the present invention is a communication terminal of the millimeter wave wireless communication system that can be switched as the control station or the controlled station described above, a control device that communicates with the communication terminal and controls communication between the communication terminals, It is possible to provide a wireless communication system (denoted with reference numeral 1A for convenience).

  In the wireless communication system 1A, the control device (denoted by reference numeral 100A for convenience) can be realized by the communication device 100 having the hardware configuration shown in FIG. 13 as with the control terminal 10 according to the embodiment. That is, the control device 100A includes a wireless LAN communication unit 105 that performs wireless LAN communication, a millimeter wave wireless communication unit 106 that performs millimeter wave wireless communication, and a control station function unit 106A that operates as a control station for millimeter wave wireless communication. It is the structure which has these. The control station function unit 106A is realized as one function in the millimeter wave wireless communication unit 106, for example, when the CPU 101 executes a program.

  The control device 100A further includes a control management unit 101A that executes the following functions. That is, the control management unit 101A has a function of receiving, from each of the communication terminals 100B, the terminal identification information of the communication terminal 100B in an operable state as a control station by the wireless LAN communication unit 105. In addition, the control management unit 101A has a function of receiving communication reliability information between the communication terminal 100B in an operable state as a control station and the communication terminal 100B.

  Further, the control management unit 101A selects a predetermined number or less of communication terminals 100B as controlled stations for millimeter wave radio communication as the next hop of the communication terminal 100B in the operable state based on the communication reliability information. Have In addition, the control management unit 101A has a function in which the communication terminal 100B selected as the controlled station selects the communication terminal 100B to be connected by the millimeter wave radio communication unit 106 as the next hop as the control station.

  In addition, the control management unit 101A transmits the communication path information including the communication terminal 100B selected as the controlled station and the communication terminal 100B selected as the next hop control station of the selected communication terminal 100B to the wireless LAN communication unit. 105 has a function of delivering.

  The control management unit 101A having each function described above is realized as one function of the main control unit (CPU 101) when the CPU 101 executes a program.

  Moreover, the communication terminal 100B is implement | achieved by the communication apparatus 100 which has the hardware constitutions shown in FIG. 13, like the control apparatus 100A. That is, the communication terminal 100B includes a wireless LAN communication unit 105 and a millimeter wave wireless communication unit 106.

  Further, the communication terminal 100B includes a control station function unit 106A responsible for operation as a control station for millimeter wave wireless communication, a controlled station function unit 106B responsible for operation as a controlled station for millimeter wave wireless communication, and communication path reception. Unit 101B and a communication role switching unit 101C. The control station function unit 106A and the controlled station function unit 106B are realized as functions in the millimeter wave wireless communication unit 106, for example, when the CPU 101 executes a program.

  The communication path receiving unit 101B is based on a control station or controlled station selection processing result based on terminal identification information and communication reliability information collected from one or more communication terminals 100B by the control management unit 101A of the control device 100A. The communication path information to be distributed is received by its own wireless LAN communication unit 105. This communication path information includes information on the communication terminal 100B selected as the controlled station and information on the communication terminal 100B selected as the next hop control station of the selected communication terminal 100B.

  The communication role switching unit 101C is distributed as a control station or a controlled station in its own millimeter wave radio communication based on the communication path information distributed by the control management unit of the control device 100A and received by the communication path receiving unit 101B. It is a function part which switches the role of.

  In the communication terminal 100B, the communication path receiving unit 101B and the communication role switching unit 101C described above are realized as functions of the main control unit (CPU 101) when the CPU 101 executes a program.

  The communication terminal 100B having the above configuration configures the wireless communication system 1A together with the control device 100A including the wireless LAN communication unit 105 and the millimeter wave wireless communication unit 106, and performs multi-hop communication under the control of the control device 100A.

  As described above, according to the present invention, when wireless communication terminal density is high, that is, when information exchange by wireless communication is performed in a space where the amount of wireless communication information is very large, conventional wireless communication (wireless LAN or the like) Even when high-speed communication is not possible due to the effects of radio wave interference and congestion, multi-hop transmission is performed by using a high-speed wireless communication terminal with an antenna having a very large directivity such as millimeter-wave wireless communication. All terminals can perform high-speed real-time communication even in the above space without impairing high-speed radio wave communication and ensuring communication reliability. The present invention is useful in the fields of high-speed wireless communication systems and communication terminals using microwave wireless communication and millimeter-wave wireless communication.

  Note that the millimeter wave wireless communication of the present invention is an example of wireless communication that performs communication using radio waves having directivity, and can be applied to other communication systems having the same communication function for realizing the present invention. It is.

DESCRIPTION OF SYMBOLS 1 Wireless communication system 10 Control terminal 11 Millimeter wave radio communication means 12 Wireless LAN communication means 13 Beacon information transmission means 14 Terminal information reception means 15 Communication path selection means 16 Communication path distribution means 20 Multihop terminal 21 Millimeter wave radio communication means 22 Wireless LAN communication means 23 Beacon information transmission means 24 Terminal information search means 25 Terminal information transmission means 26 Communication path reception means 27 Communication role switching means 100 Communication device 100A Control device 100B Communication terminal 101 CPU
101A Control management unit 101B Communication path receiving unit 101C Communication role switching unit 105 Wireless LAN communication unit 106 Millimeter wave wireless communication unit 106A Control station function unit 106B Controlled station function unit

Special table 2010-5315559 gazette

Claims (9)

A wireless communication system comprising a plurality of terminals including millimeter wave wireless communication means, wireless LAN communication means, and beacon information transmission means for transmitting beacon information including its own terminal identification information by the millimeter wave wireless communication means Because
The plurality of terminals are:
One control terminal serving as a personal basic service set control point (PCP) in millimeter wave wireless communication;
The control terminal and one or more multi-hop terminals that can communicate with each other by the wireless LAN communication means,
The control terminal
From each of the one or more multi-hop terminals, terminal identification information of the terminal in the PCP state and communication reliability information between the terminal in the PCP state and the multi-hop terminal are transmitted by the wireless LAN communication means. Terminal information receiving means for receiving;
Based on the communication reliability information received by the terminal information receiving means, a predetermined number or less of the multi-hop terminals are selected as STAs as next hops of the terminals in the PCP state, and the multi-hops selected as the STAs are selected. A communication path selection means for repeatedly executing a procedure for selecting, as the PCP, the multi-hop terminal to be connected by the millimeter wave wireless communication means as the next hop of the hop terminal;
Communication path information including the multihop terminal selected as the STA by the communication path selection means and the multihop terminal selected as the PCP of the next hop of the selected multihop terminal is used as the wireless LAN communication. Communication path distribution means for distributing by means,
The multi-hop terminal further includes:
Terminal information search means for always searching the terminal identification information and the communication reliability information of other terminals in the PCP state that can be connected by the millimeter wave wireless communication at regular time intervals by the millimeter wave wireless communication When,
Terminal information transmission means for transmitting the terminal identification information and the communication reliability information of the other terminal searched by the terminal information search means to the control terminal by the wireless LAN communication means;
Communication path receiving means for receiving the communication path information by the wireless LAN communication means;
A wireless communication system comprising: communication role switching means for switching the role in the millimeter-wave wireless communication based on the communication path information received by the communication path receiving means.   The wireless communication system according to claim 1, wherein the communication path selection unit selects a larger number of the multi-hop terminals than a selection based only on the communication reliability information. A new terminal can participate as the multi-hop terminal, and the new terminal searches for another terminal in the PCP state that can be connected by the millimeter-wave wireless communication means at the beginning of the participation, and the other terminal Terminal identification information and the communication reliability information are transmitted to the control terminal by the wireless LAN communication means;
The control terminal selects the terminal identification information and the communication reliability information of the other terminal in the PCP state to which the new terminal is to be connected by the communication path selection means, and the wireless LAN communication means Send it to a new device,
The wireless communication system according to claim 1, wherein the new terminal plays a role of the STA.   If the terminal identification information and the communication reliability information of the other terminal in the PCP state to which the new terminal is to be connected cannot be selected by the communication path selection means, the new terminal plays the role of the PCP. The wireless communication system according to claim 3, wherein the wireless communication system is responsible.   When a disconnection occurs in communication between the multihop terminals by the millimeter-wave wireless communication means, the multihop terminal that has detected the disconnection notifies the control terminal that the disconnection has occurred, and the communication path selection means The wireless communication system according to claim 1, wherein the communication path is newly selected.   In the communication route selection means, each multi-hop terminal belongs to one of a plurality of groups, and when there are groups to which three or more multi-hop terminals belong, a group other than the group and the group The wireless communication according to claim 1, wherein the communication path is selected so that the multi-hop terminals that communicate directly by means of millimeter-wave wireless communication means have only two multi-hop terminals having different roles. Communications system.   The wireless communication system according to claim 6, wherein a user can designate in advance the group to which each of the multi-hop terminals belongs. In a wireless communication system comprising a communication terminal and a control device that performs communication with the communication terminal and controls communication between the communication terminals,
The controller is
Millimeter-wave wireless communication unit that performs millimeter-wave wireless communication;
A wireless LAN communication unit for performing wireless LAN communication;
A control station function unit responsible for operation as a control station for controlling the millimeter-wave wireless communication;
From each of the one or more communication terminals, terminal identification information of a communication terminal in an operable state as the control station and communication reliability information between the communication terminal in the operable state and the communication terminal, Based on the communication reliability information received by the wireless LAN communication unit, a predetermined number or less of the communication terminals as the next connection destination of the communication terminal in the operable state are transmitted by the control station to the millimeter wave wireless communication. Is selected as the controlled station to be controlled, and the communication terminal selected as the controlled station is selected as the control station the communication terminal to be connected by the millimeter wave wireless communication unit as the next connection destination, Communication path information including the communication terminal selected as the controlled station and the communication terminal selected as the control station of the next connection destination of the selected communication terminal, And a control management section for distributing the AN communication unit,
The communication terminal includes a millimeter wave wireless communication unit, a wireless LAN communication unit, a control station function unit,
A controlled station function unit responsible for the operation as the controlled station;
A wireless communication system comprising: a communication role switching unit that switches its role as the control station or the controlled station based on the communication path information received by the wireless LAN communication unit. A communication terminal that configures a wireless communication system together with a control device having a wireless LAN communication unit and a millimeter wave wireless communication unit, and performs multi-hop communication under the control of the control device,
A millimeter-wave wireless communication unit, a wireless LAN communication unit,
A control station function unit responsible for operation as a control station for controlling the millimeter-wave wireless communication;
A controlled station function unit responsible for the operation as a controlled station of the millimeter wave wireless communication,
The control device receives from each of the one or more communication terminals terminal identification information of a communication terminal that is operable as the control station and communication between the communication terminal that is operable and the communication terminal. Reliability information is received by the wireless LAN communication unit, and based on the communication reliability information, a predetermined number or less of the communication terminals are connected as the next connection destination of the communication terminal in the operable state. Select as a controlled station for communication, and the communication terminal selected as the controlled station selects the communication terminal to be connected as the next connection destination by the millimeter wave radio communication unit as the control station. Based on the communication terminal selected as the controlled station and the selected control station as the next connection destination of the selected communication terminal, distributed by the wireless LAN communication unit based on The communication path information including a signal terminal, and a communication path receiving unit that received by the wireless LAN communication unit,
A communication terminal comprising: a communication role switching unit that switches a role as the control station or the controlled station based on the communication reliability information.

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