JP2019186756A - Relay device, transmission device, control method, and program - Google Patents

Abstract

To appropriately switch a communication link between a direct link and a relay link.SOLUTION: When a relay device that relays communication between a transmission device and a reception device receives from the transmission device instructions on timing when the relay device should transmit a radio frame to the reception device when a communication link on which data is transmitted from the transmission device to the reception device is switched from a direct link not going through the relay device to a relay link going through the relay device, the relay device performs control to transmit the radio frame to the reception device according to the instructions in response to the reception.SELECTED DRAWING: Figure 4

Description

  The present invention relates to relay communication technology.

  In wireless communication, a technique for relaying and transmitting a received wireless signal is known. The relay includes a regenerative relay that transmits a signal after baseband processing such as demodulation is performed on the received signal, and a non-regenerative relay that transmits a signal obtained by amplifying the received signal without performing such baseband processing. And exist. Patent Document 1 describes a method of using a non-regenerative relay circuit when a regenerative relay circuit fails in a relay device having a regenerative relay circuit and a non-regenerative relay circuit.

JP 2007-318314 A

  In a wireless communication system using a relay device, communication used between a direct link in which a transmitting device directly transmits data to a receiving device and a relay link in which the transmitting device transmits data to the receiving device via the relay device It is assumed that the link is switched. In addition, the relay device may relay a signal received via a wired connection. The requirements for signal transmission between the transmission device and the relay device may differ between the case where the transmission device and the relay device are wirelessly connected and the case where the transmission device and the relay device are wired. For this reason, in consideration of the case where the transmission apparatus and the relay apparatus can be connected by wire, processing for appropriately switching the communication link between the direct link and the relay link is necessary.

  This invention is made | formed in view of this subject, and it aims at providing the technique which performs appropriately switching of the communication link between a direct link and a relay link.

  A relay device according to an aspect of the present invention is a relay device that relays communication between a transmission device and a reception device, and includes a first communication unit that performs communication with the transmission device, and the reception device. And a communication link for transmitting data from the transmitting device to the receiving device is switched from a direct link not via the relay device to a relay link via the relay device. Control means for controlling the second communication means so as to transmit a radio frame according to the instruction in response to receiving an instruction from the transmitting apparatus when transmitting a radio frame to the receiving apparatus. Have.

  According to the present invention, it is possible to appropriately switch the communication link between the direct link and the relay link.

It is a figure which shows the structural example of a communication system. It is a block diagram which shows the structural example of an apparatus. It is a flowchart which shows the example of the flow of the process which a transmitter performs. It is a flowchart which shows the example of the flow of the process which a transmitter performs. It is a flowchart which shows the example of the flow of the process which a relay apparatus performs. It is a flowchart which shows the example of the flow of the process which a relay apparatus performs. It is a flowchart which shows the example of the flow of the process which a receiver performs.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The technical terms described below are merely examples, and various changes and modifications can be made to the following embodiments, such as using other standards having similar communication functions, other device configurations, and the like.

(Configuration of communication system)
FIG. 1 shows a configuration example of a communication system according to the present embodiment. The communication system includes a transmission apparatus 101, a relay apparatus 102, and a reception apparatus 103. This communication system shows a part of a wireless network in various topologies such as a tree type, a star type, and a mesh type. In other words, there may be many devices other than the device shown in the communication system of FIG. 1, and the configuration of FIG. 1 is a configuration in which a section between the transmission device 101 and the reception device 103 in multihop communication is cut out. There may be. In this communication system, the transmission apparatus 101 transmits a frame including data to the relay apparatus 102, and the relay apparatus 102 transmits the frame to the reception apparatus 103. Note that the transmission device 101 and the reception device 103 are terms for convenience, and these devices may be communication devices that can perform both transmission and reception. In addition, the relay apparatus 102 may be a relay-dedicated communication apparatus in one example, but can transmit data other than relay data such as data generated in the own apparatus and receive data that is not subject to relay. A general communication device may be used.

  In the present embodiment, the transmission device 101 and the relay device 102 are configured to be able to establish a wireless communication line and a wired communication line between these devices. A wireless communication line can be established between the transmission apparatus 101 and the reception apparatus 103 and between the relay apparatus 102 and the reception apparatus 103. The wired communication line can be established in accordance with, for example, the Ethernet (registered trademark) standard, and the wireless communication line can be established in accordance with, for example, the IEEE 802.11ad standard.

  In one example, the transmission apparatus 101 operates as a source REDS that transmits a signal in the normal mode of the FD-AF relay of the IEEE802.11ad standard in relation to the reception apparatus 103. Note that FD-AF is an acronym for Full Duplex-Amplify and Forward, and REDS is an acronym for Relay Endpoint DMG (Directional Multi Gigabit) Station. In the normal mode of FD-AD relay, communication is performed via either a direct link or a relay link between the transmission side and the reception side until the current link becomes unavailable. In relation to the relay device 102, the transmission device 101 transmits a data addressed to the reception device 103 to the relay device 102 by wireless communication and a wired relay mode to transmit the data to the relay device 102 by wired communication. Works with either.

  The relay apparatus 102 operates as an RDS (Relay DMG Station) that relays signals in the normal mode of the FD-AF relay of the IEEE802.11ad standard in relation to the receiving apparatus 103. Note that the relay device 102 operates in either a standard mode in which data addressed to the receiving device 103 is received by wireless communication or a wired relay mode in which the data is received by wired communication. . In the transmission apparatus 101 and the relay apparatus 102, wireless communication in the standard mode can be performed according to the IEEE 802.11ad standard, and wired communication in the wired relay mode can be performed according to the Ethernet standard.

  The receiving apparatus 103 is a destination REDS that operates in the normal mode of the FD-AF relay of the IEEE 802.11ad standard.

  In a wireless network that uses radio waves with strong straightness such as millimeter waves, the receiving device 103 tries to receive a frame by directing the antenna toward the transmitting device 101 for a predetermined period. An attempt may be made to receive the frame with the antenna pointing at 102. Similarly, the reception device 103 can switch the direction of the antenna from the relay device 102 to the transmission device 101 when the frame from the relay device 102 cannot be received. Even if the transmission apparatus 101 cannot transmit data directly to the reception apparatus 103 due to an obstruction of radio waves due to an obstacle or the like, the communication with the reception apparatus 103 is disconnected by using the relay apparatus 102. Can be prevented.

  Further, even when the transmission apparatus 101 can directly transmit data to the reception apparatus 103, the transmission apparatus 101 can also transmit a frame to the reception apparatus 103 via the relay apparatus 102. For example, the transmission apparatus 101 does not transmit a communication frame at the predetermined time described above, so that the data is transferred from the direct link directly established between the transmission apparatus 101 and the reception apparatus 103 to the relay link via the relay apparatus 102. Can be switched. In this case, since the receiving device 103 cannot receive a communication frame within a predetermined period on the direct link, the direction of the antenna directed toward the transmitting device 101 is switched to the direction of the relay device 102. The transmission apparatus 101 transmits the communication frame with the antenna directed toward the relay apparatus 102 instead of the reception apparatus 103. As a result, the communication path between the transmission apparatus 101 and the reception apparatus 103 is switched from the direct link to the relay link. The same can be done when switching from a relay link to a direct link. That is, when the relay apparatus 102 does not transmit a communication frame during communication on the relay link, the receiving apparatus 103 directs the antenna toward the transmitting apparatus 101, so that the communication path can be switched from the relay link to the direct link. .

  When the transmission apparatus 101 and the relay apparatus 102 are connected via a wired network, the transmission apparatus 101 transmits a wired frame to the relay apparatus 102 instead of a wireless frame. Then, the relay device 102 converts the wired frame into a wireless frame and transmits it to the receiving device 103. Thereby, noise added to the signal in the transmission path between the transmission apparatus 101 and the relay apparatus 102 can be reduced.

  On the other hand, the relay apparatus 102 needs to operate so that the receiving apparatus 103 can perform communication conforming to the IEEE 802.11ad standard. That is, it is important that the relay apparatus 102 can perform the same operation as when the communication between the transmission apparatus 101 and the relay apparatus 102 is wired communication even when the communication is wireless communication. It is. For this reason, for example, the transmission apparatus 101 controls the relay apparatus 102 to transmit a wired frame received by wired communication as a wireless frame at an appropriate timing. This appropriate timing can be, for example, after the data sensing time at the timing before switching the communication link when switching the communication link from the direct link to the relay link. In other words, the relay device 102 ensures that the communication link is switched from the direct link to the relay link by ensuring that the reception device 103 does not receive the radio frame from the transmission device 101 during the data sensing time. . Then, the relay apparatus 102 transmits the radio frame after the data sensing time that is the timing at which the receiving apparatus 103 can receive the radio frame from the relay link. In addition, a wired communication line may have a transmission delay larger than that of a wireless communication line. On the other hand, the relay apparatus 102 must transmit a radio frame whose transmission source is the transmission apparatus 101 during the data sensing time while transmitting the radio frame to the reception apparatus 103 via the relay link. For this reason, the relay apparatus 102 transmits a radio frame including dummy data even when the arrival of the communication frame from the transmission apparatus 101 is not in time for transmission of the radio frame at the data sensing time. This prevents the receiving apparatus 103 from unnecessarily switching from the relay link to the direct link due to, for example, the relay apparatus 102 being unable to transmit a radio frame during the data sensing time.

  Hereinafter, an example of the configuration and processing flow of each device as described above will be described in detail.

(Device configuration)
FIG. 2 is a block diagram illustrating a configuration example of the transmission device 101, the relay device 102, and the reception device 103. For example, each device includes a control unit 201, a storage unit 202, an input unit 203, an output unit 204, a wired interface 205, and a wireless interface 206. These blocks are interconnected by, for example, an internal bus. This is merely an example, and the configuration may be changed, modified, omitted, or added. For example, the receiving device 103 may not have the wired interface 205.

  The control unit 201 controls the entire apparatus including other blocks. The control unit 201 is realized by, for example, a processor such as one or more central processing units (CPU), a microprocessor (MPU), an application specific integrated circuit (ASIC), or a gate array circuit such as a field programmable gate array (FPGA). Can be done. The storage unit 202 is a volatile or non-volatile storage device that temporarily or permanently stores programs executed by the control unit 201, setting values or data necessary for the operation of the device, and the like. The storage unit 202 is an arbitrary storage device such as a read-only memory (ROM), a random access memory (RAM), or a hard disk drive (HDD). The input unit 203 is an interface that receives a user operation input via an input device such as a switch, a mouse, a keyboard, or a camera. The output unit 204 is an interface for outputting information to an output device such as a display or a printer. The wired interface 205 is a first communication unit that executes processing of a medium access control layer and a physical layer for wired communication using Ethernet or the like in cooperation with the control unit 201. The wired interface 205 is, for example, a network interface card. The wireless interface 206 is a second communication unit that cooperates with the control unit 201 to execute processing of a medium access control layer and a physical layer for wireless communication according to the IEEE 802.11ad standard or the like. The wireless interface 206 is a wireless module compliant with, for example, the IEEE 802.11ad standard.

(Transmission device processing flow)
Next, an example of the flow of processing executed by the transmission apparatus 101 will be described with reference to FIGS. FIG. 3 is a flowchart illustrating an example of interface setting processing in the transmission apparatus 101. This process is executed when the control unit 201 of the transmission apparatus 101 executes a program stored in the storage unit 202 of the transmission apparatus 101. Further, this process is executed as one of the initial setting processes, for example, after the transmission apparatus 101 is turned on and the reset is released.

  When the process is started, the transmission apparatus 101 determines whether or not to operate in the wired relay mode (S301). At this time, in the transmission apparatus 101, the control unit 201 acquires data from the storage unit 202, the input unit 203, the wired interface 205, and the like, and the determination of S301 is performed based on the data. The data used for this determination may be data stored in the storage unit 202 at the time of manufacture, data indicating a value designated by a user operation using an input device connected to the input unit 203, or the like. . In this determination, data indicating whether a cable for wired connection is connected to the wired interface 205, data indicating whether the relay apparatus 102 is connected to the wired network, or the like may be used. . That is, this determination may be performed based on whether or not the transmission device 101 and the relay device 102 are in a state where they can communicate via a wired network. For example, the control unit 201 uses the wired relay mode when data indicating at least one of a case where a cable is connected to the wired interface 205 and a case where the relay device 102 is connected to a wired network is input. It can be determined that it operates.

  When it is determined that the transmission apparatus 101 operates in the wired relay mode (YES in S301), the transmission interface 101 sets the wired interface 205 and the wireless interface 206 so as to operate in the wired relay mode (S302). For example, the transmission apparatus 101 sets the wired interface 205 to perform wired communication, and sets the wireless interface 206 so as not to operate in the standard mode in the IEEE802.11ad standard. At this time, the transmitting apparatus 101 sets the value of the data sensing time for the wired relay mode. On the other hand, when determining that the transmission apparatus 101 does not operate in the wired relay mode (NO in S301), the transmission apparatus 101 sets the wireless interface 206 to operate in the standard mode (S303). In addition, the transmission apparatus 101 sets the data sensing time value for the standard mode.

  The data sensing time is one of the periods used when the transmission apparatus 101 switches the link. When the transmission apparatus 101 or the relay apparatus 102 is in a role of transmitting a radio frame to the reception apparatus 103 via the switched link, the transmission apparatus 101 or the relay apparatus 102 transmits the radio frame after the data sensing time. That is, when the link is switched, the radio frame is not transmitted during the data sensing time. On the other hand, when the link is not switched, a radio frame is transmitted during the data sensing time. The receiving apparatus 103 switches the link used for communication from the current link to another link by not successfully receiving data during this period.

  Note that the first value of the data sensing time when operating in the wired relay mode may be the same as the second value of the data sensing time when operating in the standard mode, for example, the first value May be different, such as greater than the second value. In one example, by making the first value larger than the second value, even if the receiving apparatus 103 relays transmission data via a wired line with a large delay, the signal from the relay apparatus 102 is transmitted. Probability of receiving increases. Thereby, it is possible to prevent unnecessary link switching such as switching to a direct link even when the relay link is to be maintained. These values can be, for example, values registered in the storage unit 202 in advance at the time of manufacturing the device or values input from the input device via the input unit 203. These values are transmitted to the receiving apparatus 103 and shared between the transmitting apparatus 101 and the receiving apparatus 103 in an RLS (Relay Link Setup) procedure executed after the processing of FIG.

  Next, a flow of processing in which the transmission apparatus 101 transmits data addressed to the reception apparatus 103 will be described with reference to FIG. In this process, after the RLS procedure between devices and the assignment of SP (Service Period) for communication between the transmission device 101 and the reception device 103 are completed, preparation of data addressed to the reception device 103 is completed. It is executed while Note that the process of FIG. 4 is a process executed when the wired relay mode is set as the relay mode, and when the standard mode is selected, the relay can be performed by a conventional method. For this reason, as long as the data addressed to the receiving apparatus 103 is prepared, the process of FIG. 4 can be newly restarted after the process of FIG. 4 ends. Here, the data addressed to the receiving device 103 is stored in the storage unit 202 of the transmitting device 101. This data may be data input from an external device via the input unit 203, the wired interface 205, or the like, or may be data generated by the control unit 201.

  In this process, the transmission apparatus 101 determines whether the currently used link is a direct link or a relay link (S401). In one example, data indicating a link that is currently used is stored in the storage unit 202, and the control unit 201 reads the data, so that the determination in S401 can be performed. If the transmitting apparatus 101 determines that the currently used link is a direct link (YES in S401), the process proceeds to S402, and if the transmitting apparatus 101 determines that the currently used link is a relay link (S401). NO) advances the process to S407. In the initial state after completion of the RLS procedure, for example, a direct link is set as a link to be used.

  In S402, the transmission apparatus 101 stands by until the assigned SP arrives, and when the current time falls within the SP (YES in S402), the process proceeds to S403. In S403, the transmission apparatus 101 acquires data addressed to the reception apparatus 103 stored in the storage unit 202, and generates a radio frame including the data. At this time, the MAC address of the wireless interface 206 of the receiving apparatus 103 is set in the RA (Receiver Address) field of the wireless frame. In addition, the MAC address of the wireless interface 206 of the transmitting apparatus 101 itself is set in a TA (Transmitter Address) field of the wireless frame. In the transmission apparatus 101, the control unit 201 controls the wireless interface 206 and transmits the wireless frame with the antenna facing the reception apparatus 103. Thereafter, the transmission apparatus 101 determines whether or not an ACK frame or a BA (Block ACK) frame for the radio frame transmitted in S403 is received from the reception apparatus 103 via the radio interface 206 (S404). If the transmitting apparatus 101 determines that an ACK frame or a BA frame has been received (YES in S404), the process of FIG. On the other hand, when the transmission apparatus 101 does not succeed in receiving these ACK frames (for example, within a predetermined period), the transmission apparatus 101 switches the link to be used from the direct link to the relay link (S405). Then, the transmission apparatus 101 generates transmission instruction data instructing the relay apparatus 102 to transmit the wireless frame after the data sensing time, and transmits the transmission instruction data to the relay apparatus 102 via the wired interface 205 ( S406). Thereafter, the transmission apparatus 101 returns the process to S401.

  When the link currently used is not a direct link (NO in S401), the transmission apparatus 101 generates a wired frame including data addressed to the reception apparatus 103. Then, the transmission apparatus 101 transmits this wired frame to the relay apparatus 102 via the wired interface 205 (S407). The MAC address of the wired interface 205 of the relay apparatus 102 is set in the destination MAC address field of this wired frame. In the source MAC address field, the MAC address of the wired interface 205 of the transmission apparatus 101 itself is set. Thereafter, the transmitting apparatus 101 determines whether or not the relay apparatus 102 has received the ACK reception notification that notifies that the ACK frame or the BA frame has been received from the receiving apparatus 103 via the wired interface 205 (S408). When receiving the ACK reception notification (YES in S408), the transmission apparatus 101 ends the process of FIG. On the other hand, when the transmission apparatus 101 does not receive the ACK reception notification (NO in S408), the transmission apparatus 101 switches the link to be used from the relay link to the direct link (S409). If the relay device 102 does not transmit a radio frame while the relay link is being used, the receiving device 103 may attempt to switch to the direct link in response to the inability to receive the radio frame from the relay device 102. . This is the same even when the relay device 102 cannot receive transmission data from the transmission device 101. For this reason, when the transmission data does not arrive while the relay link is being used, the relay apparatus 102 transmits a radio frame including dummy data without including actual data. On the other hand, when switching to the direct link is executed in S409, if a radio frame including dummy data continues to be transmitted thereafter, the receiving apparatus 103 cannot recognize that switching to the direct link is necessary. There is a case. For this reason, the transmission apparatus 101 generates transmission suppression instruction data for instructing stop of transmission of a radio frame including dummy data when the switching to the direct link is performed in S409, and transmits the transmission suppression instruction data to the relay apparatus 102. (S410). The transmitting apparatus 101 waits for the set data sensing time to end (S411), returns the process to S401, and directly transmits the radio frame to the receiving apparatus 103 within the SP (YES in S402, S403). ).

(Relay device processing flow)
Next, the flow of processing executed by the relay apparatus 102 will be described with reference to FIGS. 5 and 6. 5 and 6 are executed by the control unit 201 of the relay apparatus 102 executing a program stored in the storage unit 202 of the relay apparatus 102. First, an example of generation processing of a radio frame transmitted from the relay apparatus 102 to the receiving apparatus 103 will be described with reference to FIG. This process is executed while data destined for the receiving apparatus 103 is ready. That is, as long as the data addressed to the receiving apparatus 103 is prepared, the process of FIG. 5 is repeatedly executed. Here, data addressed to the receiving device 103 can be input from an external device including the transmitting device 101 via the input unit 203, the wired interface 205, and the like and stored in the storage unit 202. Further, this data may be data generated by the control unit 201. That is, the relay device 102 has the ability to transmit not only data to be relayed but also data generated in the device itself and data that is not relayed and stored in the device itself to other devices. sell.

  In this process, the relay apparatus 102 determines whether data addressed to the receiving apparatus 103 has been received from the transmitting apparatus 101 (S501). When the relay apparatus 102 determines that the data addressed to the receiving apparatus 103 has been received from the transmitting apparatus 101 (YES in S501), the relay apparatus 102 generates a first radio frame including the data addressed to the receiving apparatus 103 (S502). At this time, in the first radio frame, the MAC address of the radio interface 206 of the receiving apparatus 103 is set in the RA field, and the MAC address of the radio interface 206 of the transmitting apparatus 101 is set in the TA field. Note that the relay apparatus 102 may simply amplify the radio frame signal received from the transmission apparatus 101 and transmit it at the SP while operating in the standard mode. That is, the relay apparatus 102 may operate as a simple repeater that receives a radio frame from the transmission apparatus 101, performs signal amplification and delay processing, and transmits the signal without adding a header. The relay apparatus 102 may amplify the received radio frame signal and add a newly generated header portion such as an address portion to the amplified radio frame for transmission. Further, the relay device 102 may perform regenerative relay. Note that the MAC address of the transmission device 101 can be input from an external device including the transmission device 101 via the input unit 203, the wired interface 205, or the like and stored in the storage unit 202, for example. On the other hand, when determining that the data addressed to the receiving device 103 is not received from the transmitting device 101 (NO in S501), the relay device 102 generates a second radio frame including the data addressed to the receiving device 103. (S503). At this time, in the second radio frame, the MAC address of the radio interface 206 of the receiving apparatus 103 is set in the RA field, and the MAC address of the radio interface 206 of the relay apparatus 102 is set in the TA field.

  FIG. 6 is a flowchart illustrating an example of a processing flow in which the relay apparatus 102 transmits data addressed to the receiving apparatus 103. This process is executed in the wireless network after the RLS procedure between the devices and the assignment of SPs for communication between the transmission device 101 and the reception device 103 are completed.

  First, the relay device 102 determines whether data instructing the end of the transmission process is stored in, for example, the storage unit 202 (S601). Note that data instructing the end of the transmission process can be input from an external device via the input unit 203, the wired interface 205, the wireless interface 206, or the like. When there is data instructing the end of the transmission process (YES in S601), the relay apparatus 102 ends the process of FIG.

  On the other hand, when there is no instruction to end the transmission process (NO in S601), the relay apparatus 102 determines whether the assigned SP has arrived (S602). The relay apparatus 102 determines whether the wireless frame generated in S502 is stored in the storage unit 202 while the assigned SP has not arrived (NO in S602) (S614). When such a radio frame is stored (YES in S614), the relay apparatus 102 transmits the radio frame generated in S502 toward the receiving apparatus 103 with the antenna direction of the radio interface 206 set (S615). The relay apparatus 102 returns the process to S601 after transmission of the wireless frame generated in S502 (S615) or when the wireless frame generated in S502 is not stored in the storage unit 202 (NO in S614). On the other hand, the relay device 102 determines whether there is unexecuted transmission instruction data during the assigned SP (YES in S602) (S603). As described above, the transmission instruction data is transmitted from the direct link to the relay link, and when the communication path from the transmission apparatus 101 to the reception apparatus 103 is switched, the relay apparatus 102 transmits a radio frame after the data sensing time. This is data for instructing transmission. This data can be received by the wired interface 205 and stored in the storage unit 202. Note that if the relay apparatus 102 determines that there is unexecuted transmission instruction data (YES in S603), and if there is transmission suppression instruction data instructing to stop transmission of the wireless frame including the above-described dummy data. The transmission suppression instruction is invalidated. Thereby, even if relay target data is not acquired, a radio frame including dummy data is transmitted, so that the receiving apparatus 103 can perform switching to the relay link. Note that the transmission suppression instruction data can be received by the wired interface 205 or the wireless interface 206 and stored in the storage unit 202. For example, when the transmission apparatus 102 receives transmission instruction data, the relay apparatus 102 can delete the transmission suppression instruction data from the storage unit 202. The relay apparatus 102 waits for the data sensing time to end (S604). Then, after the end of the data sensing time (YES in S604), the relay device 102 transmits the wireless frame generated in S501 toward the receiving device 103 with the antenna direction of the wireless interface 206 directed (S605). The relay apparatus 102 determines whether an ACK frame or a BA frame for the radio frame transmitted in S605 has been received (S606). When the relay apparatus 102 receives these ACK frames (YES in S606), the relay apparatus 102 transmits an ACK reception notification to the transmission apparatus 101 (S607). After S607 or when these ACK frames have not been received (NO in S606), or when it is determined that there is no unexecuted transmission instruction data (NO in S603), the relay apparatus 102 is still effective in suppressing transmission. It is determined whether there is an instruction (S608). For example, when the transmission suppression instruction data is deleted after the transmission instruction data is received and new transmission suppression instruction data is received from the transmission apparatus 101, it is determined that there is a valid transmission suppression instruction. When it is determined that there is a valid transmission suppression instruction (YES in S608), the relay apparatus 102 returns the process to S601. When there is a valid transmission suppression instruction, the relay apparatus 102 does not transmit a signal within the SP and does not transmit a radio frame including dummy data unless there is a transmission end instruction.

  On the other hand, if the relay apparatus 102 determines that there is no effective transmission suppression instruction (NO in S608), can the wireless frame generated in S501 be transmitted at the data sensing time that has arrived or will arrive at that time? It is determined whether or not (S609). For example, it is determined whether or not the generation of the wireless frame in S501 is completed at the timing when the data sensing time is started. If the relay apparatus 102 determines that a radio frame can be transmitted at the data sensing time (YES in S609), the relay apparatus 102 transmits the radio frame generated in S501 toward the reception apparatus 103 with the antenna direction of the radio interface 206 set. (S610). Then, the relay apparatus 102 determines whether an ACK frame or a BA frame for the radio frame transmitted in S610 has been received (S611). When the relay apparatus 102 determines that these ACK frames have been received (YES in S611), the relay apparatus 102 transmits an ACK reception notification to the transmission apparatus 101 (S612), and when it has not received an ACK frame (S611). NO), ACK reception notification is not transmitted. Thereafter, the relay apparatus 102 returns the process to S601. When it is determined that the wireless frame cannot be transmitted at the data sensing time (NO in S609), the relay device 102 generates and transmits a wireless frame including dummy data (S613). At this time, the MAC address of the wireless interface 206 of the receiving apparatus 103 is set in the RA field of the wireless frame, and the MAC address of the wireless interface 206 of the transmitting apparatus 101 is set in the TA field. After the process of S613, the relay apparatus 102 returns the process to S601.

  As described above, in this embodiment, when the communication link between the transmission device 101 and the reception device 103 is switched from the direct link to the relay link, the relay device 102 transmits a radio frame after the data sensing time. Is done. According to this, a radio frame including data from the transmission device 101 transmitted by the relay device 102 is unintentionally received by the reception device 103 during the data sensing time, so that the communication link is switched. It can be prevented from disappearing. In addition, by transmitting the radio frame after the receiving apparatus 103 switches the communication link, it is possible to reliably deliver the data from the transmitting apparatus 101 to the receiving apparatus 103 via the relay apparatus 102. Further, while the relay link is used after the switching, the relay apparatus 102 transmits some radio frame in which TA is set to the address of the transmission apparatus 101 during the data sensing time. Thereby, for example, due to a propagation delay in a communication link between the transmission apparatus 101 and the relay apparatus 102, the reception apparatus 103 unnecessarily switches the communication link used from the relay link to the direct link. Can be prevented.

(Processing flow of the receiving device)
Next, the flow of processing executed by the receiving apparatus 103 will be described with reference to FIG. This process is executed when the control unit 201 of the transmission apparatus 101 executes a program stored in the storage unit 202 of the transmission apparatus 101. Further, this processing is executed after the RLS procedure between the devices and the arrangement of the SP for the traffic between the transmission device 101 and the reception device 103 are completed in the wireless network.

  First, the receiving apparatus 103 determines whether there is data instructing to end the receiving process (S701). In one example, this data is data input from an external device including the transmission device 101 via the input unit 203, the wireless interface 206, and the like, and is stored in the storage unit 202. Then, when the control unit 201 determines whether or not this data is stored in the storage unit 202, the determination in S701 is executed. If there is an instruction to end reception (YES in S701), the receiving apparatus 103 ends the process. On the other hand, if there is no reception end instruction (NO in S701), the receiving apparatus 103 determines whether the current communication link for communication with the transmitting apparatus 101 is a direct link or a relay link ( S702). Note that the current link information is stored in the storage unit 202 in one example, and this determination is performed by the control unit 201 referring to the storage unit 202. If the receiving device 103 determines that the current link is a direct link (YES in S702), the receiving device 103 performs control to point the antenna toward the transmitting device 101 (S703). On the other hand, if the receiving apparatus 103 determines that the current link is a relay link (not a direct link) (NO in S702), the receiving apparatus 103 performs control to direct the antenna toward the relay apparatus 102 (S704). Note that the processing of S703 and S704 is performed by the control unit 201 controlling the wireless interface 206. Further, a direct link is used in the initial state after completion of the RLS procedure.

  Thereafter, the receiving apparatus 103 determines whether or not the current time is within the SP (S705). If the receiving apparatus 103 determines that the current time is within the SP (YES in S705), the receiving apparatus 103 then determines whether the current time is within the data sensing time (S706). If the receiving apparatus 103 determines that the current time is within the data sensing time (YES in S706), the receiving apparatus 103 determines whether a radio frame from the transmitting apparatus 101 has been received (S707). Note that the radio frame from the transmission apparatus 101 is either the radio frame transmitted from the transmission apparatus 101 in S403 or the radio frame transmitted from the relay apparatus 102 in S605, S610, or S613. If the receiving apparatus 103 determines that the wireless frame has not been received (NO in S707), the process returns to S706. On the other hand, if the receiving apparatus 103 determines that this radio frame has been received (YES in S707), it transmits an ACK frame or BA frame for the received radio frame (S708), and returns the process to S706.

  If the receiving apparatus 103 determines in S706 that the current time is not within the data sensing time (NO in S706), the receiving apparatus 103 determines whether or not the wireless frame from the transmitting apparatus 101 has been received within the immediately preceding data sensing time ( S709). If the receiving apparatus 103 determines that the wireless frame from the transmitting apparatus 101 has been received within the immediately preceding data sensing time (YES in S709), the receiving apparatus 103 determines whether the wireless frame from the transmitting apparatus 101 has been received (S710). ). Here, the radio frame from the transmission apparatus 101 is either the radio frame transmitted by the transmission apparatus 101 in S403 or the radio frame transmitted by the relay apparatus 102 in S605, S610, or S613. If the receiving apparatus 103 determines that a radio frame has been received (YES in S710), it transmits an ACK frame or a BA frame for the radio frame (S711), and then returns the process to S705. On the other hand, if the receiving apparatus 103 determines that a radio frame has not been received (NO in S710), the process returns to S705 without transmitting an ACK frame or the like. If the receiving device 103 determines that the wireless frame from the transmitting device 101 has not been received within the immediately preceding data sensing time (NO in S709), the receiving device 103 switches the current link to the other link (S712), and performs processing. Return to S701.

  The receiving apparatus 103 performs antenna settings such as directing the antenna to an apparatus that is assumed to receive a radio frame or changing its directivity to a pseudo omni pattern in a period other than the SP (S713). Then, for example, the receiving apparatus 103 determines whether or not the relay apparatus 102 has received the radio frame transmitted in S615 or another radio frame (S714). When receiving the wireless frame (YES in S714), the receiving apparatus 103 transmits an ACK frame or a BA frame (S715), and returns the process to S701. On the other hand, if the receiving apparatus 103 has not received this radio frame (NO in S714), the process returns to S701 without transmitting an ACK frame or a BA frame.

  As described above, in the present embodiment, when the transmission apparatus 101 switches from a direct link to communication using a relay link via wired communication, the relay apparatus 102 transmits data after the data sensing time. Send instructions to According to this, the relay apparatus 102 does not immediately convert the wired frame received from the transmission apparatus 101 into a wireless frame and transmits it, but transmits the wireless frame after the data sensing time. Therefore, the relay apparatus 102 transmits the radio frame after turning the direction of the antenna toward the relay apparatus 102 in response to the reception apparatus 103 having failed to receive the radio frame via the direct link at the data sensing time. It becomes. As a result, even when the relay apparatus 102 is not operating in the standard mode, the receiving apparatus 103 compliant with the IEEE 802.11ad standard can receive a radio frame. Further, when the relay apparatus 102 transmits a radio frame during the data sensing time when switching the communication link, if the receiving apparatus 103 succeeds in receiving this radio frame unintentionally, the communication link is not switched. End up. On the other hand, according to the present embodiment, when the communication link is switched, the relay apparatus 102 does not transmit a radio frame during the data sensing time, so that this event can be prevented from occurring. In addition, the relay device 102 substantially does not include data when the wireless frame including the data addressed to the receiving device cannot be transmitted at the data sensing time even though the relay link is used after the communication link is switched ( A radio frame (including dummy data) is transmitted. As a result, it is possible to prevent the relay link from being switched to the direct link unnecessarily due to a delay or the like caused by a wired line.

  In addition, the length of the first data sensing time when operating in the wired relay mode may be different from the length of the second data sensing time when operating in the standard mode, for example, the first data sensing time. Can be set longer than the second sensing time. According to this, even when it takes time to reach a wired frame including data addressed to the receiving device 103 from the transmitting device 101 or when it takes time to generate a wireless frame including the content of the wired frame, The probability that a radio frame including data can be transmitted increases. Thereby, since the opportunity for transmitting the radio frame including the dummy data is reduced, it is possible to suppress the deterioration of the utilization efficiency of the radio resource.

  In the above-described embodiment, the case where communication between the transmission apparatus 101 and the relay apparatus 102 is mainly wired communication has been described. However, the present invention is not limited to this. For example, the communication between the transmission apparatus 101 and the relay apparatus 102 may be wireless communication. In one example, when relay transmission not based on the IEEE 802.11ad standard is performed, the above-described processing may be executed as a configuration in which the transmission apparatus 101 controls the operation of the relay apparatus 102. That is, the above-described method can be applied to any system in which the transmission apparatus 101 controls transmission of a relay frame by the relay apparatus 102 and the relay apparatus 102 transmits a relay frame according to the control.

<< Other Embodiments >>
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  101: Transmission device, 102: Relay device, 201: Control unit, 205: Wired interface, 206: Wireless interface

Claims (18)

A relay device that relays communication between a transmission device and a reception device,
First communication means for communicating with the transmission device;
Second communication means for performing wireless communication with the receiving device;
Instruction regarding timing to transmit a radio frame to the receiving apparatus when a communication link for transmitting data from the transmitting apparatus to the receiving apparatus is switched from a direct link not via the relay apparatus to a relay link via the relay apparatus Control means for controlling the second communication means so as to transmit a radio frame in accordance with the instruction in response to receiving from the transmission device;
A relay apparatus comprising: The instruction regarding the timing indicates that the receiving apparatus should transmit a radio frame after a predetermined period for determining switching of the communication link.
The relay apparatus according to claim 1. The control means controls the second communication means so as to transmit a radio frame in the predetermined period after the communication link is switched from a direct link to a relay link.
The relay apparatus according to claim 2. The control means includes a radio that does not include data to be relayed when the data to be relayed is not received from the transmitting device in the predetermined period after the communication link is switched from the direct link to the relay link. Controlling the second communication means to transmit a frame;
The relay apparatus according to claim 3. The control means transmits a radio frame not including the data to be relayed in the predetermined period in response to receiving an instruction from the transmitting device to suppress transmission of a radio frame not including the data to be relayed. Controlling the second communication means to stop
The relay apparatus according to claim 4. The radio frame that does not include the data to be relayed is configured to include the address of the transmission device as a transmission source address.
The relay apparatus according to claim 4 or 5, wherein The predetermined period is a data sensing time in the IEEE 802.11ad standard.
The relay device according to claim 2, wherein the relay device is a relay device. The first communication unit is a communication unit that performs wired communication.
The relay device according to any one of claims 1 to 7, wherein: The second communication means is a Relay Directive Multi-Gigabit Station (RDS) that relays signals in the normal mode of the Full Duplex-Amplify and Forward (FD-AF) relay in the IEEE 802.11ad standard in relation to the receiving device. Works as a
The relay device according to claim 1, wherein the relay device is a relay device. A transmission device that transmits data to a reception device using either a relay link involving relay by a relay device or a direct link not involving relay by the relay device,
First communication means for communicating with the relay device;
Second communication means for performing wireless communication with the receiving device;
Controlling the first communication means to transmit to the relay device an instruction regarding a timing to transmit a radio frame when switching a communication link for transmitting data to the receiving device from the direct link to the relay link; Control means;
A transmission device comprising: The instruction regarding the timing indicates that the receiving apparatus should transmit a radio frame after a predetermined period for determining switching of the communication link.
The transmitter according to claim 10. The predetermined period is a data sensing time in the IEEE 802.11ad standard.
The transmission device according to claim 11. The control means sends the instruction to the relay apparatus to suppress transmission of a radio frame not including data to be relayed when switching the communication link from the relay link to the direct link. To control the
The transmission device according to claim 10, wherein the transmission device is a device. The first communication unit is a communication unit that performs wired communication.
The transmission device according to any one of claims 10 to 13, wherein the transmission device is configured as described above. The control unit relays the relay device in a normal mode of Full Duplex-Amplify and Forward (FD-AF) relay in the IEEE 802.11ad standard in relation to the receiving device. Control to operate as RDS)
The transmission device operates as a relay endpoint multi-gigabit station (REDS) that transmits a signal in a normal mode of FD-AF relay in the IEEE 802.11ad standard in relation to the reception device.
The transmission device according to claim 10, wherein the transmission device is a device. A first communication unit that communicates with the transmission device; and a second communication unit that communicates wirelessly between the reception device and relays communication between the transmission device and the reception device. A method for controlling the relay device,
The control means transmits a radio frame to the receiving device when a communication link for transmitting data from the transmitting device to the receiving device is switched from a direct link not via the relay device to a relay link via the relay device. A control method comprising: a control step of controlling the second communication means so as to transmit a radio frame according to the instruction in response to receiving the instruction regarding the power timing from the transmitting apparatus. A first communication unit that communicates with the relay device, and a second communication unit that communicates wirelessly with the reception device, the relay link that involves relaying by the relay device, and the relay device A method of controlling a transmitting device that transmits data to the receiving device using any of a direct link without relaying,
The first communication so that the control means transmits to the relay device an instruction regarding a timing for transmitting a radio frame when switching a communication link for transmitting data to the receiving device from the direct link to the relay link. A control method comprising a control step of controlling the means.   The program for functioning a computer as the said control means in the relay apparatus of any one of Claims 1-9, or the transmission apparatus of any one of Claims 10-15.

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