JP6636864B2 - Communication device, communication system, communication method, and computer program - Google Patents

Description

  The present invention relates to a communication device, a communication system, a communication method, and a computer program.

  Conventionally, as a MAC (Medium Access Control) protocol, for example, CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) is known. CSMA / CA is widely used in WLANs (Wireless Local Area Networks). As a WLAN communication standard, for example, the IEEE 802.11 series is known.

  In CSMA / CA, a node, which can be either an AP (Access Point) or a STA (station, base station), initiates CS (carrier sensing, carrier sense, carrier sense) before starting transmission on the shared communication medium. ) To detect whether another transmission is being performed. The node waits for its own transmission for a random time when another transmission is detected. The random waiting time is called BO (backoff). BO reduces the likelihood that more than one standby node will start its own transmission at the same time as the end of the transmission detected by the CS, thus reducing the occurrence of collisions.

  In the WLAN, upon successfully receiving a frame requiring an acknowledgment, the destination node returns a MAC-level acknowledgment (ACK) to the source node as shown in FIG. When frame aggregation is used, the destination node returns a BA (Block ACK, Block ACK). In order for the source node to receive the ACK / BA correctly, it is necessary that the destination node obtains the right to access the shared communication medium and that the transmission of the ACK / BA is not interrupted.

  In the WLAN, the acquisition of the access right of the shared communication medium is performed by the source node performing CS and BO before transmitting the data packet. Avoidance of interruption of ACK / BA transmission is realized by TXOP (transmission opportunity) protection and NAV (Network Allocation Vector) protection. TXOP protection and NAV protection are implemented by data packets.

  In the IEEE802.11 series WLAN, TXOP protection is implemented by, for example, a “Signal field” of IEEE802.11a / g included in a PHY header or L-SIG such as IEEE802.11n and IEEE802.11ac. When the third-party node using the shared communication medium receives the “Signal field”, as shown in FIG. 28, the transmission waits for a specific time interval until the next ACK / BA ends. The specific time interval can be obtained from LENGTH and RATE indicated in the Signal field.

  NAV is a protection function that is logically present in the MAC header and provides a virtual CS that extends physical carrier sensing. NAV protection can be set using either the RTS / CTS (Request To Send / Clear To Send) mechanism or the Duration field in the MAC header of the frame. Each MAC frame carries a time value in the Duration field used to update the NAV of the other node sharing the communication channel, and causes the other nodes to wait for their transmission until the next ACK / BA ends . For example, Patent Document 1 discloses a NAV protection method.

U.S. Pat. No. 7,953,104

  However, in the above-described conventional technique, packet collision may occur.

  In the first case shown in FIG. 29, the source node AP transmits data packets included in the same data frame to each of the different destination nodes STA1, STA2, and STA3 to each of the destination nodes STA1, STA2, and STA3. Transmission is performed through communication channels CH1, CH2, and CH3. On the other hand, the destination nodes STA1, STA2, and STA3 share a communication channel CH4 as a communication channel to the source node AP. Therefore, each of the destination nodes STA1, STA2, and STA3 simultaneously returns ACK packets ACK1, ACK2, and ACK3 as acknowledgment signals for data packets included in the same data frame, over the same communication channel CH4. Therefore, a collision of ACK packets ACK1, ACK2, and ACK3 occurs in the communication channel CH4.

  In the second case shown in FIG. 30, the transmission source node transmits a data packet to the destination node using the first shared communication medium. On the other hand, the destination node returns an ACK / BA packet as an acknowledgment signal for the data packet via the second shared communication medium. The second shared communication medium is shared with a third party node. The third party node does not use the first shared communication medium. Therefore, in the PHY layer, the third-party node does not receive the TXOP of the data packet transmitted from the transmission source node by the first shared communication medium, and does not wait for transmission in the TXOP protection period. As a result, during the TXOP protection period, a collision between the ACK / BA packet transmitted by the destination node and the data packet transmitted by the third party node may occur. In the MAC layer, the third-party node does not receive the NAV of the data packet transmitted from the transmission source node via the first shared communication medium, and does not wait for transmission in the NAV protection period. As a result, during the NAV protection period, a collision between the ACK / BA packet transmitted by the destination node and the data packet transmitted by the third party node may occur.

  The present invention has been made in view of such circumstances, and a communication channel in which a transmission source node transmits a data signal to a destination node, and a response signal about the data signal transmitted from the destination node to the transmission source node are returned. It is an object of the present invention to provide a communication device, a communication system, a communication method, and a computer program that can improve the success rate of receiving a response signal in a transmission source node when a communication channel to be used is different.

(1) One aspect of the present invention is to provide a first frame generation unit that generates a first frame including a data signal to be transmitted to each of a plurality of destination nodes, and a response signal for a data signal included in the first frame. A second frame generating unit that generates a second frame representing a different timing reference at which each of the plurality of destination nodes transmits a third frame including the third frame, and a second frame generating unit that generates the first frame corresponding to each of the plurality of destination nodes. A transmission unit for transmitting the second frame using a first communication channel and transmitting the second frame using a second communication channel different from the first communication channel and used for transmitting the third frame; A receiving unit that receives the third frame via a channel.
(2) In one aspect of the present invention, in the communication device according to (1), the first frame is a different timing at which each of the plurality of destination nodes transmits the third frame, and the second frame is transmitted at a different timing. A communication device including response timing information indicating a timing based on a reference.
(3) In one aspect of the present invention, in the communication device according to (1), the second frame is a different timing at which each of the plurality of destination nodes transmits the third frame, and the second frame is A communication device including response timing information indicating a timing based on a reference.
(4) One aspect of the present invention is the communication device according to (1), wherein the second frame includes frame identification information of the first frame.
(5) In one aspect of the present invention, in the communication device according to any one of (1) to (4), the second frame is selected from a plurality of communication channels usable for transmission of the third frame. A communication device including response channel information designating a second communication channel.
(6) One aspect of the present invention is the communication device according to (5), wherein the second communication channel is different between a first destination node and a second destination node among the plurality of destination nodes. .
(7) In one aspect of the present invention, in the communication device according to any one of (1) to (6), the third frame includes a data signal transmitted from the destination node to the own communication device. Device.

(8) In one aspect of the present invention, a source node receives a first frame including a data signal to be transmitted to each of a plurality of destination nodes through a first communication channel corresponding to its own communication device, and transmits the first frame to the first frame. A third frame including a response signal for the included data signal is transmitted by each of the plurality of destination nodes. A second frame representing a different timing reference is transmitted by a third communication channel different from the first communication channel, and A receiving unit that receives by a second communication channel used for transmitting a frame, a third frame generating unit that generates the third frame, and a third frame generating unit that generates the third frame at a timing of its own communication device based on a reference represented by the second frame. A transmission unit for transmitting a frame.

(9) One aspect of the present invention is to provide a first frame generation unit that generates a first frame including a data signal to be transmitted to each of a plurality of destination nodes, and a response signal for a data signal included in the first frame. A second frame generating unit that generates a second frame representing a different timing reference at which each of the plurality of destination nodes transmits a third frame including the third frame, and a second frame generating unit that generates the first frame corresponding to each of the plurality of destination nodes. A first transmission unit that transmits by a first communication channel and transmits the second frame by a second communication channel different from the first communication channel and used for transmission of the third frame; A first receiving unit that receives the third frame via two communication channels, and a first communication corresponding to the first destination node corresponding to the first frame. A second receiving unit for receiving the second frame via the second communication channel, a third frame generating unit for generating the third frame, and a self-destination node based on a reference represented by the second frame. And a second transmission unit that transmits the third frame at the timing described in the following.

(10) One aspect of the present invention is a first frame generating step in which a source node generates a first frame including a data signal to be transmitted to each of a plurality of destination nodes; A second frame generating step of generating a second frame representing a reference of a different timing at which each of the plurality of destination nodes transmits a third frame including a response signal for a data signal included in the frame; Transmitting the first frame over a first communication channel corresponding to each of the plurality of destination nodes, and using the second frame on a communication channel different from the first communication channel and transmitting the third frame. A first transmission step of transmitting over the second communication channel performed by the destination node, wherein the destination node transmits the first frame to the first communication node corresponding to its own destination node. A second receiving step of receiving the second frame over the second communication channel; a third frame generating step of generating the third frame by the destination node; A second transmitting step of transmitting the third frame at a timing of the own destination node based on a criterion represented by two frames, and a first receiving step of receiving the third frame by the source node via the second communication channel. And a communication method including:

(11) One embodiment of the present invention provides a computer of a communication device with a first frame generation function of generating a first frame including a data signal to be transmitted to each of a plurality of destination nodes, and data included in the first frame. A second frame generation function for generating a second frame representing a different timing reference at which each of the plurality of destination nodes transmits a third frame including a response signal for the signal; and transmitting the first frame to the plurality of destination nodes. A transmission function of transmitting the second frame over a second communication channel that is different from the first communication channel and that is used for transmitting the third frame. And a receiving function of receiving the third frame through the second communication channel. .
(12) One embodiment of the present invention provides a computer of a communication device that receives a first frame including a data signal transmitted from a source node to each of a plurality of destination nodes via a first communication channel corresponding to the communication device. Transmitting a third frame including a response signal for a data signal included in the first frame to each of the plurality of destination nodes, a second frame representing a different timing reference, using a communication channel different from the first communication channel. And a receiving function for receiving on a second communication channel used for transmitting the third frame, a third frame generating function for generating the third frame, and a self-communication device based on a reference represented by the second frame. And a transmission function of transmitting the third frame at the timing of (1).

  According to the present invention, when a communication channel in which a source node transmits a data signal to a destination node is different from a communication channel in which the destination node returns a response signal about the data signal to the source node, the source node In this case, the response success rate of the response signal can be improved.

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system 1 according to an embodiment. It is a figure showing the example of composition of source node SRC concerning one embodiment. FIG. 3 is a diagram illustrating a configuration example of a destination node DST according to an embodiment. FIG. 4 is an explanatory diagram of an example of a communication method according to an embodiment. FIG. 3 is a diagram illustrating a configuration example of a data frame according to an embodiment. FIG. 3 is a diagram illustrating a configuration example of a trigger frame according to an embodiment. FIG. 14 is an explanatory diagram of Application Example 1 according to one embodiment. FIG. 14 is a diagram illustrating a network topology of an application example 2 according to an embodiment. It is an explanatory view of a conventional communication method. FIG. 14 is an explanatory diagram of a communication method of Application Example 2 according to one embodiment. FIG. 14 is a diagram illustrating a network topology of an application example 3 according to an embodiment. It is an explanatory view of a conventional communication method. FIG. 14 is an explanatory diagram of a communication method of Application Example 3 according to one embodiment. FIG. 14 is a diagram illustrating a network topology of Application Example 4 according to one embodiment. It is an explanatory view of a conventional communication method. FIG. 14 is an explanatory diagram of a communication method of Application Example 4 according to one embodiment. It is a figure showing the network topology of example 5 of application concerning one embodiment. It is an explanatory view of a conventional communication method. FIG. 19 is an explanatory diagram of a communication method of Application Example 5 according to one embodiment. FIG. 14 is an explanatory diagram of Application Example 6 according to one embodiment. It is explanatory drawing of the modification 1 which concerns on one Embodiment. FIG. 9 is a diagram illustrating a configuration example of a trigger frame according to a first modification of the embodiment. FIG. 14 is an explanatory diagram of Modification 2 according to one embodiment. FIG. 14 is a diagram illustrating a configuration example of a trigger frame according to a second modification of the embodiment. FIG. 14 is an explanatory diagram of Modification 3 according to one embodiment. FIG. 14 is an explanatory diagram of Modification 4 according to one embodiment. It is explanatory drawing of the modification 5 which concerns on one Embodiment. It is an explanatory view of a conventional communication method. It is an explanatory view of a conventional communication method. It is an explanatory view of a conventional communication method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of a wireless communication system 1 according to an embodiment. In FIG. 1, the wireless communication system 1 includes a base station device 10 and a terminal device 30. The wireless communication system 1 constructs, for example, a WLAN (wireless LAN). The WLAN is, for example, an IEEE 802.11 series WLAN. For example, the base station device 10 is an IEEE 802.11 series WLAN access point (Access Point: AP), and the terminal device 30 is an IEEE 802.11 series WLAN terminal device.

  The base station device 10 and the terminal device 30 perform communication using the first shared communication medium and the second shared communication medium. The first shared communication medium and the second shared communication medium are different communication media. For example, among a plurality of frequency bands that can be used by the wireless communication system 1, a relatively high frequency band may be used as the first shared communication medium, and the first shared communication medium may be used as the second shared communication medium. A relatively low frequency band different from the frequency band may be used. Further, the first shared communication medium may include a plurality of continuous frequency bands or a plurality of discontinuous frequency bands among a plurality of frequency bands available for the wireless communication system 1. In addition, the second shared communication medium may include a plurality of continuous frequency bands or a plurality of discontinuous frequency bands among a plurality of frequency bands available for the wireless communication system 1.

  For example, the first shared communication medium may be mainly used for transmitting a data signal in a direction from the base station device 10 to the terminal device 30, and the second shared communication medium may be mainly used for the terminal device 30. May be used for transmission of a data signal in a direction from to the base station apparatus 10.

  FIG. 2 is a diagram illustrating a configuration example of the source node SRC according to the present embodiment. The base station device 10 (communication device) shown in FIG. 1 has the configuration of the source node SRC shown in FIG. 2, the source node SRC includes a receiving unit 11, a control unit 12, a data frame generating unit 13, a trigger frame generating unit 14, and a transmitting unit 15.

  The data frame generation unit 13 generates a data frame including a data signal to be transmitted to each of the plurality of destination nodes. In the present embodiment, the data frame corresponds to the first frame. The trigger frame generator 14 generates a trigger frame. The trigger frame is a frame representing a different timing reference at which each of the plurality of destination nodes transmits an ACK frame. The ACK frame is a frame including an acknowledgment signal for a data signal included in the data frame. In the present embodiment, the trigger frame corresponds to the second frame. In the present embodiment, the ACK frame corresponds to the third frame.

  The transmitting unit 15 transmits the data frame using a first communication channel corresponding to each of the plurality of destination nodes. The transmitting unit 15 transmits the trigger frame through the second communication channel. The second communication channel is a communication channel different from the first communication channel and used for transmitting an ACK frame. The receiving unit 11 receives an ACK frame through the second communication channel. The control unit 12 controls the source node SRC.

  FIG. 3 is a diagram illustrating a configuration example of the destination node DST according to the present embodiment. The terminal device 30 (communication device) illustrated in FIG. 1 includes the configuration of the destination node DST illustrated in FIG. 3, the destination node DST includes a receiving unit 31, a control unit 32, an ACK frame generating unit 33, and a transmitting unit 34.

  The receiving unit 31 receives a data frame including a data signal transmitted from the source node SRC to each of the plurality of destination nodes via a first communication channel corresponding to the own destination node DST. The receiving unit 31 receives the trigger frame through the second communication channel. The ACK frame generation unit 33 generates an ACK frame. The transmitting unit 34 transmits an ACK frame via the second communication channel at the timing of the own destination node based on the reference represented by the trigger frame. The control unit 32 controls the destination node DST.

  Next, an example of a communication method according to the present embodiment will be described with reference to FIG. FIG. 4 is an explanatory diagram of an example of the communication method according to the present embodiment. The source node SRC transmits a data packet to the M destination nodes DST. In the example of FIG. 4, M is 3, and the source node SRC transmits a data packet to three destination nodes DST1, DST2, and DST3. The destination nodes DST1, DST2 and DST3 have the configuration of the destination node DST shown in FIG.

  The source node SRC and the destination nodes DST1, DST2, and DST3 perform communication using the first shared communication medium and the second shared communication medium. The first shared communication medium and the second shared communication medium are different communication media. For example, among a plurality of frequency bands available to the wireless communication system 1, the first shared communication medium is a relatively high frequency band, and the second shared communication medium is different from the frequency band of the first shared communication medium. It may be a very low frequency band.

  The communication channels CH1, CH2 and CH3 are provided on the first shared communication medium. The communication channel CH4 is provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2, CH3 and CH4. The destination node DST1 uses the communication channels CH1 and CH4. The destination node DST2 uses the communication channels CH2 and CH4. The destination node DST3 uses the communication channels CH3 and CH4.

(Step S1) In the source node SRC, the data frame generation unit 13 generates a data frame including a data packet to be transmitted to each of the destination nodes DST1, DST2, and DST3. In the present embodiment, a data packet corresponds to a data signal. The transmitting unit 15 transmits the data frame via communication channels CH1, CH2, and CH3 corresponding to the destination nodes DST1, DST2, and DST3, respectively.

  The control unit 12 instructs the receiving unit 11 on CS (carrier sense) of the communication channels CH1, CH2, and CH3 before the transmitting unit 15 transmits the data frame through the communication channels CH1, CH2, and CH3. The receiving unit 11 performs CS on the communication channels CH1, CH2, and CH3 according to the instruction from the control unit 12. In the example of FIG. 4, the control unit 12 has confirmed the idle state of the communication channels CH1, CH2, and CH3 by the CS of the receiving unit 11. Next, the control unit 12 instructs the transmission unit 15 to transmit data frames on the communication channels CH1, CH2, and CH3. As a result, the transmission unit 15 transmits the data frame through the communication channels CH1, CH2, and CH3 whose idle state has been confirmed by the CS of the reception unit 11.

  In addition, in CS of the communication channels CH1, CH2, and CH3, when all of the communication channels CH1, CH2, and CH3 are busy, the source node SRC waits for transmission of a data frame only for BO (back-off) and performs channel access. Look for the next opportunity to earn. On the other hand, in the CS of the communication channels CH1, CH2, and CH3, if any of the communication channels CH1, CH2, or CH3 is in the idle state, the source node SRC waits for the transmission of the data frame by BO, and then enters the idle state The data frame may be transmitted through the communication channel.

(Step S2) In the source node SRC, the trigger frame generation unit 14 generates a trigger frame. The transmitting unit 15 transmits a trigger frame to the destination nodes DST1, DST2, and DST3 via the communication channel CH4.

  The control unit 12 instructs the receiving unit 11 to perform CS on the communication channel CH4 before the transmitting unit 15 transmits the trigger frame via the communication channel CH4. The receiving unit 11 performs CS on the communication channel CH4 according to the instruction from the control unit 12. In the example of FIG. 4, the control unit 12 has confirmed the idle state of the communication channel CH4 by the CS of the receiving unit 11. Next, the control unit 12 instructs the transmission unit 15 to transmit a trigger frame on the communication channel CH4 after waiting only for BO. Thereby, the transmitting unit 15 transmits a trigger frame by using the communication channel CH4 after waiting for BO only after the idle state of the communication channel CH4 is confirmed by the CS of the receiving unit 11. On the other hand, when the busy of the communication channel CH4 is confirmed by the CS of the communication channel CH4, the transmission source node SRC waits for the transmission of the trigger frame only by BO, and searches for the next opportunity to acquire the channel access.

  Note that CS of the communication channel CH4 may be started after transmission of the data frame is completed, or may be started before transmission of the data frame is completed. However, when the CS of the communication channel CH4 is started before the transmission of the data frame is completed, the control unit 12 sets the transmission unit 15 so that the transmission of the trigger frame on the communication channel CH4 is completed after the transmission of the data frame. Control.

(Step S3) In the transmission source node SRC, when the transmission of the trigger frame is completed, the control unit 12 starts a timer for waiting for ACK. If the source node SRC receives ACKs from all of the destination nodes DST1, DST2, and DST3 before the ACK waiting timer times out, the process proceeds to step S1 described above. On the other hand, if the timer for waiting for ACK times out before receiving ACKs from all of the destination nodes DST1, DST2 and DST3, the source node SRC executes step S5 described later.

(Step S4) In each of the destination nodes DST1, DST2, and DST3, the receiving unit 31 receives a data frame via a communication channel corresponding to its own destination node. In the example of FIG. 4, the destination node DST1 receives a data frame on the communication channel CH1, the destination node DST2 receives a data frame on the communication channel CH2, and the destination node DST3 receives a data frame on the communication channel CH3.

  Next, in each of the destination nodes DST1, DST2, and DST3, the control unit 32 instructs the ACK frame generation unit 33 to generate an ACK frame. The ACK frame generation unit 33 generates an ACK frame according to an instruction from the control unit 32. The ACK frame is a frame including an ACK packet for a data packet included in the data frame. In the present embodiment, the ACK packet corresponds to the acknowledgment signal.

  Next, in each of the destination nodes DST1, DST2, and DST3, the receiving unit 31 receives the trigger frame through the communication channel CH4. The control unit 32 instructs the transmission unit 34 to transmit the ACK frame on the communication channel CH4 at the timing of the own destination node based on the timing at which the trigger frame is received. In response to the instruction from the control unit 32, the transmitting unit 34 transmits an ACK frame at the timing of the own destination node via the communication channel CH4.

  In the example of FIG. 4, the destination node DST1 transmits an ACK frame ACK1 via the communication channel CH4 after a lapse of time t1 from the timing at which the reception of the trigger frame has been completed, and the destination node DST2 has an ACK after a lapse of time t2 from the timing at which the reception of the trigger frame has been completed. The frame ACK2 is transmitted on the communication channel CH4, and the destination node DST3 transmits the ACK frame ACK3 on the communication channel CH4 after a lapse of time t3 from the timing when the reception of the trigger frame is completed. The time t2 is a time longer than the total time of the time t1 and the time required for transmitting the ACK frame ACK1. The time t3 is a time longer than the total time of the time t2 and the time required for transmitting the ACK frame ACK2. Thereby, collision of ACK frames ACK1, ACK2, and ACK3 transmitted from each of the destination nodes DST1, DST2, and DST3 in the communication channel CH4 is avoided.

  The times t1, t2 and t3 are indicated by the response timing information. The response timing information indicating the time t1 is included in the data packet received by the destination node DST1. The control unit 32 of the destination node DST1 acquires the response timing information from the data packet and recognizes the time t1. The response timing information indicating the time t2 is included in the data packet received by the destination node DST2. The control unit 32 of the destination node DST2 acquires the response timing information from the data packet and recognizes the time t2. The response timing information indicating the time t3 is included in the data packet received by the destination node DST3. The control unit 32 of the destination node DST3 acquires response timing information from the data packet and recognizes the time t3.

  Note that each of the destination nodes DST1, DST2, and DST3 transmits an ACK frame when decoding of its own data packet succeeds, and does not transmit an ACK frame when decoding of its own data packet fails.

(Step S5) Before the ACK waiting timer times out before receiving the ACK frame from all of the destination nodes DST1, DST2, and DST3 via the communication channel CH4, the source node SRC sends the ACK frame to the destination node that has not received the ACK frame. The data packet is retransmitted.

  Next, a configuration example of a data frame and a trigger frame according to the present embodiment will be described with reference to FIGS. FIG. 5 is a diagram illustrating a configuration example of a data frame according to the present embodiment. FIG. 6 is a diagram illustrating a configuration example of the trigger frame according to the present embodiment.

  First, a configuration example of the data frame will be described. FIG. 5 shows a configuration example of one data packet stored in a data frame. When M data packets are stored in one data frame (M = 3 in the example of FIG. 4), the data frame includes M data packet configurations shown in FIG.

  In FIG. 5, the data frame includes a PHY (physical) header, a MAC header, a payload (Payload), and an FCS (Frame Check Sequence). The MAC header of the data frame includes at least a data frame ID field and a Relative Duration field. The data frame ID field is a field for storing data frame identification information (data frame ID). The RelativeDuration field is a field for storing response timing information.

  The MAC header of the data frame may further include an MCS_ACK field. The MCS_ACK field is a field for storing information of MCS (Modulation and Coding Scheme) used by the destination node DST for the ACK frame. The MCS used for the ACK frame by the destination node DST may be determined in advance between the source node SRC and the destination node DST. In the MAC header of the data frame, the arrangement of the data frame ID field, the relative duration field, and the MCS_ACK field only needs to be determined in advance at an arbitrary position in the MAC header.

  The data frame ID included in the data frame is used by the destination node DST for comparison with the data frame ID included in the trigger frame. The destination node DST uses a trigger frame including the same data frame ID as the data frame ID included in the data frame as a reference for the timing of returning an ACK frame for the data frame.

  The MCS_ACK field stores information indicating the MCS used by the destination node DST to transmit an ACK frame. There are various algorithms for determining the MCS for ACK, and an example of the algorithm is shown below, but is not limited thereto.

(Example of algorithm for MCS selection)
From the given MCS set, the lowest rate MCS is selected as the initial value. Next, the source node SRC updates the MCS according to the RSSI (Received Signal Strength Indicator, received signal strength) of the received ACK. If the RSSI indicates that a higher rate MCS is acceptable, it is updated to the next higher rate MCS and the new MCS is specified in the next data packet. The MCS selected is the MCS at a rate below both the maximum rate MCS in the given MCS set and the maximum allowable rate MCS indicated by the previous RSSI and background noise.
The above is the description of the example of the algorithm for MCS selection.

  The RelativeDuration field stores response timing information. In the example illustrated in FIG. 4, the relative duration field of the data packet to the destination node DST1 stores response timing information indicating the time t1. The relative duration field of the data packet to the destination node DST2 stores response timing information indicating the time t2. Further, the RelativeDuration field of the data packet to the destination node DST3 stores response timing information indicating the time t3.

  Various algorithms for calculating the time indicated by the response timing information may exist, and an example of the algorithm is shown below, but the present invention is not limited to this.

(Example of algorithm for calculating response timing information)
Here, a case where the times t1, t2, and t3 are calculated will be described with reference to the example of FIG.
t1 = SIFS
t2 = t1 + t_ACK1 + SIFS
t3 = t2 + t_ACK2 + SIFS
t_ACK1 = (size of ACK1) / (transmission rate of ACK1)
t_ACK2 = (size of ACK2) / (transmission rate of ACK2)
However, SIFS (Short Inter Frame Space) is a waiting time before transmitting an ACK frame. t_ACK1 is a time required for transmitting the ACK frame ACK1. t_ACK2 is a time required for transmitting the ACK frame ACK2. The size of the ACK frame is the same. The transmission rate of the ACK frame is determined by the MCS specified in the MCS_ACK field.
The above is the description of the example of the algorithm for calculating the response timing information.

Next, a configuration example of the trigger frame will be described. In FIG. 6, the trigger frame includes a PHY header, a MAC header, and an FCS. In the present embodiment, the trigger frame has the following three functions.
As a first function, the communication channel used for transmission of the trigger frame and the next ACK for both the trigger frame and the next ACK by CS and BO performed before transmission of the trigger frame (FIG. 4). In the example, the access right of the communication channel CH4) is acquired.
As a second function, the PHY header of the trigger frame provides TXOP protection for other nodes that can decode the PHY header of the trigger frame. Accordingly, the next ACK can be protected from interference of a communication device such as a conventional legacy Wi-Fi device that can decode at least the PHY header of the trigger frame.
Third, the MAC header of the trigger frame provides NAV protection for other nodes that can decode the trigger frame.

  The PHY header of the trigger frame has the same configuration as the PHY header of the legacy Wi-Fi packet. Thereby, the legacy Wi-Fi device can recognize the PHY header of the trigger frame. As shown in FIG. 6, the Signal field of the PHY header of the trigger frame stores RATE and LENGTH. The wait time can be calculated using the RATE and LENGTH. Upon detecting the Signal field in the trigger frame, the legacy Wi-Fi device waits for its own transmission for a standby time calculated using RATE and LENGTH of the Signal field.

  RATE is set to, for example, 6 Mbps, and LENGTH is set based on the RATE “6 Mbps” so as to be a standby time that can cover up to the final ACK returned for the data frame. In the example of FIG. 4, the waiting time applied to the Signal field of the PHY header of the trigger frame is equal to or longer than “t_trigger + t3 + t_ACK3”. Here, t_trigger is a duration from the end of the Signal field of the PHY header of the trigger frame to the end of the trigger frame. t_ACK3 is the time required for transmitting the ACK frame ACK3, and is “t_ACK3 = (size of ACK3) / (transmission rate of ACK3)”.

  The MAC header of the trigger frame includes at least a FrameControl field, a Duration field, and a data frame ID field. The FrameControl field stores information for identifying the function of the frame. The FrameControl field of the trigger frame stores information indicating that the frame is a trigger frame.

  The Duration field stores the value of NAV. The value of NAV stored in the Duration field of the trigger frame is a value at which NAV protection is continued from completion of transmission of the trigger frame to completion of transmission of the final ACK. In the example of FIG. 4, the value of the NAV stored in the Duration field of the trigger frame is “t3 + t_ACK3” or more.

  The data frame ID field stores a data frame ID. The data frame ID stored in the data frame ID field of the trigger frame is the data frame ID of the data frame corresponding to the trigger frame. The destination node DST determines whether the data frame ID stored in the data frame ID field of the received trigger frame is the same as the data frame ID of the previously received data frame. If the result of the determination is that they are the same, the destination node DST indicates the response timing information stored in the RelativeDuration field of the data frame of the same data frame ID with reference to the reception completion timing of the trigger frame. ACK frame for the data frame with the same data frame ID is returned at the same timing.

  Next, an application example according to the present embodiment will be described.

(Application example 1)
An application example 1 according to the present embodiment will be described with reference to FIG. FIG. 7 is an explanatory diagram of Application Example 1 according to the present embodiment. In the application example 1, it is applied to an immediate ACK (Immediate ACK). If immediate ACK is applied, the source node SRC receives the next ACK frame for the transmitted data frame, or waits for the ACK waiting timer for any ACK frame to time out before the next node. Unable to send data frame.

  The source node SRC and the destination nodes DST1, DST2, and DST3 perform communication using a first shared communication medium and a second shared communication medium. The communication channels CH1, CH2 and CH3 are provided on the first shared communication medium. The communication channel CH4 is provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2, CH3 and CH4. The destination node DST1 uses the communication channels CH1 and CH4. The destination node DST2 uses the communication channels CH2 and CH4. The destination node DST3 uses the communication channels CH3 and CH4.

  The first example in FIG. 7 is a case where the idle state of the communication channels CH1 and CH2 and the busy state of the communication channel CH3 are confirmed by the CS before the transmission of the first data frame. The first data frame includes a data packet to destination node DST1 and a data packet to destination node DST2. The source node SRC transmits the first data frame using the communication channels CH1 and CH2. Next, the source node SRC transmits a first trigger frame corresponding to the first data frame via the communication channel CH4. Each data packet of the first data frame and the first trigger frame include the same data frame ID1.

  The destination node DST1 receives the first data frame on the communication channel CH1, and then receives the first trigger frame on the communication channel CH4. The destination node DST2 receives the first data frame on the communication channel CH2, and then receives the first trigger frame on the communication channel CH4. The destination node DST1 transmits the ACK frame ACK1 for the first data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the first trigger frame. The destination node DST2 transmits an ACK frame ACK2 for the first data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of completion of receiving the first trigger frame. In the example of FIG. 7, the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK1 of the destination node DST1 is completed for the first data frame on the communication channel CH4. As a result, in the communication channel CH4, the collision between the ACK frame ACK1 and the ACK frame ACK2 for the first data frame is avoided.

The example next to FIG. 7 is a case where the idle state of the communication channel CH3 and the busy states of the communication channels CH1 and CH2 are confirmed by the CS before the transmission of the second data frame.
The second data frame includes a data packet to the destination node DST3. The source node SRC transmits the second data frame via the communication channel CH3. Next, the source node SRC transmits a second trigger frame corresponding to the second data frame via the communication channel CH4. The data packet of the second data frame and the second trigger frame include the same data frame ID1.

  The destination node DST3 receives the second data frame on the communication channel CH3, and then receives the second trigger frame on the communication channel CH4. The destination node DST3 transmits an ACK frame ACK3 for the second data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of completion of receiving the second trigger frame.

The next example of FIG. 7 is a case where the idle state of the communication channels CH1, CH2, and CH3 is confirmed by the CS before the transmission of the third data frame. The communication channel whose idle state has been confirmed by the CS is used for communication, and the communication channel whose busy has been confirmed by the CS is not used for communication.
The third data frame includes a data packet to destination node DST1, a data packet to destination node DST2, and a data packet to destination node DST3. The source node SRC transmits the third data frame using the communication channels CH1, CH2, and CH3. Next, the source node SRC transmits a third trigger frame corresponding to the third data frame via the communication channel CH4. Each data packet of the third data frame and the third trigger frame include the same data frame ID1.

  The destination node DST1 receives the third data frame on the communication channel CH1, and then receives the third trigger frame on the communication channel CH4. The destination node DST2 receives the third data frame on the communication channel CH2, and then receives the third trigger frame on the communication channel CH4. The destination node DST3 receives the third data frame on the communication channel CH3, and then receives the third trigger frame on the communication channel CH4.

  The destination node DST1 transmits the ACK frame ACK1 for the third data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of the reception of the third trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the third data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the third trigger frame. The destination node DST3 transmits the ACK frame ACK3 for the third data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of the reception of the third trigger frame. In the example of FIG. 7, on the communication channel CH4, regarding the third data frame, after the transmission of the ACK frame ACK1 of the destination node DST1, the ACK frame ACK2 of the destination node DST2 is transmitted, and the transmission of the ACK frame ACK2 of the destination node DST2. After completion, the ACK frame ACK3 of the destination node DST3 is transmitted. As a result, in the communication channel CH4, the collision between the ACK frame ACK1, the ACK frame ACK2, and the ACK frame ACK3 regarding the third data frame is avoided.

  In the example of FIG. 7, the data frame IDs of the first data frame, the second data frame, and the third data frame are all the same, but the data frame IDs of the data frames may be different.

(Application example 2)
An application example 2 according to the present embodiment will be described with reference to FIGS. 8, 9, and 10. FIG. 8 is a diagram illustrating a network topology of Application Example 2 according to the present embodiment. In the network topology shown in FIG. 8, a source node SRC, destination nodes DST1 and DST2, and a conventional Wi-Fi device exist. In FIG. 8, as indicated by the solid line of the bidirectional arrow, the signal of the other party can be detected between the source node SRC and each of the destination nodes DST1 and DST2. Similarly, as indicated by the solid line of the bidirectional arrow, the signal of the other party can be detected between the source node SRC and the Wi-Fi device. Similarly, as indicated by the solid line of the bidirectional arrow, the destination node DST1 and the destination node DST2 are in a state where the signal of the other party can be detected. On the other hand, in FIG. 8, as indicated by the broken line of the bidirectional arrow, between the destination nodes DST1 and DST2 and the Wi-Fi device are in a state where the signal of the other party cannot be detected. In this application example 2, a conventional Wi-Fi device will be described as an example of a communication device capable of decoding at least a PHY header of a trigger frame. However, a communication device other than the conventional Wi-Fi device may be used. Can also be applied.

  FIG. 9 is an explanatory diagram of a conventional communication method for describing application example 2 according to the present embodiment. FIG. 10 is an explanatory diagram of a communication method of Application Example 2 according to the embodiment. 9 and 10, communication channels CH1 and CH2 are provided on a first shared communication medium. The communication channel CH4 is provided on the second shared communication medium.

  First, a conventional communication method will be described with reference to FIG. 9, the source node SRC_old is the source node SRC in the network topology of FIG. 8, the destination node DST1_old is the destination node DST1 in the network topology of FIG. 8, and the destination node DST2_old is the destination node DST2 in the network topology of FIG. , And the Wi-Fi device correspond to the respective signal detection states (whether or not a partner signal can be detected) to the Wi-Fi device in the network topology of FIG.

  The data frame includes a data packet to the destination node DST1_old and a data packet to the destination node DST2_old. The source node SRC_old transmits a data frame using the communication channels CH1 and CH2. The destination node DST1_old receives the data frame via the communication channel CH1. The destination node DST2_old receives the data frame via the communication channel CH2.

  After completing the reception of the data frame, the destination node DST1_old performs CS and BO on the communication channel CH4, and then transmits the ACK frame ACK1 on the communication channel CH4. The destination node DST2_old performs BO after performing CS on the communication channel CH4, performs BO after performing CS after completing transmission of the ACK frame ACK1 of the destination node DST1_old, and then transmits the ACK frame ACK2 on the communication channel CH4. . As a result, in the communication channel CH4, collision between the ACK frame ACK1 and the ACK frame ACK2 is avoided.

  However, between each of the destination nodes DST1_old and DST2_old and the Wi-Fi device, a signal of the other party cannot be detected. Therefore, the Wi-Fi device cannot detect the use of the communication channels CH4 of the destination nodes DST1_old and DST2_old even if CS is performed on the communication channel CH4. Further, each of the destination nodes DST1_old and DST2_old cannot detect the use of the communication channel CH4 of the Wi-Fi device even if CS is performed on the communication channel CH4. Therefore, as shown in FIG. 9, a collision (collision type 1) occurs between the ACK frames ACK1 and ACK2 transmitted by the respective destination nodes DST1_old and DST2_old and the data frame transmitted by the Wi-Fi device in the communication channel CH4. There was a possibility.

  Next, a communication method of Application Example 2 according to the present embodiment will be described with reference to FIG. The data frame includes a data packet to destination node DST1 and a data packet to destination node DST2. The source node SRC performs CS and BO on the communication channels CH1 and CH2, and then transmits a data frame. Next, the source node SRC performs CS and BO on the communication channel CH4, and then transmits a trigger frame corresponding to the data frame on the communication channel CH4. Each data packet of the data frame and the trigger frame include the same data frame ID.

  The destination node DST1 receives the data frame on the communication channel CH1, and then receives the trigger frame on the communication channel CH4. The destination node DST2 receives the data frame on the communication channel CH2, and then receives the trigger frame on the communication channel CH4. The destination node DST1 transmits the ACK frame ACK1 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. In the example of FIG. 10, the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK1 of the destination node DST1 is completed for the same data frame on the communication channel CH4. This prevents collision between ACK frame ACK1 and ACK frame ACK2 for the same data frame on communication channel CH4.

  Further, between the Wi-Fi device and the source node SRC, a signal of the other party can be detected. For this reason, the Wi-Fi device detects the trigger frame transmitted by the source node SRC on the communication channel CH4. The Wi-Fi device waits for its own transmission on the communication channel CH4 for the waiting time indicated by the Signal field of the trigger frame. Thereby, as shown in FIG. 10, the transmission of the Wi-Fi device is waited for in the communication channel CH4 until the TXOP protection period by the trigger frame ends. The TXOP protection period by the trigger frame continues until each of the destination nodes DST1 and DST2 completes transmitting the ACK frames ACK1 and ACK2. As a result, in the communication channel CH4, collision between the ACK frames ACK1 and ACK2 transmitted by the respective destination nodes DST1 and DST2 and the transmission from the Wi-Fi device is avoided. The Wi-Fi device waits for its own transmission for the standby time indicated by the Signal field of the trigger frame, performs CS and BO on the communication channel CH4, and then transmits the data frame on the communication channel CH4.

(Application example 3)
An application example 3 according to the present embodiment will be described with reference to FIGS. 11, 12, and 13. FIG. 11 is a diagram illustrating a network topology of Application Example 3 according to the present embodiment. In the network topology shown in FIG. 11, a source node SRC and destination nodes DST1, DST2, and DST3 exist. In FIG. 11, as indicated by the solid line of the bidirectional arrow, the signal of the other party can be detected between the source node SRC and each of the destination nodes DST1, DST2, and DST3. On the other hand, in FIG. 11, as indicated by the broken line of the bidirectional arrow, between the destination node DST1 and the destination node DST2, between the destination node DST1 and the destination node DST3, and between the destination node DST2 and the destination node DST3. Is in a state where the signal of the other party cannot be detected.

  FIG. 12 is an explanatory diagram of a conventional communication method for describing application example 3 according to the present embodiment. FIG. 13 is an explanatory diagram of a communication method of Application Example 3 according to the present embodiment. 12 and 13, communication channels CH1, CH2, and CH3 are provided on a first shared communication medium. The communication channel CH4 is provided on the second shared communication medium.

  First, a conventional communication method will be described with reference to FIG. 12, the source node SRC_old is the source node SRC in the network topology of FIG. 11, the destination node DST1_old is the destination node DST1 in the network topology of FIG. 11, and the destination node DST2_old is the destination node DST2 in the network topology of FIG. , Destination signal DST3_old corresponds to the destination node DST3 in the network topology of FIG. 11 in the respective signal detection states (whether or not the partner signal can be detected).

  The data frame includes a data packet to destination node DST1_old, a data packet to destination node DST2_old, and a data packet to destination node DST3_old. The source node SRC_old transmits a data frame using the communication channels CH1, CH2, and CH3. The destination node DST1_old receives the data frame via the communication channel CH1. The destination node DST2_old receives the data frame via the communication channel CH2. The destination node DST3_old receives the data frame via the communication channel CH3.

  Each of the destination nodes DST1_old, DST2_old, and DST3_old performs CS on the communication channel CH4 after completing the reception of the data frame. However, the destination nodes DST1_old, DST2_old, and DST3_old cannot detect each other's signals. Therefore, even if another destination node performs transmission on the communication channel CH4, the transmission cannot be detected. Therefore, as shown in FIG. 12, each of the destination nodes DST1_old, DST2_old, and DST3_old performs CS and BO on the communication channel CH4 after the data frame reception is completed, and then transmits each ACK frame ACK1, ACK2, and ACK3 to the communication channel. Transmit by CH4. As a result, a collision (collision type 2) between the ACK frames ACK1, ACK2, and ACK3 may occur.

  Next, a communication method of Application Example 3 according to the present embodiment will be described with reference to FIG. The data frame includes a data packet to destination node DST1, a data packet to destination node DST2, and a data packet to destination node DST3. After performing CS and BO, the source node SRC transmits a data frame through the communication channels CH1, CH2, and CH3. Next, the source node SRC performs CS and BO on the communication channel CH4, and then transmits a trigger frame corresponding to the data frame on the communication channel CH4. Each data packet of the data frame and the trigger frame include the same data frame ID.

  The destination node DST1 receives the data frame on the communication channel CH1, and then receives the trigger frame on the communication channel CH4. The destination node DST2 receives the data frame on the communication channel CH2, and then receives the trigger frame on the communication channel CH4. The destination node DST3 receives the data frame on the communication channel CH3, and then receives the trigger frame on the communication channel CH4. The destination node DST1 transmits the ACK frame ACK1 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST3 transmits the ACK frame ACK3 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. In the example of FIG. 13, with respect to the same data frame, in the communication channel CH4, the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK1 of the destination node DST1, and the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK2 of the destination node DST2 is completed. The ACK frame ACK3 of the destination node DST3 is transmitted. As a result, in the communication channel CH4, for the same data frame, collision between the ACK frames ACK1, ACK2, and ACK3 is avoided.

(Application example 4)
An application example 4 according to the present embodiment will be described with reference to FIGS. 14, 15, and 16. FIG. 14 is a diagram illustrating a network topology of Application Example 4 according to the present embodiment. In the network topology shown in FIG. 14, there are transmission source nodes SRC1 and SRC2 and destination nodes DST1, DST2, DST5 and DST6. The source node SRC1 and the destination nodes DST1 and DST2 belong to group 1. The source node SRC2 and the destination nodes DST5 and DST6 belong to group 2. The source nodes SRC1 and SRC2 have the configuration of the source node SRC shown in FIG. The destination nodes DST1, DST2, DST5, and DST6 have the configuration of the destination node DST shown in FIG.

  In FIG. 14, as shown by the solid line of the bidirectional arrow, between the source node SRC1 and the source node SRC2, between the source node SRC1 and each of the destination nodes DST1, DST2, DST5 and DST6, and Between the node SRC2 and each of the destination nodes DST1, DST2, DST5 and DST6, there is a state where the signal of the other party can be detected. Also, destination nodes belonging to the same group, that is, between the destination nodes DST1 and DST2 and between the destination nodes DST5 and DST5 are in a state where signals of the other party can be detected. On the other hand, the destination nodes belonging to different groups, that is, between the destination node DST1 and each of the destination nodes DST5 and DST6 and between the destination node DST2 and each of the destination nodes DST5 and DST6 cannot detect the signal of the other party. is there.

  FIG. 15 is an explanatory diagram of a conventional communication method for describing application example 4 according to the present embodiment. FIG. 16 is an explanatory diagram of a communication method of Application Example 4 according to the present embodiment. 15 and 16, communication channels CH1, CH2, CH5, and CH6 are provided in a first shared communication medium. The communication channel CH4 is provided on the second shared communication medium.

  First, a conventional communication method will be described with reference to FIG. 15, the source node SRC1_old is the source node SRC1 in the network topology of FIG. 14, the source node SRC2_old is the source node SRC2 in the network topology of FIG. 14, and the destination node DST1_old is the destination node in the network topology of FIG. DST1, destination node DST2_old is the destination node DST2 in the network topology of FIG. 14, destination node DST5_old is the destination node DST5 in the network topology of FIG. 14, and destination node DST6_old is the destination node DST6 in the network topology of FIG. The signal detection state (whether the signal of the other party can be detected or not) corresponds.

  The first data frame includes a data packet to the destination node DST1_old and a data packet to the destination node DST2_old. The source node SRC1_old performs CS and BO, and then transmits the first data frame through the communication channels CH1 and CH2. The destination node DST1_old receives the first data frame via the communication channel CH1. The destination node DST2_old receives the first data frame via the communication channel CH2.

  The second data frame includes a data packet to the destination node DST5_old and a data packet to the destination node DST6_old. The source node SRC2_old performs CS and BO, and then transmits the second data frame through the communication channels CH5 and CH6. The destination node DST5_old receives the second data frame via the communication channel CH5. The destination node DST6_old receives the second data frame via the communication channel CH6.

  Each of the destination nodes DST1_old, DST2_old, DST5_old, and DST6_old performs CS on the communication channel CH4 after completing the reception of the data frame. Since the destination nodes belonging to the same group are in a state where the signal of the other party can be detected, the transmission of another destination node can be detected by the CS. For this reason, between destination nodes belonging to the same group, collision between ACK frames is avoided by performing CS and BO on the communication channel CH4. However, since destination nodes belonging to different groups cannot detect a signal of the other party, transmission of another destination node cannot be detected even if CS is performed. Therefore, between destination nodes belonging to different groups, as shown in FIG. 15, even if CS and BO are performed on the communication channel CH4, there is a possibility that collision between ACK frames (collision type 3) may occur. Was.

  Next, a communication method of Application Example 4 according to the present embodiment will be described with reference to FIG. The first data frame includes a data packet to destination node DST1 and a data packet to destination node DST2. After performing CS and BO, the source node SRC1 transmits the first data frame through the communication channels CH1 and CH2. The source node SRC1 performs CS and BO on the communication channel CH4 after the first data frame, and then transmits a first trigger frame corresponding to the first data frame on the communication channel CH4. Each data packet of the first data frame and the first trigger frame include the same data frame ID.

  The destination node DST1 receives the first data frame on the communication channel CH1, and then receives the first trigger frame on the communication channel CH4. The destination node DST2 receives the first data frame on the communication channel CH2, and then receives the first trigger frame on the communication channel CH4. The destination node DST1 transmits the ACK frame ACK1 for the first data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the first trigger frame. The destination node DST2 transmits an ACK frame ACK2 for the first data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of completion of receiving the first trigger frame. In the example of FIG. 16, on the communication channel CH4, the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK1 of the destination node DST1 is completed for the first data frame. As a result, in the communication channel CH4, the collision between the ACK frame ACK1 and the ACK frame ACK2 for the first data frame is avoided.

  The second data frame includes a data packet to destination node DST5 and a data packet to destination node DST6. After performing CS and BO, the source node SRC2 transmits the second data frame via the communication channels CH5 and CH6. Next, the source node SRC2 performs CS and BO on the communication channel CH4 before transmitting the second trigger frame corresponding to the second data frame. The source node SRC2 detects the first trigger frame transmitted from the source node SRC1 on the communication channel CH4 by performing the CS and the BO. Then, the transmission source node SRC2 waits for its own transmission in the communication channel CH4 until the TXOP protection period and the NAV protection period by the first trigger frame have ended. The TXOP protection period and the NAV protection period by the first trigger frame continue until each destination node DST1 and DST2 completes transmitting ACK frames ACK1 and ACK2. As a result, in the communication channel CH4, collision between ACK frames ACK1 and ACK2 transmitted by the destination nodes DST1 and DST2 and transmission from the source node SRC2 is avoided. The transmission source node SRC2 waits for its own transmission until the TXOP protection period and the NAV protection period by the first trigger frame expire, and then performs CS and BO on the communication channel CH4, and then transmits the second trigger frame. Transmit on channel CH4. Each data packet of the second data frame and the second trigger frame include the same data frame ID.

  The destination node DST5 receives the second data frame on the communication channel CH5, and then receives the second trigger frame on the communication channel CH4. The destination node DST6 receives the second data frame on the communication channel CH6, and then receives the second trigger frame on the communication channel CH4. The destination node DST5 transmits the ACK frame ACK5 for the second data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the second trigger frame. The destination node DST6 transmits an ACK frame ACK6 for the second data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of completion of receiving the second trigger frame. In the example of FIG. 16, on the communication channel CH4, the ACK frame ACK6 of the destination node DST6 is transmitted after the transmission of the ACK frame ACK5 of the destination node DST5 is completed for the second data frame. As a result, in the communication channel CH4, the collision between the ACK frame ACK5 and the ACK frame ACK6 regarding the second data frame is avoided. Further, the transmission completion of each ACK frame ACK5 and ACK6 by each destination node DST5 and DST6 is protected by the TXOP protection period and the NAV protection period by the second trigger frame.

(Application example 5)
An application example 5 according to the present embodiment will be described with reference to FIGS. 17, 18, and 19. FIG. 17 is a diagram illustrating a network topology of Application Example 5 according to the present embodiment. In the network topology shown in FIG. 17, a source node SRC and destination nodes DST1, DST2, and DST3 exist. In FIG. 17, as indicated by the solid line of the bidirectional arrow, the signal of the other party can be detected between the source node SRC and each of the destination nodes DST1, DST2, and DST3. Similarly, as indicated by the solid line of the two-way arrow, there is a connection between the destination nodes DST1 and DST2, a connection between the destination nodes DST1 and DST3, and a connection between the destination nodes DST2 and DST3. In a state where the signal of the other party can be detected.

  FIG. 18 is an explanatory diagram of a conventional communication method for describing application example 5 according to the present embodiment. FIG. 19 is an explanatory diagram of the communication method of Application Example 5 according to the embodiment. 18 and 19, communication channels CH1, CH2, and CH3 are provided in a first shared communication medium. The communication channel CH4 is provided on the second shared communication medium.

  First, a conventional communication method will be described with reference to FIG. In FIG. 18, the source node SRC_old is the source node SRC in the network topology of FIG. 17, the destination node DST1_old is the destination node DST1 in the network topology of FIG. 17, and the destination node DST2_old is the destination node DST2 in the network topology of FIG. The destination node DST3_old corresponds to the destination node DST3 in the network topology in FIG. 17 in the respective signal detection states (whether or not a partner signal can be detected).

  The data frame includes a data packet to destination node DST1_old, a data packet to destination node DST2_old, and a data packet to destination node DST3_old. The source node SRC_old transmits a data frame using the communication channels CH1, CH2, and CH3. The destination node DST1_old receives the data frame via the communication channel CH1. The destination node DST2_old receives the data frame via the communication channel CH2. The destination node DST3_old receives the data frame via the communication channel CH3.

  Each of the destination nodes DST1_old, DST2_old, and DST3_old performs CS on the communication channel CH4 after completing the reception of the data frame. The destination nodes DST1_old, DST2_old, and DST3_old are in a state where they can detect each other's signals. Therefore, when another destination node performs transmission on the communication channel CH4, the transmission can be detected. Therefore, as shown in FIG. 12, each of the destination nodes DST1_old, DST2_old, and DST3_old performs CS and BO on the communication channel CH4 after the data frame reception is completed, and then transmits each ACK frame ACK1, ACK2, and ACK3 to the communication channel. Transmit by CH4. As a result, in the example of FIG. 18, with respect to the same data frame in the communication channel CH4, after the transmission of the ACK frame ACK1 of the destination node DST1_old is completed, the ACK frame ACK2 of the destination node DST2_old is transmitted, and the ACK frame ACK2 of the destination node DST2_old. Is transmitted, the ACK frame ACK3 of the destination node DST3_old is transmitted. As a result, in the communication channel CH4, collision between the ACK frame ACK1, the ACK frame ACK2, and the ACK frame ACK3 for the same data frame is avoided.

  However, since each of the destination nodes DST1_old, DST2_old, and DST3_old performs CS and BO on the communication channel CH4 before transmitting its own ACK frame, the utilization efficiency of the communication channel CH4 is reduced. Further, when the number of destination nodes for the same data frame increases, the total time of the BO increases by the increase. Also, if the time required to complete the transmission of the ACK frame of all the destination nodes is longer than the timeout period of the ACK waiting timer in the transmission source node, the transmission source node retransmits the corresponding data packet. Communication efficiency decreases.

  Next, a communication method of application example 5 according to the present embodiment will be described with reference to FIG. The data frame includes a data packet to destination node DST1, a data packet to destination node DST2, and a data packet to destination node DST3. After performing CS and BO, the source node SRC transmits a data frame through the communication channels CH1, CH2, and CH3. Next, the source node SRC performs CS and BO on the communication channel CH4, and then transmits a trigger frame corresponding to the data frame on the communication channel CH4. Each data packet of the data frame and the trigger frame include the same data frame ID.

  The destination node DST1 receives the data frame on the communication channel CH1, and then receives the trigger frame on the communication channel CH4. The destination node DST2 receives the data frame on the communication channel CH2, and then receives the trigger frame on the communication channel CH4. The destination node DST3 receives the data frame on the communication channel CH3, and then receives the trigger frame on the communication channel CH4. The destination node DST1 transmits the ACK frame ACK1 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST3 transmits the ACK frame ACK3 for the data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. In the example of FIG. 19, with respect to the same data frame on the communication channel CH4, the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK1 of the destination node DST1, and the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK2 of the destination node DST2 is completed. The ACK frame ACK3 of the destination node DST3 is transmitted. As a result, in the communication channel CH4, for the same data frame, collision between the ACK frames ACK1, ACK2, and ACK3 is avoided.

  Further, each of the destination nodes DST1, DST2, and DST3 does not perform CS and BO on the communication channel CH4 before transmitting its own ACK frame. Thereby, the use efficiency of the communication channel CH4 is improved as compared with the conventional communication method shown in FIG. 18 described above. Further, even if the number of destination nodes for the same data frame increases, the BO time is only required to be one time before the transmission of the trigger frame. For this reason, it is possible to suppress that the time required until the transmission of the ACK frame of all the destination nodes is longer than the timeout time of the ACK waiting timer in the transmission source node. As a result, the effect of reducing the occurrence of retransmission of data packets at the transmission source node and preventing a decrease in communication efficiency is obtained.

(Application example 6)
An application example 6 according to the present embodiment will be described with reference to FIG. FIG. 20 is an explanatory diagram of Application Example 6 according to the embodiment. In application example 6, the invention is applied to a delayed ACK (Delayed ACK). When the delayed ACK is applied, unlike the immediate ACK described above, the source node SRC can transmit the next data frame without waiting for the ACK frame for the transmitted data frame.

  The source node SRC and the destination nodes DST1, DST2, and DST3 perform communication using the first shared communication medium and the second shared communication medium. The communication channels CH1, CH2 and CH3 are provided on the first shared communication medium. The communication channel CH4 is provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2, CH3 and CH4. The destination node DST1 uses the communication channels CH1 and CH4. The destination node DST2 uses the communication channels CH2 and CH4. The destination node DST3 uses the communication channels CH3 and CH4.

  The first data frame includes a data packet to destination node DST1 and a data packet to destination node DST2. The second data frame includes a data packet to destination node DST1 and a data packet to destination node DST3. The source node SRC transmits the first data frame using the communication channels CH1 and CH2. Next, the source node SRC transmits the second data frame using the communication channels CH1 and CH3. Next, the source node SRC transmits a first trigger frame corresponding to the first data frame via the communication channel CH4. Each data packet of the first data frame and the first trigger frame include the same data frame ID1. Each data packet of the second data frame includes a data frame ID2.

  The destination node DST1 receives the first data frame on the communication channel CH1, then receives the second data frame on the communication channel CH1, and then receives the first trigger frame on the communication channel CH4. The destination node DST2 receives the first data frame on the communication channel CH2, and then receives the first trigger frame on the communication channel CH4. The destination node DST3 receives the second data frame on the communication channel CH3, and then receives the first trigger frame on the communication channel CH4.

  The destination node DST1 transmits the ACK frame ACK1 for the first data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the first trigger frame. The destination node DST2 transmits an ACK frame ACK2 for the first data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of completion of receiving the first trigger frame. The destination node DST3 receives the first trigger frame. However, since the data frame ID1 included in the first trigger frame is different from the data frame ID2 included in the second data frame, the ACK frame ACK3 for the second data frame is received. Not yet sent. In the example of FIG. 20, the ACK frame ACK2 of the destination node DST2 is transmitted on the communication channel CH4 after the transmission of the ACK frame ACK1 of the destination node DST1 is completed for the first data frame. As a result, in the communication channel CH4, the collision between the ACK frame ACK1 and the ACK frame ACK2 for the first data frame is avoided.

  Next, the source node SRC transmits a second trigger frame corresponding to the second data frame via the communication channel CH4. The second trigger frame includes the data frame ID2. Each of the destination nodes DST1, DST2 and DST3 receives the second trigger frame via the communication channel CH4. The destination node DST1 transmits the ACK frame ACK1 for the second data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of completion of receiving the second trigger frame. The destination node DST3 transmits an ACK frame ACK3 for the second data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of completion of receiving the second trigger frame. The destination node DST2 receives the second trigger frame, but does not receive the second data frame corresponding to the data frame ID2 included in the second trigger frame, and thus transmits the ACK frame ACK2 for the second data frame. do not do. In the example of FIG. 20, on the communication channel CH4, the ACK frame ACK3 of the destination node DST3 is transmitted after the transmission of the ACK frame ACK1 of the destination node DST1 is completed for the second data frame. As a result, in the communication channel CH4, collision between the ACK frame ACK1 and the ACK frame ACK3 for the second data frame is avoided.

  The third data frame includes a data packet to destination node DST1, a data packet to destination node DST2, and a data packet to destination node DST3. After performing CS and BO, the source node SRC transmits a third data frame through the communication channels CH1, CH2, and CH3. Next, the source node SRC transmits a third trigger frame corresponding to the third data frame via the communication channel CH4. Each data packet of the third data frame and the third trigger frame include the same data frame ID3.

  The destination node DST1 receives the third data frame on the communication channel CH1, and then receives the third trigger frame on the communication channel CH4. The destination node DST2 receives the third data frame on the communication channel CH2, and then receives the third trigger frame on the communication channel CH4. The destination node DST3 receives the third data frame on the communication channel CH3, and then receives the third trigger frame on the communication channel CH4.

  The destination node DST1 transmits the ACK frame ACK1 for the third data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of the reception of the third trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the third data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the third trigger frame. The destination node DST3 transmits the ACK frame ACK3 for the third data frame via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of the reception of the third trigger frame. In the example of FIG. 20, with respect to the third data frame on the communication channel CH4, after the transmission of the ACK frame ACK1 of the destination node DST1 is completed, the ACK frame ACK2 of the destination node DST2 is transmitted, and the ACK frame ACK2 of the destination node DST2 is transmitted. After completion, the ACK frame ACK3 of the destination node DST3 is transmitted. As a result, in the communication channel CH4, the collision between the ACK frame ACK1, the ACK frame ACK2, and the ACK frame ACK3 regarding the third data frame is avoided.

  For example, when the source node SRC retransmits the data packet to the destination node DST3 included in the second data frame and transmitted, the source node SRC adds the data packet to the destination node DST3 to the third data frame. It may be transmitted together.

  Next, a modified example according to the present embodiment will be described.

(Modification 1)
Modification 1 according to the present embodiment will be described with reference to FIGS. FIG. 21 is an explanatory diagram of Modification Example 1 according to the embodiment. FIG. 22 is a diagram illustrating a configuration example of a trigger frame according to the first modification of the present embodiment. In the first modification, a plurality of communication channels that can be used for transmitting an ACK frame are provided. In the example of FIG. 21, two communication channels CH7 and CH8 are provided as communication channels that can be used for transmitting an ACK frame.

  With reference to FIG. 21, a communication method according to the first modification of the present embodiment will be described. The source node SRC and the destination nodes DST1 and DST2 perform communication using a first shared communication medium and a second shared communication medium. The communication channels CH1 and CH2 are provided on the first shared communication medium. The communication channels CH7 and CH8 are provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2, CH7 and CH8. The destination node DST1 uses the communication channels CH1, CH7 and CH8. The destination node DST2 uses the communication channels CH2, CH7 and CH8. Of the communication channels CH7 and CH8 provided in the second shared communication medium, the communication channel CH7 is designated as a primary channel. The destination nodes DST1 and DST2 set at least a primary channel as a communication channel to be received.

  The data frame includes a data packet to destination node DST1 and a data packet to destination node DST2. After performing CS and BO, the source node SRC transmits a data frame via the communication channels CH1 and CH2. Next, the source node SRC performs CS on the communication channels CH7 and CH8. Due to this CS, in the example of FIG. 21, the communication channel CH7 was in the idle state, and the communication channel CH8 was busy. After performing the BO on the communication channel CH7, the source node SRC transmits a trigger frame corresponding to the data frame via the communication channel CH7. Each data packet of the data frame and the trigger frame include the same data frame ID. When the communication channel CH7, which is the primary channel, is busy, the source node SRC delays the transmission of the trigger frame.

  Destination node DST1 receives a data frame on communication channel CH1, and then receives a trigger frame on communication channel CH7. The destination node DST2 receives the data frame on the communication channel CH2 and then receives the trigger frame on the communication channel CH7. The destination node DST1 transmits the ACK frame ACK1 for the data frame via the communication channel CH7 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the data frame via the communication channel CH7 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. In the example of FIG. 21, the ACK frame ACK2 of the destination node DST2 is transmitted after the transmission of the ACK frame ACK1 of the destination node DST1 is completed for the same data frame on the communication channel CH7. As a result, in the communication channel CH7, collision between the ACK frame ACK1 and the ACK frame ACK2 for the same data frame is avoided.

  With reference to FIG. 22, a configuration example of the trigger frame of the first modification according to the present embodiment will be described. The trigger frame of the modification 1 shown in FIG. 22 is different from the configuration example of the trigger frame shown in FIG. 6 in that fields DST1 and DST2 corresponding to the destination nodes DST1 and DST2 are further provided. Except for this point, the configuration is the same as the configuration example of the trigger frame shown in FIG.

  Field DST1 is a field for storing information to be notified to destination node DST1, and includes a RelativeDuration field. The relative duration field of the field DST1 is a field for storing response timing information to be notified to the destination node DST1. Field DST1 is a field for storing information to be notified to destination node DST1, and may include an MCS_ACK field. The MCS_ACK field of the field DST1 is a field for storing information of the MCS used for the ACK frame by the destination node DST1. Similarly, the field DST2 is a field for storing information to be notified to the destination node DST2, and includes a relative duration field. Further, field DST2 is a field for storing information to be notified to destination node DST2, and may include an MCS_ACK field.

  In the first modification, of the communication channels that can be used for transmitting the ACK frame, which communication channel is actually used is determined by the CS before transmitting the trigger frame. Therefore, at the time of transmission of the data frame, the communication channel used for transmission of the ACK frame is undecided, and the MCS used for the ACK frame, that is, the transmission rate of the ACK frame is also undecided, and the response timing information is not determined. Therefore, in the first modification, a relative duration field is provided in the trigger frame. When the MCS_ACK field is provided, it is provided in the trigger frame. On the other hand, the relative frame and the MCS_ACK field may not be provided in the data frame.

(Modification 2)
Modification 2 according to the present embodiment will be described with reference to FIGS. FIG. 23 is an explanatory diagram of Modification 2 according to the present embodiment. FIG. 24 is a diagram illustrating a configuration example of a trigger frame of Modification 2 according to the present embodiment. In the second modification, as in the first modification, a plurality of communication channels that can be used for transmitting the ACK frame are provided. In the example of FIG. 23, as in the example of FIG. 21 described above, two communication channels CH7 and CH8 are provided as communication channels that can be used for transmitting an ACK frame. However, in the second modification, a plurality of destination nodes DST may transmit an ACK frame using a plurality of communication channels.

  With reference to FIG. 23, a communication method of Modification 2 according to the present embodiment will be described. The source node SRC and the destination nodes DST1 and DST2 perform communication using a first shared communication medium and a second shared communication medium. The communication channels CH1 and CH2 are provided on the first shared communication medium. The communication channels CH7 and CH8 are provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2, CH7 and CH8. The destination node DST1 uses the communication channels CH1, CH7 and CH8. The destination node DST2 uses the communication channels CH2, CH7 and CH8. Of the communication channels CH7 and CH8 provided in the second shared communication medium, the communication channel CH7 is designated as a primary channel. The destination nodes DST1 and DST2 set at least a primary channel as a communication channel to be received.

  The data frame includes a data packet to destination node DST1 and a data packet to destination node DST2. After performing CS and BO, the source node SRC transmits a data frame via the communication channels CH1 and CH2. Next, the source node SRC performs CS on the communication channels CH7 and CH8. Due to this CS, in the example of FIG. 23, both the communication channels CH7 and CH8 were in the idle state. The source node SRC performs a BO on the communication channel CH7, which is the primary channel, and then transmits a trigger frame corresponding to the data frame via the communication channel CH7. Each data packet of the data frame and the trigger frame include the same data frame ID. When the communication channel CH7, which is the primary channel, is busy, the source node SRC delays the transmission of the trigger frame.

  Destination node DST1 receives a data frame on communication channel CH1, and then receives a trigger frame on communication channel CH7. The destination node DST2 receives the data frame on the communication channel CH2 and then receives the trigger frame on the communication channel CH7.

  The destination node DST1 transmits the ACK frame ACK1 for the data frame through its own communication channel at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the data frame through its own communication channel at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. ACK channel information indicating a communication channel through which each of the destination nodes DST1 and DST2 transmits an ACK frame is included in the trigger frame. In the example of FIG. 23, for the same data frame, destination node DST1 transmits ACK frame ACK1 on communication channel CH7, while destination node DST2 transmits ACK frame ACK2 on communication channel CH8. That is, in the trigger frame, ACK channel information that specifies the communication channel CH7 for the destination node DST1 and ACK channel information that specifies the communication channel CH8 for the destination node DST2, as communication channels used for transmitting the ACK frame. And are included. Thereby, regarding the same data frame, collision between ACK frame ACK1 and ACK frame ACK2 is avoided.

  With reference to FIG. 24, a configuration example of the trigger frame of Modification 2 according to the present embodiment will be described. The trigger frame of the modification 2 shown in FIG. 24 is different from the configuration example of the trigger frame of the modification 1 shown in FIG. 22 described above in that a CH_ACK field corresponding to each of the destination nodes DST1 and DST2 is further provided. Except for this point, the configuration is the same as the configuration example of the trigger frame of the first modification shown in FIG. 22 described above.

  The CH_ACK field corresponding to the destination node DST1 is provided in the field DST1. The CH_ACK field of the field DST1 is a field for storing ACK channel information to be notified to the destination node DST1. The ACK channel information is information indicating a communication channel for transmitting an ACK frame. Similarly, a CH_ACK field corresponding to the destination node DST2 is provided in the field DST2. The CH_ACK field of the field DST2 is a field for storing ACK channel information to be notified to the destination node DST2. Each of the destination nodes DST1 and DST2 recognizes the communication channel on which the ACK frame is to be transmitted, based on the ACK channel information included in the trigger frame.

(Modification 3)
Modification 3 according to the present embodiment will be described with reference to FIG. FIG. 25 is an explanatory diagram of Modification 3 according to the present embodiment. In the third modification, similarly to the second modification described above, a plurality of communication channels usable for transmitting the ACK frame may be provided, and the plurality of destination nodes DST may transmit the ACK frame through the plurality of communication channels. In the example of FIG. 25, as in the example of FIG. 23 described above, two communication channels CH7 and CH8 are provided as communication channels that can be used for transmitting an ACK frame. However, in the third modification, the trigger frame may be transmitted through a plurality of communication channels.

  With reference to FIG. 25, a communication method of Modification 3 according to the present embodiment will be described. The source node SRC and the destination nodes DST1 and DST2 perform communication using a first shared communication medium and a second shared communication medium. The communication channels CH1 and CH2 are provided on the first shared communication medium. The communication channels CH7 and CH8 are provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2, CH7 and CH8. The destination node DST1 uses the communication channels CH1, CH7 and CH8. The destination node DST2 uses the communication channels CH2, CH7 and CH8. Of the communication channels CH7 and CH8 provided in the second shared communication medium, the communication channel CH7 is designated as a primary channel. The destination nodes DST1 and DST2 set at least a primary channel as a communication channel to be received.

  The data frame includes a data packet to destination node DST1 and a data packet to destination node DST2. After performing CS and BO, the source node SRC transmits a data frame via the communication channels CH1 and CH2. Next, the source node SRC performs CS on the communication channels CH7 and CH8. Due to this CS, in the example of FIG. 25, both the communication channels CH7 and CH8 were in the idle state. After performing the BO, the source node SRC transmits a trigger frame corresponding to the data frame on both the communication channels CH7 and CH8. Each data packet of the data frame and the trigger frame include the same data frame ID. When the communication channel CH7, which is the primary channel, is busy, the source node SRC delays the transmission of the trigger frame.

  The destination node DST1 receives a data frame on the communication channel CH1, and then receives a trigger frame on at least the communication channel CH7, which is the primary channel. The destination node DST2 receives the data frame on the communication channel CH2, and then receives the trigger frame on at least the communication channel CH7, which is the primary channel.

  The destination node DST1 transmits the ACK frame ACK1 for the data frame through its own communication channel at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 transmits the ACK frame ACK2 for the data frame through its own communication channel at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. ACK channel information indicating a communication channel through which each of the destination nodes DST1 and DST2 transmits an ACK frame is included in the trigger frame. In the example of FIG. 25, for the same data frame, destination node DST1 transmits ACK frame ACK1 on communication channel CH7, while destination node DST2 transmits ACK frame ACK2 on communication channel CH8. That is, in the trigger frame, ACK channel information that specifies the communication channel CH7 for the destination node DST1 and ACK channel information that specifies the communication channel CH8 for the destination node DST2 as communication channels used for transmitting the ACK frame. And are included. As a result, for the same data frame, collision between ACK frame ACK1 and ACK frame ACK2 is avoided. Further, the transmission completion of the ACK frame ACK1 by the destination node DST1 in the communication channel CH7 is protected by the TXOP protection period and the NAV protection period by the trigger frame of the communication channel CH7. Similarly, the transmission completion of the ACK frame ACK2 by the destination node DST2 in the communication channel CH8 is protected by the TXOP protection period and the NAV protection period by the trigger frame of the communication channel CH8.

  The above-described configuration example of the trigger frame of the second modification shown in FIG. 24 can be applied to the trigger frame of the third modification.

(Modification 4)
Modification 4 according to the present embodiment will be described with reference to FIG. FIG. 26 is an explanatory diagram of Modification 4 according to the present embodiment. The source node SRC and the destination nodes DST1 and DST2 perform communication using a first shared communication medium and a second shared communication medium. The communication channels CH1 and CH2 are provided on the first shared communication medium. The communication channel CH4 is provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2 and CH4. The destination node DST1 uses the communication channels CH1 and CH4. The destination node DST2 uses the communication channels CH2 and CH4.

  In the fourth modification, the DL frame includes ULACK and DL-DATA. Further, the UL frame includes DLACK and UL-DATA. The DL frame is a downlink (DL) frame in the direction from the source node to the destination node. The UL frame is an uplink (UL) frame in a direction from the destination node to the source node. UL-DATA is a packet of a UL data signal. DL-DATA is a packet of a DL data signal. ULACK is an ACK signal for UL-DATA. DLACK is an ACK signal for DL-DATA.

  UL-DATA piggybacks on DLACK. DL-DATA piggybacks on ULACK. The UL frame (m) includes DLACK1 for DL-DATA1 of the DL frame (n) and DL-DATA1 for the UL frame (m). The UL frame (m + 1) includes DLACK2 for DL-DATA2 of the DL frame (n) and DL-DATA2 for the UL frame (m + 1).

  The source node SRC transmits the DL frame (n) using the communication channels CH1 and CH2. Next, after performing CS and BO on the communication channel CH4, the source node SRC transmits a trigger frame corresponding to the DL frame (n) via the communication channel CH4. Each DL-DATA of the DL frame (n) and the trigger frame include the same data frame ID.

  The destination node DST1 receives the DL frame (n) on the communication channel CH1, and then receives the trigger frame on the communication channel CH4. The destination node DST2 receives the DL frame (n) on the communication channel CH2, and then receives the trigger frame on the communication channel CH4. The destination node DST1 transmits the UL frame (m) via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST1 includes, in the UL frame (m), DLACK1 for DL-DATA1 of the DL frame (n) and UL-DATA1 for the UL frame (m).

  The destination node DST2 transmits the UL frame (m + 1) via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 includes, in the UL frame (m + 1), DLACK2 for DL-DATA2 of the DL frame (n) and UL-DATA2 for the UL frame (m + 1).

  The source node SRC receives the UL frame (m) and the UL frame (m + 1) via the communication channel CH4. Next, the source node SRC performs CS and BO on the communication channels CH1 and CH2, and then transmits the DL frame (n + 1) via the communication channels CH1 and CH2. The transmission source node SRC stores, in the DL frame (n + 1), ULACK1 for UL-DATA1 of the UL frame (m), DL-DATA1 for the DL frame (n + 1), and ULACK2 for UL-DATA2 of the UL frame (m + 1). And DL-DATA1 in the DL frame (n + 1).

  According to the fourth modification, collision of DLACK and UL-DATA in the communication channel CH4 is avoided.

  The destination node DST notifies the source node SRC of the existence of its own UL-DATA. For example, information indicating the presence of UL-DATA may be included in DLACK. When recognizing the existence of UL-DATA of the destination node DST, the source node SRC adjusts the TXOP protection period and the NAV protection period by the trigger frame so as to protect the transmission of the UL-DATA.

(Modification 5)
Modification 5 according to the present embodiment will be described with reference to FIG. FIG. 27 is an explanatory diagram of Modification Example 5 according to the present embodiment. The source node SRC and the destination nodes DST1 and DST2 perform communication using a first shared communication medium and a second shared communication medium. The communication channels CH1 and CH2 are provided on the first shared communication medium. The communication channel CH4 is provided on the second shared communication medium. The source node SRC uses the communication channels CH1, CH2 and CH4. The destination node DST1 uses the communication channels CH1 and CH4. The destination node DST2 uses the communication channels CH2 and CH4. In the fifth modification, the transmission source node SRC uses a trigger frame to notify the transmission timing of UL-DATA to the destination node DST, and protects transmission of UL-DATA.

  After performing CS and BO on the communication channel CH4, the source node SRC transmits a trigger frame on the communication channel CH4. Each of the destination nodes DST1 and DST2 receives the trigger frame via the communication channel CH4. The destination node DST1 transmits the UL frame (m) via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The destination node DST2 transmits the UL frame (m + 1) via the communication channel CH4 at the timing of its own response timing information based on the timing of the completion of receiving the trigger frame. The configuration example of the trigger frame of the first modification shown in FIG. 22 described above can be applied to the trigger frame of the fifth modification.

  The source node SRC receives the UL frame (m) and the UL frame (m + 1) via the communication channel CH4. Next, the source node SRC performs CS and BO on the communication channels CH1 and CH2, and then transmits ULACK1 for UL-DATA1 of the UL frame (m) via the communication channel 1 to UL-DATA2 of the UL frame (m + 1). Are transmitted over the communication channel 2 respectively.

According to Modifications 4 and 5 described above, the following effects can be obtained.
PCF (Point Coordination Function) and HCCA (Hybrid Coordination Function Controlled Channel Access) in the conventional Wi-Fi protocol can alleviate the collision problem of UL data packets to some extent, but have the following limitations.

  PCF is implemented during the Contention Free Period (CFP), but faces at least two limitations. First, it introduces potential delays in both PCF and DCF (Distributed Coordination Function) traffic, which can severely impact delay-sensitive traffic. Second, if the total duration of CFPs in a coexisting Basic Service Set (BSS) is longer than the CFP repetition interval in each BSS, the service guarantee provided by the PCF cannot be achieved.

  HCCA can be implemented in both CFP and Contention Period (CP), but if multiple co-existing BSSs are regularly trying to gain access to the second shared communication medium, the frequent UL data packet You may face a collision.

  On the other hand, according to Modifications 4 and 5 described above, it is possible to relax the restrictions on both PCF and HCCA as described below.

  First, unlike PCF, Modifications 4 and 5 described above are communication methods based on contention. Therefore, by dividing the CFP repetition period into CFP and CP, it is possible to solve a problem occurring in PCF. Second, since the BO is performed before the transmission of the trigger frame, the possibility that the plurality of trigger frames are transmitted simultaneously can be significantly reduced even if the transmission opportunities of the plurality of trigger frames overlap.

  As described above, according to the present embodiment, when the communication channel for transmitting a data frame from the source node to the destination node is different from the communication channel for transmitting the ACK frame for the data frame from the destination node to the source node In addition, the transmission of the ACK frame can be protected by the trigger frame. As a result, an effect is obtained that the success rate of ACK frame reception at the transmission source node can be improved.

  In the above-described embodiment, the acknowledgment signal (ACK) is used as the response signal, but a negative acknowledgment signal (NACK) may be used as the response signal. Further, both the acknowledgment signal (ACK) and the negative acknowledgment signal (NACK) may be used as the response signal.

Further, a computer program for realizing the function of the above-mentioned transmission source node SRC or destination node DST is recorded on a computer-readable recording medium, and the program recorded on this recording medium is read and executed by a computer system. You may do so. Here, the “computer system” may include an OS and hardware such as peripheral devices.
The “computer-readable recording medium” includes a writable nonvolatile memory such as a flexible disk, a magneto-optical disk, a ROM, and a flash memory, a portable medium such as a DVD (Digital Versatile Disc), and a computer system. Storage device such as a hard disk.

Further, a “computer-readable recording medium” refers to a volatile memory (for example, a DRAM (Dynamic Random Access Memory), which holds programs for a certain period of time.
Further, the above program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the "transmission medium" for transmitting a program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
Further, the program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes a design change or the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 10 ... Base station apparatus, 11, 31 ... Receiving part, 12, 32 ... Control part, 13 ... Data frame generating part, 14 ... Trigger frame generating part, 15, 34 ... Transmitting part, 30 ... Terminal Device, 33: ACK frame generation unit, DST: destination node, SRC: source node

Claims (12)

A first frame generation unit that generates a first frame including a data signal to be transmitted to each of the plurality of destination nodes;
A second frame generation unit that generates a second frame representing a reference of different timing at which each of the plurality of destination nodes transmits a third frame including a response signal for a data signal included in the first frame;
Transmitting the first frame over a first communication channel corresponding to each of the plurality of destination nodes; and transmitting the second frame over a communication channel different from the first communication channel and used for transmitting the third frame. A transmitting unit for transmitting by a second communication channel,
A receiving unit that receives the third frame through the second communication channel;
A communication device comprising: The first frame includes response timing information indicating different timings at which each of the plurality of destination nodes transmits the third frame and indicating timing based on a reference represented by the second frame.
The communication device according to claim 1. The second frame includes response timing information indicating different timing at which each of the plurality of destination nodes transmits the third frame, the timing being based on a criterion represented by the second frame.
The communication device according to claim 1. The second frame includes frame identification information of the first frame,
The communication device according to claim 1. The second frame includes response channel information designating the second communication channel from among a plurality of communication channels available for transmission of the third frame,
The communication device according to claim 1. The second communication channel is different between a first destination node and a second destination node of the plurality of destination nodes.
The communication device according to claim 5. The third frame includes a data signal transmitted by the destination node to the own communication device,
The communication device according to claim 1. A source node receives a first frame including a data signal to be transmitted to each of a plurality of destination nodes via a first communication channel corresponding to its own communication device, and includes a response signal for a data signal included in the first frame. A second frame representing a different timing reference at which each of the plurality of destination nodes transmits a third frame, the second frame being a communication channel different from the first communication channel and being used for transmitting the third frame; A receiving unit for receiving by a channel;
A third frame generation unit that generates the third frame;
A transmitting unit that transmits the third frame at a timing of the own communication device based on a reference represented by the second frame;
A communication device comprising: A first frame generation unit that generates a first frame including a data signal to be transmitted to each of the plurality of destination nodes;
A second frame generation unit that generates a second frame representing a reference of different timing at which each of the plurality of destination nodes transmits a third frame including a response signal for a data signal included in the first frame;
Transmitting the first frame over a first communication channel corresponding to each of the plurality of destination nodes; and transmitting the second frame over a communication channel different from the first communication channel and used for transmitting the third frame. A first transmission unit for transmitting over a second communication channel,
A source node comprising: a first receiving unit that receives the third frame via the second communication channel;
A second receiving unit that receives the first frame through a first communication channel corresponding to the own destination node and receives the second frame through the second communication channel;
A third frame generation unit that generates the third frame;
A destination node comprising: a second transmitting unit that transmits the third frame at a timing of the own destination node based on a criterion represented by the second frame;
A communication system comprising: A first frame generating step in which a source node generates a first frame including a data signal to be transmitted to each of a plurality of destination nodes;
A second frame in which the source node generates a second frame representing a different timing reference at which each of the plurality of destination nodes transmits a third frame including a response signal for a data signal included in the first frame; Generating step;
The source node transmits the first frame through a first communication channel corresponding to each of the plurality of destination nodes, and transmits the second frame to a third communication channel different from the first communication channel. A first transmitting step of transmitting over a second communication channel used for transmitting the frame;
A second receiving step in which a destination node receives the first frame on a first communication channel corresponding to the destination node, and receives the second frame on the second communication channel;
A third frame generating step in which the destination node generates the third frame;
A second transmission step in which the destination node transmits the third frame at the timing of its own destination node based on a criterion represented by the second frame;
A first receiving step in which the source node receives the third frame via the second communication channel;
Communication method including. In the computer of the communication device,
A first frame generation function for generating a first frame including a data signal to be transmitted to each of the plurality of destination nodes;
A second frame generation function of generating a second frame representing a different timing reference at which each of the plurality of destination nodes transmits a third frame including a response signal for a data signal included in the first frame;
Transmitting the first frame over a first communication channel corresponding to each of the plurality of destination nodes; and transmitting the second frame over a communication channel different from the first communication channel and used for transmitting the third frame. A transmission function of transmitting over a second communication channel,
A receiving function of receiving the third frame via the second communication channel;
A computer program for realizing. In the computer of the communication device,
A source node receives a first frame including a data signal to be transmitted to each of a plurality of destination nodes via a first communication channel corresponding to its own communication device, and includes a response signal for a data signal included in the first frame. A second frame representing a different timing reference at which each of the plurality of destination nodes transmits a third frame, the second frame being a communication channel different from the first communication channel and being used for transmitting the third frame; A receiving function for receiving by a channel,
A third frame generation function for generating the third frame;
A transmission function of transmitting the third frame at a timing of the own communication device based on a reference represented by the second frame;
A computer program for realizing.

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