JP2022141388A - Wireless communication terminal and wireless communication method - Google Patents

Abstract

To provide a wireless communication terminal that is highly likely to satisfy a delay characteristic, which is a time allowed for delay, when information is relayed.SOLUTION: In a wireless communication system, a first wireless communication terminal wirelessly communicates with a second wireless communication terminal via a first wireless link by setting a first reception waiting period, and wirelessly communicates with a third wireless communication terminal via a second wireless link by setting a second reception waiting period different from the first reception waiting period. The first wireless communication terminal performs wireless communication via the first wireless link by setting a third reception waiting period waiting for transmission of information toward a downlink direction from the second wireless communication terminal, which is part or all of a period different from the first reception waiting period and the second reception waiting period, and the second wireless communication terminal does not wait for transmission of information toward an uplink direction from the first wireless communication terminal in the third reception waiting period.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a wireless communication terminal, a wireless communication system, and a wireless communication method, and more particularly to a wireless communication terminal, a wireless communication system, and a wireless communication method that preferentially transmit and receive information to be transmitted and received with priority.

For example, Non-Patent Document 1 discloses a technique for equally handling wireless resources regardless of the direction of relayed information when relaying information.

IEEE802.15.10, “IEEE Recommended Practice for Routing Packets in IEEE 802.15.4 Dynamically Changing Wireless Networks,” 2017.

However, in the conventional method as described in Non-Patent Document 1, when relaying information, there are cases where terminals with insufficient delay characteristics with respect to information exceed the permissible delay time.

An object of one aspect of the embodiments of the present invention is to provide a wireless communication terminal that is highly likely to satisfy delay characteristics, which is the time allowed for delay when information is relayed.

In a wireless communication system in which three or more wireless communication terminals communicate via a wireless link between each of the two or more wireless communication terminals, a first wireless communication terminal that is one of the three or more wireless communication terminals sets a second wireless communication terminal, which is one of three or more wireless communication terminals, through a first wireless link, which is one of two or more wireless links, and a first reception waiting period; wirelessly communicating with a third wireless communication terminal via a second wireless link, which is one of two or more wireless links, by setting a second reception waiting period different from the first reception waiting period; Communicating, the first wireless communication terminal uses a first wireless link for a part or all of a period different from the first reception waiting period and the second reception waiting period, and the second Wireless communication is performed by setting a third reception waiting period for waiting for transmission of downlink information from the wireless communication terminal, and during the third reception waiting period, the second wireless communication terminal performs the first wireless communication. To provide a wireless communication system characterized by not waiting for transmission of information in an uplink direction from a terminal.

Advantageous Effects of Invention According to the present invention, it is possible to realize a wireless communication terminal that is highly likely to satisfy the delay characteristic, which is the allowable delay time when information is relayed.

FIG. 1 is a block diagram showing the configuration of a radio communication system including a radio communication terminal according to this embodiment. FIG. 2 is a timing chart for explaining the functions of the wireless communication terminal according to this embodiment. FIG. 3 is a timing chart for explaining the functions of the wireless communication terminal according to this embodiment. FIG. 4 is a flow chart showing the procedure of wireless communication processing according to the present embodiment. FIG. 5 is a diagram for explaining the effects of this embodiment.

One aspect of the embodiment of the present invention will be described in detail below with reference to the drawings. One aspect of the embodiment of the present invention is applied to the IEEE802.15.4 standard, for example, and is used for IoT (Internet of Things), for example.

Compared to wired communication systems, wireless communication systems can reduce the amount of space required for wiring, and reduce the portability of portable terminals such as mobile phones, smartphones, tablet terminals, and wearable terminals. There are advantages such as being able to connect to a communication network without

In addition, the speed of wireless communication, which is communication by radio, is increasing, and the equipment required for wireless communication is becoming less expensive, and the use of wireless communication is increasing. For this reason, standardization of wireless communication is being promoted by IEEE (Institute of Electrical and Electronics Engineering).

The IEEE 802.15.4 standard is a standard that allows terminals to be used in wireless communication networks to be small, inexpensive, and consume little power. A wireless communication network conforming to IEEE 802.15.4 is configured to include, for example, a collection control station (CS) and one or more nodes as described in Non-Patent Document 1.

In such a configuration, a lower node transmits sensing information, which is information sensed by a lower node, toward a higher node including CS. Also, the upper nodes including the CS transmit control information, which is information for controlling the lower nodes.

In such a configuration, the communication network is multi-hop, and the communication between the nodes may use the same communication method, such as the frequency band.

In such a configuration, for example, when information is relayed, wireless resources are treated equally regardless of the direction of information to be relayed. A configuration and the like for resolving such concerns are shown below.

(this embodiment)
FIG. 1 is a block diagram showing the configuration of a radio communication system including a radio communication terminal 1B according to this embodiment. The radio communication system according to this embodiment includes radio communication terminals 1 (1A to 1C).

In a radio communication system including a radio communication terminal 1B according to this embodiment, three or more radio communication terminals 1 are connected to a first radio link 5 and a second radio link between two or more radio communication terminals 1, respectively. 6 to relay the communication.

The wireless communication terminal 1 is, for example, a collection control station (CS), a mobile phone, a smart phone, a tablet terminal, a wearable terminal, an actuator, or any other terminal capable of wireless communication. For example, when a control system such as an actuator is used, the wireless communication terminal 1 can control the opening and closing of valves to stop the gas, and can control robots.

A radio communication terminal 1 includes a radio transmitting/receiving section 2 and a control section 3, which are integrated circuits or the like. Here, for example, the radio communication terminal 1B (which may be referred to as a first radio terminal hereinafter) will be described. The radio transmission/reception unit 2 of the radio communication terminal 1B communicates with the radio communication terminal 1A (hereinafter referred to as the second (which may be called a wireless terminal) and a wireless communication terminal 1C (which may be called a third wireless terminal hereinafter) in a receiving state.

When the radio transmitting/receiving unit 2 of the radio communication terminal 1B receives the information, the control unit 3 of the radio communication terminal 1B instructs the radio transmitting/receiving unit 2 of the radio communication terminal 1B to switch from the receiving state to the transmitting state. For example, the wireless communication terminal 1B relays information transmission/reception between the wireless communication terminals 1A and 1C.

In the receiving state, the radio transmitting/receiving unit 2 of the radio communication terminal 1B sets a reception waiting period 8 (see FIG. 2, hereinafter, this may be referred to as a first reception waiting period) in the first radio link 5. . In addition, the radio transmitting/receiving unit 2 of the radio communication terminal 1B sets a reception waiting period 9 (see FIG. 2, hereinafter, this may be referred to as a second reception waiting period) in the second radio link 6 in the receiving state. .

When the radio communication terminal 1B is used as a reference, the transmission of information via the first radio link 5 is defined as the uplink direction, and the transmission of information via the second radio link 6 is defined as the downlink direction. It is assumed that the reception waiting period 8 is also set in the wireless communication terminal 1A. It is also assumed that the reception waiting period 9 is set in the wireless communication terminal 1C as well.

A reception waiting period 8 in the radio communication terminal 1B is a period of waiting for information such as downlink control information, which will be described later, transmitted from the radio communication terminal 1A. A reception waiting period 11 in the wireless communication terminal 1B is a period in which the wireless communication terminal 1C or the like waits for transmission of uplink sensor information, which will be described later.

It is assumed that control information that is desired to be delayed in a short time is transmitted as control information from the wireless communication terminal 1A to the wireless communication terminal 1B. On the other hand, it is assumed that sensor information, which is a sensing result that consumes less power, is transmitted from the wireless communication terminal 1C to the wireless communication terminal 1B, although the delay time may be long.

In this case, for example, the control unit 3 of the radio communication terminal 1B lengthens the reception waiting period for the first radio link 5 in the receiving state of the radio transceiver unit 2 of the radio communication terminal 1B, and To preset a short reception waiting period.

For example, if the reception waiting period 8 and the reception waiting period 9 are of the same length, the length of the reception waiting period 10 (see FIG. 2, hereinafter may be referred to as the third reception waiting period) is adjusted. , it is possible to lengthen the reception waiting period for the first wireless link 5 and shorten the reception waiting period for the second wireless link 6 . The radio communication terminal 1B waits for information from the radio communication terminal 1A during the reception waiting period 10, but at this time the radio communication terminal 1A does not wait for information from the radio communication terminal 1B.

For example, the parameters of the reception waiting periods 8 to 13, 15, and 16 (see FIGS. 2 and 3), which are the reception waiting periods for the first radio link 5 and the reception waiting periods for the second radio link 6, are It is preset based on previous communication heuristics. For example, the parameters of the reception waiting periods 8 to 13, 15 and 16 refer to the lengths and start times of the reception waiting periods 8 to 13, 15 and 16. Note that the previous time refers to, for example, the operation before the wireless communication terminal 1B is powered on.

Further, for example, reception waiting periods 8 to 13, 15, and 16 (see FIGS. 2 and 3), which are reception waiting periods for the first wireless link 5 and reception waiting periods for the first wireless link 5, are wireless communication It is preset based on the delay characteristics required for the system. Here, the delay characteristics refer to average delay time and maximum delay time, for example.

As a result, for example, the control unit 3 of the wireless communication terminal 1B makes adjustments such as shortening the delay time for the first wireless link 5 and lengthening the delay time for the second wireless link 6. can do. Note that the beacon interval may be arbitrary when waiting for reception.

After receiving an instruction from the control unit 3 of the wireless communication terminal 1B, the wireless transmission/reception unit 2 of the wireless communication terminal 1B receives an instruction from the control unit 3 of the wireless communication terminal 1B. Information is transmitted to the communication terminal 1C.

The wireless communication terminal 1B relays the control information by further transmitting it to the wireless communication terminal 1C and the like. For example, the wireless communication terminal 1C may be attached to a machine tool, and the machine tool may be controlled based on the control information received by the wireless communication terminal 1C. Also, the wireless communication terminal 1B relays the sensing information by further transmitting it to the wireless communication terminal 1A and the like.

In the above example, the ratio between the reception waiting period for the first wireless link 5 and the reception waiting period for the second wireless link 6 is determined according to the type of information such as control information and sensing information. is not limited to this.

For example, the period of waiting for reception on the second radio link 6 in which the interference 7 described later is occurring may be shortened. The radio transceiver 2 of the radio communication terminal 1B may detect interference 7 to the second radio link 6 .

For example, the interference 7 is generated by a system unrelated to the wireless communication terminal 1 according to the present embodiment, such as magnetic fields and radio waves generated by working vehicles such as electric forklifts. Also, for example, the radio transmitting/receiving unit 2 of the radio communication terminal 1B senses interference 7 to the second radio link 6 when the bit error rate exceeds a predetermined value.

The control unit 3 of the radio communication terminal 1B changes the parameters of the second radio link 6 when the radio transmitting/receiving unit 2 of the radio communication terminal 1B senses the interference 7 . The parameters shall for example comprise at least one of frequency band, modulation scheme and link duration in the radio link where said interference is detected.

The link period refers to the period of waiting for reception in the wireless communication terminal 1 , for example, the sum of the period of waiting for reception on the first wireless link 5 and the period of waiting for reception on the second wireless link 6 .

For example, it is assumed that a radio channel can be selected by changing the frequency band. The control unit 3 of the radio communication terminal 1B may repeat parameter changes until the bit error rate is improved to an improvement threshold value that is a predetermined value.

Note that the control unit 3 of the radio communication terminal 1B, when the radio transmitting/receiving unit 2 of the radio communication terminal 1B senses the interference 7, sends the control unit 3 of the further radio communication terminal 1C on the second radio link 6, for example The parameters are transmitted via the radio transmitting/receiving section 2 of the radio communication terminal 1B by utilizing the sleep period or the like during which no main control is performed. Note that the application of changed parameters is also performed during the sleep period.

Next, description will be made with reference to FIG. In particular, the case where the radio communication terminal 1B relays information in the upstream direction between the radio communication terminals 1A and 1C will be described. FIG. 2 is a timing chart for explaining the functions of the wireless communication terminal 1 according to this embodiment. For example, in the receiving state of the wireless communication terminal 1B, the wireless communication terminal 1B is waiting for reception from the wireless communication terminal 1A and the wireless communication terminal 1C via the first wireless link 5 and the second wireless link 6. Receiving standby periods 8, 9, and 10 are set to wait for reception.

The wireless communication terminal 1A transmits information during reception waiting periods 8 and 10, which are reception waiting periods during which the wireless communication terminal 1B waits for reception of the wireless communication terminal 1A. The radio communication terminal 1C transmits information during a reception waiting period 9 during which the radio communication terminal 1B waits for reception from the radio communication terminal 1C.

For example, when the wireless communication terminal 1B receives information from the wireless communication terminal 1C, it enters a transmission state and stops waiting for reception. The radio transmitting/receiving unit 2 of the radio communication terminal 1B transmits to the radio communication terminal 1A during reception waiting periods 8 and 11 during which the radio communication terminal 1A waits for reception from the radio communication terminal 1B. Send information.

The radio communication terminal 1A waits for information from the radio communication terminal 1B during a reception waiting period 11 (hereinafter, this may be called a fourth reception waiting period). Do not wait for information from 1A.

Note that the reception waiting period 10 is, for example, part or all of a period 12 different from the reception waiting periods 8 and 9 in a repeating period 13 that is periodically repeated. Further, as described above, when information is relayed in the upstream direction, the reception waiting period 10, which is a period during which only the downstream communication is performed, and the reception waiting period 16, which will be described later, are not set.

The repetition period 13 may include at least the reception waiting periods 8 to 10 and may not include the reception waiting period 11 . In the present embodiment, it is assumed that the repetition period 13 is repeated two or more times, but the present invention is not limited to this, and each of the reception waiting periods 8 to 10 may be provided.

Next, description will be made with reference to FIG. In particular, the case where the radio communication terminal 1B relays information in the downstream direction between the radio communication terminals 1A and 1C will be described. FIG. 3 is a timing chart for explaining the functions of the wireless communication terminal 1 according to this embodiment.

For example, in the receiving state of the wireless communication terminal 1C, the wireless communication terminal 1C is waiting for reception from the wireless communication terminal 1B and the wireless communication terminal 1D via the second wireless link 6 and the third wireless link 14. Receiving standby periods 9, 15, and 16 are set to wait for reception. The radio communication terminal 1D is assumed to be one of three or more radio communication terminals farther from the radio communication terminal 1B than the radio communication terminal 1C.

The radio communication terminal 1A transmits information during reception waiting periods 8 and 10 during which the radio communication terminal 1B waits for reception of the radio communication terminal 1A. The radio communication terminal 1C transmits information during the reception waiting periods 9 and 16 during which the radio communication terminal 1B waits for reception from the radio communication terminal 1C.

Note that the radio transmitting/receiving section 2 of the radio communication terminal 1C sets a reception waiting period 15 (hereinafter, this may be referred to as a fifth reception waiting period) in the third radio link 14 in the receiving state. It is also assumed that the reception waiting period 15 is set in the wireless communication terminal 1D as well.

The radio communication terminal 1C waits for information from the radio communication terminal 1B during a reception waiting period 16 (hereinafter, this may be called a sixth reception waiting period). Do not wait for information from 1C.

Note that the reception waiting period 16 is, for example, part or all of a period 17 different from the reception waiting period 9 and the reception waiting period 15 in the repetition period 13 which is a period that is periodically repeated. Further, as described above, when information is relayed in the downstream direction, the reception waiting period 11, which is a period during which only upstream communication is performed, is not set.

Next, description will be made with reference to FIG. FIG. 4 is a flow chart showing the procedure of wireless communication processing according to the present embodiment. For example, the control unit 3 of the radio communication terminal 1B determines whether or not the radio transmitting/receiving unit 2 of the radio communication terminal 1B has received information (S1).

If the control unit 3 of the radio communication terminal 1B determines that the radio transmitting/receiving unit 2 of the radio communication terminal 1B has not received the information and the result of step S1 is negative (S1: NO), the radio communication terminal 1B The control unit 3 executes step S1 again.

If the control unit 3 of the radio communication terminal 1B determines that the radio transmitting/receiving unit 2 of the radio communication terminal 1B is receiving information and the result of step S1 is affirmative (S1: YES), the radio communication terminal 1B is controlled. The unit 3 instructs the wireless transmission/reception unit 2 of the wireless communication terminal 1B to switch to the transmission state (S2).

Next, the control unit 3 instructs the radio transmitting/receiving unit 2 of the radio communication terminal 1B to transmit information to the other radio communication terminal 1A or further radio communication terminal 1C, which is the source of the received information ( S3).

Next, description will be made with reference to FIG. FIG. 5 is a diagram for explaining the effects of this embodiment. Graph 20 is a graph when the beacon interval is 5 seconds, and graph 21 is a graph when the beacon interval is 10 seconds.

As shown in graphs 20 and 21, compared to the case of evenly assigning 50% of the reception waiting period as in the prior art regardless of the beacon interval, the reception waiting period is not made uniform, resulting in a delay. The average time of eg 10 packets of time can be reduced.

For example, as shown in graphs 20 and 21, if 70% of the link period is allocated for waiting for reception to upper nodes, the average delay time can be halved regardless of the beacon interval. .

Note that FIG. 5 is a diagram of the wireless communication terminal 1B, and the upper node indicates the wireless communication terminal 1A. The other node is, for example, the wireless communication terminal 1C.

As described above, according to the wireless communication terminal 1 according to the present embodiment, it is possible to increase the possibility of satisfying the delay characteristic, which is the allowable delay time, when information is relayed. According to the radio communication terminal 1 according to the present embodiment, by setting the reception waiting period with the intention of relaying with a short delay time, it is possible to realize a relay with a short delay time as desired. be able to.

By allocating a long time to the information to be preferentially transmitted/received by performing such a relay, it is possible to preferentially transmit/receive the information to be preferentially transmitted/received. Further, according to the wireless communication terminal 1 according to the present embodiment, it is possible to set a predetermined delay time or extend the delay time.

Note that the wireless communication terminal 1B according to the present embodiment can also be applied to, for example, a tree-type wireless communication system or a bus-type wireless communication system rooted by a CS. For example, the wireless communication terminal 1A serves as CS, which is a master device in the tree-type wireless communication system, and collects information on the wireless communication terminals 1B and 1C, which are mobile phones, smart phones, tablet terminals, wearable terminals, personal computers, actuators, and the like.

For example, the radio communication terminal 1A controls each node such as the radio communication terminals 1A to 1C of the radio communication system, and controls lower nodes such as the radio communication terminals 1B and 1C. to send.

A lower node communicates, for example, sensing information, which is information sensed by a lower node, to a higher node. For example, the radio communication terminal 1A is a first layer node, the radio communication terminal 1B is a second layer node, and the radio communication terminal 1C is a third layer node.

It is assumed that the order of the first hierarchy, the second hierarchy, and the third hierarchy is from top to bottom. A third layer node transmits sensing information to a second layer node and a first layer node. Nodes in the second layer transmit sensing information to nodes in the first layer.

As described above, in the radio communication system according to the present embodiment, three or more radio communication terminals 1 communicate via radio links between two or more radio communication terminals. The first wireless communication terminal 1B, which is one of the three or more wireless communication terminals, communicates with the three or more wireless communication terminals via the first wireless link 5, which is one of the two or more wireless links. A first reception waiting period 8 is set with the second wireless communication terminal 1A, which is one of the wireless communication terminals, and wireless communication is performed.

Also, the first wireless communication terminal 1B communicates with the third wireless communication terminal 1C via a second wireless link 6, which is one of the two or more wireless links, in a second wireless communication terminal different from the first reception waiting period 8. wireless communication is performed by setting the reception waiting period 9 of

The first radio communication terminal 1B sets a third reception waiting period 10 for waiting for downlink information transmission from the second radio communication terminal 1A via the first radio link 5, and performs radio communication. I do.

The third reception waiting period 10 is part or all of the period 12 different from the first reception waiting period 8 and the second reception waiting period 9 . Further, in the third reception waiting period 10, the second radio communication terminal 1A does not wait for transmission of uplink information from the first radio communication terminal 1B.

Further, as described above, in the present embodiment, the second wireless communication terminal 1A communicates with the first wireless communication terminal 1B during the third reception waiting period 10 for wireless communication via the first wireless link 5. Information may be transmitted in the downlink direction.

Further, as described above, in this embodiment, the wireless communication system may relay information in the downlink direction. Specifically, the third wireless communication terminal 1C uses a third wireless link 14, which is one of two or more wireless links, to communicate with the second wireless communication terminal 1A rather than the third wireless communication terminal 1C. Radio communication is performed with a fourth radio communication terminal 1D, which is one of three or more radio communication terminals away from the terminal, by setting a fifth reception waiting period 15.例文帳に追加

When the first wireless communication terminal 1B receives the information from the second wireless communication terminal 1A via the first wireless link 5 during the first reception waiting period 8 or the third reception waiting period 10, The wireless communication terminal 1C of No. 3 sets the sixth reception waiting period 16 or sets the second reception waiting period 9 via the second wireless link 6 to perform wireless communication.

The sixth reception waiting period 16 is part or all of the period 17 different from the second reception waiting period 9 and the fifth reception waiting period 15 . In the sixth reception waiting period 16, the third radio communication terminal 1C waits for downlink information transmission from the first radio communication terminal 1B. It does not wait for transmission of information in the upstream direction from 1C. When the radio communication system relays downlink information, the second radio communication terminal 1A does not set the fourth reception waiting period 11. FIG.

Further, as described above, in this embodiment, the radio communication system may relay information in the uplink direction. Specifically, the first radio communication terminal 1B receives an uplink signal from the third radio communication terminal 1C via the second radio link 6 during the second reception waiting period 9 or the sixth reception waiting period 16. , the second wireless communication terminal 1A sets the fourth reception waiting period 11 via the first wireless link 5, or sets the first reception waiting period 8 to perform wireless communication.

The fourth reception waiting period 11 is part or all of the period 12 different from the first reception waiting period 8 and the second reception waiting period 9 . In the fourth reception waiting period, the second radio communication terminal 1A waits for the transmission of the information in the uplink direction from the first radio communication terminal 1B to the second radio communication terminal 1A, The communication terminal 1B does not wait for the downlink transmission of the information from the second wireless communication terminal.

When the wireless communication system relays information in the uplink direction, the first wireless communication terminal 1B does not set the third reception waiting period 10, and the third wireless communication terminal 1C sets the sixth reception waiting period 10. No waiting period 16 is set.

Further, as described above, in the present embodiment, the parameters of the first to sixth reception waiting periods 8 to 13, 15, and 16 are empirical rules of communication during operation before the power is turned on, and It is preset based on one or more delay characteristics required for the wireless communication system. The parameters of the first to sixth reception waiting periods 8 to 13, 15 and 16 are, for example, lengths and start times of the reception waiting periods 8 to 13, 15 and 16. FIG.

Note that the number of lower nodes such as the wireless communication terminals 1B and 1C may be one or more, and the type of branching such that the wireless communication terminal 1B communicates with a lower node other than the wireless communication terminal 1C is also limited. Suppose not.

In addition, in the above-described embodiment, the case where the radio transmitting/receiving unit 2 and the control unit 3 are integrated circuits has been described, but the present embodiment is not limited to this. For example, the radio transmitting/receiving unit 2 and the control unit 3 may be programs stored in a RAM (random access memory) (not shown) of the radio communication terminal 1 . For example, the program is executed by being called by a CPU (Central Processing Unit) (not shown) provided in the wireless communication terminal 1 .

1, 1A, 1B, 1C... wireless communication terminal, 2... wireless transmitter/receiver, 3... control unit, 5... first wireless link, 6... second wireless link, 7... interference.

Claims (6)

In a wireless communication system in which three or more wireless communication terminals communicate via wireless links between each of the two or more wireless communication terminals,
A first wireless communication terminal that is one of the three or more wireless communication terminals communicates with one of the three or more wireless communication terminals via a first wireless link that is one of the two or more wireless links. wirelessly communicate with a second wireless communication terminal, which is one of the two or more wireless links, through the second wireless link, which is one of the two or more wireless links; and performing wireless communication by setting a second reception waiting period different from the first reception waiting period,
The first wireless communication terminal, through the first wireless link, during a part or all of a period different from the first reception waiting period and the second reception waiting period, performing wireless communication by setting a third reception waiting period for waiting for transmission of downlink information from the wireless communication terminal of
In the third reception waiting period, the second wireless communication terminal does not wait for transmission of the information in an uplink direction from the first wireless communication terminal,
A wireless communication system characterized by: In the third reception waiting period of wireless communication via the first wireless link, the second wireless communication terminal transmits the information in a downlink direction to the first wireless communication terminal;
The wireless communication system according to claim 1, characterized by: 3, wherein the third wireless communication terminal is further away from the second wireless communication terminal than the third wireless communication terminal via a third wireless link that is one of the two or more wireless links; Performing wireless communication with a fourth wireless communication terminal, which is one of the above wireless communication terminals, by setting a fifth reception waiting period,
When the first wireless communication terminal receives the information from the second wireless communication terminal during the first reception waiting period or the third reception waiting period via the first wireless link,
The third wireless communication terminal, through the second wireless link, during a part or all of a period different from the second reception waiting period and the fifth reception waiting period, setting a sixth reception waiting period for waiting for the transmission of the information in the downlink direction from the wireless communication terminal of or setting the second reception waiting period to perform wireless communication;
In the sixth reception waiting period, the first wireless communication terminal does not wait for transmission of the information in the uplink direction from the third wireless communication terminal,
The second wireless communication terminal transmits the first signal to the second wireless communication terminal during part or all of a period different from the first reception waiting period and the second reception waiting period. not setting a fourth reception waiting period for waiting for transmission of the information in the uplink direction from the wireless communication terminal;
The wireless communication system according to claim 1, characterized by: The first radio communication terminal transmits the information in the uplink direction from the third radio communication terminal via the second radio link in the second reception waiting period or the sixth reception waiting period. If received,
the second wireless communication terminal performs wireless communication via the first wireless link by setting the fourth reception waiting period or by setting the first reception waiting period;
In the fourth reception waiting period, the first wireless communication terminal does not wait for transmission of the information in the downlink direction from the second wireless communication terminal,
The first wireless communication terminal does not set the third reception waiting period,
The third wireless communication terminal does not set the sixth reception waiting period,
4. The wireless communication system according to claim 3, characterized by: The parameter of the third reception waiting period is set in advance based on one or more empirical rules of communication during operation before power is turned on and delay characteristics required for the wireless communication system. Ru
The wireless communication system according to claim 1, characterized by: The first wireless communication terminal includes at least the first reception waiting period, the second reception waiting period, and the third reception waiting period in the repetition period, which is a period that is periodically repeated.
The wireless communication system according to claim 1, characterized by:

Images