A communication scheduling method of a micro-energy-powered passive device and an internet-of-things passive device

Abstract

This invention provides a communication scheduling method for a low-energy-powered passive device and an IoT passive device, relating to the field of IoT power management technology. The method includes: the passive device real-time acquisition of its current energy reserve, determining its current energy storage state range based on the current energy reserve and interval switching hysteresis conditions, then switching to a communication mode adapted to the power consumption based on the determined energy storage state range, and executing corresponding communication control based on the communication mode. The beneficial effects are: effectively avoiding frequent switching of energy storage states caused by fluctuations in energy reserve, improving device operational stability; and adaptively switching to a communication mode adapted to the power consumption based on the energy storage state range, and executing communication control based on the matched communication mode, ensuring that the device's communication behavior is highly adapted to the current energy reserve, avoiding abnormal device operation caused by insufficient energy support triggering mismatched communication behavior, and ensuring reliable operation of the low-energy-powered passive device.

Description

Technical Field

[0001] This invention relates to the field of Internet of Things (IoT) power management technology, and in particular to a communication scheduling method for a low-energy-powered passive device and an IoT passive device. Background Technology

[0002] Micro-energy harvesting technology provides a feasible path for passive IoT devices to break free from battery constraints, enabling them to operate for extended periods without external power sources or battery replacements. However, in practical applications, micro-energy-powered passive devices face significant challenges in energy management and communication scheduling.

[0003] Because the energy supply of passive devices is inherently random and unstable, and is constrained by factors such as size and cost, their energy storage capacity is very limited, making it difficult to stably support various communication operations. Furthermore, the power consumption of different communication methods varies greatly. If high-power communication is initiated blindly when energy storage is insufficient, it can easily lead to a rapid drop in system voltage, causing the device to malfunction or even fail.

[0004] More importantly, the energy reserve of the device fluctuates dynamically in real time with the collection and consumption. If the interval judgment and mode scheduling are based solely on the instantaneous energy state, frequent switching of energy storage state intervals and repeated start-stop of communication modes are likely to occur, seriously affecting the stability of system operation. Traditional energy management methods are mostly designed for large-capacity batteries and only use coarse-grained power alarm and protection mechanisms, which cannot achieve fine interval division and stable judgment based on energy reserve. Existing low-power communication strategies also fail to match the communication mode with the power consumption according to the actual energy state of the device, and cannot suppress the frequent state switching caused by energy fluctuations through a stable hysteresis switching mechanism, making it difficult to meet the requirements of reliable and stable operation of micro-energy passive devices. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a communication scheduling method for a passive device powered by low energy, comprising pre-configuring at least three consecutive energy storage state intervals and corresponding interval switching hysteresis conditions, wherein the energy storage state intervals are used to characterize the energy reserve state of the passive device; the communication scheduling method includes: Step 1: The passive device collects its current energy reserve in real time, and determines the current energy storage state interval based on the current energy reserve and the interval switching hysteresis condition. Step 2: The passive device switches to a communication mode that matches the power consumption according to the determined energy storage state range, and performs corresponding communication control based on the communication mode.

[0006] Preferably, the interval switching hysteresis condition includes an upward hysteresis condition and a downward hysteresis condition. The upward hysteresis condition includes an upward hysteresis amount and a first hysteresis time, and the downward hysteresis condition includes a downward hysteresis amount and a second hysteresis time. In step 1, when the current energy reserve shows a switching trend from a low energy reserve state interval to an adjacent high energy reserve state interval, and the current energy reserve is higher than the sum of the interval boundary value of the corresponding low energy reserve state interval and the adjacent high energy reserve state interval and the rising hysteresis amount for the first hysteresis time, the passive device determines the adjacent high energy reserve state interval as the current energy storage state interval. When the passive device shows a switching trend from a high energy reserve state interval to an adjacent low energy reserve state interval, and the current energy reserve is lower than the difference between the interval boundary value of the corresponding high energy reserve state interval and the adjacent low energy reserve state interval and the decreasing hysteresis amount for the second hysteresis time, the adjacent low energy reserve state interval is determined as the current energy storage state interval.

[0007] Preferably, each of the energy storage state intervals includes an enhancement zone, a basic zone, and a survival zone in descending order of energy reserve status, and is respectively associated with a high-power communication mode, a low-power communication mode, and a minimum-power communication mode.

[0008] Step 2, which involves performing corresponding communication control based on the communication mode, includes: When the communication mode is the lowest power communication mode, the passive device shuts down all its active radio frequency modules and retains only the passive response device. When the communication mode is the low-power communication mode, the passive device activates its own low-power short-range communication module to perform Mesh networking or beacon broadcasting. When the communication mode is the high-power communication mode, the passive device activates its own wide-area cellular communication module to perform remote data reporting.

[0009] Preferably, it also includes a communication strategy that pre-configures different service priorities for each of the energy storage state intervals and adapts them to the power consumption of the corresponding communication mode; In step 2, when the passive device needs to send service data, the corresponding communication control based on the communication mode further includes: In the switched communication mode, the corresponding communication strategy is executed to process the service data based on the service priority of the service data.

[0010] Preferably, step 2, whereby the passive device switches to the corresponding communication mode according to the determined energy storage state range, includes: When the passive device is currently in the life-saving zone, the determined energy storage state interval is the basic zone, and the passive response device is triggered, the passive device switches from the lowest power communication mode to the low power communication mode. When the passive device is currently in the basic zone, and the determined energy storage state interval is the enhanced zone and there is service data to be sent, the passive device switches from the low-power communication mode to the high-power communication mode. The passive device is currently in the enhancement zone, the determined energy storage state interval is the basic zone, or when wide-area cellular communication is completed or timed out, the passive device switches from the high-power communication mode to the low-power communication mode. When the passive device is currently in the basic zone, the determined energy storage state interval is the life-saving zone, or when the data to be sent has been processed, the passive device switches from the low-power communication mode to the lowest power communication mode. When the energy reserve state decreases to the absolute protection state, the passive device immediately shuts down all radio frequency modules and directly switches from the current communication mode to the lowest power consumption communication mode.

[0011] Preferably, in step 2, before the passive device switches from the low-power communication mode to the high-power communication mode, an off-network pre-detection process is further included, which includes: Step A1: The passive device only turns on the radio frequency front-end of the wide-area cellular communication module, without starting the complete cellular protocol stack; Step A2: The passive device performs a fast RSSI scan on a preset frequency band and determines whether the maximum RSSI value detected exceeds a preset threshold. If so, the full cellular protocol stack is activated for communication in order to switch to the high-power communication mode; If not, the radio frequency front end is shut down, the low-power communication mode is maintained, and retries are prohibited within a future preset heartbeat cycle.

[0012] Preferably, in step A2, before the passive device initiates communication using the complete cellular protocol stack, a cold start energy threshold detection is also performed. The cold start energy threshold detection process includes: The system calculates the minimum energy required to complete a full cellular communication, and initiates the full cellular protocol stack for communication when its available energy is greater than a preset multiple of the minimum energy; otherwise, it abandons the current cellular communication.

[0013] Preferably, in step 2, when the passive device detects that it is in an energy fluctuation environment, it further includes performing an energy budget before performing communication, including: Step B1: The passive device calculates the cumulative energy collection and cumulative energy consumption within a preset window period prior to the current moment. Step B2: The passive device calculates the net energy balance within the preset window time based on the cumulative energy collection and the cumulative energy consumption, and determines whether the net energy balance is greater than zero. If so, then continue communication within the current heartbeat cycle; If not, cellular communication is permitted when the current energy margin is in the enhancement zone and the time required for the current energy margin to drop to the boundary value between the enhancement zone and the base zone is greater than twice the time required to complete one cellular communication; and when the current energy margin is in the base zone, only low-power short-range communication is permitted, and the current heartbeat cycle is extended.

[0014] Preferably, in step 2, when the passive device detects that it is in a zero-energy environment and no external event is detected, it uses an exponential backoff algorithm to continuously extend the heartbeat interval until it reaches the preset maximum heartbeat interval.

[0015] The present invention also provides a passive IoT device that uses the above-described communication scheduling method for communication, the passive IoT device comprising: The storage module is used to store at least three pre-configured consecutive energy storage state intervals and the corresponding interval switching hysteresis conditions. An energy monitoring module, connected to an energy storage element, is used to collect the current energy balance of the energy storage element in real time, and determine the current energy storage state interval based on the current energy balance and the interval switching hysteresis condition. The communication scheduling module is connected to the storage module and the energy monitoring module respectively. It is used to switch to a communication mode that matches the power consumption according to the determined energy storage state range, and to perform corresponding communication control based on the communication mode.

[0016] The above technical solution has the following advantages or beneficial effects: This invention, by pre-configuring at least three continuous energy storage state intervals and interval switching hysteresis conditions, combined with real-time energy margin acquisition and hysteresis determination, can stably determine the current energy storage state interval of a passive device, effectively avoiding frequent energy storage state switching caused by energy margin fluctuations and improving device operational stability. Simultaneously, this invention adaptively switches to a communication mode adapted to power consumption based on the energy storage state interval and performs communication control based on the matched communication mode, ensuring that the device's communication behavior is highly adapted to the current energy margin. This avoids device malfunctions caused by insufficient energy support triggering mismatched communication behaviors, ensuring reliable operation of micro-energy powered passive devices. Overall, it achieves coordinated control of stable energy state determination, on-demand communication mode switching, and fine-grained communication behavior scheduling. Without requiring complex hardware or additional algorithms, it significantly improves the operational stability and energy utilization efficiency of micro-energy passive devices, possessing strong practicality and wide applicability. Attached Figure Description

[0017] Figure 1 A flowchart illustrating a communication scheduling method for a low-energy-powered passive device is provided in a preferred embodiment of the present invention. Figure 2 In a preferred embodiment of the present invention, a schematic diagram showing the corresponding switching of the energy storage state interval and its corresponding interval switching hysteresis condition and communication mode is provided. Figure 3 In a preferred embodiment of the present invention, a schematic diagram of a passive device switching to a corresponding communication mode according to a determined energy storage state range is shown. Figure 4 A schematic diagram of the off-grid pre-detection process is shown in a preferred embodiment of the present invention. Figure 5 A schematic diagram of cold start energy threshold detection in a preferred embodiment of the present invention; Figure 6 This is a flowchart illustrating the energy budgeting process before communication is performed, as a preferred embodiment of the present invention. Figure 7 A schematic diagram of the structure of a passive IoT device in a preferred embodiment of the present invention; Figure 8 This is a schematic diagram of the internal structure of a logistics pallet in Embodiment 1 of the present invention; Figure 9 This is a schematic diagram of the heartbeat interval of the exponential backoff algorithm in Embodiment 3 of the present invention; Figure 10 This is the overall voltage-time curve during different scene switching in Embodiment 5 of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within the scope of the present invention.

[0019] In a preferred embodiment of the present invention, based on the above-mentioned problems existing in the prior art, a communication scheduling method for a passive device powered by micro-energy is provided. This method is applicable to IoT passive devices powered by micro-energy harvesting, such as vibration power generation, photovoltaic power generation, and thermoelectric power generation, and is particularly suitable for mobile asset tracking scenarios without batteries or external power sources, such as logistics pallets, turnover boxes, and passive sensors.

[0020] When implementing this communication scheduling method, at least three consecutive energy storage state intervals and corresponding interval switching hysteresis conditions need to be pre-configured. The energy storage state interval is used to characterize the energy reserve status of passive devices, and the energy reserve status is preferably reflected directly by collecting the voltage value of the energy storage element of the passive device. The interval switching hysteresis condition is used to suppress frequent switching of energy storage states caused by fluctuations in energy reserve at interval boundaries, reduce the additional energy loss caused by repeated start-stop of the RF module, and improve the stability of system operation.

[0021] like Figure 1 As shown, the communication scheduling method includes: Step 1: The passive device collects its current energy reserve in real time and determines the current energy storage state range based on the current energy reserve and the interval switching hysteresis condition. Step 2: The passive device switches to a communication mode that matches the power consumption according to the determined energy storage state range, and performs corresponding communication control based on the communication mode.

[0022] In a preferred embodiment of the present invention, the interval switching hysteresis condition includes an upward hysteresis condition and a downward hysteresis condition. The upward hysteresis condition includes an upward hysteresis amount and a first hysteresis time, and the downward hysteresis condition includes a downward hysteresis amount and a second hysteresis time. Specifically, in this embodiment, the passive device uses its internally integrated voltage monitoring circuit to collect the current voltage value of its energy storage element in real time to represent the current energy reserve. Based on this, the corresponding rising hysteresis condition includes the rising hysteresis amount ΔV_up and the first hysteresis time T_stable, and the falling hysteresis condition includes the falling hysteresis amount ΔV_down and the second hysteresis time T_stable. The first hysteresis time and the second hysteresis time can be the same or different, and are not limited here.

[0023] Furthermore, the rules for determining the current energy storage state range based on the current energy surplus and the interval switching hysteresis condition are as follows: When there is a switching trend from a low energy margin state interval to an adjacent high energy margin state interval in the current energy margin of the passive device, it is judged whether the current energy margin is higher than the sum of the interval boundary value between the corresponding low energy margin state interval and the adjacent high energy margin state interval and the rising hysteresis amount during the continuous first hysteresis time; if it is satisfied, the adjacent high energy margin state interval is determined as the current energy storage state interval. When there is a switching trend from a high energy margin state interval to an adjacent low energy margin state interval in the current energy margin of the passive device, it is judged whether the current energy margin is lower than the difference between the interval boundary value between the corresponding high energy margin state interval and the adjacent low energy margin state interval and the falling hysteresis amount during the continuous second hysteresis time; if it is satisfied, the adjacent low energy margin state interval is determined as the current energy storage state interval.

[0024] In a preferred embodiment of the present invention, each energy storage state interval includes an enhancement area, a basic area, and a life-saving area in order of decreasing energy margin state, and the corresponding interval boundary values are the first threshold V1 and the second threshold V2 respectively. Among them, the energy margin in the life-saving area is the lowest, corresponding to the voltage value V < V1; the energy margin in the basic area is medium, corresponding to the voltage value V1 ≤ V < V2; the energy margin in the enhancement area is the highest, corresponding to the voltage value V < V2.

[0025] Preferably, the value range of the first threshold V1 is 2.8V to 3.2V, the value range of the second threshold V2 is 3.5V to 4.0V, which is adapted to the working voltage characteristics of the lithium-ion capacitor LIC or the supercapacitor. The value of the rising hysteresis amount ΔV_up is preferably 50mV to 200mV, the value of the falling hysteresis amount ΔV_down is preferably 50mV to 150mV, and the value of the hysteresis stable time T_stable is preferably 5 seconds to 60 seconds. It can be understood that the above values are only examples and do not limit the present invention.

[0026] Furthermore, the passive device switches to a communication mode adapted to the power consumption according to the energy storage state interval determined in step 1, and performs corresponding communication control based on the communication mode, so that the communication behavior is strictly matched with the current energy margin, avoiding sudden death of the device due to a sharp drop in voltage caused by starting high-power communication due to insufficient energy, and realizing fine-grained collaborative scheduling of energy and communication.

[0027] Specifically, in this embodiment, as Figure 2 shown, the three energy storage state spaces respectively correspond to three communication modes with different power consumption levels. Among them, the enhancement area corresponds to the high-power communication mode, the basic area corresponds to the low-power communication mode, and the life-saving area corresponds to the lowest-power communication mode. It is preferred to dynamically switch communication modes with different power consumption levels through a communication state machine.

[0028] The corresponding communication control based on each communication mode includes: When the communication mode is the lowest power communication mode (corresponding to the S0 deep sleep state of the communication state machine), the passive device shuts down all its active radio frequency modules, retaining only the MCU's lowest power operation, acceleration interrupt wake-up, and RFID / NFC passive response, and prohibiting all active radio frequency communication; When the communication mode is low-power communication mode (corresponding to the S1 low-power communication state of the communication state machine), the passive device turns on its own low-power short-range communication module (such as BLE) to perform Mesh networking or beacon broadcasting, and prohibits the wide-area cellular communication module from being turned on. When the communication mode is high-power communication mode (corresponding to the S2 wide-area communication state of the communication state machine), the passive device turns on its own wide-area cellular communication module (such as NB-IoT / Cat.1) to perform remote data reporting.

[0029] In a preferred embodiment of the present invention, the invention further includes pre-configuring communication strategies with different service priorities adapted to the power consumption of the corresponding communication modes for each energy storage state interval; wherein, preferably, the service level of the service data is divided into P0 level (survival heartbeat), P1 level (state / location change), and P2 level (batch historical data), and a two-dimensional mapping relationship between energy intervals and service priorities is established as shown in Table 1 below: Table 1. Two-dimensional mapping relationship between energy range and business priority

[0030] In step 2, when the passive device needs to send service data, it performs the corresponding communication control based on the two-dimensional mapping relationship between the energy range and service priority mentioned above: In the switched communication mode, the corresponding communication strategy is executed to process the business data based on the business priority of the business data.

[0031] Specifically, in the life-saving zone, P0 level data is passively written and saved using RFID / NFC and is not discarded; P1 level data is cached in local Flash; and P2 level data can be discarded or compressed for storage.

[0032] In the basic zone, P0 / P1 level data is reported via BLE broadcast or Mesh relay; P2 level data is buffered and awaits the enhancement zone; in the enhancement zone, P0 / P1 / P2 level data are reported instantly or in batches via NB-IoT.

[0033] Therefore, P0-level business data (survival heartbeat) is not discarded in any energy storage state range. In the life-saving zone, it is saved by passive writing via RFID / NFC EEPROM and awaits reading by an external reader. P2-level business data (batch historical data) is only reported through the cellular channel in the enhanced zone. In the life-saving zone, it can be discarded or compressed to save Flash space.

[0034] In a preferred embodiment of the present invention, such as Figure 3 As shown, in step 2, the passive device switches to the corresponding communication mode according to the determined energy storage state range, including: When the passive device is currently in the survival zone, the determined energy storage state range is the basic zone, and the passive response device is triggered, the passive device switches from the lowest power communication mode to the low power communication mode. When the passive device is currently in the basic zone, the determined energy storage state interval is the enhanced zone, and there is pending service data (P1 / P2 level service data), the passive device switches from low-power communication mode to high-power communication mode. The passive device is currently in the enhancement zone, the determined energy storage state range is the basic zone, or when wide-area cellular communication is completed or timed out, the passive device switches from high-power communication mode to low-power communication mode. The passive device is currently in the basic zone, the determined energy storage state range is the survival zone, or when the data to be sent has been processed, the passive device switches from the low power communication mode to the lowest power communication mode. When the energy reserve drops to the absolute protection state (typically 2.5V), the passive device immediately shuts down all RF modules and directly switches from the current communication mode to the lowest power communication mode.

[0035] To further prevent devices from suddenly dying due to blindly starting cellular communication, passive devices must perform off-network pre-detection and cold start energy threshold detection before switching from low-power mode to high-power mode. Only after passing both verifications can the device be started.

[0036] Among them, such as Figure 4 As shown, the off-grid pre-detection process includes: In step A1, the passive device only turns on the radio frequency front-end of the wide-area cellular communication module, without starting the complete cellular protocol stack, and the power consumption is reduced to less than 1 / 10 of normal communication. Step A2: The passive device performs a fast RSSI scan on a preset frequency band (e.g., Band 5 / Band 8), with a scan duration of ≤3 seconds, and determines whether the maximum RSSI value detected exceeds a preset threshold (preferably -110dBm to -100dBm). If so, then the network is determined to be reachable; If not, the RF front-end will be shut down, while maintaining low-power communication mode. Retry will be prohibited within a preset heartbeat cycle (e.g., 3-10 heartbeat cycles) to avoid unnecessary power consumption.

[0037] After determining network reachability as described above, and before initiating full cellular protocol stack communication, a cold start energy threshold detection is also included. The cold start energy threshold detection process includes: The passive device calculates the minimum energy required to complete a full cellular communication, and starts the full cellular protocol stack for communication when its available energy is greater than a preset multiple of the minimum energy; otherwise, it abandons the current cellular communication.

[0038] Among them, such as Figure 5 As shown, taking a capacitor as an example of an energy storage element, the usable energy .

[0039] Minimum Energy This includes the energy consumption of the entire process, from module wake-up and network attachment to data transmission, confirmation of reception, and module shutdown, with a minimum energy requirement. Typical values ​​are 0.3mWh to 0.8mWh, corresponding to NB-IoT communication time of 5 to 15 seconds and peak power consumption of 120mW to 200mW.

[0040] Only when the current available energy > When the safety factor is × (1.5 to 2.0), switching to high-power communication mode to start cellular communication is allowed; otherwise, the current communication is abandoned, the data is cached in Flash, and the power is restored.

[0041] In a preferred embodiment of the present invention, step 2, when the passive device detects that it is in an energy fluctuation environment, further includes performing an energy budget before performing communication, such as... Figure 6 As shown, it includes: Step B1: The passive device calculates the cumulative energy collection and cumulative energy consumption within a preset window period prior to the current moment. Step B2: The passive device calculates the net energy balance within a preset window period based on the cumulative energy collected and the cumulative energy consumed, and determines whether the net energy balance is greater than zero. If so, then continue communication within the current heartbeat cycle; If not, cellular communication is permitted when the current energy margin is in the enhancement zone and the time required for the current energy margin to drop to the boundary value between the enhancement zone and the base zone is greater than twice the time required to complete a cellular communication; and when the current energy margin is in the base zone, only low-power short-range communication is permitted, and the current heartbeat cycle is extended.

[0042] Specifically, in this embodiment, the preset sliding window is preferably 1-24 hours. Under energy fluctuation environment, it is preferable to perform energy budgeting for each heartbeat cycle, and the calculation of the energy budgeting algorithm is performed on the MCU. The calculation time for a single calculation does not exceed 5ms, and the additional power consumption is negligible.

[0043] Furthermore, net energy balance The calculation formula is: ; in, This represents the cumulative energy harvested. This represents the cumulative energy consumption. This is the preset window time.

[0044] like > 0 (Energy Surplus): Allows communication to be performed based on the current heartbeat.

[0045] like < 0 (energy deficit): Enhancement zone: Cellular communication is permitted only when the energy drops to the second threshold V2 for more than twice the communication duration; Basic area: Only BLE communication is allowed, and the heartbeat interval is extended.

[0046] In a preferred embodiment of the present invention, in step 2, when the passive device detects that it is in a zero-energy-harvesting environment and no external event is detected, it uses an exponential backoff algorithm to continuously extend the heartbeat interval until it reaches the preset maximum heartbeat interval.

[0047] Specifically, in this embodiment, the exponential backoff algorithm defines the heartbeat interval sequence as follows:

[0048] in: The initial heart rate interval is 1 minute to 30 minutes (typical value is 10 minutes). This is the retreat coefficient, with a value ranging from 1.5 to 3.0 (typical value 2.0). The maximum heart rate interval is 48 hours to 96 hours (typical value is 96 hours). Count the number of heartbeat cycles when no external event (vibration, RFID read / write, BLE connection) is detected consecutively.

[0049] When any external event is detected, the heartbeat interval is immediately reset to [normal]. The backoff sequence restarts; the above exponential backoff algorithm enables a LIC supercapacitor with a storage capacity of 2mWh to support the device's survival for no less than 10 days in a zero-energy-harvesting scenario.

[0050] This invention also provides a passive IoT device that uses the aforementioned communication scheduling method for communication, such as... Figure 7 As shown, passive IoT devices include: Storage module 1 is used to store at least three pre-configured consecutive energy storage state intervals and corresponding interval switching hysteresis conditions. Energy monitoring module 2 is connected to energy storage element 3 and is used to collect the current energy balance of energy storage element 3 in real time, and determine the current energy storage state range based on the current energy balance and the range switching hysteresis condition. The communication scheduling module 4 is connected to the storage module 1 and the energy monitoring module 2 respectively. It is used to switch to a communication mode that matches the power consumption according to the determined energy storage state range, and to perform corresponding communication control based on the communication mode.

[0051] Example 1 In this embodiment, a passive device is used as an example to illustrate how the present invention determines the current energy storage state range by combining the current energy reserve and the interval switching hysteresis condition.

[0052] Among them, such as Figure 8 As shown, the logistics pallet is equipped with a vibration energy harvesting module (power 0.5-15mW) and an LIC supercapacitor (capacity 2mWh, operating voltage 2.2V-3.8V).

[0053] The hardware configuration of this logistics pallet is as follows: Voltage monitoring: 12-bit ADC (resolution approximately 1mV) Hardware comparator: TI TLV3691 (response time <1μs) MCU: nRF52832 (ARM Cortex-M4, power consumption <5mA@64MHz) The pre-configured interval switching hysteresis condition parameters include the first threshold V1 = 3.0V (life-saving zone / basic zone boundary), the second threshold V2 = 3.6V (basic zone / enhanced zone boundary), the rising hysteresis ΔV_up = 100mV, the falling hysteresis ΔV_down = 80mV, and the settling time T_stable = 10 seconds.

[0054] During operation, the logistics pallet is initially in the safety zone (V=2.8V), and all RF modules are turned off. Subsequently, as vibration energy harvesting begins, the voltage slowly rises. When the voltage V rises to 3.0V, the hardware comparator generates an interrupt, and the MCU starts a 10-second timer.

[0055] During the timer's countdown, the MCU samples the voltage once per second. If any sampled value is lower than 3.1V (V1 + ΔV_up), the timer is reset. If the voltage remains above 3.1V for 10 seconds, it confirms entry into the basic region and enables the BLE module. If the voltage subsequently drops below 2.92V (V1 - ΔV_down) and remains below for 10 seconds, it confirms a return to the safety region and disables the BLE module.

[0056] In actual testing, the aforementioned hysteresis mechanism reduced the number of state transitions from an average of 15 times per hour without hysteresis to 2 times per hour, avoiding the extra energy consumption caused by frequent switching of the BLE module (each switch consumes approximately 0.01mWh), and fundamentally preventing frequent state transitions caused by voltage critical fluctuations.

[0057] Example 2 In this embodiment, the off-network pre-detection process of the present invention is illustrated by taking the transportation of a logistics pallet from a warehouse (with BLE gateway coverage) to a remote area (without cellular network coverage) in Example 1 as an example.

[0058] The passive devices reported their status via BLE Mesh within the warehouse, with sufficient energy storage (V=3.7V, in the enhancement zone). Vibration energy harvesting continued during transportation, maintaining energy storage within the enhancement zone. Upon arrival in remote areas, the devices attempted to report location information via NB-IoT.

[0059] Traditional solutions directly activate the NB-IoT module and execute the complete network attachment process (taking 10-30 seconds and consuming 0.5-1.0 mWh). If there is no cellular network coverage in the area, attachment will fail, and energy will be wasted. If the device repeatedly retryes (e.g., once per hour), the energy storage will be quickly depleted, and the device will "die" suddenly.

[0060] Before attempting to initiate NB-IoT, this invention only activates the RF front-end (power consumption approximately 20mW) and does not activate the protocol stack. A fast RSSI scan is then performed on Band 5 (850MHz) and Band 8 (900MHz), with a scan time of 2 seconds. The maximum detected RSSI value is -120dBm, below the threshold Rmin = -110dBm, indicating an off-network status. The RF front-end is immediately shut down. This off-network detection consumes only 0.01mWh (approximately 1 / 50th of a full NB-IoT communication). The detection failure timestamp is then recorded, and retrying is prohibited for the next 5 heartbeat cycles (approximately 50 minutes). The device reverts to BLE communication mode, waiting to re-enter an area with network coverage.

[0061] In actual testing, in scenarios without network coverage, off-network pre-detection extends the device's survival time from approximately 2 hours in the traditional solution to approximately 20 hours (a 10-fold improvement).

[0062] Example 3 In this embodiment, the exponential backoff algorithm of the present invention is illustrated using the example of energy collection without vibration for a long time in the warehouse in Example 1 (zero energy collection scenario).

[0063] The logistics pallet is initially in an energy storage state: V=3.5V, with approximately 1.8mWh of usable energy; Heart rate interval: T0 = 10 minutes.

[0064] Assuming a retreat coefficient of k=2.0 and a maximum heart rate interval of Tmax=96 hours, as follows... Figure 9 As shown, the heartbeat sequence using the exponential backoff algorithm of this invention is as follows: First heartbeat (t=0): The surviving heartbeat is broadcast via BLE beacon, consuming 0.02mWh, leaving 1.78mWh.

[0065] Second heartbeat (t=10min): No external event was detected, and the heartbeat interval was extended to 20 minutes.

[0066] Third heartbeat (t=30min): The heartbeat interval is extended to 40 minutes.

[0067] Fourth heartbeat (t=70min): The heartbeat interval is extended to 80 minutes.

[0068] Fifth heartbeat (t=150min): The heartbeat interval is extended to 160 minutes.

[0069] 6th heartbeat (t=310min): The heartbeat interval is extended to 320 minutes.

[0070] 7th heartbeat (t=630min): The heartbeat interval is extended to 640 minutes.

[0071] The 8th heartbeat (t=1270min≈21 hours): The heartbeat interval extended to 1280 minutes.

[0072] The 9th heartbeat (t=2550min≈42.5 hours): the heartbeat interval extended to 2560 minutes.

[0073] The 10th heartbeat (t=5110min≈85 hours): The heartbeat interval reaches Tmax=96 hours and does not extend further.

[0074] Subsequent heartbeats: sent once every 96 hours until the energy storage is depleted.

[0075] Energy consumption analysis is as follows: The cumulative energy consumption of the first 10 heartbeats was 0.2 mWh. Subsequent heartbeat consumption: 0.02mWh The remaining energy of 1.58 mWh can support approximately 79 heartbeats. Total survival time: 85 hours + 79 x 96 hours ≈ 316 days Actual test results: In a zero-energy-harvesting scenario, a 2mWh LIC supercapacitor supports a device that can survive for approximately 11 days (264 hours). If a fixed 10-minute heartbeat interval is used, the device can only survive for about 4 hours. The exponential backoff strategy extends the survival time by approximately 66 times.

[0076] Example 4 In this embodiment, the energy budgeting algorithm of the present invention is illustrated using the scenario of a logistics pallet undergoing intercity transportation in Example 1, where the vibration energy harvesting power fluctuates drastically.

[0077] Assuming a sliding window W = 1 hour, current time t = 0, energy storage V = 3.7V, and available energy 1.9mWh. The cumulative energy harvested in the past hour is E_harvest = 0.8mWh (average power 0.22mW), and the cumulative energy consumed is E_consume = 0.3mWh (BLE communication + MCU operation). The net energy balance is P_net = (0.8 - 0.3) / 1 = 0.5mWh / h.

[0078] Since P_net = 0.5mWh / h > 0, it is determined to be an energy surplus state, currently in the enhancement zone (V = 3.7V), allowing NB-IoT communication to be performed.

[0079] The NB-IoT communication is expected to consume 0.5mWh, and the energy storage will drop to 1.4mWh after the communication (V≈3.5V). Based on P_net=0.5mWh / h, the energy storage is expected to recover to 1.9mWh after 2.8 hours.

[0080] Then, NB-IoT communication is performed to report location and status data.

[0081] At t=2 hours, the truck stops to rest, vibration energy collection stops, and the scene changes. At this time, E_harvest=0.1mWh (only weak vibration), E_consume=0.2mWh, P_net=(0.1-0.2) / 1=-0.1mWh / h in the past hour.

[0082] Since P_net = -0.1mWh / h < 0, the system is considered to be in an energy deficit state. The current energy storage voltage V = 3.6V, still within the enhancement zone. The calculation of the time T_drain required for the energy storage to decrease from 3.6V to V2 = 3.6V is as follows: Since P_net < 0, if the current power consumption continues, the energy storage will continue to decrease. The calculation of the time T_comm required to complete one NB-IoT communication is 10 seconds, and the required energy E_comm = 0.5mWh.

[0083] Assessment: If NB-IoT communication is implemented, energy storage will drop to 1.4mWh (V≈3.5V), still above the basic range, and the P_net depletion rate is slow, allowing communication. However, to be conservative, the heartbeat interval will be extended from 10 minutes to 30 minutes to reduce the energy consumption rate.

[0084] In actual testing, the energy budget algorithm increased the communication success rate of the device in energy-fluctuating environments from about 60% with traditional fixed strategies to about 95%, while avoiding the risk of "sudden death" caused by blind communication.

[0085] Example 5 In this embodiment, by combining a hysteresis determination mechanism, communication mode switching, and security verification strategy, the entire communication scheduling process of the intercity transportation → warehouse storage → loading and transportation → remote area → arrival at the destination is fully reconstructed. The overall voltage-time curve during different scenario switching is shown below. Figure 10 As shown, from Figure 10 It can be seen from this: Phase A: Intercity Transportation - Vibration Energy Harvesting (0~4h) In intercity transportation scenarios, passive devices move with the vehicle, generating sufficient power through vibration and rapidly increasing the energy storage voltage.

[0086] The scheduling process is as follows: 1. Initial state: The device is powered on, the energy storage voltage is lower than V1, it is in the life-saving zone, and maintains the minimum power consumption (only the MCU is running at minimum).

[0087] 2. Entering the basic region (trigger point ①): The voltage exceeds V1+ΔVup (approximately 3.1V) and the duration exceeds Tstable.

[0088] Action: Switch to Low Power Communication (BLE) mode, enable the BLE module, and execute beacon broadcast.

[0089] 3. Entering the enhancement zone (trigger point ②): The voltage exceeds V2+ΔVup (approximately 3.6V+0.15V) and the duration exceeds Tstable.

[0090] action: 1) Perform off-network pre-detection: Enable NB-IoT radio front-end scanning RSSI to confirm good network coverage (RSSI > threshold).

[0091] 2) Perform cold start energy test: Current energy > Ecomm × 1.5, safe start.

[0092] 3) Switch to high-power communication mode (NB-IoT) to perform remote data reporting (such as location, temperature and humidity).

[0093] Phase B: Warehouse inactivity – Zero energy extraction (4h~16h)

[0094] In this scenario, the equipment enters the warehouse, vibration monitoring stops, energy is consumed without replenishment, and the voltage drops slowly.

[0095] The scheduling process is as follows: 1. Energy surplus stage (4h~6h): The voltage is maintained near the peak value of the enhancement region, and Pnet>0.

[0096] Scheduling: Continuous BLE heartbeat + periodic NB-IoT reporting ensures real-time data transmission.

[0097] 2. The initial stage of index retreat (6h~16h): If the voltage drops below V2 but has not yet dropped below V2−ΔVdown, the device is determined to be in an energy deficit state.

[0098] Scheduling: Initiate the exponential backoff heartbeat algorithm, continuously increasing the heartbeat interval (from T0 to Tmax) to reduce communication frequency and extend survival time.

[0099] 3. Back-off state (trigger point ③): The voltage remains below V2−ΔVdown for more than Tstable.

[0100] Action: Return to S1 (Basic Zone / BLE Mode), turn off the NB-IoT module, and only retain the BLE low-power heartbeat to save energy.

[0101] Phase C: Warehouse Remains Static – Continue Zero Energy Extraction (16h~24h) In this scenario, with no energy input for an extended period, the voltage continues to decline, reaching the edge of the base zone.

[0102] The scheduling process is as follows: 1. Pnet<0 Strict control: Net energy balance is negative, the device executes energy budget, and only low-power BLE communication is allowed.

[0103] If there is data to be sent (P2), it will be cached in the local Flash and not reported for the time being.

[0104] 2. Critical state: The voltage is approaching the V1 warning line, ready to enter the life-saving zone at any time.

[0105] Phase D: Loading and Transportation – Energy Recovery (24h~28h) In this scenario, the equipment is moved and loaded onto a vehicle, re-enters the vibration acquisition environment, and its energy rapidly recovers.

[0106] The scheduling process is as follows: 1. External event wake-up (trigger point ④): Vibration acquisition resumes, voltage rebounds rapidly.

[0107] Action: When triggered by an external event (acceleration change), the heartbeat interval is reset to the initial value T0, and the normal communication cycle restarts.

[0108] 2. Re-enter the basic area: If the voltage exceeds V1, switch back to BLE mode and resume data acquisition and caching.

[0109] 3. Re-entering the enhancement zone: The voltage quickly exceeds V2, meeting the rise hysteresis condition, and the NB-IoT communication preparation state is restarted.

[0110] Phase E: Remote areas — No network coverage (28h~40h) In this scenario, the device leaves the urban network coverage area and enters a remote area, where it has sufficient power but lacks network coverage.

[0111] The scheduling process is as follows: 1. Off-network pre-detection failure (trigger point ⑤): The device attempts to start NB-IoT and perform a fast RSSI scan, but the scan result is below the threshold.

[0112] Action: If the pre-detection fails (at the triangle marker), shut down the RF front end and prohibit retrying (do not attempt to connect to the network within the next N heartbeat cycles).

[0113] 2. Energy budgeting and survival: With sufficient local power (Pnet>0), the device maintains a BLE heartbeat, caches data, avoids sudden death caused by blindly high-power communication, and maximizes the use of existing energy while waiting for the network to recover.

[0114] Phase F: Arrival at destination — Network restored (40h~48h) In this scenario, the device arrives at its destination and re-enters the network coverage area.

[0115] The scheduling process is as follows: 1. Network recovery trigger: When the voltage touches the V2 threshold again, the device performs an off-network pre-detection, detects a strong RSSI signal, and the network recovers.

[0116] 2. Batch reporting (marked at ⑤): Switch to high power mode and batch report P2 level historical data (such as long-term trajectory data) cached in Phase E stage.

[0117] 3. Subsequent dynamics: After the data reporting is completed, the energy consumption causes the voltage to drop and return to the basic zone (BLE); if the energy continues to be exhausted, it will eventually slide to the life-saving zone or emergency protection state (Vprotect), completely shutting down all radio frequencies.

[0118] As can be seen, this invention fully covers all operating scenarios from high energy to zero energy, and from network access to network outage, realizing long survival, high reliability, and refined communication scheduling for low-energy passive devices.

[0119] In summary, this invention addresses logistics vehicles powered by low-energy harvesting. It avoids frequent state switching caused by voltage critical fluctuations through a hysteresis judgment mechanism, prevents "sudden death" caused by blindly attempting high-power communication through off-grid pre-detection, maximizes device survival time in zero-energy harvesting scenarios through an exponential backoff heartbeat strategy (2mWh of energy storage can support more than 10 days), and achieves "capable-for-energy" communication scheduling through an energy budget algorithm. This invention categorizes business data into three priorities and employs differentiated communication strategies at different energy levels to ensure that critical data is not lost. It is applicable to passive IoT devices powered by low-energy harvesting, such as vibration-generated and photovoltaic power generation systems.

[0120] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. A method for communication scheduling of a micro-energy powered passive device, characterized in that, The method includes pre-configuring at least three consecutive energy storage state intervals and corresponding interval switching hysteresis conditions, wherein the energy storage state intervals are used to characterize the energy reserve status of the passive device; the communication scheduling method includes: Step 1: The passive device collects its current energy reserve in real time, and determines the current energy storage state interval based on the current energy reserve and the interval switching hysteresis condition. Step 2: The passive device switches to a communication mode that matches the power consumption according to the determined energy storage state range, and performs corresponding communication control based on the communication mode.

2. The communication scheduling method of claim 1, wherein, The interval switching hysteresis conditions include an upward hysteresis condition and a downward hysteresis condition. The upward hysteresis condition includes an upward hysteresis amount and a first hysteresis time. The downward hysteresis condition includes a downward hysteresis amount and a second hysteresis time. In step 1, when the current energy reserve shows a switching trend from a low energy reserve state interval to an adjacent high energy reserve state interval, and the current energy reserve is higher than the sum of the interval boundary value of the corresponding low energy reserve state interval and the adjacent high energy reserve state interval and the rising hysteresis amount for the first hysteresis time, the passive device determines the adjacent high energy reserve state interval as the current energy storage state interval. When the passive device shows a switching trend from a high energy reserve state interval to an adjacent low energy reserve state interval, and the current energy reserve is lower than the difference between the interval boundary value of the corresponding high energy reserve state interval and the adjacent low energy reserve state interval and the decreasing hysteresis amount for the second hysteresis time, the adjacent low energy reserve state interval is determined as the current energy storage state interval.

3. The communication scheduling method of claim 1, wherein, Each of the energy storage state intervals includes an enhancement zone, a basic zone, and a survival zone in descending order of energy reserve, and is respectively associated with a high-power communication mode, a low-power communication mode, and a minimum-power communication mode. Step 2, which involves performing corresponding communication control based on the communication mode, includes: When the communication mode is the lowest power communication mode, the passive device shuts down all its active radio frequency modules and retains only the passive response device. When the communication mode is the low-power communication mode, the passive device activates its own low-power short-range communication module to perform Mesh networking or beacon broadcasting. When the communication mode is the high-power communication mode, the passive device activates its own wide-area cellular communication module to perform remote data reporting.

4. The communication scheduling method of claim 3, wherein, It also includes communication strategies that pre-configure different service priorities for each of the energy storage state intervals and adapt them to the power consumption of the corresponding communication modes; In step 2, when the passive device needs to send service data, the corresponding communication control based on the communication mode further includes: In the switched communication mode, the corresponding communication strategy is executed to process the service data based on the service priority of the service data.

5. The communication scheduling method of claim 3, wherein, Step 2, the passive device switching to the corresponding communication mode according to the determined energy storage state range includes: When the passive device is currently in the life-saving zone, the determined energy storage state interval is the basic zone, and the passive response device is triggered, the passive device switches from the lowest power communication mode to the low power communication mode. When the passive device is currently in the basic zone, and the determined energy storage state interval is the enhanced zone and there is service data to be sent, the passive device switches from the low-power communication mode to the high-power communication mode. The passive device is currently in the enhancement zone, the determined energy storage state interval is the basic zone, or when wide-area cellular communication is completed or timed out, the passive device switches from the high-power communication mode to the low-power communication mode. When the passive device is currently in the basic zone, the determined energy storage state interval is the life-saving zone, or when the data to be sent has been processed, the passive device switches from the low-power communication mode to the lowest power communication mode. When the energy reserve state decreases to the absolute protection state, the passive device immediately shuts down all radio frequency modules and directly switches from the current communication mode to the lowest power consumption communication mode.

6. The communication scheduling method of claim 3, wherein, In step 2, before the passive device switches from the low-power communication mode to the high-power communication mode, an off-network pre-detection process is also included, which includes: Step A1: The passive device only turns on the radio frequency front-end of the wide-area cellular communication module, without starting the complete cellular protocol stack; Step A2: The passive device performs a fast RSSI scan on a preset frequency band and determines whether the maximum RSSI value detected exceeds a preset threshold. If so, the full cellular protocol stack is activated for communication in order to switch to the high-power communication mode; If not, the radio frequency front end is shut down, the low-power communication mode is maintained, and retries are prohibited within a future preset heartbeat cycle.

7. The communication scheduling method of claim 6, wherein, In step A2, before the passive device starts the complete cellular protocol stack for communication, it also includes cold start energy threshold detection. The cold start energy threshold detection process includes: The system calculates the minimum energy required to complete a full cellular communication, and initiates the full cellular protocol stack for communication when its available energy is greater than a preset multiple of the minimum energy; otherwise, it abandons the current cellular communication.

8. The communication scheduling method according to claim 3, characterized in that, In step 2, when the passive device detects that it is in an energy fluctuation environment, it also includes performing an energy budget before performing communication, including: Step B1: The passive device calculates the cumulative energy collection and cumulative energy consumption within a preset window period prior to the current moment. Step B2: The passive device calculates the net energy balance within the preset window time based on the cumulative energy collection and the cumulative energy consumption, and determines whether the net energy balance is greater than zero. If so, then continue communication within the current heartbeat cycle; If not, cellular communication is permitted when the current energy margin is in the enhancement zone and the time required for the current energy margin to drop to the boundary value between the enhancement zone and the base zone is greater than twice the time required to complete one cellular communication; and when the current energy margin is in the base zone, only low-power short-range communication is permitted, and the current heartbeat cycle is extended.

9. The communication scheduling method according to claim 1, characterized in that, In step 2, when the passive device detects that it is in a zero-energy environment and no external event is detected, it uses an exponential backoff algorithm to continuously extend the heartbeat interval until it reaches the preset maximum heartbeat interval.

10. A passive Internet of Things (IoT) device, characterized in that, The IoT passive device performs communication using the communication scheduling method described in any one of claims 1-9, and includes: The storage module is used to store at least three pre-configured consecutive energy storage state intervals and the corresponding interval switching hysteresis conditions. An energy monitoring module, connected to an energy storage element, is used to collect the current energy balance of the energy storage element in real time, and determine the current energy storage state interval based on the current energy balance and the interval switching hysteresis condition. The communication scheduling module is connected to the storage module and the energy monitoring module respectively. It is used to switch to a communication mode that matches the power consumption according to the determined energy storage state range, and to perform corresponding communication control based on the communication mode.

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