JP5684661B2 - Wireless communication system and wireless communication method - Google Patents

Description

  The present invention relates to wireless communication, and relates to a wireless communication system and a wireless communication method in which communication is performed by a transmission unit and a reception unit mounted in the same moving body such as an automobile.

  Conventionally, a frequency hopping method exists as a method for performing reliable communication between wireless devices in an environment where there are many jamming radio waves or strong influence of fading. The frequency hopping method avoids the influence of interference and fading depending on a specific channel or frequency by changing the channel used simultaneously by two wireless devices that communicate with each other and using various channels. It is.

  For example, in bluetooth, 72 channels are used, the master wireless device transmits on a certain channel A, and at the same time the slave wireless device receives this on channel A, and then the slave wireless device returns a confirmation of reception on the same channel. At the same time, the master wireless device receives it. After that, the channel is switched from A to B, the same communication is performed between the master wireless device and the slave wireless device, and then the channel is switched, so that communication is performed while sequentially switching the channel. Yes.

  Further, Patent Document 1 discloses a frequency hopping method in mobile phone communication. In Patent Document 1, it is determined whether the mobile station or the base station performs frequency hopping between the mobile station and the base station based on the moving speed of the mobile station. Shows a frequency hopping method that reduces the information required for handoff (switching base stations) for mobile stations that move at high speed without performing frequency hopping when hopping is performed and the moving speed of the mobile station is fast ing.

  That is, in Patent Document 1, since a mobile station that moves at high speed is strongly affected by fading (fluctuation in radio wave reception level) and cannot sufficiently obtain the effect of frequency hopping, it is necessary to stop this frequency hopping and perform handoff. It is intended to reduce the information that is said to be.

Japanese Patent Laid-Open No. 11-308153

  As described above, the frequency hopping method can greatly improve the resistance to jamming and fading as compared with a simple method using a single channel. However, it is difficult to adopt the frequency hopping method of the mobile phone disclosed in Patent Document 1 for a wireless communication system in an automobile.

  A radio communication system in a vehicle is a system that communicates between a switch signal or a sensor signal provided in a vehicle and a control unit that receives those signals, such as a power window (PW). The electric wire between the control unit and the motor unit can be omitted. The operation switch is operated by a built-in small battery, and each electric part has a built-in drive motor (actuator) and is driven by a car battery.

  In Patent Document 1, since the wireless communication power is large, the influence of interference radio waves (noise radio waves) is small. However, in wireless communication in a car, it is easy to be affected by external noise radio waves because of low power communication, and communication reliability is improved. In order to ensure, it is necessary to continue the frequency hopping method. However, this frequency hopping method has a problem that power consumption increases because wireless devices are synchronized with each other during hopping.

  In a wireless communication system in an automobile, the battery of the operation switch is required to have a life span (about 10 years) over the lifetime of the automobile, and the battery itself is also required to be smaller and less expensive. It is an important issue. Further, even in a control unit on the receiving side that receives a switch or a switch signal that is supplied with power from a vehicle battery instead of a battery, reducing the power consumption of the vehicle battery is an important issue for improving fuel efficiency.

  The present invention provides a wireless communication system and a wireless communication method that improve communication reliability and reduce power consumption in view of the above-described drawbacks of the prior art.

In order to solve the above-described problem, the present invention provides a wireless communication system that includes a transmitter and a receiver in the same moving body and transmits and receives signals.
The transmission unit and the reception unit are configured to transmit and receive while hopping the frequency, and the reception unit determines the hopping speed based on the speedometer that measures the moving speed of the moving body and the moving speed of the moving body. A reception control unit that receives a signal from the transmission unit at a hopping speed is provided.

  Further, in the wireless communication system described above, the transmission unit and the reception unit include a memory for storing a common channel pattern to be hopped, and the transmission unit randomly determines one of the channels, and determines this It is characterized by comprising a transmission control unit for transmitting on a channel, transmitting on the next channel when reception fails at the receiving unit, and transmitting by changing the channel until reception by the receiving unit.

In the wireless communication system described above, the reception control unit of the reception unit stores the current time and hopping speed in a beacon packet and transmits the packet to the transmission unit, and the transmission unit receives from the reception unit. And a transmission control unit that transmits data using a channel synchronized with the reception unit.

  In the wireless communication system described above, the transmission unit and the reception unit include a memory that stores a common channel pattern to be hopped, and the transmission control unit receives the reception from the reception time of the beacon received first. The current channel of the unit is predicted and transmitted using the predicted channel. When reception fails in the receiving unit, transmission is performed using the next channel. .

In order to solve the above problems, the present invention provides a wireless communication method for transmitting and receiving signals by including a transmitter and a receiver in the same moving body.
The transmission unit and the reception unit are configured to transmit and receive while hopping frequencies. The reception unit measures the moving speed of the moving body, determines the hopping speed based on the moving speed of the moving body, and determines the hopping speed thus determined. And receiving a signal from the transmitter.

  In the wireless communication method described above, the transmission unit and the reception unit store a common channel pattern to be hopped in a memory, and the transmission unit randomly determines one of the channels, and determines the determined channel. And when the reception unit fails, the transmission is performed on the next channel, and the channel is changed until the reception unit receives the transmission.

In the wireless communication method described above, the receiving unit stores the current time and hopping speed in a beacon packet and transmits the packet to the transmitting unit, and the transmitting unit is based on transmission from the receiving unit. And transmitting on a channel synchronized with the receiving unit.

  In the wireless communication method described above, the transmission unit and the reception unit store a common channel pattern to be hopped in a memory, and the transmission unit receives the beacon received from the reception time of the beacon received first. A current channel is predicted and transmitted using the predicted channel. When reception fails in the reception unit, transmission is performed using the next channel, and transmission is performed by changing the channel until reception is performed by the reception unit.

  According to the present invention, by changing the frequency hopping speed according to the speed of the moving body, the responsiveness of communication can be improved by reducing the frequency hopping speed as much as possible while greatly improving the resistance to interference and fading. And low power consumption can be realized.

It is a block diagram of the radio | wireless communications system of this invention Example. It is an operation | movement flowchart of the receiving part of 1st Example of this invention. It is an operation | movement flowchart of the transmission part of 1st Example of this invention. It is an operation | movement flowchart of the receiving part of the 2nd Example of this invention. It is an operation | movement flowchart of the transmission part of the 2nd Example of this invention. It is operation | movement explanatory drawing of the transmission part of 1st Example of this invention, and a receiving part. It is operation | movement explanatory drawing of the transmission part of 2nd Example of this invention, and a receiving part.

  Since a wireless device in a car as a moving body is required to have low power consumption, it is difficult to realize a simple frequency hopping method because power is consumed every time hopping is performed. As a method of reducing power consumption by the frequency hopping method, it is possible to reduce the frequency of hopping by lowering the frequency hopping speed (increasing the period), but in that case, it is resistant to jamming and fading. It will decline.

  The embodiments of the present invention provide a wireless communication system and a wireless communication method characterized by changing the speed (cycle) of frequency hopping according to the speed of an automobile. Experiments have shown that the source of jamming waves in in-car communications is a radio device that is primarily used in buildings outside the car. In addition, it has been found that fading depends not only on reflection inside the automobile but also on the environment outside the automobile. That is, when the speed of the automobile is high, even if the channel is not changed, the channel of the interference noise and the fading condition change from time to time, and it becomes difficult to receive the interference noise. On the other hand, when the speed of the automobile is low, for example, when the vehicle is stopped, a specific channel is strongly subject to interference noise.

  Hereinafter, examples will be described with reference to the drawings. FIG. 1 shows an internal configuration of a wireless communication system as an embodiment.

  Reference numeral 1 denotes a transmission unit, and reference numeral 2 denotes a reception unit, both of which are configured by a radio having both transmission and reception functions, and are mounted in a vehicle as a moving body. In this embodiment, the transmission unit 1 constitutes an operation unit for a power window (PW) of an automobile, and the reception unit 2 constitutes a power window drive unit that is driven based on the operation of the operation unit.

  In the transmission unit 1, 101 is a central processing unit (CPU) of the transmission unit 1 and constitutes a transmission control unit that controls the entire transmission unit 1 together with a memory ROM 102 in which a program for transmission processing is stored. Data for operating the power window is generated by the transmission control unit 101 of the transmission unit 1, and an operation signal is transmitted by packet communication from the RF unit 104 via the antenna 105 each time the operation switch (SW) 103 is operated. (Call). Reference numeral 106 denotes a built-in battery that supplies power to the entire transmitter 1.

  In the receiving unit 2, 201 is a central processing unit (CPU) of the receiving unit 2, and constitutes a reception control unit that controls the entire receiving unit 2 together with a memory ROM 202 in which a program for receiving processing is stored. Reference numeral 206 denotes a speedometer that measures the moving speed of the automobile, and the output is input to the reception control unit 201. Reference numeral 207 denotes an actuator driven by a command from the CPU 201, and more specifically, a power window drive motor. Reference numeral 208 denotes a general battery that is larger in capacity than the battery 106 and is generally mounted in an automobile, and supplies power to the receiving unit 2.

  In the receiving unit 2, a packet transmitted from the transmitting unit 1 is received by the RF unit 204 via the antenna 205 and processed by the CPU 201. The CPU 201 has a built-in timer function, sends a channel change command to the RF unit 204 in a timely manner, changes the channel by hopping, and sets the reception state. Further, the hopping speed of the frequency is determined based on the moving speed of the moving body input from the speedometer 206, and a signal from the transmission unit is received at the determined hopping speed.

  The transmission unit 1 does not have a built-in speedometer or actuator, is specialized in transmitting operation signals so as to consume as little power as possible, and is configured to ensure, for example, about 10 years as a battery life. .

Hereinafter, some implementation variations that perform transmission and reception by the frequency hopping method will be described.
[First embodiment]
In this embodiment, the transmission unit 1 and the reception unit 2 store common channel patterns for frequency hopping in the memory ROMs 102 and 202 in common.

  The operation flow of the receiving unit 2 is shown in FIG. This operation program is stored in the memory ROM 202 of FIG. In step 301 of FIG. 2, the arrangement of hopping patterns is determined. Here, it is read from the memory ROM 202, and is Ch (channel) 11, Ch16, and Ch21.

  Next, in step 302, the current speed of the automobile is read from the speedometer 206, and the hopping speed (period t) is determined with respect to the moving speed of the automobile. Specifically, the cycle (t) is 10 ms when the vehicle speed is 10 km or less, the cycle (t) is 20 ms when the vehicle speed is 40 km or less, and the cycle (t) is 30 ms when the vehicle speed is higher.

  In the process 303, the packet transmitted from the transmission unit 1 is received by the first channel Ch11 for a time t. Next, in the process 304, the second channel Ch16 is received for the time t. In the next process 305, the third channel Ch21 is received for time t. In any process, when the packet transmitted from the transmission unit 1 is successfully received, this process is repeated while transmitting an acknowledgment packet to the transmission unit 1. The packet reception time t is the above-described hopping speed (cycle) that varies depending on the moving speed of the automobile.

  The operation flow of the transmission unit 1 is shown in FIG. This operation program is stored in the memory ROM 102 of FIG. In the flowchart, an arrangement of hopping patterns is determined in process 401. Here, it is read from the memory ROM 102, and is set to Ch (channel) 11, Ch16, and Ch21.

  Next, the process waits for the operation switch 103 to be pressed in the process 402. When the switch 103 is pressed, the process proceeds to the process 403. In the process 403, a channel to be transmitted first is determined. This first channel is determined using a random number from the channels read from the memory ROM 102. In process 404, the packet is transmitted on the determined first channel Ch (X). If reception is successful with this transmission, the process returns to process 402.

  If reception fails in the transmission of processing 404 (there is no response from the reception unit 2), transmission is performed on the second channel Ch (X + 1) in processing 405. If reception is successful with this transmission, the process returns to 402. If reception fails in the transmission of the process 405, the process transmits in the third channel Ch (X + 2) in the process 406. If reception is successful in transmission, the process returns to process 402, and if it fails, the process returns to process 404 and is repeated from the first channel Ch (X).

  Here, the success of the transmission is determined by receiving a reply of an acknowledgment packet from the other party (receiving unit 2).

  Next, the transmission / reception operation of the transmission unit 1 and the reception unit 2 will be described with reference to FIG. In FIG. 6, (1) is the moving speed of the moving body, (2) is a transmission channel by SW operation of the transmission unit, (3) is a reception channel of the reception unit, and (4) is noise generated outside. The hopping channels Ch11, Ch16, and Ch21 described above are represented as A, B, and C, respectively. In addition, the moving body first moves at a high speed and changes to a low speed from the middle.

  As shown in (3), the receiving unit 2 is in a receiving state while changing the channel by hopping at a period t in the order of A, B, and C in the determined hopping pattern arrangement. As shown in (2), it is assumed that the transmission unit 1 transmits packets while hopping in the order of channels C and B determined by random numbers when the operation switch 103 of the power window is pressed. The hopping cycle of the transmission channel of the transmission unit 1 is smaller than the hopping cycle t of the reception channel of the reception unit 2 and is set to a constant cycle (for example, 1 ms) without depending on the speed of the moving body.

  Assuming that there is no external noise in the operation of the first switch 103, an acknowledgment packet (OK) is returned from the receiving unit 2 when the channel B of the transmitting unit 1 and the receiving unit 2 match as shown in FIG. success. Accordingly, the actuator 207 of the receiving unit 2 is driven, and the power window is opened.

  As described above, under the condition where no noise is generated, transmission / reception is successful in a short time on the first channel (channel B in the above example) of hopping in the receiving unit 2 after the operation switch 103 is pressed in the transmitting unit 1. Therefore, the response of communication is improved, and the transmission time in the transmission unit 1 is short and the power consumption is small.

  Next, the second operation of the operation switch 103 will be described. At this timing, it is assumed that noise of the frequency of channel B is generated as external noise. In the second operation of the operation switch 103, it is assumed that packets are transmitted while hopping in the order of channels A, B, and C determined by random numbers. As shown in the figure, after the second operation, there is a timing at which the transmission unit 1 and the reception unit 2 match in channel B. However, channel B frequency noise interferes with channel B packet reception.

  The transmission unit 1 continuously transmits packets while hopping in the order of channels A, B, and C. There is a timing at which the channels of the transmission unit 1 and the reception unit 2 coincide with each other at C, and the external noise at this timing is the frequency of the channel B. Therefore, an acknowledgment packet (OK) is returned from the receiver 2 on the channel C at this timing, and transmission / reception is successful. Then, the actuator 207 of the receiving unit 2 is driven to open the power window.

  Thus, even under conditions where external noise occurs, transmission / reception has succeeded in a short time on the first channel (channel C in the above) that is different from the external noise channel after the operation switch 103 is pressed by the transmitter 1. Therefore, the response of communication is improved, and the transmission time in the transmission unit 1 is short and the power consumption is small. In this case, the reception unit 2 succeeds in transmission and reception with a delay of one channel compared to the case without external noise.

  Further, when the moving body moves at a low speed, the influence of external noise becomes large, and transmission and reception are likely to be disturbed. In the present embodiment, as shown in FIG. 6A, when the moving body speed is lowered from the middle, the speed at the receiving unit 2 is increased to perform hopping. Specifically, for example, when the moving body speed is reduced to 10 km or less, the hopping speed (period t) is changed to 10 ms and the apparatus is on standby in a receiving state. Therefore, the influence of external noise can be reduced by high-speed hopping.

  In this control, the CPU 201 determines the hopping speed of the frequency based on the moving speed of the moving body input from the speedometer 206, and sends it to the RF unit 204 as a channel change command in time to control the receiving state.

  In the present embodiment, it is not necessary to synchronize the time of the two radio units of the transmission unit 1 and the reception unit. Therefore, since the packet transmission operation in the transmission unit 1 is started after the operation switch 103 is pressed, the power consumption can be extremely reduced by putting the CPU 101 in the sleep state while waiting for the switch operation. it can. In addition, since the reception unit succeeds in reception at an early timing from the start of packet transmission by the transmission unit 1, the transmission time of the packet in the transmission unit 1 can be shortened and power consumption can be reduced. Furthermore, since the hopping speed varies depending on the speed of the automobile, it is possible to improve the communication responsiveness and achieve low power consumption while greatly improving the resistance to interference waves and fading.

  As described above, the present embodiment is easy to control, and is particularly suitable for a device with a small number of communications (the button is hardly pressed). It should be noted that the specific numerical values, the number of channels, the speed of the automobile, and the hopping speed given here are examples, and are not limited to those numerical values.

In this embodiment, if the channel selected by the transmission unit with a random number does not match the channel received by the reception unit at that time, the transmission is wasted, but the channel is received with the next channel matching timing. Is done.
[Second Embodiment]
In this embodiment, an example suitable for a device having a relatively large number of communications will be described. Operation flow of the receiving unit 2 is shown in Figure 4. This operation program is stored in the memory ROM 202 of FIG.

The processing 501 and processing 502 in FIG. 4 are the same as the processing 301 and 302 in FIG. Process 503 is a process of transmitting (transmitting) a beacon packet from the receiving unit 2. The beacon packet includes the current time and hopping speed as data. Processes 504 to 506 are the same as processes 303 to 305 in FIG. The processes 504 to 506 are repeated for a predetermined time. For example, if the fixed time is 0.6 seconds, the hopping speed (cycle) is repeated 60 times when t = 10 ms, 30 times when t = 20 ms, and 20 times when t = 30 ms. Thereafter, the process returns to the process 502 and the above operation is repeated.

  The operation flow on the transmission side is shown in FIG. This operation program is stored in the memory ROM 102 of FIG. The process 601 in FIG. 5 is the same as the process 401 in FIG. In process 602, the beacon transmitted by the receiving unit 2 is received. In process 603, while monitoring the operation of the operation switch 103, it waits until the next beacon time based on the hopping speed obtained by the previous beacon reception. When the next beacon time is reached in a state where the switch 103 is not operated, the process returns to step 602 to receive a beacon. Since the timer of the transmission unit 1 and the timer of the reception unit 2 do not necessarily match exactly, the correction is performed by returning to the processing 602 early in anticipation of the deviation.

  When the switch 103 is pressed, in process 604, the current channel of the receiving unit 2 is predicted from beacon information and time, and this is set as X. Processes 605 to 607 are the same as processes 404 to 407 in FIG. That is, while the channel X is obtained by a random number in the process of FIG. 3, in the process 604 of FIG. 5, the channel X is obtained by prediction from the information of the beacon received immediately before. The other processes are the same as those in FIG.

  It is conceivable that the beacon cannot be received correctly or the channel X of the transmission unit 1 and the channel of the reception unit 2 predicted from the beacon information do not match due to a timer shift or the like. Therefore, after the process 605, the communication with the processes 606 and 607 is performed while changing the channel, and further, it is possible to reduce the influence of this shift.

  In the present embodiment, since the transmission unit 1 and the reception unit 2 maintain time synchronization, the power consumption is slightly larger than the operation of FIG. However, since communication failure due to channel deviation can be reduced, the packet transmission time in the transmission unit 1 can be shortened and a quick response can be obtained, and power consumption can be suppressed. In addition, since the packet transmission time can be short, interference with other devices can be reduced.

  Since the beacon itself is transmitted at a constant interval regardless of the hopping speed, it is easy to maintain time synchronization even when the hopping speed is changed. Accordingly, since the hopping speed changes depending on the speed of the automobile, it is possible to improve communication responsiveness and realize low power consumption while greatly improving resistance to interference waves and fading.

  Next, the transmission / reception operations of the transmission unit 1 and the reception unit 2 of this embodiment will be described with reference to FIG. In FIG. 7, (1) is a transmission channel by SW operation of the transmission unit 1, (2) is a reception channel of the reception unit 2, (3) is noise generated outside, and the hopping channel Ch11, Ch16 and Ch21 are represented as A, B, and C, respectively.

  As shown in (2), the receiving unit 2 maintains the reception state while changing the channel by hopping of the period t in the order of A, B, and C in the determined hopping pattern arrangement. The receiving unit 2 transmits a beacon at a constant timing. The transmission unit 1 receives (R) the beacon and takes in the hopping information of the reception channel of the reception unit 2. It is assumed that the operation switch 103 is pressed after time T from receiving the beacon. The transmission unit 1 grasps the channel (B) of the reception unit 2 at the timing when the operation switch 103 is operated (time T after receiving the beacon). Therefore, the transmission unit 1 transmits the packet of channel B by operating the operation switch 103, while the reception unit 2 is in the reception state of channel B at this timing, and thus receives the packet from the transmission unit 1 immediately. , Succeed in sending and receiving. At this time, the transmission unit 1 ends with the packet transmission of the first channel B, and the power consumption is extremely small.

  Next, the second operation of the operation switch 103 will be described. At this timing, it is assumed that noise of the frequency of channel C is generated as external noise. When the operation switch 103 is operated, the first packet of the same channel as the channel C of the reception unit 2 at the time of operation is transmitted from the transmission unit 1. The receiving unit 2 is in a receivable state because the channels are the same, but is disturbed by the external noise C having the frequency of the channel C.

  The transmission unit 1 transmits a packet while hopping in the order of A, B, and C following channel C of the first packet. There is a timing at which the channels of the transmission unit 1 and the reception unit 2 coincide with each other at A, and the external noise at this timing is the frequency of the channel C. Therefore, an acknowledgment packet (OK) is returned from the receiver 2 on the channel A at this timing, and transmission / reception is successful. Then, the actuator 207 of the receiving unit 2 is driven to open the power window.

  As described above, even when external noise is generated, transmission / reception is successfully completed in a short time on the first channel (channel A) different from the external noise channel after the operation switch 103 is pressed in the transmission unit 1. As a result, communication responsiveness is improved and transmission time in the transmission unit 1 is short, and power consumption is small. In this case, the reception unit 2 succeeds in transmission and reception with a delay of one channel compared to the case without external noise.

  Although not shown in the drawing, when the moving body speed drops from the middle, the hopping is performed by increasing the speed at the receiving unit 2 as in the first embodiment. In this case, the changed hopping speed information is transmitted in a subsequent beacon.

  DESCRIPTION OF SYMBOLS 1 ... Transmission part, 2 ... Reception part, 101 ... Transmission control part, 102 ... Memory, 201 ... Reception control part, 202 ... Memory, 206 ... Speedometer, CH11, CH16, CH21, A, B, C ... Channel, t ... hopping speed (cycle), SW ... operation switch, PW ... actuator (power window).

Claims (8)

In a wireless communication system that includes a transmitter and a receiver in the same mobile body and transmits and receives signals,
The transmission unit and the reception unit are configured to transmit and receive while hopping the frequency, and the reception unit determines the hopping speed based on the speedometer that measures the moving speed of the moving body and the moving speed of the moving body. A radio communication system comprising a reception control unit for receiving a signal from a transmission unit at a hopping speed. The wireless communication system according to claim 1,
The transmission unit and the reception unit include a memory for storing a common channel pattern to be hopped. The transmission unit randomly determines one of the channels, transmits the channel using the determined channel, and causes the reception unit to fail reception. A wireless communication system comprising: a transmission control unit that transmits a signal on the next channel and changes the channel until it is received by the receiving unit. The wireless communication system according to claim 1,
The reception control unit of the reception unit stores the current time and hopping speed in a beacon packet and transmits the packet to the transmission unit. The transmission unit is a channel synchronized with the reception unit based on transmission from the reception unit. A wireless communication system, comprising a transmission control unit for transmitting data. The wireless communication system according to claim 3,
The transmission unit and the reception unit include a memory for storing a common channel pattern to be hopped, and the transmission control unit predicts the current channel of the reception unit from the reception time of the previously received beacon, and the predicted channel A wireless communication system, characterized in that when a reception failure occurs at a receiving unit, transmission is performed on the next channel, and transmission is performed by changing the channel until reception by the receiving unit. In a wireless communication method of transmitting and receiving signals with a transmitter and a receiver in the same mobile body,
The transmission unit and the reception unit are configured to transmit and receive while hopping frequencies. The reception unit measures the moving speed of the moving body, determines the hopping speed based on the moving speed of the moving body, and determines the hopping speed thus determined. A wireless communication method characterized by receiving a signal from a transmitter. The wireless communication method according to claim 5,
The transmission unit and the reception unit store a common channel pattern to be hopped in a memory, and the transmission unit randomly determines one of the channels, transmits the determined channel, and when reception by the reception unit fails, A wireless communication method, wherein transmission is performed on the next channel and transmission is performed while changing the channel until reception is performed by the reception unit. The wireless communication method according to claim 5,
The receiving unit stores the current time and hopping speed in a beacon packet and transmits the packet to the transmitting unit, and the transmitting unit transmits on a channel synchronized with the receiving unit based on transmission from the receiving unit. A wireless communication method characterized by the above. The wireless communication method according to claim 7,
The transmission unit and the reception unit store a common channel pattern to be hopped in a memory, and the transmission unit predicts the current channel of the reception unit from the reception time of the beacon received earlier and transmits the predicted channel on the predicted channel. A radio communication method comprising: transmitting on the next channel when reception fails in the reception unit, and transmitting by changing the channel until reception by the reception unit.

Images