Communication system, receiving device, transmitting device, and radio environment improvement method

Abstract

To enable improvement of the communication environment even when the communication environment deteriorates due to the effects of multipath fading.SOLUTION: A communication system includes a transmitter 11 that transmits electromagnetic waves, a receiver 21 that receives the electromagnetic waves transmitted from the transmitter 11, and a pattern switching unit 23 in the receiver 21 that switches the directivity pattern used for receiving electromagnetic waves over time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a communication system, a receiving device, a transmitting device, and a method for improving a radio wave environment. [Background technology]

[0002] 2. Description of the Related Art There is a communication system that includes a transmitter that transmits electromagnetic waves and a receiver that receives the electromagnetic waves transmitted from the transmitter. As an example of such a communication system, Patent Document 1 discloses a system that includes a camera device with a phased array antenna and multiple monitor devices. The camera device knows its relative position to the multiple monitor devices, and when it receives a connection request signal from one of the monitor devices, it aligns the directivity of the phased array antenna with the monitor device that sent the connection request signal and then transmits a video signal to that monitor device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-171820 Summary of the Invention [Problem to be solved by the invention]

[0004] In wireless communications, multipath fading can occur as the communication environment changes. Therefore, even if a receiver can receive electromagnetic waves transmitted from a transmitter, changes in the communication environment can cause the receiver to be unable to receive the electromagnetic waves, or to receive electromagnetic waves that should not be received. If the surrounding environment is changing, the deterioration of the communication environment due to multipath fading often improves in a short time, so communication can sometimes be resumed by retrying the transmission of electromagnetic waves. However, if, for example, people leave the area and the environment remains unchanged, and the deteriorated communication environment remains fixed, communication cannot be resumed by retrying. The system disclosed in Patent Document 1 had the problem that when the receiver was unable to receive video signals from the camera device due to the effects of multipath fading, it would be unable to resume receiving video signals as long as the same communication environment continued, or it would end up receiving electromagnetic waves that should not have been received.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a communication system that can improve the communication environment even if the communication environment deteriorates due to the effects of multipath fading. [Means for solving the problem]

[0006] The communication system according to the present disclosure includes a transmitter that transmits electromagnetic waves, a receiver that receives the electromagnetic waves transmitted from the transmitter, and a pattern switching unit that switches the directivity pattern used by the receiver to receive the electromagnetic waves over time. [Effects of the Invention]

[0007] According to the present disclosure, even if the communication environment deteriorates due to the influence of multipath fading, it is possible to improve the communication environment. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing a communication system according to a first embodiment. [Figure 2] FIG. 1 is an explanatory diagram showing a state in which a direct wave path (1) and a reflected wave path (2) are generated due to the presence of an object (A) in the communication environment. [Figure 3]FIG. 1 is an explanatory diagram showing a state in which a direct wave path (1) and a reflected wave path (3) are generated due to the presence of an object (B) in the communication environment. [Figure 4] FIG. 1 is an explanatory diagram showing a state in which a direct wave path (1) and a reflected wave path (3) are generated due to the presence of an object (B) in the communication environment. [Figure 5] 1 is an explanatory diagram showing an example of a plurality of directivity patterns in which electromagnetic waves are received in different directions; [Figure 6] FIG. 10 is a configuration diagram showing a communication system according to a second embodiment. [Figure 7] FIG. 1 is an explanatory diagram showing an example of three directivity patterns (1) to (3) that receive electromagnetic waves in different directions. [Figure 8] FIG. 10 is a configuration diagram showing a communication system according to a third embodiment. [Figure 9] FIG. 10 is a configuration diagram showing a communication system according to a fourth embodiment. [Figure 10] FIG. 10 is an explanatory diagram showing an example in which electromagnetic waves transmitted from a transmitter 71-3 reach a receiver 81-1 due to constructive interference caused by multipath fading. DETAILED DESCRIPTION OF THE INVENTION

[0009] In order to explain the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0010] Embodiment 1 FIG. 1 is a configuration diagram showing a communication system according to the first embodiment. The communication system shown in FIG. 1 includes a transmitting device 1 and a receiving device 2. The transmitting device 1 includes a transmitter 11 and a transmitting antenna 12 . The transmitting device 1 is a device that transmits electromagnetic waves to the receiving device 2. The transmitter 11 transmits electromagnetic waves from the transmission antenna 12 .

[0011] The receiving device 2 includes a receiver 21, a receiving antenna 22, and a pattern switching unit . The receiving device 2 is a device that receives the electromagnetic waves transmitted from the transmitting device 1. The receiver 21 performs reception processing of the electromagnetic waves received by the receiving antenna 22 . The receiving antenna 22 is realized by, for example, a phased array antenna.

[0012] The pattern switching unit 23 is realized by, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination of these. The pattern switching unit 23 switches the directivity pattern used by the receiver 21 to receive electromagnetic waves over time. The pattern switching unit 23 switches the directivity pattern by, for example, sequentially selecting a directivity pattern used by the receiver 21 to receive the electromagnetic waves from among a plurality of directivity patterns each having a different receiving direction of the electromagnetic waves.

[0013] FIG. 2 is an explanatory diagram showing a state in which a path (1) of a direct wave and a path (2) of a reflected wave are generated due to the presence of an object (A) in the communication environment. In the state shown in FIG. 2 (hereinafter referred to as "state (A)"), the direct wave and the reflected wave do not cancel each other out, and wireless communication between the transmitter 11 and the receiver 21 can be performed.

[0014] FIG. 3 is an explanatory diagram showing a state in which a path (1) of a direct wave and a path (3) of a reflected wave are generated due to the presence of an object (B) in the communication environment. In the state of FIG. 3 (hereinafter referred to as "state (B)"), the direct wave and the reflected wave cancel each other out, so the received power at receiver 21 decreases and wireless communication between transmitter 11 and receiver 21 cannot be performed.

[0015] FIG. 4 is an explanatory diagram showing a state in which a path (1) of a direct wave and a path (3) of a reflected wave are generated due to the presence of an object (B) in the communication environment. 4 (hereinafter referred to as "state (C)"), the directivity pattern is switched to one different from that in state B. This reduces the sensitivity in the direction of path (3), which was the cause of the direct wave and the reflected wave canceling each other out, and as a result, the decrease in received power at receiver 21 is alleviated, allowing wireless communication between transmitter 11 and receiver 21.

[0016] Next, the operation of the communication system shown in FIG. 1 will be described. The communication system shown in FIG. 1 is applied to a communication environment where multipath fading occurs, for example, in a room or among high-rise buildings. The transmitter 11 transmits electromagnetic waves from the transmission antenna 12 . The receiver 21 performs reception processing of the electromagnetic waves received by the receiving antenna 22 .

[0017] The pattern switching unit 23 switches the directivity pattern used by the receiver 21 to receive electromagnetic waves over time. Specifically, as shown in FIG. 5, the pattern switching unit 23 switches the directivity pattern by sequentially selecting a directivity pattern to be used by the receiver 21 to receive electromagnetic waves from among a plurality of directivity patterns each having a different receiving direction of the electromagnetic waves. FIG. 5 is an explanatory diagram showing an example of a plurality of directivity patterns in which the electromagnetic waves are received in different directions. The receiving directions of electromagnetic waves in the multiple directivity patterns are different from one another, but if the differences are too great, there is a high possibility that a directivity pattern will appear that cannot receive the direct waves from the transmitter 11. For this reason, although the receiving directions of electromagnetic waves in the multiple directivity patterns are different from one another, the difference in the receiving directions is, for example, an angle of several degrees to several tens of degrees.

[0018] Even if wireless communication between the transmitter 11 and the receiver 21 becomes impossible, as in state (B), the directivity pattern can be switched over time to change to a state in which wireless communication between the transmitter 11 and the receiver 21 is possible, as in state (C). That is, it is possible to prevent the communication environment from becoming fixed in a state like state (B), in which wireless communication between the transmitter 11 and the receiver 21 is not possible.

[0019] In the above-described first embodiment, the communication system is configured to include a transmitter 11 that transmits electromagnetic waves, a receiver 21 that receives the electromagnetic waves transmitted from the transmitter 11, and a pattern switching unit 23 that switches the directivity pattern used by the receiver 21 to receive the electromagnetic waves over time. Therefore, even if the communication environment deteriorates due to the influence of multipath fading, the communication system can improve the communication environment. Specifically, even if wireless communication between the transmitter 11 and the receiver 21 becomes impossible when multipath fading occurs due to a change in the communication environment, wireless communication can be resumed.

[0020] 1, the pattern switching unit 23 switches the directivity pattern by sequentially selecting, from a plurality of directivity patterns having different receiving directions of electromagnetic waves, a directivity pattern to be used for receiving electromagnetic waves by the receiver 21. However, this is merely an example, and the pattern switching unit 23 may switch the directivity pattern by adjusting the phase and amplitude of the received signal of each of a plurality of element antennas included in the phased array antenna, which is the receiving antenna 22. 1, pattern switching unit 23 switches, over time, the directivity pattern used by receiver 21 to receive electromagnetic waves. However, this is merely an example, and pattern switching unit 23 may switch the directivity pattern used by receiver 21 to receive electromagnetic waves when receiver 21 detects a deterioration in the communication environment. Examples of detection of a deterioration in the communication environment by receiver 21 include detection that electromagnetic waves transmitted from transmitter 11 cannot be received, detection that the signal level of the received signal of electromagnetic waves transmitted from transmitter 11 is below a threshold, or detection that noise other than electromagnetic waves transmitted from transmitter 11 is received and the level of the received noise exceeds a threshold.

[0021] Embodiment 2 In the first embodiment, the communication system includes one transmitter 11. In the second embodiment, a communication system including a plurality of transmitters 11 will be described.

[0022] Fig. 6 is a configuration diagram showing a communication system according to embodiment 2. In Fig. 6, the same reference numerals as in Fig. 1 indicate the same or corresponding parts, and detailed description thereof will be omitted. The communication system shown in Fig. 6 includes transmitting devices 1-1 to 1-N, a receiving device 2, and a pattern switching unit 23. N is an integer equal to or greater than 1. Fig. 6 shows an example where N=3. The transmitting device 1-n (n=1, 2, 3) includes a transmitter 11-n and a transmitting antenna 12-n. The transmitting device 1-n is a device that transmits electromagnetic waves to the receiving device 2. The transmitter 11-n transmits electromagnetic waves from the transmission antenna 12-n.

[0023] Next, the operation of the communication system shown in FIG. 6 will be described. The pattern switching unit 23 prepares, for example, three directivity patterns (1) to (3) as shown in FIG. 7 as a plurality of directivity patterns having mutually different receiving directions of electromagnetic waves. FIG. 7 is an explanatory diagram showing an example of three directivity patterns (1) to (3) that receive electromagnetic waves in different directions. Directivity pattern (1) is a directivity pattern that allows communication with transmitters 11-1 and 11-2, but does not allow communication with transmitter 11-3. Directivity pattern (2) is a directivity pattern in which communication with transmitter 11-2 is possible, but communication with transmitters 111-1 and 111-3 is not possible. Directivity pattern (3) is a directivity pattern that allows communication with transmitters 11-2 and 11-3, but does not allow communication with transmitter 11-1.

[0024] The pattern switching unit 23 switches the directivity pattern used by the receiver 21 to receive electromagnetic waves over time. Specifically, the pattern switching unit 23 switches the directivity pattern by sequentially selecting a directivity pattern to be used by the receiver 21 to receive electromagnetic waves from three directivity patterns (1) to (3) which have mutually different receiving directions of electromagnetic waves. The pattern switching unit 23 selects, for example, directivity pattern (1), directivity pattern (2), directivity pattern (3), and directivity pattern (1) in this order as the directivity pattern used to receive the electromagnetic waves. As a result, even if the communication system includes a plurality of transmitters 11, the receiver 21 can perform wireless communication with the plurality of transmitters 11.

[0025] Embodiment 3 In the third embodiment, a communication system including a pattern switching unit 43 that switches the directivity pattern used for transmitting electromagnetic waves will be described.

[0026] FIG. 8 is a configuration diagram showing a communication system according to the third embodiment. The communication system shown in Fig. 8 includes a transmitting device 4 and receiving devices 5-1 to 5-M, where M is an integer equal to or greater than 1. Fig. 8 shows an example where M=3. The transmitting device 4 includes a transmitter 41, a transmitting antenna 42, and a pattern switching unit 43. The transmitter 41 transmits electromagnetic waves from a transmission antenna 42 . The transmitting antenna 42 is realized by, for example, a phased array antenna.

[0027] The receiving device 5-m (m=1, 2, 3) includes a receiver 51-m and a receiving antenna 52-m. The receiving device 5-m is a device that receives the electromagnetic waves transmitted from the transmitting device 1. The receiver 51-m performs reception processing on the electromagnetic waves received by the receiving antenna 52-m. When the receiver 51-m receives the electromagnetic waves, it transmits an ACK (ACKnowledgement) signal from the receiving antenna 52-m as an acknowledgment signal indicating that the electromagnetic waves have been received.

[0028] The pattern switching unit 43 is realized by, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. If an ACK signal is not returned from the receiver 51-m, the pattern switching unit 43 switches the directivity pattern used by the transmitter 41 to transmit the electromagnetic waves. The pattern switching unit 43 switches the directivity pattern by, for example, sequentially selecting a directivity pattern to be used by the transmitter 41 to transmit the electromagnetic wave from among a plurality of directivity patterns having mutually different transmission directions of the electromagnetic wave.

[0029] Next, the operation of the communication system shown in FIG. 8 will be described. The communication system shown in FIG. 8 is applied to a communication environment where multipath fading occurs, for example, in a room or among high-rise buildings. The transmitter 41 transmits electromagnetic waves from a transmission antenna 42 . The receiver 51-m (m=1, 2, 3) performs reception processing on the electromagnetic waves received by the receiving antenna 52-m. When the receiver 51-m receives the electromagnetic wave, it causes the receiving antenna 22 to transmit an ACK signal. If the receiver 51-m cannot receive the electromagnetic waves, it does not transmit an ACK signal from the receiving antenna 22. When the transmitting antenna 42 of the transmitter 41 receives an ACK signal transmitted from the receiver 51-m (m=1, 2, 3), the transmitter 41 outputs the ACK signal to the pattern switching unit 43.

[0030] If, for example, within a certain period of time after the electromagnetic waves are transmitted from the transmitter 41, ACK signals are transmitted from all of the receivers 51-1 to 51-M and those ACK signals are output from the transmitter 41, the pattern switching unit 43 will not switch the directivity pattern used by the transmitter 41 to transmit the electromagnetic waves. If, for example, within a certain time period after electromagnetic waves are transmitted from transmitter 41, an ACK signal is not transmitted from one or more of receivers 51-1 to 51-M and an ACK signal is not output from transmitter 41 from one or more receivers, pattern switching unit 43 switches the directivity pattern used by transmitter 41 to transmit the electromagnetic waves.

[0031] Specifically, the pattern switching unit 43 switches the directivity pattern by sequentially selecting a directivity pattern to be used by the transmitter 41 to transmit the electromagnetic waves from among a plurality of directivity patterns having mutually different transmission directions of the electromagnetic waves. Thereafter, when ACK signals are transmitted from all of receivers 51-1 to 51-M, pattern switching unit 43 causes transmitter 41 to fix the directivity pattern used for transmitting electromagnetic waves. After the directivity pattern is fixed, if a situation occurs in which an ACK signal is not transmitted from one or more of the receivers 51-1 to 51-M, the pattern switching unit 43 restarts the process of switching the directivity pattern used by the transmitter 41 to transmit electromagnetic waves.

[0032] In the above-described third embodiment, the communication system is configured to include a transmitter 41 that transmits electromagnetic waves, a receiver 51-m that receives the electromagnetic waves transmitted from the transmitter 41, and a pattern switching unit 43 that switches the directivity pattern used to transmit the electromagnetic waves by the transmitter 41 if an acknowledgment signal indicating that the electromagnetic waves have been received is not returned from the receiver 51-m. Therefore, the communication system can improve the communication environment even if the communication environment deteriorates due to the effects of multipath fading. Specifically, even if wireless communication between the transmitter 41 and the receiver 51-m becomes impossible when multipath fading occurs due to a change in the communication environment, wireless communication can be resumed.

[0033] 8, the pattern switching unit 43 switches the directivity pattern by sequentially selecting a directivity pattern to be used for transmitting electromagnetic waves by the transmitter 41 from among a plurality of directivity patterns having mutually different transmission directions of the electromagnetic waves. However, this is merely an example, and the pattern switching unit 43 may switch the directivity pattern by adjusting the phase and amplitude of each transmission signal from a plurality of element antennas included in the phased array antenna, which is the transmitting antenna 42. 8, if an acknowledgment signal indicating that electromagnetic waves have been received is not returned from receiver 51-m, pattern switching unit 43 switches the directivity pattern used to transmit electromagnetic waves by transmitter 41. However, this is merely an example, and pattern switching unit 43 may switch the directivity pattern used to transmit electromagnetic waves by transmitter 41 over time. In addition, in the communication system shown in FIG. 8, when the transmitter 41 detects a deterioration in the communication environment, the pattern switching unit 43 may switch the directivity pattern used by the transmitter 41 to transmit electromagnetic waves. The transmitter 41 may detect a deterioration in the communication environment, for example, by detecting that it has received an acknowledgment signal from a receiver other than the receiver 51-m, or by detecting that the level of the received noise exceeds a threshold.

[0034] Embodiment 4 In the fourth embodiment, a communication system in which two communication areas CA1 and CA2 exist will be described.

[0035] FIG. 9 is a configuration diagram showing a communication system according to the fourth embodiment. The communication system shown in FIG. 9 includes transmitting devices 7-1 to 7-4 and receiving devices 8-1 and 8-2. The transmitting device 7-p (p=1, 2, 3, 4) includes a transmitter 71-p and a transmitting antenna 72-p. The transmitting devices 7-1 and 7-2 are devices that transmit electromagnetic waves to the receiving device 8-1. The transmitters 71-1 and 71-2 transmit electromagnetic waves from the transmission antennas 72-1 and 72-2. The transmitting devices 7-3 and 7-4 are devices that transmit electromagnetic waves to the receiving device 8-2. The transmitters 71-3 and 71-4 transmit electromagnetic waves from the transmission antennas 72-3 and 72-4.

[0036] The receiving device 8-q (q=1, 2) includes a receiver 81-q, a receiving antenna 82-q, and a pattern switching unit 83-q. The receiving device 8-1 is a device that receives electromagnetic waves transmitted from the transmitting devices 7-1 and 7-2. The receiver 81-1 performs reception processing on the electromagnetic waves received by the receiving antenna 82-1. The receiving antenna 82-1 is realized by, for example, a phased array antenna. The receiving device 8-2 is a device that receives the electromagnetic waves transmitted from the transmitting devices 7-3 and 7-4. The receiver 81-2 performs reception processing on the electromagnetic waves received by the receiving antenna 82-2. The receiving antenna 82-2 is realized by, for example, a phased array antenna.

[0037] The pattern switching unit 83-q (q=1, 2) is realized by, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination of these. The pattern switching unit 83-q switches, over time, the directivity pattern used by the receiver 81-q to receive electromagnetic waves. The pattern switching unit 83-q switches the directivity pattern by, for example, sequentially selecting a directivity pattern to be used by the receiver 81-q to receive electromagnetic waves from among a plurality of directivity patterns each having a different receiving direction of the electromagnetic waves.

[0038] Next, the operation of the communication system shown in FIG. 9 will be described. FIG. 10 is an explanatory diagram showing an example of two communication areas CA1 and CA2. The communication area CA1 is a communication area in which the transmitting devices 7-1 and 7-2 and the receiving device 8-1 communicate wirelessly. The communication area CA2 is a communication area in which the transmitting devices 7-3 and 7-4 and the receiving device 8-2 communicate wirelessly.

[0039] The communication area CA1 and the communication area CA2 are separate areas, so that the electromagnetic waves transmitted from the transmitting devices 7-1 and 7-2 usually reach the receiving device 8-1 but do not reach the receiving device 8-2. Furthermore, the electromagnetic waves transmitted by the transmitters 7-3 and 7-4 usually reach the receiver 8-2 but do not reach the receiver 8-1. However, as the communication environment changes, as shown in the left diagram of FIG. 10, for example, electromagnetic waves transmitted from the transmitter 71-3 may reach the receiver 81-1 due to constructive interference caused by multipath fading. The left diagram in FIG. 10 shows an example in which electromagnetic waves transmitted from a transmitter 71-3 reach a receiver 81-1 due to constructive interference caused by multipath fading. Even if transmitters in the same communication area are transmitting in sync, they are often asynchronous with transmitters in different communication areas, creating the risk of collision. If there is no change in the communication environment after that, the system will remain in a state where there is a risk of malfunction due to collision.

[0040] The pattern switching unit 83-1 switches, over time, the directivity pattern used by the receiver 81-1 to receive the electromagnetic waves transmitted from the transmitters 71-1 and 71-2. Furthermore, when the receiver 81-1 receives electromagnetic waves transmitted from the transmitter 71-3 or the transmitter 71-4 in a communication area CA2 different from its own communication area CA1, the pattern switching unit 83-1 switches the directivity pattern used for receiving the electromagnetic waves by the receiver 81-1. This makes it possible to prevent the receiver 81-1 from receiving the electromagnetic waves transmitted from the transmitter 71-3 or the transmitter 71-4, as shown in the right diagram of FIG.

[0041] The pattern switching unit 83-2 switches, over time, the directivity pattern used by the receiver 81-2 to receive the electromagnetic waves transmitted from the transmitters 71-3 and 71-4. Furthermore, when the receiver 81-2 receives electromagnetic waves transmitted from the transmitter 71-1 or the transmitter 71-2 in a communication area CA1 different from its own communication area CA2, the pattern switching unit 83-2 switches the directivity pattern used by the receiver 81-2 to receive the electromagnetic waves. This makes it possible to improve the communication environment even if the communication environment deteriorates due to the effects of multipath fading. Specifically, it is possible to prevent the receiver 81-2 from receiving the electromagnetic waves transmitted from the transmitter 71-1 or the transmitter 71-2.

[0042] In addition, the present disclosure allows for free combination of the respective embodiments, modification of any of the components of the respective embodiments, or omission of any of the components of the respective embodiments. [Explanation of symbols]

[0043] 1,1-1~1-3 Transmitting device 2. Receiving device 4. Transmitting device 5-1~5-3 Receiving device 7-1~7-4 Transmitting device 8-1, 8-2 Receiving device 11,11-1~11-3 Transmitters 12, 12-1 to 12-3 Transmitting antenna 21 Receiver 22 receiving antenna 23 Pattern switching section 41 Transmitter 42 transmitting antenna 43 Pattern switching section 51-1~51-3 Receiver 52-1~52-3 Receiving antenna 71-1~71-4 Transmitters 72-1~72-4 Transmitting antenna 81-1, 81-2 receiver 82-1, 82-2 Receiving antenna 83-1, 83-2 Pattern switching section

Claims

1. a transmitter for transmitting electromagnetic waves; a receiver that receives the electromagnetic waves transmitted from the transmitter; a pattern switching unit that switches a directivity pattern used for receiving the electromagnetic waves over time by the receiver; A communication system comprising:

2. 2. The communication system according to claim 1, comprising a plurality of said transmitters.

3. a transmitter for transmitting electromagnetic waves; a receiver that receives the electromagnetic waves transmitted from the transmitter; a pattern switching unit that switches a directivity pattern used for transmitting the electromagnetic wave by the transmitter if an acknowledgement signal indicating that the electromagnetic wave has been received is not returned from the receiver; A communication system comprising:

4. a transmitter for transmitting electromagnetic waves; a receiver that receives the electromagnetic waves transmitted from the transmitter; a pattern switching unit that switches a directivity pattern used for transmitting the electromagnetic waves over time by the transmitter; A communication system comprising:

5. 5. The communication system according to claim 3, wherein a plurality of the receivers are provided.

6. a receiver that receives electromagnetic waves transmitted from a transmitter; a pattern switching unit that switches a directivity pattern used for receiving the electromagnetic waves over time by the receiver; A receiving device comprising:

7. The pattern switching unit 7. The receiving device according to claim 6, wherein the receiver switches the directivity pattern by sequentially selecting a directivity pattern to be used for receiving electromagnetic waves from among a plurality of directivity patterns having mutually different receiving directions of electromagnetic waves.

8. a transmitter for transmitting electromagnetic waves; a pattern switching unit that switches a directivity pattern used for transmitting the electromagnetic waves by the transmitter when an acknowledgement signal indicating that the electromagnetic waves have been received is not returned from the receiver that receives the electromagnetic waves; A transmitting device comprising:

9. a transmitter for transmitting electromagnetic waves; a pattern switching unit that switches a directivity pattern used for transmitting the electromagnetic waves over time by the transmitter; A transmitting device comprising:

10. The pattern switching unit 10. The transmitting device according to claim 8, wherein the transmitter switches the directivity pattern by sequentially selecting a directivity pattern to be used for transmitting the electromagnetic wave from among a plurality of directivity patterns having mutually different transmission directions of the electromagnetic wave.

11. The pattern switching unit switches, over time, the directivity pattern used for receiving the electromagnetic waves by the receiver that receives the electromagnetic waves transmitted from the transmitter. How to improve the radio wave environment.

12. When a receiver that receives electromagnetic waves transmitted from a transmitter detects a deterioration in the communication environment, a pattern switching unit switches the directivity pattern used by the receiver to receive the electromagnetic waves. How to improve the radio wave environment.

13. If a receiver that receives electromagnetic waves does not return an acknowledgement signal indicating that the electromagnetic waves have been received, the pattern switching unit switches the directivity pattern used to transmit the electromagnetic waves by the transmitter. How to improve the radio wave environment.

14. A pattern switching unit switches the directivity pattern used for transmitting the electromagnetic waves by the transmitter over time. How to improve the radio wave environment.

15. When the transmitter detects a deterioration in the communication environment, a pattern switching unit switches the directivity pattern used by the transmitter to transmit the electromagnetic waves. How to improve the radio wave environment.

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