Wireless communication terminal and wireless communication method

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]

[0001] 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 for preferentially transmitting and receiving information that is to be preferentially transmitted and received. [Background technology]

[0002] For example, Non-Patent Document 1 discloses a technique for handling wireless resources equally when relaying information, regardless of the direction of the information being relayed. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IEEE802.15.10, “IEEE Recommended Practice for Routing Packets in IEEE 802.15.4 Dynamically Changing Wireless Networks,” 2017. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional method described in Non-Patent Document 1, when relaying information, there are cases where a terminal has insufficient delay characteristics for information that exceeds the allowable delay time.

[0005] An object of one aspect of an embodiment of the present invention is to provide a wireless communication terminal that is likely to satisfy delay characteristics, which are the amount of time that can be delayed when relaying information. [Means for solving the problem]

[0006] In a wireless communication system in which three or more wireless communication terminals communicate via wireless links between two or more of the wireless communication terminals, a first wireless communication terminal that is one of the three or more wireless communication terminals performs wireless communication with a second wireless communication terminal that is one of the three or more wireless communication terminals via a first wireless link that is one of the two or more wireless links, by setting a first reception waiting period, and performs wireless communication with a third wireless communication terminal via a second wireless link that is one of the two or more wireless links, by setting a second reception waiting period that is different from the first reception waiting period, and the first wireless communication terminal performs wireless communication via the first wireless link by setting a third reception waiting period that is part or all of a period different from the first reception waiting period and the second reception waiting period, and the first wireless communication terminal does not wait for transmission of sensing information in the uplink direction from the first wireless communication terminal, and the third reception waiting period is set in advance based on a delay characteristic required for the wireless communication system, The control information via and the second wireless link The sensing information via The present invention provides a wireless communication system characterized in that the ratio of the reception waiting period to the control information is determined according to the type of information consisting of the control information and the sensing information. [Effects of the Invention]

[0007] According to the present invention, it is possible to realize a wireless communication terminal that is highly likely to satisfy delay characteristics, which are the amount of time that can be delayed when relaying information. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing the configuration of a wireless communication system including a wireless communication terminal according to this embodiment. [Figure 2] FIG. 2 is a timing chart illustrating the functions of the wireless communication terminal according to this embodiment. [Figure 3]FIG. 3 is a timing chart illustrating the functions of the wireless communication terminal according to this embodiment. [Figure 4] FIG. 4 is a flowchart showing the procedure of wireless communication processing according to this embodiment. [Figure 5] FIG. 5 is a diagram illustrating the effects of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described in detail below with reference to the drawings. The embodiment of the present invention is applied to, for example, the IEEE 802.15.4 standard and is used in, for example, IoT (Internet of Things).

[0010] Compared to wired communication systems, wireless communication systems have the advantage of reducing the space required for wiring and allowing portable devices such as mobile phones, smartphones, tablet devices, and wearable devices to connect to a communication network without compromising portability.

[0011] In addition, wireless communication is becoming faster and the equipment required for wireless communication is becoming cheaper, so the number of situations in which wireless communication is used is increasing. For this reason, the Institute of Electrical and Electronics Engineering (IEEE) is working on standardizing wireless communication.

[0012] The IEEE802.15.4 standard is a standard for wireless communication networks that use small, inexpensive terminals with low power consumption. A wireless communication network that complies with IEEE802.15.4 is configured to include, for example, a collection control station (CS) and one or more nodes, as in Non-Patent Document 1.

[0013] In this configuration, the lower nodes transmit sensing information, which is information sensed by the lower nodes, to the upper nodes including the CS, and the upper nodes including the CS transmit control information, which is information for controlling the lower nodes.

[0014] In such a configuration, the communication network is a multi-hop network, and the same communication method, such as the same frequency band, may be used for communication between the nodes.

[0015] In such a configuration, for example, when relaying information, wireless resources are treated equally regardless of the direction of the information being relayed, so there are cases where information that should be transmitted or received with priority cannot be transmitted or received with priority. The following configurations are shown to resolve such concerns.

[0016] (Embodiment 1) 1 is a block diagram showing the configuration of a wireless communication system including a wireless communication terminal 1B according to this embodiment. The wireless communication system according to this embodiment includes wireless communication terminals 1 (1A to 1C).

[0017] In a wireless communication system including a wireless communication terminal 1B according to this embodiment, three or more wireless communication terminals 1 perform communication relayed between two or more respective wireless communication terminals 1 via a first wireless link 5 and a second wireless link 6.

[0018] The wireless communication terminal 1 is a terminal capable of wireless communication, such as a collection control station (CS), a mobile phone, a smartphone, a tablet terminal, a wearable terminal, an actuator, etc. For example, when the wireless communication terminal 1 is a control system such as an actuator, it can control the opening and closing of a valve to stop gas or control a robot.

[0019] The wireless communication terminal 1 includes a wireless transceiver unit 2, which may be an integrated circuit or the like, and a control unit 3. Here, the wireless communication terminal 1B (which may hereinafter be referred to as a first wireless terminal) will be described as an example. The wireless transceiver unit 2 of the wireless communication terminal 1B receives information in a receiving state from the wireless communication terminal 1A (which may hereinafter be referred to as a second wireless terminal) and the wireless communication terminal 1C (which may hereinafter be referred to as a third wireless terminal) via a first wireless link 5 and a second wireless link 6, which are one of two or more wireless links.

[0020] When the wireless transceiver 2 of the wireless communication terminal 1B receives information, the control unit 3 of the wireless communication terminal 1B instructs the wireless transceiver 2 of the wireless communication terminal 1B to switch from a reception state to a transmission state. Note that, for example, the wireless communication terminal 1B relays information transmission and reception between the wireless communication terminal 1A and the wireless communication terminal 1C.

[0021] In the receiving state, the wireless transceiver 2 of the wireless 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 wireless link 5. In addition, in the receiving state, the wireless transceiver 2 of the wireless 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 wireless link 6.

[0022] When wireless communication terminal 1B is used as a reference, the transmission of information via first wireless link 5 is defined as the uplink direction, and the transmission of information via second wireless link 6 is defined as the downlink direction. It is assumed that wireless communication terminal 1A also sets a reception waiting period 8. It is also assumed that wireless communication terminal 1C also sets a reception waiting period 9.

[0023] The reception waiting period 8 in the wireless communication terminal 1B is a period during which the wireless communication terminal 1B waits for information such as control information (to be described later) in the downlink direction transmitted from the wireless communication terminal 1A. The reception waiting period 11 in the wireless communication terminal 1B is a period during which the wireless communication terminal 1B waits for transmission of sensor information (to be described later) in the uplink direction transmitted from the wireless communication terminal 1C, etc.

[0024] It is assumed that control information that is desirably transmitted from wireless communication terminal 1A to wireless communication terminal 1B with a short delay is transmitted as control information, while sensor information that is a sensing result that may be transmitted from wireless communication terminal 1C to wireless communication terminal 1B with a long delay but with low power consumption is transmitted.

[0025] In this case, for example, the control unit 3 of the wireless communication terminal 1B, in the receiving state of the wireless transceiver unit 2 of the wireless communication terminal 1B, extends the period for waiting to receive the first wireless link 5 and pre-sets the period for waiting to receive the second wireless link 6 to be short.

[0026] For example, if reception waiting period 8 and reception waiting period 9 are set to the same length, then by adjusting and setting the length of reception waiting period 10 (see FIG. 2, hereinafter this may be referred to as a third reception waiting period) described below, it is possible to lengthen the reception waiting period for first wireless link 5 and shorten the reception waiting period for second wireless link 6. During reception waiting period 10, wireless communication terminal 1B waits for information from wireless communication terminal 1A, but at this time wireless communication terminal 1A does not wait for information from wireless communication terminal 1B.

[0027] For example, the parameters of reception waiting periods 8 to 13, 15, and 16 (see FIGS. 2 and 3), which are the reception waiting periods for the first wireless link 5 and the reception waiting periods for the second wireless link 6, are set in advance based on empirical rules of communication up to the previous time. For example, the parameters of 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. The previous time refers to, for example, the time of operation before the wireless communication terminal 1B was powered on.

[0028] Furthermore, for example, the reception waiting period for the first wireless link 5 and the reception waiting periods 8 to 13, 15, and 16 (see FIGS. 2 and 3) which are the reception waiting periods for the first wireless link 5 are set in advance based on the delay characteristics required for the wireless communication system. Here, the delay characteristics refer to, for example, the average delay time and the maximum delay time.

[0029] This allows the control unit 3 of the wireless communication terminal 1B to make adjustments such as shortening the delay time for the first wireless link 5 and lengthening the delay time for the second wireless link 6. Note that the beacon interval may be any interval when waiting for reception.

[0030] After receiving instructions from the control unit 3 of the wireless communication terminal 1B, the wireless transceiver unit 2 of the wireless communication terminal 1B transmits information to the wireless communication terminal 1A or the wireless communication terminal 1C, which is the sender of the received information, at the instruction of the control unit 3 of the wireless communication terminal 1B.

[0031] The wireless communication terminal 1B relays the control information by further transmitting it to the wireless communication terminal 1C, etc. 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. The wireless communication terminal 1B also relays the sensing information by further transmitting it to the wireless communication terminal 1A, etc.

[0032] 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 or sensing information, but this is not limited to this.

[0033] For example, the period of time for waiting for reception from the second wireless link 6 in which interference 7 described below is occurring may be shortened. The wireless transceiver 2 of the wireless communication terminal 1B may be configured to sense the interference 7 to the second wireless link 6.

[0034] For example, the interference 7 may be caused by a magnetic field or radio waves generated by a work vehicle such as an electric forklift, which may be generated by a system unrelated to the wireless communication terminal 1 according to this embodiment. Also, for example, the wireless transceiver 2 of the wireless communication terminal 1B detects the interference 7 in the second wireless link 6 when the bit error rate exceeds a predetermined value.

[0035] When the wireless transceiver unit 2 of the wireless communication terminal 1B detects interference 7, the control unit 3 of the wireless communication terminal 1B changes the parameters of the second wireless link 6. The parameters include, for example, at least one of the frequency band, the modulation method, and the link duration of the wireless link in which the interference is detected.

[0036] The link period refers to the period during which the wireless communication terminal 1 waits for reception, and is the sum of the period during which the first wireless link 5 waits for reception and the period during which the second wireless link 6 waits for reception, for example.

[0037] It is assumed that the wireless channel can be selected by changing the frequency band, for example. The control unit 3 of the wireless communication terminal 1B may repeatedly change the parameters until the bit error rate is improved to an improvement threshold value that is a predetermined value.

[0038] When the wireless transceiver unit 2 of the wireless communication terminal 1B detects interference 7, the control unit 3 of the wireless communication terminal 1B transmits the parameters to the control unit 3 of the still other wireless communication terminal 1C on the second wireless link 6 via the wireless transceiver unit 2 of the wireless communication terminal 1B, for example, by utilizing a sleep period during which no main control is performed. The changed parameters are also applied during the sleep period.

[0039] Next, a description will be given using Fig. 2. In particular, a case will be described in which wireless communication terminal 1B relays information in the uplink direction between wireless communication terminal 1A and wireless communication terminal 1C. Fig. 2 is a timing chart used to explain the functions of wireless communication terminal 1 according to this embodiment. For example, in the receiving state of wireless communication terminal 1B, wireless communication terminal 1B sets reception waiting periods 8, 9, and 10, which are reception waiting periods, for wireless communication terminal 1A and wireless communication terminal 1C via first wireless link 5 and second wireless link 6, and waits for reception.

[0040] The wireless communication terminal 1A transmits information during reception waiting periods 8 and 10, which are periods during which the wireless communication terminal 1B is waiting to receive from the wireless communication terminal 1A. The wireless communication terminal 1C transmits information during reception waiting period 9, which is a period during which the wireless communication terminal 1B is waiting to receive from the wireless communication terminal 1C.

[0041] For example, when wireless communication terminal 1B receives information from wireless communication terminal 1C, it enters a transmitting state and stops waiting for reception. Wireless transceiver 2 of wireless communication terminal 1B transmits information to wireless communication terminal 1A during reception waiting periods 8 and 11, which are periods during which wireless communication terminal 1A waits for reception from wireless communication terminal 1B.

[0042] The wireless communication terminal 1A waits for information from the wireless communication terminal 1B during a reception waiting period 11 (which may hereinafter be referred to as a fourth reception waiting period), but at this time the wireless communication terminal 1B does not wait for information from the wireless communication terminal 1A.

[0043] Note that reception waiting period 10 is, for example, part or all of period 12, which is different from reception waiting period 8 and reception waiting period 9, in repetition period 13, which is a period that is repeated periodically. Also, as described above, when relaying information in the upstream direction, reception waiting period 10, which is a period in which communication is performed only in the downstream direction, and reception waiting period 16, which will be described later, are not set.

[0044] It is sufficient that repetition period 13 includes at least reception waiting periods 8 to 10, and does not have to include reception waiting period 11. In this embodiment, it is assumed that repetition period 13 is repeated two or more times, but this is not limited to this, and one of each of reception waiting periods 8 to 10 may be provided.

[0045] Next, a description will be given with reference to Fig. 3. In particular, a case where wireless communication terminal 1B relays information in the downstream direction between wireless communication terminal 1A and wireless communication terminal 1C will be described. Fig. 3 is a timing chart for explaining the functions provided in wireless communication terminal 1 according to this embodiment.

[0046] For example, in the receiving state of the wireless communication terminal 1C, the wireless communication terminal 1C sets reception waiting periods 9, 15, and 16, which are reception waiting periods, for the wireless communication terminals 1B and 1D via the second wireless link 6 and the third wireless link 14, and waits for reception. The wireless communication terminal 1D is one of three or more wireless communication terminals that is farther from the wireless communication terminal 1B than the wireless communication terminal 1C.

[0047] The wireless communication terminal 1A transmits information during reception waiting periods 8 and 10, which are periods during which the wireless communication terminal 1B is waiting to receive from the wireless communication terminal 1A. The wireless communication terminal 1C transmits information during reception waiting periods 9 and 16, which are periods during which the wireless communication terminal 1B is waiting to receive from the wireless communication terminal 1C.

[0048] In the receiving state, the wireless transceiver 2 of the wireless communication terminal 1C sets a reception waiting period 15 (hereinafter, this may be referred to as a fifth reception waiting period) in the third wireless link 14. It is also assumed that the reception waiting period 15 is set in the wireless communication terminal 1D.

[0049] The wireless communication terminal 1C waits for information from the wireless communication terminal 1B during a reception waiting period 16 (hereinafter, this may be referred to as a sixth reception waiting period), but at this time the wireless communication terminal 1B does not wait for information from the wireless communication terminal 1C.

[0050] The reception waiting period 16 is, for example, a part or all of a period 17 in a repetition period 13 that is a periodically repeated period, which is different from the reception waiting period 9 and the reception waiting period 15. As described above, when relaying information in the downstream direction, the reception waiting period 11, which is a period in which only upstream communication is performed, is not set.

[0051] Next, explanation will be made with reference to Fig. 4. Fig. 4 is a flowchart showing the processing procedure of wireless communication processing according to this embodiment. For example, the control unit 3 of the wireless communication terminal 1B determines whether the wireless transceiver unit 2 of the wireless communication terminal 1B has received information (S1).

[0052] If the control unit 3 of the wireless communication terminal 1B determines that the wireless transceiver unit 2 of the wireless communication terminal 1B has not received information and the result of step S1 is negative (S1: NO), the control unit 3 of the wireless communication terminal 1B executes step S1 again.

[0053] If the control unit 3 of the wireless communication terminal 1B determines that the wireless transceiver unit 2 of the wireless communication terminal 1B is receiving information and the result of step S1 is positive (S1: YES), the control unit 3 of the wireless communication terminal 1B instructs the wireless transceiver unit 2 of the wireless communication terminal 1B to switch to a transmission state (S2).

[0054] Next, the control unit 3 instructs the wireless transmission / reception unit 2 of the wireless communication terminal 1B to transmit the information to the other wireless communication terminal 1A, which is the sender of the received information, or to the further other wireless communication terminal 1C (S3).

[0055] Next, an explanation will be given using Fig. 5. Fig. 5 is a diagram used to explain the effects of this embodiment. Graph 20 is a graph when the beacon interval is set to 5 seconds, and graph 21 is a graph when the beacon interval is set to 10 seconds.

[0056] As shown in graphs 20 and 21, compared to the conventional technology in which the waiting period for reception is allocated equally to each packet at 50%, regardless of the beacon interval, by not allocating the waiting period for reception equally, it is possible to reduce the delay time, for example, the average time for 10 packets.

[0057] For example, as shown in graphs 20 and 21, if 70% of the link period is allocated to the period waiting for reception from the higher-level node, the average delay time can be reduced to about half, regardless of the beacon interval.

[0058] 5 is a diagram of the wireless communication terminal 1B, and the upper node refers to the wireless communication terminal 1A. The other node refers to, for example, the wireless communication terminal 1C.

[0059] As described above, the wireless communication terminal 1 according to this embodiment can increase the possibility of satisfying delay characteristics, which are the amount of time that can be delayed, when relaying information. The wireless communication terminal 1 according to this embodiment can achieve relaying with a desired short delay by setting a reception waiting period with the intention of relaying with a short delay.

[0060] By performing such relaying, a longer time is allocated to information that is to be transmitted and received with priority, and thus the information that is to be transmitted and received with priority can be transmitted and received with priority. Furthermore, according to the wireless communication terminal 1 of this embodiment, it is possible to set a predetermined delay time or to deliberately lengthen the delay time.

[0061] The wireless communication terminal 1B according to this embodiment can also be applied to a tree-type wireless communication system or a bus-type wireless communication system with a CS as the root. For example, the wireless communication terminal 1A serves as a CS, which is a master device in the tree-type wireless communication system, and collects information from the wireless communication terminals 1B and 1C, which are mobile phones, smartphones, tablet devices, wearable devices, personal computers, actuators, etc.

[0062] For example, the wireless communication terminal 1A controls each node such as the wireless communication terminals 1A to 1C in the wireless communication system, and transmits control information for controlling the lower nodes such as the wireless communication terminals 1B and 1C.

[0063] The lower node communicates sensing information, which is information sensed by the lower node, to the upper node. For example, the wireless communication terminal 1A is a node in the first layer, the wireless communication terminal 1B is a node in the second layer, and the wireless communication terminal 1C is a node in the third layer.

[0064] The order is from top to bottom: first layer, second layer, third layer. Nodes in the third layer send sensing information to nodes in the second layer and the first layer. Nodes in the second layer send sensing information to nodes in the first layer.

[0065] As described above, in the wireless communication system of this embodiment, three or more wireless communication terminals 1 communicate with each other via wireless links between two or more of the wireless communication terminals. A first wireless communication terminal 1B, which is one of the three or more wireless communication terminals, performs wireless communication with a second wireless communication terminal 1A, which is also one of the three or more wireless communication terminals, via a first wireless link 5, which is one of the two or more wireless links, by setting a first reception waiting period 8.

[0066] In addition, the first wireless communication terminal 1B performs wireless communication with the third wireless communication terminal 1C via a second wireless link 6, which is one of the two or more wireless links, by setting a second reception waiting period 9 different from the first reception waiting period 8.

[0067] The first wireless communication terminal 1B performs wireless communication via the first wireless link 5, setting a third reception waiting period 10 in which it waits for downstream information transmission from the second wireless communication terminal 1A.

[0068] The third reception waiting period 10 is a part or all of a period 12 that is different from the first reception waiting period 8 and the second reception waiting period 9. In addition, during the third reception waiting period 10, the second wireless communication terminal 1A does not wait for upstream information transmission from the first wireless communication terminal 1B.

[0069] As described above, in this embodiment, the second wireless communication terminal 1A may transmit information downstream to the first wireless communication terminal 1B during the third reception waiting period 10 of the wireless communication via the first wireless link 5.

[0070] As described above, in this embodiment, the wireless communication system may relay information in the downstream direction. Specifically, the third wireless communication terminal 1C performs wireless communication with the fourth wireless communication terminal 1D, which is one of the three or more wireless communication terminals and is farther away from the second wireless communication terminal 1A than the third wireless communication terminal 1C, via the third wireless link 14, which is one of the two or more wireless links, by setting a fifth reception waiting period 15.

[0071] When the first wireless communication terminal 1B receives the information from the second wireless communication terminal 1A via the first wireless link 5 in the first reception waiting period 8 or the third reception waiting period 10, the third wireless communication terminal 1C sets the sixth reception waiting period 16 or the second reception waiting period 9 via the second wireless link 6 and performs wireless communication.

[0072] The sixth reception waiting period 16 is a part or all of a period 17 that is different from the second reception waiting period 9 and the fifth reception waiting period 15. In the sixth reception waiting period 16, the third wireless communication terminal 1C waits for downstream information transmission from the first wireless communication terminal 1B, and the first wireless communication terminal 1B does not wait for upstream information transmission from the third wireless communication terminal 1C. Note that when the wireless communication system relays downstream information, the second wireless communication terminal 1A does not set the fourth reception waiting period 11.

[0073] As described above, in this embodiment, the wireless communication system may relay information in the uplink direction. Specifically, when the first wireless communication terminal 1B receives the information in the uplink direction from the third wireless communication terminal 1C via the second wireless link 6 in 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 or the first reception waiting period 8 via the first wireless link 5 and performs wireless communication.

[0074] The fourth reception waiting period 11 is a part or all of a period 12 that is different from the first reception waiting period 8 and the second reception waiting period 9. During the fourth reception waiting period, the second wireless communication terminal 1A waits for the transmission of the information from the first wireless communication terminal 1B in the upstream direction to the second wireless communication terminal 1A, and the first wireless communication terminal 1B does not wait for the transmission of the information in the downstream direction from the second wireless communication terminal.

[0075] 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 does not set the sixth reception waiting period 16.

[0076] As described above, in this embodiment, the parameters of the first to sixth reception waiting periods 8 to 13, 15, and 16 are set in advance based on one or more of the empirical rules of communication during operation before power is turned on and the 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, the lengths and start times of the reception waiting periods 8 to 13, 15, and 16.

[0077] It is sufficient that there are one or more lower nodes of the wireless communication terminals 1B, 1C, etc., and the type of branching is not limited, such as wireless communication terminal 1B communicating with a lower node other than wireless communication terminal 1C.

[0078] In the above embodiment, the wireless transceiver 2 and the control unit 3 are described as integrated circuits, but the present embodiment is not limited to this. For example, the wireless transceiver 2 and the control unit 3 may be programs stored in a RAM (Random Access Memory, not shown) provided in the wireless communication terminal 1. For example, the programs are executed by being called by a CPU (Central Processing Unit, not shown) provided in the wireless communication terminal 1. [Explanation of symbols]

[0079] 1, 1A, 1B, 1C...wireless communication terminal, 2...wireless transceiver unit, 3...control unit, 5...first wireless link, 6...second wireless link, 7...interference.

Claims

1. In a wireless communication system in which three or more wireless communication terminals communicate with each other via wireless links between two or more of the wireless communication terminals, a first wireless communication terminal which is one of the three or more wireless communication terminals performs wireless communication with a second wireless communication terminal which is one of the three or more wireless communication terminals via a first wireless link which is one of the two or more wireless links, by setting a first reception waiting period, and performs wireless communication with a third wireless communication terminal via a second wireless link which is one of the two or more wireless links, by setting a second reception waiting period which is 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, which is a part or all of a period different from the first reception waiting period and the second reception waiting period, for waiting for transmission of control information in a downlink direction from the second wireless communication terminal; during the third reception waiting period, the second wireless communication terminal does not wait for upstream transmission of sensing information from the first wireless communication terminal; the third reception waiting period is set in advance based on a delay characteristic required for the wireless communication system; a ratio between a period for waiting to receive the control information via the first wireless link and a period for waiting to receive the sensing information via the second wireless link is determined depending on the type of information consisting of the control information and the sensing information; A wireless communication system comprising:

2. When interference occurs in the second wireless link, the ratio of the waiting period for reception for the second wireless link is made shorter.

2. The wireless communication system according to claim 1, wherein:

3. during the third reception waiting period of the wireless communication via the first wireless link, the second wireless communication terminal transmits the information in a downstream direction to the first wireless communication terminal; 2. The wireless communication system according to claim 1.

4. the third wireless communication terminal performs wireless communication with a fourth wireless communication terminal, which is one of the three or more wireless communication terminals and is farther from the second wireless communication terminal than the third wireless communication terminal, via a third wireless link, which is one of the two or more wireless links, by setting a fifth reception waiting period; When the first wireless communication terminal receives the information from the second wireless communication terminal via the first wireless link during the first reception waiting period or the third reception waiting period, the third wireless communication terminal sets a sixth reception waiting period, which is a part or all of a period different from the second reception waiting period and the fifth reception waiting period, for waiting for transmission of the information in a downstream direction from the first wireless communication terminal, or sets the second reception waiting period, and performs wireless communication via the second wireless link; during the sixth reception waiting period, the first wireless communication terminal does not wait for transmission of the information in an uplink direction from the third wireless communication terminal; the second wireless communication terminal does not set a fourth reception waiting period, which is a part or all of a period different from the first reception waiting period and the second reception waiting period, and which waits for transmission of the information in an uplink direction from the first wireless communication terminal to the second wireless communication terminal; 2. The wireless communication system according to claim 1.

5. When the first wireless communication terminal receives the information in the uplink direction from the third wireless communication terminal via the second wireless link during the second reception waiting period or the sixth reception waiting period, the second wireless communication terminal performs wireless communication via the first wireless link by setting the fourth reception waiting period or the first reception waiting period; during the fourth reception waiting period, the first wireless communication terminal does not wait for the transmission of the information in a downstream 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; 5. The wireless communication system according to claim 4.

6. 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 a repetition period that is a period that is repeated periodically; 2. The wireless communication system according to claim 1.

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