WiFi low-power-consumption method and device for Internet of Things

Abstract

The invention provides an Internet of Things WiFi low power consumption method and device, the device comprises STA equipment and a WiFi hotspot capable of distributing a unique association identifier to the STA equipment, and the STA equipment comprises a timer, a judgment logic module, a CPU module, a radio frequency module and an analysis module; the method further comprises the following steps that S1, the timer sends a pre-starting signal to the judgment logic module according to a preset starting period, and the judgment logic module starts the radio frequency module; s2, the radio frequency module receives the transmission frame and transmits the transmission frame to an analysis module, and the analysis module analyzes the transmission frame according to the association identifier to obtain an indication signal and transmits the indication signal to a judgment logic module; and S3, the judgment logic module judges whether data transmission exists or not according to the indication signal, if not, the judgment logic module closes the radio frequency module, and the CPU module is kept in a dormant state. By adopting the method and the device, the total standby power consumption is reduced by more than 60%, and the delay of receiving the transmission frame by the STA equipment is doubly reduced.

Description

Technical Field

[0001] This invention relates to Internet of Things (IoT) WiFi, specifically to a low-power method and apparatus for IoT WiFi. Background Technology

[0002] With the popularization of IoT technology, WiFi hotspots have become the mainstream communication technology in scenarios such as smart homes, industrial monitoring, and smart agriculture. For example, temperature and humidity sensors in factory workshops, smart smoke detectors in homes, and soil moisture monitoring equipment in farmland all connect to the network via WiFi STA mode. The core requirement for these devices is "long battery life": most are battery-powered, which has high replacement and maintenance costs, and requires a battery life of 6-12 months on a single charge. Therefore, reducing power consumption has become a core technical challenge.

[0003] The power consumption of a WiFi STA mainly comes from two core modules: the radio frequency module (responsible for receiving Beacon frames and data frames) and the CPU module (responsible for parsing Beacon frames and determining sleep logic). To balance communication needs and power consumption, the industry generally adopts the PSM mode defined by the WiFi standard, whose core logic is to "wake up the device only when it needs to receive data, and keep it in sleep mode the rest of the time".

[0004] The operation of PSM mode relies on the coordination between the WiFi hotspot and the STA device: the WiFi hotspot broadcasts Beacon frames at fixed time intervals (TBTT), and the STA device is woken up by TBTT interrupts at the same intervals. After receiving the Beacon frame, it parses the TIM field—if it finds targeted data buffer (unicast bit set to 1) or multicast data (multicast indicator bit set to 1), it remains awake to receive data; otherwise, it re-enters sleep mode. This mechanism performs well in traditional consumer electronics scenarios (such as mobile phones and tablets) because these devices have high communication frequencies, and after waking up, they are likely to obtain valid data, resulting in a low percentage of power consumption from invalid wake-ups.

[0005] However, in IoT scenarios, the inherent defects of the PSM mode are amplified: the communication characteristics of IoT STA devices are "low frequency and small data"—for example, a temperature and humidity sensor uploads 10 bytes of data every 10 seconds, a smart smoke detector only sends data when alarming, and in most cases, the WiFi hotspot does not send any data to the STA device. At this time, the problem of the traditional PSM mode becomes prominent: the STA device still needs to be woken up by the TBTT interrupt every 102 milliseconds to start the RF module to receive Beacon frames, and then the CPU module parses the TIM field to confirm that there is no data. The whole process takes about 10 milliseconds, but does not generate any effective communication value, resulting in "ineffective wake-up power consumption".

[0006] According to actual test data, in the traditional PSM mode, the power consumption of a certain type of IoT WiFi sensor accounts for 65% of the total power consumption during the invalid wake-up process—the battery life is only 3 months when powered by battery, which is far from meeting the industry's needs.

[0007] Therefore, there is a need for a low-power method and apparatus that can optimize the invalid wake-up problem in PSM mode and reduce the meaningless operation of the CPU module and RF module. Summary of the Invention

[0008] To overcome the existing technical problems, the present invention provides a low-power WiFi method and apparatus for the Internet of Things.

[0009] The present invention adopts the following technical solution.

[0010] A low-power WiFi method for the Internet of Things includes a STA device and a WiFi hotspot capable of assigning a unique association identifier to the STA device. The STA device includes a timer, a judgment logic module, a CPU module, a radio frequency module, and a parsing module. It also includes the following steps: S1. The timer sends a pre-start signal to the judgment logic module according to the preset start cycle, and the judgment logic module starts the radio frequency module. S2. The radio frequency module receives the transmission frame and transmits it to the parsing module. The parsing module parses the transmission frame according to the associated identifier to obtain the indication signal and transmits it to the judgment logic module. S3. The judgment logic module determines whether data transmission exists based on the indication signal. If so, the judgment logic module wakes up the CPU module. The CPU module obtains the transmission frame from the radio frequency module and sends a completion signal to the judgment logic module. The judgment logic module then shuts down the radio frequency module and drives the CPU module into sleep mode. If not, the logic module will shut down the RF module and keep the CPU module in sleep mode.

[0011] As a further improvement of the present invention, the transmission frame includes a Beacon frame, and the parsing module is a TIM parsing module; The TIM parsing module includes a frame synchronization unit for detecting the frame preamble of the Beacon frame, a field positioning unit for locating and extracting the TIM field, and a signal output unit for converting the TIM field into an indication signal.

[0012] As a further improvement of the present invention, the field positioning unit locates the TIM field by offset and extracts the Bitmap Control subfield and Part Virt Bmap subfield from the TIM field; The specific steps to convert the TIM field into an indication signal include: when the TrafficInd bit of the Bitmap Control subfield is 1, the multicast indication signal is set high; otherwise, the multicast indication signal is set low. When the bit corresponding to the STA device association identifier in the Part Virt Bmap subfield is 1, the unicast indicator signal is set high; otherwise, the unicast indicator signal is set low.

[0013] As a further improvement of the present invention, the TIM parsing module also includes a target AID register storing an associated identifier, which is used to match the bits of the Part Virt Bmap subfield according to the associated identifier.

[0014] As a further improvement of the present invention, the specific steps of the judgment logic module to determine whether data transmission exists based on the indication signal include: if both the multicast indication signal and the unicast indication signal are set low, then the judgment is no; If the multicast indicator signal or the unicast indicator signal is set high, then it is determined as yes.

[0015] As a further improvement of the present invention, the startup period is equal to the sending period of the WiFi hotspot sending transmission frames; The timer has a preset start advance. When the time until the next start cycle is equal to the start advance, the timer sends a pre-start signal.

[0016] As a further improvement of the present invention, the STA device also includes an interrupt controller; The specific steps for determining whether the logic module wakes up the CPU module include: determining whether the logic module triggers the interrupt controller to send a wake-up signal to the CPU model; The specific steps to keep the CPU module in a sleep state include: disabling interrupt signals to keep the CPU module in a sleep state.

[0017] As a further improvement of the present invention, the transmission frame includes a Beacon frame and a data frame; The transmission frame in step S2 is a Beacon frame, and the transmission frame in step S3 is a Beacon frame and a data frame.

[0018] This invention also proposes an IoT WiFi low-power device, which employs the above-described IoT WiFi low-power method, including: WiFi hotspots are used to assign a unique association identifier to STA devices and to send transmission frames periodically. The STA device includes a timer that sends a pre-start signal to a judgment logic module according to a preset start cycle, a judgment logic module for turning off or starting the radio frequency module and the CPU module, a radio frequency module for receiving transmission frames and transmitting them to a parsing module, a parsing module for parsing transmission frames according to an associated identifier to obtain an indication signal and transmitting it to the judgment logic module, and a CPU module for acquiring transmission frames and sending a completion signal to the judgment logic module.

[0019] As a further improvement of the present invention, the transmission frame includes a Beacon frame, and the parsing module is a TIM parsing module; The TIM parsing module includes a frame synchronization unit for detecting the frame preamble of the Beacon frame, a field positioning unit for locating and extracting the TIM field, and a signal output unit for converting the TIM field into an indication signal.

[0020] The beneficial effects of this invention are as follows: 1. When there is no data transmission in the WiFi hotspot, even if a transmission frame is sent, the CPU module will not be woken up. Only 0.3μA of low-power hardware works, which reduces the power consumption of invalid wake-up from 0.44mA to 0.3μA, which is almost close to 0, thereby reducing the total standby power consumption by more than 60%.

[0021] 2. The timer sends a pre-start signal to start the RF module in advance, and the RF module's startup time is faster than the CPU module's startup time. This doubles the reduction in the latency of the STA device receiving transmission frames. Even if the WiFi hotspot's transmission time fluctuates, the STA device can still completely parse the transmission frames, thereby reducing the data loss rate from 3%-5% to below 0.1%. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the method flow of the present invention; Detailed Implementation

[0024] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product.

[0025] It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings. The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Reference Figure 1 A low-power WiFi method for the Internet of Things includes a STA device and a WiFi hotspot capable of assigning a unique association identifier to the STA device. The STA device includes a timer, a judgment logic module, a CPU module, a radio frequency module, and a parsing module. It also includes the following steps: S1. The timer sends a pre-start signal to the judgment logic module according to the preset start cycle, and the judgment logic module starts the radio frequency module. S2. The radio frequency module receives the transmission frame and transmits it to the parsing module. The parsing module parses the transmission frame according to the associated identifier to obtain the indication signal and transmits it to the judgment logic module. S3. The judgment logic module determines whether data transmission exists based on the indication signal. If so, the judgment logic module wakes up the CPU module. The CPU module obtains the transmission frame from the radio frequency module and sends a completion signal to the judgment logic module. The judgment logic module then shuts down the radio frequency module and drives the CPU module into sleep mode. If not, the logic module will shut down the RF module and keep the CPU module in sleep mode.

[0027] As a further improvement of the present invention, the transmission frame includes a Beacon frame and a data frame; The transmission frame in step S2 is a Beacon frame, and the transmission frame in step S3 is a Beacon frame and a data frame.

[0028] In existing technologies, the probability of WiFi hotspots having no data in IoT scenarios exceeds 95%. Each time a STA device wakes up, its CPU module needs to perform approximately 3 milliseconds of ineffective operations. During this process, both the CPU and RF modules continuously consume power, resulting in a high proportion of ineffective power consumption. Actual test data shows that the average power consumption of ineffective wake-ups in this solution is approximately 15mA·3ms / 102ms≈0.44mA, accounting for more than 60% of the device's standby power consumption, which cannot meet the requirements for long battery life.

[0029] By adopting the steps of this invention, when the WiFi hotspot is not transmitting data, even if a transmission frame is sent, the CPU module will not be woken up. Only 0.3μA of low-power hardware operates, thereby reducing the power consumption for invalid wake-up from 0.44mA to 0.3μA, almost approaching zero, and thus reducing the total standby power consumption by more than 60%. Actual test data: After adopting this solution, the proportion of invalid wake-up power consumption of a certain IoT sensor decreased from 65% to 3%, and the battery life was extended from 3 months to 12 months, fully meeting industry requirements.

[0030] Existing technology sets the CPU module's sleep depth to "deep sleep," requiring a 1-millisecond initialization time to recover from sleep to an operational state. If the WiFi hotspot sends a Beacon frame prematurely after a TBTT interrupt (with network latency fluctuating by ±2 milliseconds), the STA device's RF module may not start up in time, missing the Beacon frame reception. At this point, the CPU module cannot parse the TIM field, will default to no data, and will re-enter sleep mode, ultimately resulting in the loss of cached unicast / multicast data from the WiFi hotspot. Actual measurements show a data loss rate of approximately 3%-5% in this scenario, impacting device communication reliability.

[0031] By adopting the steps of this invention, the timer sends a pre-start signal to start the RF module in advance, and the RF module's startup time is faster than the CPU module's startup time. This doubly reduces the latency of the STA device receiving transmission frames. Even if the WiFi hotspot's transmission time fluctuates, the STA device can still completely parse the transmission frames, thereby reducing the data loss rate from 3%-5% to below 0.1%. In industrial scenario testing, 200 STAs worked continuously for 30 days, with only one data loss occurring, meeting reliability requirements.

[0032] As a further improvement of the present invention, the transmission frame includes a Beacon frame, and the parsing module is a TIM parsing module; The TIM parsing module includes a frame synchronization unit for detecting the frame preamble of the Beacon frame, a field positioning unit for locating and extracting the TIM field, and a signal output unit for converting the TIM field into an indication signal.

[0033] Specifically, the frame synchronization unit achieves synchronization by detecting the frame preamble (an 8-byte fixed sequence) of the Beacon frame, ensuring that only the Beacon frame is parsed and other data frames and noise are filtered out.

[0034] Furthermore, as a second embodiment of the present invention, the TIM parsing module can be replaced with an FPGA programmable module, and the parsing rules can be modified through a configuration file (such as adapting to non-standard Beacon frame formats). Advantages: stronger compatibility, able to handle customized frame structures for special industrial APs; Disadvantages: FPGA costs more than fixed logic circuits (approximately 0.5 yuan / chip), suitable for high-end industrial scenarios.

[0035] As a further improvement of the present invention, the field positioning unit locates the TIM field by offset and extracts the Bitmap Control subfield and Part Virt Bmap subfield from the TIM field; The specific steps to convert the TIM field into an indication signal include: when the TrafficInd bit of the Bitmap Control subfield is 1, the multicast indication signal is set high; otherwise, the multicast indication signal is set low. When the bit corresponding to the STA device association identifier in the Part Virt Bmap subfield is 1, the unicast indicator signal is set high; otherwise, the unicast indicator signal is set low.

[0036] Specifically, the TIM field is fixed at the 97th byte of the Beacon frame, the Bitmap Control subfield is located at the 101st byte, and the Part Virt Bmap subfield is located at the 102nd-103rd bytes. No other fields need to be parsed, and the parsing time is ≤100μs.

[0037] Existing simplified parsing functions are strongly tied to the CPU architecture of WiFi hotspots—for example, the parsing function of the ESP8266 cannot be directly ported to the MT7681 chip and needs to be redeveloped and optimized for different CPU instruction sets. Furthermore, if the Beacon frame format sent by the AP has non-standard extensions (such as custom fields added to some industrial APs), it will cause the simplified parsing function to fail, triggering misjudgments (treating data as no data), requiring software upgrades to fix, increasing subsequent maintenance costs.

[0038] By adopting the technical solution of this invention, the fixed field offset based on the WiFi 802.11 standard is parsed without relying on the CPU architecture, and is compatible with different models of WiFi chips. The non-standard extended field of the Beacon frame does not affect the parsing of the TIM field. There is no need to modify the software for different chips or WiFi hotspots, the adaptation cost is reduced by 90%, and the later maintenance cost is almost zero.

[0039] In addition, the newly added TIM parsing module and judgment logic module are pure digital logic circuits that can be integrated into the existing WiFi MAC layer chip without the need for an additional independent chip, increasing the hardware area by only 0.05mm. 2 (Based on 40nm process), the cost increase per chip is ≤0.1 yuan, which is far less than the value brought by the improvement in battery life, and it has the conditions for large-scale mass production.

[0040] As a further improvement of the present invention, the TIM parsing module also includes a target AID register storing an association identifier. The target AID register is used to match the bits of the Part Virt Bmap subfield according to the association identifier, thereby achieving a fast matching effect.

[0041] As a further improvement of the present invention, the specific steps of the judgment logic module to determine whether data transmission exists based on the indication signal include: if both the multicast indication signal and the unicast indication signal are set low, then the judgment is no; If the multicast indicator signal or the unicast indicator signal is set high, then it is determined as yes.

[0042] As a further improvement of the present invention, the startup period is equal to the sending period of the WiFi hotspot sending transmission frames; The timer has a preset start advance. When the time until the next start cycle is equal to the start advance, the timer sends a pre-start signal.

[0043] The startup lead time is specifically 5 milliseconds. The timer sends a pre-start signal to start the RF module in advance based on the startup lead time, and the startup time of the RF module is faster than that of the CPU module. This doubly reduces the latency of the STA device in receiving transmission frames. Even if the WiFi hotspot transmission time fluctuates, the STA device can still completely parse the transmission frame, thereby reducing the data loss rate from 3%-5% to below 0.1%.

[0044] As a further improvement of the present invention, the STA device also includes an interrupt controller; The specific steps for determining whether the logic module wakes up the CPU module include: determining whether the logic module triggers the interrupt controller to send a wake-up signal to the CPU model; The specific steps to keep the CPU module in a sleep state include: disabling interrupt signals to keep the CPU module in a sleep state.

[0045] This invention also proposes an IoT WiFi low-power device, which employs the above-described IoT WiFi low-power method, including: WiFi hotspots are used to assign a unique association identifier to STA devices and to send transmission frames periodically. The STA device includes a timer that sends a pre-start signal to a judgment logic module according to a preset start cycle, a judgment logic module for turning off or starting the radio frequency module and the CPU module, a radio frequency module for receiving transmission frames and transmitting them to a parsing module, a parsing module for parsing transmission frames according to an associated identifier to obtain an indication signal and transmitting it to the judgment logic module, and a CPU module for acquiring transmission frames and sending a completion signal to the judgment logic module.

[0046] As a further improvement of the present invention, the transmission frame includes a Beacon frame, and the parsing module is a TIM parsing module; The TIM parsing module includes a frame synchronization unit for detecting the frame preamble of the Beacon frame, a field positioning unit for locating and extracting the TIM field, and a signal output unit for converting the TIM field into an indication signal.

[0047] The effects of adopting the technical solution of the present invention are shown in Table 1 below: ; Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A low-power WiFi method for the Internet of Things, characterized in that, It includes STA devices and WiFi hotspots that can assign unique association identifiers to STA devices. STA devices include timers, judgment logic modules, CPU modules, radio frequency modules, and parsing modules. It also includes the following steps: S1. The timer sends a pre-start signal to the judgment logic module according to the preset start cycle, and the judgment logic module starts the radio frequency module. S2. The radio frequency module receives the transmission frame and transmits it to the parsing module. The parsing module parses the transmission frame according to the associated identifier to obtain the indication signal and transmits it to the judgment logic module. S3. The judgment logic module determines whether data transmission exists based on the indication signal. If so, the judgment logic module wakes up the CPU module. The CPU module obtains the transmission frame from the radio frequency module. The CPU module sends a completion signal to the judgment logic module. The judgment logic module shuts down the radio frequency module and drives the CPU module into a sleep state. If not, the logic module will shut down the RF module and keep the CPU module in sleep mode.

2. The IoT WiFi low-power method according to claim 1, characterized in that, The transmission frame includes a Beacon frame, and the parsing module is a TIM parsing module; The TIM parsing module includes a frame synchronization unit for detecting the frame preamble of the Beacon frame, a field positioning unit for locating and extracting the TIM field, and a signal output unit for converting the TIM field into an indication signal.

3. The IoT WiFi low-power method according to claim 2, characterized in that, The field positioning unit locates the TIM field by offset and extracts the Bitmap Control subfield and Part Virt Bmap subfield from the TIM field; The specific steps to convert the TIM field into an indication signal include: when the Traffic Ind bit of the Bitmap Control subfield is 1, the multicast indication signal is set high; otherwise, the multicast indication signal is set low. When the bit corresponding to the STA device association identifier in the Part Virt Bmap subfield is 1, the unicast indicator signal is set high; otherwise, the unicast indicator signal is set low.

4. The IoT WiFi low-power method according to claim 3, characterized in that, The TIM parsing module also includes a target AID register storing an associated identifier, which is used to match the bits of the PartVirt Bmap subfield according to the associated identifier.

5. The IoT WiFi low-power method according to claim 3, characterized in that, The specific steps for the judgment logic module to determine whether data transmission exists based on the indication signals include: if both the multicast indication signal and the unicast indication signal are set low, then the judgment is no; If the multicast indicator signal or the unicast indicator signal is set high, then it is determined as yes.

6. The IoT WiFi low-power method according to claim 1, characterized in that, The startup period is equal to the transmission period of the WiFi hotspot sending transmission frames; The timer has a preset start advance. When the time until the next start cycle is equal to the start advance, the timer sends a pre-start signal.

7. The IoT WiFi low-power method according to claim 1, characterized in that, STA devices also include an interrupt controller; The specific steps for determining whether the logic module wakes up the CPU module include: determining whether the logic module triggers the interrupt controller to send a wake-up signal to the CPU model; The specific steps to keep the CPU module in a sleep state include: disabling interrupt signals to keep the CPU module in a sleep state.

8. The IoT WiFi low-power method according to claim 1, characterized in that, The transmission frame includes Beacon frames and data frames; The transmission frame in step S2 is a Beacon frame, and the transmission frame in step S3 is a Beacon frame and a data frame.

9. An IoT WiFi low-power device, characterized in that, It employs an IoT WiFi low-power method as described in claims 1-8, comprising: WiFi hotspots are used to assign a unique association identifier to STA devices and to send transmission frames periodically. The STA device includes a timer that sends a pre-start signal to a judgment logic module according to a preset start cycle, a judgment logic module for turning off or starting the radio frequency module and the CPU module, a radio frequency module for receiving transmission frames and transmitting them to a parsing module, a parsing module for parsing transmission frames according to an associated identifier to obtain an indication signal and transmitting it to the judgment logic module, and a CPU module for acquiring transmission frames and sending a completion signal to the judgment logic module.

10. The IoT WiFi low-power device according to claim 9, characterized in that, The transmission frame includes a Beacon frame, and the parsing module is a TIM parsing module; The TIM parsing module includes a frame synchronization unit for detecting the frame preamble of the Beacon frame, a field positioning unit for locating and extracting the TIM field, and a signal output unit for converting the TIM field into an indication signal.

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