Remote wireless device

Abstract

A remote wireless device (20) that wirelessly communicates with a base station wireless device (10) is provided with: a communication unit (120) that can receive, at a reception period (Tr), a synchronization establishment signal (SE) transmitted at a transmission period (Tt); and a synchronization unit (122) that, when the synchronization establishment signal is received, synchronizes the generation timing of the clock signal of the remote wireless device with the clock signal of the base station wireless device. The reception period is the sum of a first period (T1) in which the communication unit can receive the synchronization establishment signal and a second period (T2) in which the communication unit cannot receive the synchronization establishment signal, and is not a value that is a positive integer multiple of the transmission period or a value that is a reciprocal multiple of the positive integer of the transmission period.

Description

Technical Field

[0001] This invention relates to a remote wireless device. Background Technology

[0002] Japanese Patent Application Publication No. 2021-190855 discloses a wireless sensor terminal capable of operating in a low-power mode. This wireless sensor terminal periodically searches for and receives control signals from a base station. When operating in a low-power mode, the wireless sensor terminal periodically pauses its base station search.

[0003] According to the information disclosed in Japanese Patent Application Publication No. 2021-190855, when a wireless sensor terminal suspends base station search, it cannot receive a control signal sent from a base station. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems.

[0005] One aspect of the present invention is a remote wireless device that wirelessly communicates with a base station wireless device, comprising: a communication unit capable of receiving a synchronization establishment signal transmitted from the base station wireless device according to a transmission period; and a synchronization unit that, upon receiving the synchronization establishment signal, synchronizes the generation time of a clock signal of the remote wireless device with the clock signal of the base station wireless device, wherein the reception period is the sum of a first period and a second period, the first period being a period during which the communication unit can receive the synchronization establishment signal, the second period being a period during which the communication unit cannot receive the synchronization establishment signal, and the reception period is neither a positive integer multiple of the transmission period nor a reciprocal multiple of a positive integer of the transmission period.

[0006] According to the present invention, wireless communication synchronization can be easily established.

[0007] The above-mentioned objectives, features, and advantages will be readily understood through the description of the following embodiments with reference to the accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a diagram illustrating a structural example of a wireless communication system that includes a base station wireless device and multiple remote wireless devices.

[0009] Figure 2 This is a diagram illustrating a sequence of wireless communications between a base station wireless device and a remote wireless device.

[0010] Figure 3A and Figure 3B This is a diagram illustrating the change in internal voltage within a remote wireless device during the establishment of wireless communication synchronization.

[0011] Figure 4A and Figure 4B This is a diagram illustrating the relationship between the transmission and reception periods of the synchronization establishment signal.

[0012] Figure 5A and Figure 5B This is a diagram illustrating the change in internal voltage within a remote wireless device during the establishment of wireless communication synchronization.

[0013] Figure 6 This is a diagram illustrating the change in internal voltage within a remote wireless device during the establishment of wireless communication synchronization.

[0014] Figure 7A This is a diagram illustrating an example of parameters used for changes during the first period. Figure 7B and Figure 7C This is a diagram illustrating the table used for changes during the first period.

[0015] Figure 8 This is a flowchart illustrating the synchronization establishment process of wireless communication in a remote wireless device. Detailed Implementation

[0016] Figure 1 This is a diagram illustrating a structural example of a wireless communication system 30 comprising a base station wireless device 10 and multiple remote wireless devices 20. The wireless communication system 30 is used, for example, in wireless communication within industrial equipment disclosed in Japanese Patent Application Publication No. 2017-188868. The base station wireless device 10 is powered by a commercial power supply.

[0017] Multiple remote wireless devices 20 are powered by a low-power power supply 40. The low-power power supply 40 may be, for example, an energy harvester, a wireless power supply device, or a small-capacity battery. The energy harvester may be, for example, a small generator that generates electricity using light, sound, pressure, vibration, etc. The power output of these generators may sometimes decrease depending on environmental conditions.

[0018] Figure 1 An example is shown where a small generator powered by solar energy is used as the low-power power source 40. In the case of a solar-powered generator, the power output decreases as the duration of sunlight decreases. The voltage supplied to each of the multiple remote wireless devices 20 is a low voltage of approximately a few volts and varies with the power output of the low-power power source 40. In this embodiment, the power output of the low-power power source 40 decreases due to the reduced duration of sunlight.

[0019] The base station wireless device 10 communicates wirelessly with each of the remote wireless devices 20. The base station wireless device 10 is controlled by a control device (not shown) connected via wired or wireless connection. This control device may be, for example, a PLC (Programmable Logic Controller) for monitoring and controlling industrial equipment.

[0020] The remote wireless device 20 receives sensor signals from the sensor 50, which is an external device. Based on the input sensor signals, the remote wireless device 20 transmits data DT to the base station wireless device 10 via wireless communication. The base station wireless device 10 forwards the data DT received from each of the remote wireless devices 20 to the aforementioned control device. The control device uses the forwarded data DT for data processing.

[0021] The base station wireless device 10 includes a computing unit 80, a storage unit 82, and a communication module 84. The computing unit 80 includes a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). That is, the computing unit 80 includes processing circuitry.

[0022] The arithmetic unit 80 can be implemented by electronic circuits containing integrated circuits such as ASICs (Application Specific Integrated Circuits) or FPGAs (Field Programmable Gate Arrays), or discrete devices.

[0023] The storage unit 82 includes volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory) or flash memory. The volatile memory serves as the processor's working memory. The non-volatile memory is used to store programs executed by the processor.

[0024] The arithmetic unit 80 establishes and maintains wireless communication synchronization with the remote wireless device 20 by executing the aforementioned program stored in the storage unit 82. Specifically, the arithmetic unit 80 broadcasts a synchronization establishment signal SE for establishing wireless communication synchronization via the communication module 84. After the wireless communication synchronization with the remote wireless device 20 is established, the arithmetic unit 80 broadcasts a synchronization maintenance signal SM via the communication module 84 to maintain the synchronization.

[0025] Furthermore, the arithmetic unit 80, by executing the aforementioned program stored in the storage unit 82, receives the aforementioned data DT via the communication module 84 when wireless communication synchronization has been established or maintained. Moreover, in wireless communication after synchronization is established, the frequency is periodically switched. In other words, in wireless communication after synchronization is established, a frequency hopping method is employed. The storage unit 82 pre-stores data that will be combined with… Figure 7B and Figure 7C Tables 180 and 190 are described later. Communication module 84 is used for the aforementioned wireless communication.

[0026] The remote wireless device 20 includes a processing unit 100, a storage unit 102, a communication module 104, and a power supply module 106. The processing unit 100 includes a processor such as a CPU or GPU, meaning it contains processing circuitry. The storage unit 102 includes volatile memory such as RAM and non-volatile memory such as ROM or flash memory. The volatile memory serves as the processor's working memory. The non-volatile memory stores programs executed by the processor.

[0027] The communication module 104 is used for the aforementioned wireless communication. The power module 106 converts the power from the low-power power supply 40 and supplies power to the remote wireless device 20.

[0028] The arithmetic unit 100 includes a communication unit 120, a synchronization unit 122, an acquisition unit 124, a modification unit 126, and a generation unit 128. The arithmetic unit 100 executes the program stored in the storage unit 102, thereby realizing the communication unit 120, the synchronization unit 122, the acquisition unit 124, the modification unit 126, and the generation unit 128.

[0029] The communication unit 120 receives a synchronization establishment signal SE for establishing wireless communication synchronization via the communication module 104. The communication unit 120 also receives a synchronization maintenance signal SM for maintaining wireless communication synchronization via the communication module 104. The communication unit 120 transmits the data DT generated by the generation unit 128 (described later) to the base station wireless device 10 via the communication module 104. The communication unit 120 receives an acknowledgment signal ACK sent from the base station wireless device 10 in response to the transmitted data DT via the communication module 104.

[0030] When the synchronization establishment signal SE is received by the communication unit 120, the synchronization unit 122 synchronizes the occurrence time of the clock signal of the remote wireless device 20 with the occurrence time of the clock signal of the base station wireless device 10. When the communication unit 120 receives the synchronization maintenance signal SM, the synchronization unit 122 corrects the occurrence time of the clock signal of the remote wireless device 20 to maintain the synchronization of wireless communication with the base station wireless device 10.

[0031] Therefore, after synchronization is established, the frequency switching time based on frequency hopping can, in principle, be kept consistent in both the base station wireless device 10 and the remote wireless device 20. To maintain this consistency, a synchronization maintenance signal SM is periodically transmitted.

[0032] As described above, power is supplied to the remote wireless device 20 via the power module 106. The acquisition unit 124 acquires the internal voltage V within the remote wireless device 20.

[0033] As described later, there exists a first period T1 during which the communication unit 120 can receive the synchronization establishment signal SE, and a second period T2 during which the communication unit 120 cannot receive the synchronization establishment signal SE. The modification unit 126 modifies at least one of the first period T1 and the second period T2 based on the change in the internal voltage V within the remote wireless device 20 during the second period T2. If the internal voltage V at the beginning of the first period T1 is below a predetermined voltage (described later), the modification unit 126 can perform at least one of the modification of shortening the first period T1 according to the predetermined voltage or extending the second period T2.

[0034] The generation unit 128 generates data DT to be transmitted to the base station wireless device 10 based on the sensor signal input from the sensor 50.

[0035] Figure 2 This diagram illustrates a sequence of wireless communication between a base station wireless device 10 and a remote wireless device 20. First, synchronization for wireless communication is established. For this purpose, the arithmetic unit 80 of the base station wireless device 10 periodically transmits a synchronization establishment signal SE via a predetermined frequency through a communication module 84. The transmission period Tt of the synchronization establishment signal SE takes a value within the range of approximately 1 to 1000 ms, for example, 250 ms. The synchronization establishment signal SE contains information about the clock of the base station wireless device 10.

[0036] The communication unit 120 of the remote wireless device 20, via the communication module 104, waits to receive the synchronization establishment signal SE from the base station wireless device 10 at the aforementioned predetermined frequency. Based on the information contained in the synchronization establishment signal SE, the synchronization unit 122 of the remote wireless device 20 synchronizes the clock of the remote wireless device 20 with the clock of the base station wireless device 10. Thus, synchronization of wireless communication between the remote wireless device 20 and the base station wireless device 10 is established.

[0037] When a sensor signal from sensor 50 is present, the generation unit 128 of the remote wireless device 20 generates data DT to be transmitted to the base station wireless device 10 based on that sensor signal. Alternatively, a virtual data DT not based on the sensor signal can also be generated. The communication unit 120 of the remote wireless device 20 transmits the data DT to the base station wireless device 10 via the communication module 104.

[0038] The processing unit 80 of the base station wireless device 10 receives data DT from the remote wireless device 20 via the communication module 84. This confirms the synchronization of wireless communication between the base station wireless device 10 and the remote wireless device 20. The processing unit 80 of the base station wireless device 10 sends an acknowledgment signal ACK to the remote wireless device 20 via the communication module 84. The communication unit 120 of the remote wireless device 20 receives the acknowledgment signal ACK from the base station wireless device 10 via the communication module 104.

[0039] After wireless communication synchronization is established, in order to maintain this synchronization, the arithmetic unit 80 of the base station wireless device 10 periodically transmits a synchronization maintenance signal SM via the communication module 84 in a broadcast manner. The transmission period of the synchronization maintenance signal SM is a value in the range of approximately 1 to 1000 [ms], for example, 100 [ms]. The synchronization maintenance signal SM contains clock information of the base station wireless device 10.

[0040] The communication unit 120 of the remote wireless device 20 periodically receives a synchronization maintenance signal SM from the base station wireless device 10 via the communication module 104. The synchronization unit 122 of the remote wireless device 20 corrects the clock of the remote wireless device 20 based on the information contained in the synchronization maintenance signal SM in order to maintain synchronization of wireless communication with the base station wireless device 10.

[0041] In a state where wireless communication synchronization is maintained, it is assumed that a sensor signal is input from sensor 50 to remote wireless device 20. In this case, the generation unit 128 of remote wireless device 20 generates data DT based on the sensor signal and sends it to base station wireless device 10. The communication unit 120 of remote wireless device 20 transmits the data DT to base station wireless device 10.

[0042] The processing unit 80 of the base station wireless device 10 receives data DT from the remote wireless device 20. The processing unit 80 of the base station wireless device 10 sends an acknowledgment signal ACK to the remote wireless device 20. The communication unit 120 of the remote wireless device 20 receives the acknowledgment signal ACK from the base station wireless device 10. Receiving the acknowledgment signal ACK signifies that the remote wireless device 20 successfully transmitted data DT to the base station wireless device 10.

[0043] Figure 3A and Figure 3BThis diagram illustrates the change in internal voltage V within the remote wireless device 20 during wireless communication synchronization establishment. Wireless communication is often unstable. In an unstable communication environment, signals transmitted from the base station wireless device 10 may be lost and cannot be received by the remote wireless device 20. Furthermore, during the aforementioned frequency switching, since the frequency is being used by other devices, the base station wireless device 10 may be unable to transmit signals according to the aforementioned transmission period Tt.

[0044] Therefore, the remote wireless device 20 may need a relatively long time to receive the synchronization establishment signal SE. The remote wireless device 20 continues to wait for the synchronization establishment signal SE to be received from the base station wireless device 10. Figure 3A In the conventional example shown, the waiting period T0 for the remote wireless device 20 to wait for the reception of the synchronization establishment signal SE continues until the synchronization establishment signal SE is received.

[0045] The process of waiting for the synchronization establishment signal SE to be received consumes power. When the power output of the low-power supply 40 decreases, during the aforementioned waiting period T0, the internal voltage V within the remote wireless device 20 will drop. As a result, the internal voltage V may drop from a voltage value of approximately a few volts Vf to below a voltage value Vs that could cause the remote wireless device 20 to crash.

[0046] exist Figure 3A In the conventional example shown, the base station wireless device 10 transmits a synchronization establishment signal SE according to the transmission period Tt. At time Cs, the remote wireless device 20 begins to wait for the reception of the synchronization establishment signal SE. Suppose that the remote wireless device 20 fails to receive the synchronization establishment signal SE transmitted from the base station wireless device 10 at the same time Cs as the start of the waiting. In this case, since the waiting period T0 continues, the internal voltage V continuously decreases from the initial voltage value Vf.

[0047] exist Figure 3A In the previous example shown, the internal voltage V at time Cx before the end of the transmission period Tt, which begins at time Cs, becomes the voltage value Vs at which the remote wireless device 20 may experience a system crash. Therefore, in a power supply environment from a low-power power source 40, a prolonged waiting period T0 is undesirable.

[0048] In this embodiment Figure 3B In the example shown, the remote wireless device 20 will not experience a system crash. Figure 3A Similarly, the base station wireless device 10 transmits a synchronization establishment signal SE according to the transmission period Tt. At time C11, the remote wireless device 20 begins to wait for the reception of the synchronization establishment signal SE. The first period T1 of waiting for the reception of the synchronization establishment signal SE begins at time C11.

[0049] The communication unit 120 of the remote wireless device 20 is capable of receiving the synchronization establishment signal SE arriving at the remote wireless device 20 within the first period T1. Suppose that the communication unit 120 of the remote wireless device 20 fails to receive the synchronization establishment signal SE sent from the base station wireless device 10 at the same time C11 as the waiting begins. In this case, the communication unit 120 may experience a delay in receiving the synchronization establishment signal SE. Therefore, the communication unit 120 waits for the reception of the synchronization establishment signal SE until the end of the first period T1 starting from time C11.

[0050] If the communication unit 120 does not receive the synchronization establishment signal SE during the first period T1, then at time C12 after time C11, the first period T1 ends and the second period T2 begins. The communication unit 120 of the remote wireless device 20 will be unable to receive the synchronization establishment signal SE arriving at the remote wireless device 20 during the second period T2. This can be achieved, for example, by changing the operating mode of the computing unit 100 of the remote wireless device 20 from a normal mode to a sleep mode.

[0051] The following describes the normal mode and sleep mode. In normal mode, the communication unit 120, synchronization unit 122, acquisition unit 124, modification unit 126, and generation unit 128 of the arithmetic unit 100 can be used respectively. Figure 1 Perform the above processing.

[0052] When the power supply to the arithmetic unit 100 is disconnected, sleep mode is executed. When sleep mode is executed and the arithmetic unit 100's operating mode changes to sleep mode, the communication unit 120, synchronization unit 122, acquisition unit 124, modification unit 126, and generation unit 128 each cease the aforementioned processing. At the moment the arithmetic unit 100's operating mode changes to sleep mode, the second period T2 begins. A timer or counter (not shown) configured in the peripheral circuitry of the arithmetic unit 100 is started. Hereinafter, this timer or counter will simply be referred to as a timer.

[0053] The operation mode of the arithmetic unit 100 is normal mode in the first period T1 and sleep mode in the second period T2.

[0054] The internal voltage V within the remote wireless device 20 decreases from its value Vf during the first period T1 starting from time C11. For example... Figure 3B As shown, since the first period T1 ends at time C12, the voltage drop of the internal voltage V stops at a voltage value Vk higher than the voltage value Vs. During the second period T2, from time C12 to time C21, the internal voltage V rises and recovers to the voltage value Vf. At time C21, the second period T2 ends, and the first period T1 begins again.

[0055] Furthermore, the sleep state is lifted when the timer expires. That is, the second period T2 ends at the time the timer expires. Based on the timer's expiration, a power input signal is sent from the peripheral circuitry containing the timer to the arithmetic unit 100. As a result, the power supply to the arithmetic unit 100 is turned on. Since the power supply to the arithmetic unit 100 is turned on, the sleep state is lifted.

[0056] When the sleep state is released and the operation mode of the arithmetic unit 100 returns to normal mode, the communication unit 120, synchronization unit 122, acquisition unit 124, modification unit 126, and generation unit 128 respectively return to their states where the above-mentioned processing can be performed. The communication unit 120 waits for the reception of the synchronization establishment signal SE until the end of the first period T1 starting from time C21.

[0057] The communication unit 120 is capable of receiving the synchronization establishment signal SE during the first period T1 with a reception period Tr. The reception period Tr is the period from the start of the first period T1 to the start of the next first period T1. That is, the reception period Tr is the sum of the first period T1 and the second period T2. Therefore, the first period T1 and the second period T2 alternate until the synchronization establishment signal SE is received.

[0058] exist Figure 3B In the example shown, the reception period Tr is equal to the transmission period Tt of the synchronization establishment signal SE. If the first synchronization establishment signal SE is not received, the second first period T1 begins after the second period T2 ends at time C21. The second first period T1 ends at time C22, which is after time C21. The second synchronization establishment signal SE can be received within the second first period T1.

[0059] If the second synchronization establishment signal SE is not received during the first period T1, a second second period T2 begins at time C22. The internal voltage V drops to its value Vk at time C22. During the second period T2, from time C22 to time C31, the internal voltage V rises and recovers to its value Vf. After the second period T2 ends at time C31, a third first period T1 begins. The third first period T1 ends at time C32, after time C31. The third synchronization establishment signal SE can be received during the third first period T1.

[0060] Thus, as the first period T1 is repeated according to the reception period Tr until the synchronization establishment signal SE is received, the internal voltage V repeatedly decreases and increases. Therefore, wireless communication synchronization can be established without the occurrence of a system failure of the remote wireless device 20.

[0061] As mentioned above, in Figure 3BIn the example shown, the receiving period Tr is equal to the transmitting period Tt of the synchronization establishment signal SE. Since the first period T1 repeats according to the receiving period Tr, the period of the first period T1 that can receive the synchronization establishment signal SE corresponds to the transmitting period Tt of the synchronization establishment signal SE. Figure 4A and Figure 4B This is a graph illustrating the relationship between the transmission period Tt and the reception period Tr of the synchronization establishment signal SE. Figure 4A and Figure 4B In Chinese, the use of the same symbols (e.g., C11, C21, etc.) does not necessarily represent the same moment.

[0062] exist Figure 4A In the example shown, with Figure 3B The example shown is the same, where the reception period Tr is equal to the transmission period Tt. In this example, the transmission time of the synchronization establishment signal SE from the base station wireless device 10 falls within the second period T2. For example, the transmission time Ce1 of the first synchronization establishment signal SE is not within the first period T1 from time C11 to time C12, but within the second period T2 from time C12 to time C21. Therefore, the first synchronization establishment signal SE will not be received by the communication unit 120 of the remote wireless device 20.

[0063] Since the reception period Tr equals the transmission period Tt, the transmission time Ce2 of the second synchronization establishment signal SE is not within the first period T1 (from C21 to C22), but within the second period T2 (from C22 to C31). Similarly, the transmission times Ce3, Ce4, and Ce5 of the third, fourth, and fifth synchronization establishment signals SE are also not within the first period T1, but within the second period T2. The same applies to the sixth and subsequent synchronization establishment signals SE. In other words, not only can the first synchronization establishment signal SE not be received, but the second and subsequent synchronization establishment signals SE also cannot be received. This problem must be solved.

[0064] exist Figure 4B In the example shown, the receive period Tr is not equal to the transmit period Tt. Furthermore, Figure 4B For ease of explanation, an example is shown where the first period T1 is equal to 1 / 5 of the transmission period Tt and the second period T2 is equal to the transmission period Tt, but this is not the only example. Figure 4B As shown, the transmission time Ce1 of the first synchronization establishment signal SE is not within the first period T1 from time C11 to time C12, but within the second period T2 from time C12 to time C21.

[0065] The transmission times Ce2, Ce3, and Ce4 of the second, third, and fourth synchronization establishment signals SE are also not within the first period T1, but within the second period T2. Therefore, the first to fourth synchronization establishment signals SE cannot be received. However, the transmission time Ce5 of the fifth synchronization establishment signal SE is within the first period T1 from time C51 to time C52. Therefore, the fifth synchronization establishment signal SE can be received by the communication unit 120 of the remote wireless device 20.

[0066] exist Figure 4A In the example shown, even if the reception cycle Tr is repeated, the remote wireless device 20 cannot receive the synchronization establishment signal SE. In contrast, in Figure 4B In the example shown, if the reception period Tr is repeated, the remote wireless device 20 can receive the synchronization establishment signal SE.

[0067] For example, when the receiving period Tr is not a positive integer multiple of the transmitting period Tt, the remote wireless device 20 can still receive the synchronization establishment signal SE during the repeated occurrences of the receiving period Tr. Furthermore, when the receiving period Tr is not a positive integer multiple of the reciprocal of the transmitting period Tt, the remote wireless device 20 can still receive the synchronization establishment signal SE. Therefore, synchronization in wireless communication is easier to establish. In other words, if the relationship between the receiving period Tr and the transmitting period Tt is expressed using a coefficient n (where n > 0) as Tr = n × Tt, then the coefficient n must not be a positive integer and must not be the reciprocal of a positive integer.

[0068] exist Figure 4B In the example shown, the transmission period Tt is equal to 5 times the first period T1, and the second period T2 is equal to the transmission period Tt. Therefore, during the period when the reception period Tr repeats 5 times, the transmission time of the synchronization establishment signal SE will have at least one chance to fall within the first period T1. Thus, the design of the wireless communication system 30 becomes easier. Furthermore, the transmission period Tt is not limited to a value of 5 times the first period T1; it can also be a positive integer multiple other than 5.

[0069] As mentioned above, the internal voltage V varies depending on the power output of the low-power supply 40. Therefore, when the power output of the low-power supply 40 is relatively low, the voltage V will change accordingly. Figure 3B Different, such as Figure 5A As shown, the internal voltage V may continue to decrease. Figure 5A and Figure 5B This is a graph illustrating the change of the internal voltage V within the remote wireless device 20 during the synchronization establishment of wireless communication. Figure 5A and Figure 5B In this context, the use of the same symbols (e.g., C11, C21, etc.) does not necessarily represent the same moment.

[0070] exist Figure 5A At time C11, the remote wireless device 20 begins waiting for the synchronization establishment signal SE. The internal voltage V at time C11 is voltage value Vf. Assume that the remote wireless device 20 does not receive the synchronization establishment signal SE within the first period T1 beginning at time C11. At time C12, the end of the first period T1, the internal voltage V drops to voltage value Va1. The second period T2 begins at time C12. During the second period T2, the internal voltage V rises. However, at time C21, the end of the second period T2, the internal voltage V is voltage value Vb1, which is lower than voltage value Vf.

[0071] Suppose that the remote wireless device 20 fails to receive the synchronization establishment signal SE during the first period T1, which begins at time C21. At time C22, the internal voltage V at the end of the first period T1 drops to a voltage value Va2, which is lower than the voltage value Va1. The second period T2 begins at time C22. During the second period T2, the internal voltage V rises. However, at time C31, the internal voltage V at the end of the second period T2 is a voltage value Vb2, which is lower than the voltage value Vb1.

[0072] Suppose that the remote wireless device 20 fails to receive the synchronization establishment signal SE within the first period T1 starting at time C31. At time C32, when the first period T1 ends, the internal voltage V drops to a voltage value Va3, which is lower than the voltage value Va2. The second period T2 begins at time C32. Thus, if the internal voltage V continues to drop, the internal voltage V may eventually reach the aforementioned voltage value Vs.

[0073] therefore, Figure 5B It shows the relationship with Figure 5A The example shown is a shortened version of the example with a first period T1. Figure 5B At time C11, the remote wireless device 20 begins waiting to receive the synchronization establishment signal SE. The internal voltage V at time C11 is voltage value Vf. Assume that the remote wireless device 20 fails to receive the synchronization establishment signal SE within the first period T1 beginning at time C11. At time C12, the end of the first period T1, the internal voltage V drops to voltage value Vc1.

[0074] Figure 5B The first period T1 in the example shown is compared to Figure 5A In the example shown, the first period T1 is short. Therefore, Figure 5B In the example shown, the internal voltage V has a voltage value Vc1 that is higher than... Figure 5A In the example shown, the internal voltage V has a voltage value of Va1. Therefore, during the second period T2, which begins at time C12 and ends at time C21, the internal voltage V rises and is able to recover to its voltage value Vf. Furthermore, Figure 5B The length of the second period T2 in the example shown is... Figure 5A In the example shown, the lengths of the second period T2 are equal.

[0075] During the first period T1, which begins at time C21 and ends at time C22, if the remote wireless device 20 fails to receive the synchronization establishment signal SE, the internal voltage V drops again to the voltage value Vc1. However, during the second period T2, which begins at time C22 and ends at time C31, the internal voltage V rises again to the voltage value Vf.

[0076] Subsequently, until the remote wireless device 20 receives the synchronization establishment signal SE during the first period T1, even if the internal voltage V repeatedly decreases and increases in this manner according to the reception period Tr, the internal voltage V cannot reach the aforementioned voltage value Vs. Therefore, synchronization for wireless communication can be established without the occurrence of a system failure of the remote wireless device 20.

[0077] exist Figure 5A In the example shown, the internal voltage V at time C12 has a voltage value Va1 greater than the voltage value Vs at which the remote wireless device 20 might experience a system crash. However, if the power output of the low-power supply 40 further decreases, the internal voltage V at time C11 might become close to the voltage value Vs. In this case, the internal voltage V might reach the voltage value Vs before the end of the first period T1. Even in this case, as... Figure 5B As shown, by shortening the first period T1, wireless communication synchronization can be established without the occurrence of system failure of the remote wireless device 20.

[0078] When the power output of the low-power power supply 40 is relatively high, with Figure 5B Different, such as Figure 3B As shown, the internal voltage V may recover to its value Vf within the second period T2 (before the end of the second period T2). In this case, the first period T1 can be extended. Therefore, Figure 6 The first period T1 ratio is shown. Figure 3B The example shown is a long one. Figure 6 This is a graph illustrating the change in internal voltage V within the remote wireless device 20 during wireless communication synchronization establishment. Figure 5A , Figure 5B and Figure 6 In Chinese, the use of the same symbols (e.g., C11, C21, etc.) does not necessarily represent the same moment.

[0079] exist Figure 6At time C11, the remote wireless device 20 begins waiting to receive the synchronization establishment signal SE. The internal voltage V at time C11 is voltage value Vf. Assume that the remote wireless device 20 fails to receive the synchronization establishment signal SE within the first period T1 beginning at time C11. At time C12, the end of the first period T1, the internal voltage V drops to voltage value Vc2.

[0080] Figure 6 The first period T1 in the example shown is compared to Figure 3B In the example shown, the first period T1 is longer. Therefore, Figure 6 In the example shown, the internal voltage V has a voltage value Vc2 that is lower than... Figure 3B In the example shown, the internal voltage V has a voltage value of Vk. Therefore, during the second period T2 starting at time C12, the internal voltage V rises and returns to its voltage value Vf exactly at time C21 when the second period T2 ends.

[0081] also, Figure 6 The length of the second period T2 in the example shown is... Figure 3B The examples shown and Figure 5B In the example shown, the lengths of the second period T2 are equal. Figure 6 The change in internal voltage V during the second period T2 in the example shown is greater than Figure 5B The example shown illustrates the change in internal voltage V during the second period T2. This is due to the power output of the low-power supply 40. Figure 6 In the example shown, the power output is relatively high, so the internal voltage V can rise more rapidly during the second period T2.

[0082] During the first period T1, which begins at time C21 and ends at time C22, if the remote wireless device 20 fails to receive the synchronization establishment signal SE, the internal voltage V drops again to the voltage value Vc2. However, during the second period T2, which begins at time C22 and ends at time C31, the internal voltage V rises again to the voltage value Vf.

[0083] Subsequently, until the remote wireless device 20 receives the synchronization establishment signal SE during the first period T1, even if the internal voltage V repeatedly decreases and increases in this manner according to the reception period Tr, the internal voltage V cannot reach the aforementioned voltage value Vs. Therefore, wireless communication synchronization can be established without the occurrence of a system failure of the remote wireless device 20.

[0084] also, Figure 6 The first period T1 in the example shown is compared to Figure 3B The examples shown and Figure 5B In the example shown, the first period T1 is long. Therefore, the remote wireless device 20 can easily receive the synchronization establishment signal SE within the first period T1.

[0085] use Figure 5B and Figure 6 The change in the first period T1 is performed by the aforementioned change unit 126 based on the change in the internal voltage V in the second period T2. Figure 7A This is a diagram illustrating an example of a parameter used to change the parameters for the first period T1. For example, the parameter used to change the parameters for the first period T1 is the rate of change ΔV of the internal voltage V in the second period T2. The change unit 126 calculates the rate of change ΔV based on the voltage values ​​of the internal voltage V in the first period T1 immediately before and immediately after the second period T2.

[0086] Figure 7A The example illustrates the change in internal voltage V during the synchronization establishment of wireless communication. Figure 7A At time C11, the remote wireless device 20 begins waiting to receive the synchronization establishment signal SE. The internal voltage V at time C11 is the voltage value Vf.

[0087] Suppose that the remote wireless device 20 fails to receive the synchronization establishment signal SE during the first period T1, which begins at time C11. At time C12, the internal voltage V drops to the voltage value Va. The second period T2 begins at time C12. At time C21, the internal voltage V rises to the voltage value Vb. At time C21, a new first period T1 begins.

[0088] The first period T1, immediately preceding the second period T2, ends at time C12. The acquisition unit 124 acquires the voltage value Va of the internal voltage V at time C12. Furthermore, if the rate of decrease of the internal voltage V per unit period in the first period T1 is predetermined, the acquisition unit 124 can also acquire the voltage value Va at time C12 by calculation.

[0089] Immediately following the second period T2, the first period T1 begins at time C21. The acquisition unit 124 acquires the voltage value Vb of the internal voltage V at time C21. The change unit 126 calculates the rate of change ΔV, representing the change of the internal voltage V during the second period T2, based on the voltage values ​​Va and Vb acquired by the acquisition unit 124. The rate of change ΔV of the internal voltage V is represented by mathematical formula (1).

[0090] ΔV=(Vb-Va) / (C21-C12)・・・(1)

[0091] The modification unit 126 modifies the first period T1 based on the calculated rate of change ΔV. The smaller the rate of change ΔV, the shorter the first period T1 is shortened by the modification unit 126. The larger the rate of change ΔV, the longer the first period T1 is extended by the modification unit 126. The modification unit 126 can use... Figure 7B The table 180 shown in the figure and the calculated rate of change ΔV are used to modify the first period T1.

[0092] Figure 7B This is a diagram illustrating the changes in Table 180 for the first period T1. Table 180 is stored in storage unit 102. Table 180 records the values ​​of the first period T1 as changed according to the rate of change ΔV of the internal voltage V.

[0093] like Figure 7B As shown, when the rate of change ΔV is below the first rate of change threshold D1, the modification unit 126 changes the first period T1 to a set value T1u. When the rate of change ΔV is greater than the first rate of change threshold D1 and below the second rate of change threshold D2, the modification unit 126 changes the first period T1 to a set value T1v. The set value T1v is greater than the set value T1u.

[0094] When the rate of change ΔV is greater than the second rate of change threshold D2, the modification unit 126 modifies the first period T1 to a set value T1w. The set value T1w is greater than the set values ​​T1u and T1v. The first rate of change threshold D1, the second rate of change threshold D2, and the set values ​​T1u, T1v, and T1w are all predetermined in a way that prevents the internal voltage V from reaching the aforementioned voltage value Vs. By modifying the first period T1 using Table 180, wireless communication synchronization can be established without causing a system crash of the remote wireless device 20.

[0095] Furthermore, the smaller the rate of change ΔV, the more the change unit 126 can replace the change that shortens the first period T1, and instead perform a change that extends the second period T2. In this case, the larger the rate of change ΔV, the more the change unit 126 can replace the change that extends the first period T1, and instead perform a change that shortens the second period T2.

[0096] Furthermore, the smaller the rate of change ΔV, the shorter the first period T1 and the longer the second period T2 can be in the modification unit 126. In this case, the larger the rate of change ΔV, the longer the first period T1 and the shorter the second period T2 can be in the modification unit 126. When both the first period T1 and the second period T2 are modified, these modifications can be made so that the reception period Tr, which is the sum of the first period T1 and the second period T2, does not change. When the reception period Tr does not change, it becomes easier to achieve a reception period Tr that satisfies the condition that it is neither a positive integer multiple of the transmission period Tt nor a reciprocal multiple of a positive integer of the transmission period Tt. That is, it becomes easier to design the wireless communication system 30.

[0097] As a parameter for the change of the first period T1, the voltage value Vb of the internal voltage V at the start time (time C21) of the first period T1 immediately following the second period T2 can also be used (see Figure 7A The voltage value Vb is acquired by the acquisition unit 124. The modification unit 126 modifies the first period T1 based solely on the acquired voltage value Vb.

[0098] like Figure 7A As shown, the voltage value Vb of the internal voltage V is less than or equal to the voltage value Vf of the internal voltage V at time C11. Hereinafter, the voltage value Vf of the internal voltage V at time C11 will also be referred to as the specified voltage Vf. However, other specified voltages near the voltage value Vf may also be used.

[0099] The greater the difference between the internal voltage Vb and the specified voltage Vf, the shorter the first period T1 is shortened by the modification unit 126. The smaller the difference between the internal voltage Vb and the specified voltage Vf, the longer the first period T1 is extended by the modification unit 126. The modification unit 126 can use... Figure 7C The table 190 shown in the example and the obtained voltage value Vb are used to modify the first period T1.

[0100] Figure 7C This is a diagram illustrating the changes in Table 190 for the first period T1. Table 190 is stored in storage unit 102. Table 190 records the values ​​of the first period T1 as they change according to the voltage value Vb of the internal voltage V at the start time of the first period T1. Figure 7C The first voltage threshold Vp1 shown is less than the specified voltage Vf mentioned above. The second voltage threshold Vp2 is greater than the first voltage threshold Vp1 and less than the specified voltage Vf mentioned above.

[0101] like Figure 7A As shown, the difference between the voltage value Vb and the specified voltage Vf when the voltage value Vb is less than the first voltage threshold Vp1 is greater than the difference between the voltage value Vb and the specified voltage Vf when the voltage value Vb is greater than the first voltage threshold Vp1. Similarly, the difference between the voltage value Vb and the specified voltage Vf when the voltage value Vb is greater than the second voltage threshold Vp2 is less than the difference between the voltage value Vb and the specified voltage Vf when the voltage value Vb is less than the second voltage threshold Vp2.

[0102] like Figure 7C As shown, when the voltage value Vb is below the first voltage threshold Vp1, the modification unit 126 changes the first period T1 to a set value T1u. When the voltage value Vb is greater than the first voltage threshold Vp1 and below the second voltage threshold Vp2, the modification unit 126 changes the first period T1 to a set value T1v. The set value T1v is greater than the set value T1u.

[0103] When the voltage value Vb is greater than the second voltage threshold Vp2, the modification unit 126 changes the first period T1 to a set value T1w. The set value T1w is greater than the set values ​​T1u and T1v. That is, the greater the difference between the voltage value Vb and the specified voltage Vf, the shorter the first period T1; the smaller the difference between the voltage value Vb and the specified voltage Vf, the longer the first period T1.

[0104] The first voltage threshold Vp1, the second voltage threshold Vp2, and the set values ​​T1u, T1v, and T1w are all predetermined in a way that prevents the internal voltage V from reaching the aforementioned voltage value Vs. By changing the first period T1 using Table 190, wireless communication synchronization can be established without causing a system crash of the remote wireless device 20.

[0105] Furthermore, the greater the difference between the internal voltage Vb and the specified voltage Vf, the more the modification unit 126 can perform a change that extends the second period T2, instead of shortening the first period T1. In this case, the smaller the difference between the internal voltage Vb and the specified voltage Vf, the more the modification unit 126 can perform a change that shortens the second period T2, instead of extending the first period T1.

[0106] Furthermore, the greater the difference between the internal voltage Vb and the specified voltage Vf, the shorter the first period T1 and the longer the second period T2 can be for the modification unit 126. In this case, the smaller the difference between the internal voltage Vb and the specified voltage Vf, the longer the first period T1 and the shorter the second period T2 can be for the modification unit 126.

[0107] When both the first period T1 and the second period T2 are changed, these changes can be made so that the reception period Tr, which is the sum of the first period T1 and the second period T2, remains unchanged. When the reception period Tr remains unchanged, it becomes easy to achieve a reception period Tr that is neither a positive integer multiple of the transmission period Tt nor a reciprocal multiple of a positive integer of the transmission period Tt. That is, it becomes easier to design the wireless communication system 30.

[0108] As a parameter for the change of the first period T1, the voltage value Va of the internal voltage V at the end time (time C12) of the first period T1 immediately preceding the second period T2 can also be used (see Figure 7A The voltage value Va is acquired by the acquisition unit 124. The modification unit 126 modifies the first period T1 based solely on the acquired voltage value Va.

[0109] The greater the difference between the internal voltage V's voltage value Va and the specified voltage Vf, the shorter the first period T1 is shortened by the modification unit 126. The smaller the difference between the internal voltage V's voltage value Va and the specified voltage Vf, the longer the first period T1 is lengthened by the modification unit 126. Since the same processing is performed as in the case where only the internal voltage V's voltage value Vb is used as the parameter for changing the first period T1, detailed explanation is omitted.

[0110] also, Figure 7A The rate of decrease of the internal voltage V during the first period T1 shown above varies depending on the power output of the low-power supply 40. As mentioned above, this rate of decrease can be predetermined. For example, if the rate of decrease is large, it can be predicted that the internal voltage V will reach a voltage value Vs that may cause system failure during the first period T1. Therefore, the first period T1 can also be modified by further considering the rate of decrease of the internal voltage V during the first period T1. If the rate of decrease is large, the first period T1 is shortened. Conversely, if the rate of decrease is small, the first period T1 is extended.

[0111] Figure 8 This is a flowchart illustrating the synchronization establishment process of wireless communication in the remote wireless device 20. This process is executed by, for example, the arithmetic unit 100 provided by the remote wireless device 20. When this process begins, in step S1, the acquisition unit 124 determines whether a first period T1 has started. If yes in step S1, the process proceeds to step S2. If no in step S1, the process of step S1 is repeated.

[0112] In step S2, the acquisition unit 124 acquires the internal voltage V within the remote wireless device 20 and saves it to the storage unit 102. In step S3, the modification unit 126 determines whether a change to the first period T1 is needed. This determination is based on the internal voltage V within the remote wireless device 20 or its changes. If the result is yes in step S3, the process proceeds to step S4. If the result is no in step S3, the process proceeds to step S5. In step S4, the modification unit 126 modifies the first period T1. At this time, Table 180 or Table 190 saved in the storage unit 102 can be used.

[0113] In step S5, the communication unit 120 determines whether a synchronization establishment signal SE has been received. If yes, the process proceeds to step S6. If no, the process proceeds to step S21.

[0114] In step S6, the synchronization unit 122 synchronizes the generation time of the clock signal of the remote wireless device 20 with the clock signal of the base station wireless device 10. In step S7, the communication unit 120 transmits data DT to the base station wireless device 10 via the communication module 104. Data DT is, for example, data generated by the generation unit 128 based on the sensor signal input from the sensor 50.

[0115] In step S8, the communication unit 120 determines whether it has received an acknowledgment signal ACK from the base station wireless device 10. If yes, the process ends in step S8. If no, step S8 is repeated.

[0116] In step S21, the acquisition unit 124 determines whether the first period T1 has ended. If yes in step S21, the process proceeds to step S22. If no in step S21, the process returns to step S5.

[0117] In step S22, the acquisition unit 124 acquires the internal voltage V within the remote wireless device 20 and saves it to the storage unit 102. Furthermore, the processing in step S22 can be performed before the determination processing in step S21. Additionally, if the rate of decrease of the internal voltage V during the first period T1 is predetermined, the acquisition unit 124 can acquire the voltage V by calculating the internal voltage V at the end of the first period T1. In this case, the processing in step S22 can be omitted, and the internal voltage V at the end of the first period T1 can be calculated until the processing in step S3 described above.

[0118] In step S23, the arithmetic unit 100 starts a timer. In step S24, since the power supply to the arithmetic unit 100 is disconnected, it enters sleep mode. The operating mode of the arithmetic unit 100 changes to sleep mode. Then, when the timer started in step S23 expires, in step S25, by turning the power supply to the arithmetic unit 100, the sleep mode is released, and the second period T2 ends. Through the processing in step S25, the operating mode of the arithmetic unit 100 returns to normal mode, and this processing step returns to step S1.

[0119] In response to the above-mentioned disclosures, the following additional notes are hereby disclosed.

[0120] (Note 1)

[0121] A remote wireless device 20, which wirelessly communicates with a base station wireless device 10, includes: a communication unit 120 capable of receiving a synchronization establishment signal SE transmitted from the base station wireless device according to a transmission period Tt at a reception period Tr; and a synchronization unit 122, which, upon receiving the synchronization establishment signal, synchronizes the generation time of the remote wireless device's clock signal with the clock signal of the base station wireless device. The reception period is the sum of a first period T1 and a second period T2, where the first period is the period during which the communication unit can receive the synchronization establishment signal, and the second period is the period during which the communication unit cannot receive the synchronization establishment signal. Furthermore, the reception period is neither a positive integer multiple of the transmission period nor a reciprocal multiple of a positive integer multiple of the transmission period. With this structure, wireless communication synchronization can be easily established.

[0122] (Note 2)

[0123] In the remote wireless device described in Appendix 1, the second period may be equal to the transmission period. Based on this structure, it becomes easier to design a wireless communication system.

[0124] (Note 3)

[0125] In the remote wireless device described in Appendix 2, the transmission period may be a positive integer multiple of the first period. Based on this structure, the design of a wireless communication system becomes further simplified.

[0126] (Note 4)

[0127] In any of the remote wireless devices described in Appendices 1 to 3, the device may further include: an acquisition unit 124 that acquires an internal voltage V within the remote wireless device; and a modification unit 126 that modifies at least one of the first period and the second period based on changes in the internal voltage during the second period. With this structure, wireless communication synchronization can be established without the occurrence of a system failure in the remote wireless device.

[0128] (Note 5)

[0129] In the remote wireless device described in Appendix 4, the changing unit may change the first period and the second period without changing the receiving period. Based on this structure, it becomes easier to design a wireless communication system.

[0130] (Note 6)

[0131] In any of the remote wireless devices described in Appendices 1 to 3, the device may further include: an acquisition unit that acquires an internal voltage within the remote wireless device; and a modification unit that, when the internal voltage is below a predetermined voltage Vf at the start or end of the first period, performs at least one of shortening the first period or extending the second period based on the predetermined voltage. With this structure, wireless communication synchronization can be established without causing a system failure of the remote wireless device.

[0132] (Note 7)

[0133] In the remote wireless device described in Appendix 6, the modification unit may shorten the first period and extend the second period without changing the reception period. Based on this structure, it becomes easier to design a wireless communication system.

[0134] (Postscript 8)

[0135] In the remote wireless device described in Appendix 6, the greater the difference between the specified voltage and the internal voltage, the shorter the first period altered by the alteration unit, or the longer the second period altered by the alteration unit. With this structure, wireless communication synchronization can be established without the occurrence of system failure in the remote wireless device.

[0136] Furthermore, the present invention is not limited to the above disclosure, and various structures may be adopted without departing from the spirit of the present invention.

Claims

1. A remote wireless device (20) that wirelessly communicates with a base station wireless device (10), characterized in that, have: Communication unit (120), which is capable of receiving synchronization establishment signals (SE) transmitted from the base station radio device according to the transmission period (Tt) at the receive period (Tr); and Upon receiving the synchronization establishment signal, the synchronization unit (122) synchronizes the generation time of the clock signal of the remote wireless device with the clock signal of the base station wireless device. The receiving period is the sum of a first period (T1) and a second period (T2). The first period is the period during which the communication unit can receive the synchronization establishment signal, and the second period is the period during which the communication unit cannot receive the synchronization establishment signal. The receiving period is neither a positive integer multiple of the sending period nor a reciprocal multiple of a positive integer of the sending period.

2. The remote wireless device according to claim 1, characterized in that, The second period is equal to the transmission period.

3. The remote wireless device according to claim 2, characterized in that, The transmission period is a positive integer multiple of the first period.

4. The remote wireless device according to any one of claims 1 to 3, characterized in that, It also has: Acquisition unit (124), which acquires the internal voltage (V) within the remote wireless device; and The modification unit (126) modifies at least one of the first period and the second period based on the change in the internal voltage during the second period.

5. The remote wireless device according to claim 4, characterized in that, The modification unit modifies the first period and the second period without changing the receiving cycle.

6. The remote wireless device according to any one of claims 1 to 3, characterized in that, It also has: The acquisition unit acquires the internal voltage within the remote wireless device; and If the internal voltage at the start or end of the first period is below a predetermined voltage (Vf), the modification unit performs at least one of the modification of shortening the first period and the modification of extending the second period based on the predetermined voltage.

7. The remote wireless device according to claim 6, characterized in that, The modification section shortens the first period and extends the second period without changing the receiving cycle.

8. The remote wireless device according to claim 6, characterized in that, The greater the difference between the specified voltage and the internal voltage, the shorter the first period altered by the alteration unit, or the longer the second period altered by the alteration unit.

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