JP2013192055A - Sensor device and its retransmission control method - Google Patents

Abstract

Kind Code: A1 It is possible to prevent useless retransmission processing for transmission of a link establishment signal and a sensor information signal, and further improve the transmission efficiency of sensor information.
A link establishment signal and its response signal are exchanged with a center device via a network control device to establish a link, and then a sensor information signal and its response signal are exchanged to send the sensor information to the center device. In the retransmission control method of the sensor device for transmitting the transmission signal, the retransmission timeout time of the response signal to the link establishment signal is T1, the retransmission timeout time of the response signal to the sensor information signal is T2, and the timeout of each response signal is T1> T2. When the response signal for the link establishment signal times out at T1, or when the response signal for the sensor information signal times out at T2, retransmission processing from the link establishment signal is performed.
[Selection] Figure 2

Description

  The present invention relates to a sensor device that transfers sensor information acquired from a sensor to a remote center device via a communication line, and a retransmission control method in the sensor device.

  The remote monitoring system is a system that collects meter reading values of gas, water, electricity, etc. and security information (various alarms, etc.) remotely from a center device, and is widely introduced as one of the applications of M2M communication. .

FIG. 8 shows a configuration example of a conventional remote monitoring system.
In FIG. 8, a sensor device 12 and a gas meter 13 to which the sensor 11 is connected are connected to a network control device (hereinafter referred to as “NCU”) 14 via a communication interface. The NCU 14 is connected to the center device 16 via the communication line 15 and configured to perform bidirectional communication. As the communication line 15, for example, a public line such as PSTN, ISDN, ADSL, optical line, mobile phone line, PHS line, or the like is used.

  Note that a configuration using specific low-power radio for communication between the NCU 14 and the sensor device 12 or the gas meter 13, that is, an NCU master unit and an NCU slave unit that are wirelessly connected as the NCU 14, and the NCU slave unit includes the sensor terminal 12. Or the structure which connects the gas meter 13 may be sufficient.

  Communication between the sensor device 12 and the center device 16 is performed by a sequence type communication protocol based on a combination of an upstream signal (link establishment signal and one or more sensor information signals) and a downstream signal (response signal). Here, the direction from the sensor device 12 to the center device 16 is assumed to be upward. The sensor device 12 performs link establishment processing according to the line type by the link establishment signal and its response signal, and subsequently performs sensor information transmission processing by the sensor information signal and its response signal. The sensor device 12 of the remote monitoring system does not receive a response signal within a certain time after transmitting a link establishment signal, or does not receive a response signal within a certain time after transmitting a sensor information signal. The retransmission processing is performed in units of one sequence including a link establishment signal and one or more sensor information signals.

  Such retransmission control is performed by setting a timer of an expected time when a response signal is returned when transmitting a packet in TCP (Transmission Control Protocol), and performing ARQ (Automatic Repeat Request) to perform retransmission processing when the timer times out. It is generalized (Non-Patent Document 1).

  Here, it is important to estimate the retransmission timeout time. If it is too short, there is a high possibility that unnecessary retransmission will be performed, and if it is too long, retransmission processing will be delayed, leading to a reduction in throughput. Therefore, the retransmission timeout time is set to be slightly longer than the round trip time (RTT) between communication devices.

Murayama et al., “Transport Protocol”, Iwanami Lecture Internet, 6 volumes, pp.114-117, Iwanami Shoten

  By the way, in TCP, the RTT is measured while transmitting and receiving signals, and the retransmission timeout time is dynamically changed, but the retransmission timeout time is not changed depending on the packet type. That is, there is one timer for monitoring the retransmission timeout. For example, the above-described link establishment signal and the sensor information signal are subjected to retransmission control based on the same retransmission timeout time.

  However, there are various communication lines used in the remote monitoring system, such as a telephone line, an optical line, and a wireless line, and depending on the line type, there are cases where it takes time to establish a link, and the average RTT becomes long. On the other hand, the sensor information signal after link establishment and the response signal RTT are short. In such a situation, if a short retransmission time-out period is set in accordance with the RTT of the sensor information signal, a time-out occurs frequently for the link establishment signal, and unnecessary retransmission occurs. On the other hand, if a long retransmission timeout period is set in accordance with the RTT of the link establishment signal, the time becomes longer than necessary for the RTT of the sensor information signal, the transmission efficiency of the sensor information signal is lowered, and the sensor information is retained. There was a problem that the sensor device was overloaded.

  It is an object of the present invention to provide a sensor device and a retransmission control method thereof that prevent unnecessary retransmission processing for transmission of a link establishment signal and sensor information signal and further improve the transmission efficiency of sensor information in a remote monitoring system. Objective.

  According to a first aspect of the present invention, a link establishment signal is connected between a network control device connected to a center device via a communication line and a sensor that outputs sensor information, and between the center device via the network control device. In the retransmission control method of the sensor device for exchanging the response signal and establishing the link and subsequently exchanging the sensor information signal and the response signal to transmit the sensor information to the center device, the retransmission of the response signal to the link establishment signal The timeout time is T1, the retransmission timeout time of the response signal for the sensor information signal is T2, the timeout of each response signal is monitored as T1> T2, and the response signal for the link establishment signal times out at T1, or the sensor information When the response signal to the signal times out at T2, Processing is carried out.

  In the retransmission control method of the first invention, if the transmission of the sensor information signal is not successful within the prescribed number of retransmission processes, the next retransmission interval or the prescribed number of retransmissions is increased, and if the transmission succeeds after that, Reduce the retransmission interval or the specified number of retransmissions.

  In the retransmission control method according to the first aspect of the invention, the transmission timing of the next link establishment signal is adjusted when the link establishment is not successful within the prescribed number of retransmission processes.

  In the retransmission control method according to the first aspect of the present invention, when link establishment is successful within the specified number of retransmission processes and transmission of the sensor information signal is successful, the average response time of each response signal is outside a predetermined threshold. If it is, the next retransmission interval or the prescribed number of retransmissions is increased, and if at least one of the average values is within a predetermined threshold, the next retransmission interval or the prescribed number of retransmissions is decreased.

  In the retransmission control method of the first invention, when the retransmission interval or the specified number of retransmissions exceeds a threshold value and frequent retransmission processing is detected, the sensor information acquisition interval acquired from the sensor is adjusted or the accuracy of the sensor information is lowered. Reduce the data size of sensor information.

  According to a second aspect of the present invention, a link establishment signal is connected between a network control device connected to the center device via a communication line and a sensor that outputs sensor information, and between the center device via the network control device. In the sensor device for exchanging the response signal and establishing the link, and subsequently exchanging the sensor information signal and the response signal to transmit the sensor information to the center device, the retransmission time-out time of the response signal to the link establishment signal is T1. T2 is the retransmission timeout time of the response signal to the sensor information signal, and the timeout of each response signal is monitored as T1> T2, and when the response signal to the link establishment signal times out at T1, or the response signal to the sensor information signal When a timeout occurs at T2, re-transmission from the link establishment signal is performed. And a control unit.

  In the sensor device of the second invention, the retransmission control means increases the next retransmission interval or the prescribed number of retransmissions if the transmission of the sensor information signal is not successful within the prescribed number of retransmission processes, and then succeeds in transmission. If this happens, reduce the next retransmission interval or the specified number of retransmissions.

  In the sensor device of the second invention, the retransmission control means adjusts the transmission timing of the next link establishment signal when the link establishment is not successful within the prescribed number of retransmission processes.

  In the present invention, even when a communication line that requires time for link establishment is used between the sensor device and the center device, the retransmission processing of the link establishment signal and the sensor information signal is performed according to the respective retransmission timeout times T1 and T2. Optimal control. Thereby, useless retransmission control can be avoided and power consumption can be reduced.

  Further, the number of retransmissions of the sensor information signal is monitored, and when the number of retransmissions reaches a specified number, control is performed to increase the retransmission interval or the number of retransmissions in the next communication. Alternatively, the number of retransmissions for the link establishment signal is monitored, and the next transmission timing is controlled when the number of retransmissions reaches a specified number. Thereby, retransmission control can be performed efficiently.

It is a figure which shows the structural example of Example 1 of the sensor apparatus of this invention. It is a figure which shows the basic operation | movement sequence of the sensor apparatus of this invention. It is a flowchart which shows the 1st resending control processing example of the sensor apparatus of this invention. It is a time chart which shows the operation example of the 1st resending control process of the sensor apparatus of this invention. It is a flowchart which shows the 2nd resending control processing example of the sensor apparatus of this invention. It is a time chart which shows the operation example of the 2nd resending control process of the sensor apparatus of this invention. It is a flowchart which shows the resending control processing example in Example 2 of the sensor apparatus of this invention. It is a figure which shows the structural example of a remote monitoring system.

FIG. 1 shows a configuration example of Embodiment 1 of the sensor device of the present invention.
1, the sensor device 100 according to the first embodiment includes a communication interface unit 110 that performs communication with the NCU 14, a sensor input unit 120 that inputs sensor information from the sensor 11, and a control unit 130 that controls the entire sensor device. . The control unit 130 includes a retransmission number counting unit 131 that counts the number of retransmissions due to timeout of a downstream signal (response signal) with respect to an upstream signal (link establishment signal, sensor information signal) transmitted from the sensor device 100 to the NCU 14, a retransmission interval or a retransmission time A retransmission control unit 132 that controls the specified number of times, a transmission timing control unit 133 that controls the transmission timing of the link establishment signal, and a storage unit 134 that stores the count result of the number of retransmissions and the specified number of retransmissions. The transmission timing is controlled as a waiting time before starting transmission of the link establishment signal. For example, an immediate transmission method that transmits immediately when a link establishment signal occurs and a delayed transmission method that transmits a link establishment signal after a random waiting time corresponding to the generated random number are selected.

FIG. 2 shows a basic operation sequence of the sensor device of the present invention.
In FIG. 2, one sequence executed between the sensor device 100 and the center device 16 is divided into a link establishment period and a communication period. In the link establishment period, a link establishment signal and a response signal are exchanged between the sensor device 100 and the center device 16 to establish a link. First, the sensor device 100 transmits a link establishment signal to the NCU 14, activates the T1 timer for the retransmission timeout time T1, and enters a standby state for a response signal to the link establishment signal. The NCU 14 transfers a link establishment signal to the center device 16 and, when receiving a corresponding response signal from the center device 16, transfers it to the sensor device 100. When the sensor device 100 normally receives the response signal to the link establishment signal, the sensor device 100 stops the T1 timer, ends the link establishment process, and shifts to the communication period. On the other hand, if the response signal corresponding to the link establishment signal is not normally received and the T1 timer times out, the link establishment signal is retransmitted.

  In the communication period, exchange of sensor information signals and response signals constituting one sequence is repeated between the sensor device 100 and the center device 16. The sensor device 100 transmits a sensor information signal to the NCU 14, starts a T2 timer with a retransmission timeout time T2, and enters a standby state for a response signal to the sensor information signal. The NCU 14 transfers the sensor information signal to the center device 16, and transfers the sensor information signal to the sensor device 100 when receiving the corresponding response signal from the center device 16. When the sensor device 100 normally receives a response signal to the sensor information signal, the sensor device 100 stops the T2 timer, and then repeats transmission of the sensor information signal constituting one sequence. Here, an example of two round trips is shown. On the other hand, when the response signal corresponding to the sensor information signal is not normally received and the T2 timer times out, the retransmission process from the link establishment signal is performed.

  Here, the feature of the present invention is that the link establishment between the NCU 14 and the center device 16 is such that T1> T2 in consideration of the fact that the RTT is longer than the sensor information signal. As a result, even when a communication line that requires time to establish a link is used between the NCU 14 and the center apparatus 16, the retransmission processing of the link establishment signal and the sensor information signal is optimally controlled according to each retransmission timeout time. be able to.

  Furthermore, the number of retransmissions of the link establishment signal and the sensor information signal is monitored, and when the number of retransmissions reaches a specified number, the retransmission interval or the number of retransmissions in the next communication is controlled. Alternatively, when the number of retransmissions for the link establishment signal and the sensor information signal reaches the specified number of times, respectively, the next transmission timing is controlled for the link establishment signal, and the next time for the sensor information signal. The retransmission interval or the number of retransmissions is controlled. This will be specifically described below.

  FIG. 3 shows a first retransmission control processing example of the sensor device of the present invention. Here, the prescribed number of times that the T1 timer and the T2 timer time out and perform retransmission processing is N2.

  In FIG. 3, the sensor device transmits a link establishment signal (S1), activates the T1 timer for the retransmission timeout time T1, and enters a standby state for a response signal to the link establishment signal (S2). If the response signal to the link establishment signal is normally received before the T1 timer times out (S2: No), the T1 timer is stopped, then the sensor information signal is transmitted (S3), and the T2 timer of the retransmission timeout time T2 is started. In response to the sensor information signal, a response signal is waited (S4). If the response signal to the sensor information signal is normally received before the T2 timer times out (S4: No), the T2 timer is stopped, and the processes in steps S3 and S4 are repeated as many times as the number of sensor information signal transmissions constituting one sequence ( S5). When the transmission of one sequence of sensor information signal is completed, the retransmission interval or the specified number of retransmissions N2 used in the next communication is decreased within a range not lower than the lower limit (S6), and the processing of one sequence is terminated.

  On the other hand, when the T1 timer times out while waiting for a response signal to the link establishment signal (S2: Yes), or when the T2 timer times out while waiting for a response signal to the sensor information signal (S4: Yes), the number of retransmissions is set. Increment (S7) and repeat retransmission of the link establishment signal and sensor information signal until the number of retransmissions reaches the specified number N2 (S8, S1). When the number of retransmissions reaches the specified number of times N2 (S8: Yes), the retransmission interval used at the next communication or the specified number of retransmissions N2 is increased within a range not exceeding the upper limit (S9), and the processing of one sequence is terminated. Note that the processing in step S6 may be decreased only after the retransmission interval or the specified number of retransmissions N2 is increased in step S9.

  FIG. 4 shows an operation example of the first retransmission control process of the sensor device of the present invention. Here, an example is shown in which the next retransmission interval is controlled when one sequence is configured by transmission of the link establishment signal and the sensor information signal twice, and the specified number of retransmissions N2 is 3.

  In FIG. 4, when the transmission is not successful by three retransmissions of the link establishment signal or the sensor information signal, the next retransmission interval is widened within a range not exceeding the upper limit value. Further, if the link establishment signal and the sensor information signal are successfully transmitted after increasing the retransmission interval, the next retransmission interval is reduced within a range that does not fall below the lower limit value. Note that the number of retransmissions may be increased or decreased, and both the number of retransmissions and the retransmission interval may be increased or decreased simultaneously.

  FIG. 5 shows a second retransmission control processing example of the sensor device of the present invention. Here, the prescribed number of times that the T1 timer times out and performs the retransmission processing is N1, and the prescribed number of times that the T2 timer times out and performs the retransmission processing is N2.

  In FIG. 5, the processes from step S <b> 1 to S <b> 6 until the sensor device 100 successfully transmits the link establishment signal and the sensor information signal and completes the processing of one sequence are the first retransmission control processing example illustrated in FIG. 3. It is the same.

  When the T1 timer times out while waiting for a response signal to the link establishment signal (S2: Yes), the number of retransmissions is incremented (S11), and the retransmission of the link establishment signal is repeated until the number of retransmissions reaches the specified number N1 (S12). , S1). When the number of retransmissions reaches the specified number N1 (S12: Yes), it is determined that the communication line between the sensor device 100 and the center device 16 is abnormal or busy, or the NCU 14 or the sensor device 100 itself is abnormal, and the next time The transmission timing used during communication is changed (S13), and the processing of one sequence is terminated. Note that in changing the transmission timing, for example, the immediate transmission method is switched to a delayed transmission method that transmits a link establishment signal after a random waiting time corresponding to the generated random number.

  If the T2 timer times out while waiting for a response signal to the sensor information signal (S4: Yes), the number of retransmissions is incremented (S7), and the link establishment signal and sensor information signal are increased until the number of retransmissions reaches the specified number N2. Are repeated (S8, S1). When the number of retransmissions reaches the specified number of times N2 (S8: Yes), the retransmission interval used at the next communication or the specified number of retransmissions N2 is increased within a range not exceeding the upper limit (S9), and the processing of one sequence is terminated.

  FIG. 6 shows an operation example of the second retransmission control process of the sensor device of the present invention. Here, an example is shown in which the next transmission timing is controlled when one sequence is constituted by the transmission of the link establishment signal and the sensor information signal twice, and the specified number of retransmissions N1 and N2 is 3.

  In FIG. 6, when link establishment is not successful by three retransmissions of the link establishment signal, the next transmission timing is switched from the immediate transmission method to the delayed transmission method. If the processing of one sequence is successful after switching to the delayed transmission method, the transmission timing may be switched back to the immediate transmission method in step S6.

  In the first embodiment, if the transmission is not successful even if the retransmission of the link establishment signal and the sensor information signal reaches the specified number of times, the communication line between the sensor device 100 and the center device 16 is abnormal or busy, or the NCU 14 Or the sensor device 100 itself is determined to be abnormal, and the retransmission interval, the specified number of retransmissions, or the transmission timing used for the next communication is adjusted. However, even if the response signal of the link establishment signal and the sensor information signal does not time out, if the response time is long, for example, it is estimated that the communication line is congested, and the retransmission interval used for the next communication It is also effective to adjust the specified number of retransmissions.

  In the second embodiment, the response time of the response signal to the link establishment signal and the sensor information signal is measured, the average value in each sequence is calculated, and the difference from the theoretical response time that is the shortest response time in each communication method And the increase / decrease of the retransmission interval and the specified number of retransmissions are used according to the difference.

  The sensor device 100 according to the second embodiment includes a response time measuring unit that measures response times of response signals to the link establishment signal and the sensor information signal in the control unit 130 according to the first embodiment illustrated in FIG. And calculating an average value of response times T1ave and T2ave and calculating a difference from theoretical response times T1th and T2th.

  FIG. 7 shows an example of retransmission control processing in Embodiment 2 of the sensor device of the present invention. Here, only the portion inserted between step S5 and steps S6 and S9 in the flowcharts shown in FIGS. 3 and 5 is shown.

  In FIG. 7, when the transmission of one sequence of link establishment signal and sensor information signal is successful (S5: Yes), the average value T1ave of response times measured when the response signals for the link establishment signal and sensor information signal have not timed out. , T2ave is calculated (S31). Since the link establishment signal is normally once in one sequence, the measured value becomes the average value as it is, but when the response signal to the sensor information signal after link establishment times out, retransmission is performed from the link establishment signal. In this case, an average value T1ave of response times for a plurality of link establishment signals can be calculated. In the case of a sensor information signal, an average value of response times repeated a plurality of times in one sequence is calculated.

  Next, it is determined whether or not the difference between the average response time T1ave and the theoretical response time T1th with respect to the link establishment signal exceeds a specified value. If the difference is equal to or less than the specified value, the retransmission interval or retransmission used at the next communication is determined. The predetermined number N2 is reduced within a range that does not fall below the lower limit value (S6), and one sequence process is terminated.

  On the other hand, if the difference exceeds the specified value, it is determined whether or not the difference between the average response time T2ave and the theoretical response time T2th with respect to the sensor information signal exceeds the specified value. For example, the retransmission interval or the specified number of retransmissions N2 used in the next communication is decreased within a range not lower than the lower limit (S6), and one sequence process is terminated.

  If the difference between the average response times T1ave and T2ave and the theoretical response times T1th and T2th for the link establishment signal and sensor information signal exceeds the specified value, the response signal for the link establishment signal and sensor information signal times out. Even if not, for example, it is estimated that the communication line is congested, and the retransmission interval and the prescribed number of retransmissions used at the next communication are increased (S9), and the processing of one sequence is completed.

  The sensor device temporarily stores sensor information input from the sensor in a buffer, establishes a link with the center device for each sequence, and transmits a plurality of sensor information signals to the center device via the NCU. . At this time, if retransmission processing frequently occurs between the sensor device and the center device, there is a possibility that the buffer of sensor information overflows.

  When the sensor device of the third embodiment detects that the retransmission interval and the specified number of retransmissions have exceeded a certain threshold value, it considers that retransmission processing has occurred frequently, and increases the acquisition interval of sensor information with the sensor. A sensor control unit is provided for temporarily stopping sensor information input or reducing the accuracy of the sensor information to reduce the data size of the sensor information. By such control of the sensor control unit, even when retransmission processing occurs frequently, it is possible to suppress the amount of sensor information stored in the buffer and avoid buffer overflow. When the buffer is full, the oldest data is overwritten with the latest data.

  In addition, the sensor control unit monitors the data accumulation amount of the buffer, and the retransmission control unit (FIG. 1: 132) controls the increase rate of the retransmission interval and the prescribed number of retransmissions according to the data accumulation amount. Good. For example, control is performed so that Ts> Tf, where Ts is the sensor information acquisition interval and Tf is the time until all sequences including retransmission are determined to have failed. Further, when N sensor information signals are transmitted in one sequence, control is performed so that a relationship of Tf> T1 + T2 × N is established. Also, for example, if the amount of data stored in the buffer is less than 50% of the total amount, the retransmission interval is increased by 2 minutes or the specified number of retransmissions by two, and if 50% or more, the retransmission interval is set to 1 minute or the specified retransmission The control may be such that the number is increased by one.

  In addition to the configuration in which the sensor device autonomously controls the retransmission interval and the prescribed number of retransmissions, the center device may allow the change of the retransmission interval and the prescribed number of retransmissions.

When the sensor device times out in the standby state of the response signal for the link establishment signal and the sensor information signal, or until the next retransmission process, or when the retransmission has exceeded the specified number of times and one sequence has not been successfully transmitted. Transition to sleep mode and reduce power consumption. Then, it may be started when the retransmission interval has elapsed and the next retransmission process is started, or before the transmission of the next sequence is started.

  The T1 timer value, T2 timer value, retransmission specified number initial value, retransmission interval initial value, T1th, and T2th in each of the above-described embodiments may be directly set to the sensor terminal by a setting device or the like when the sensor device is installed. A configuration may also be adopted in which a request command is transmitted from the center device to the sensor device via the NCU and remote setting is performed.

11 Sensor 12 Sensor device 13 Gas meter 14 Network control unit (NCU)
DESCRIPTION OF SYMBOLS 15 Communication line 16 Center apparatus 100 Sensor apparatus 110 Communication interface part 120 Sensor input part 130 Control part 131 Retransmission count part 132 Retransmission control part 133 Transmission timing control part 134 Storage part

Claims (8)

Connected between the network control device connected to the center device via the communication line and the sensor that outputs sensor information, and exchanges the link establishment signal and its response signal with the center device via the network control device. In the re-transmission control method of the sensor device for performing link establishment and subsequently exchanging the sensor information signal and its response signal and transmitting the sensor information to the center device,
The retransmission timeout time of the response signal to the link establishment signal is T1, the retransmission timeout time of the response signal to the sensor information signal is T2, the timeout of each response signal is monitored as T1> T2, and the response to the link establishment signal A retransmission control method comprising: performing retransmission processing from the link establishment signal when a signal times out at T1 or when a response signal to the sensor information signal times out at T2. The retransmission control method according to claim 1,
If the transmission of the sensor information signal is not successful within the specified number of retransmission processes, the next retransmission interval or the specified number of retransmissions is increased, and if the transmission succeeds thereafter, the next retransmission interval or the specified number of retransmissions A retransmission control method characterized in that The retransmission control method according to claim 1,
A retransmission control method comprising adjusting a transmission timing of a next link establishment signal when the link establishment is not successful within a specified number of times of the retransmission processing. The retransmission control method according to claim 1,
If the link establishment is successful within the specified number of retransmission processes and the transmission of the sensor information signal is successful, the next retransmission interval if the average value of the response time of each response signal is outside a predetermined threshold. Alternatively, the retransmission control method is characterized in that the specified number of retransmissions is increased, and if at least one of the average values is within a predetermined threshold, the next retransmission interval or the specified number of retransmissions is decreased. In the retransmission control method according to claim 2,
When the retransmission interval or the specified number of retransmissions exceeds a threshold and the occurrence of the retransmission processing is detected, the sensor information is adjusted by adjusting the acquisition interval of the sensor information acquired from the sensor or the sensor information is reduced. A retransmission control method characterized by reducing the data size. Connected between the network control device connected to the center device via the communication line and the sensor that outputs sensor information, and exchanges the link establishment signal and its response signal with the center device via the network control device. In the sensor device that establishes the link and then exchanges the sensor information signal and its response signal to transmit the sensor information to the center device,
The retransmission timeout time of the response signal to the link establishment signal is T1, the retransmission timeout time of the response signal to the sensor information signal is T2, the timeout of each response signal is monitored as T1> T2, and the response to the link establishment signal A sensor apparatus, comprising: a retransmission control means for performing retransmission processing from the link establishment signal when a signal times out at T1 or when a response signal to the sensor information signal times out at T2. The sensor device according to claim 6,
The retransmission control means increases the next retransmission interval or the specified number of retransmissions when the transmission of the sensor information signal is not successful within the specified number of retransmission processes, and then transmits the next retransmission when the transmission is successful. A sensor device characterized in that the specified number of intervals or retransmissions is reduced. The sensor device according to claim 6,
The retransmission control means adjusts the transmission timing of the next link establishment signal when the link establishment is not successful within a specified number of times of the retransmission processing.

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