CN118369961A - Wake-up techniques in low power wireless devices - Google Patents

Abstract

A system and method for waking up a low-power wireless device is provided. The method includes: initializing a wake-up sensitivity to a minimum value of a wake-up circuit of the wireless device; searching, by the wake-up circuit, for at least one beacon; when at least one beacon is not found, increasing the wake-up sensitivity of the wake-up circuit; and setting the wake-up sensitivity to a value of receiving at least one beacon.

Description

Wake-up Techniques in Low-Power Wireless Devices

Technical Field

The present disclosure generally relates to wake-up circuits for low power wireless devices.

Background technique

The Internet of Things (IoT) is the interconnected network of physical devices, vehicles, buildings, and other items embedded with electronics, software, sensors, actuators, and network connectivity that enable these objects to collect and exchange data. IoT is expected to provide advanced connectivity of devices, systems, and services that goes beyond machine-to-machine (M2M) communications and covers a variety of protocols, domains, and applications.

IoT can be packaged in a wide variety of devices, such as heart monitoring implants; biochip transponders on farm animals; cars with built-in sensors; automation of lighting, heating, ventilation, air conditioning (HVAC) systems; and appliances such as washers/dryers, robot vacuums, air purifiers, ovens, or refrigerators/freezers that use wireless communication protocols that enable IoT devices to be monitored remotely. Typically, IoT devices package wireless sensors or networks of such sensors.

Most IoT devices are wireless devices that collect data and transmit such data to a central controller. Several requirements need to be met to allow widespread deployment of IoT devices. Such requirements include reliable communication links, low energy consumption, low cost, and small size.

To this end, IoT devices and wireless sensors are designed to support low-power communication protocols such as Bluetooth low energy (BLE), LoRa, etc. However, IoT devices using such protocols require batteries, such as coin cells. For example, reliance on power sources (e.g., batteries) is a limiting factor for electronic devices due to cost, size, lack of durability to environmental impacts, and frequent replacement. As an alternative to using batteries, self-sufficient or self-sustainable power sources can obtain energy from sources such as light, heat, activity, piezoelectricity, and can introduce electromagnetic energy. Electromagnetic energy, including radiofrequency (RF), is favored for its relatively unrestricted spatial freedom and abundance.

The BLE standard defines 40 communication channels in the industrial, scientific, and medical (ISM) band from 2.4000 GHz to 2.4835 GHz. Of these 40 communication channels, 37 channels are used to transmit data, and the last three channels 37, 38, and 39 are used as advertising channels to establish connections and send broadcast data. The BLE standard defines a frequency hopping spread spectrum technique in which the radio jumps between channels on each connection event. Broadcasting devices can advertise on any of the 3 advertising channels. The modulation scheme defined for the BLE standard is Gaussian frequency shift keying (GFSK) modulation.

In order to reduce energy consumption and increase battery life in wireless devices, duty cycle methods with active and sleep states have been explored. For RF devices, most of the energy of the device in the active state is consumed by the transceiver when the system is actively communicating and processing such communication signals. It has been determined that the energy consumed by a device in the active state is 3 to 4 orders of magnitude higher than its sleep state. In this regard, a duty cycle method that effectively utilizes the sleep state of the system is needed.

However, random and frequent activations may adversely affect the system, depleting the energy stored in the wireless device. In particular, the 2.4 GHz ISM RF band is densely populated with signals that may falsely activate (wake up) the system. Identifying the target signal (e.g., a BLE advertising event) and selectively activating the system within a large number of signals of similar range remains a challenge.

Therefore, it would be advantageous to provide a solution that can effectively reduce energy consumption by addressing some of the challenges mentioned above.

Summary of the invention

The following is an overview of several example embodiments of the disclosure. This overview is provided for the convenience of the reader to provide a basic understanding of such embodiments, and does not fully limit the breadth of the disclosure. This overview is not an extensive overview of all contemplated embodiments, and is neither intended to identify key or critical elements of all embodiments, nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to a more detailed description presented later. For convenience, the term "some embodiments" or "certain embodiments" may be used herein to refer to a single embodiment or multiple embodiments of the disclosure.

Certain embodiments disclosed herein include a method for waking up a low-power wireless device. The method includes: initializing a wake-up sensitivity to a minimum value of a wake-up circuit of the wireless device; searching, by the wake-up circuit, for at least one beacon; when at least one beacon is not found, increasing the wake-up sensitivity of the wake-up circuit; and setting the wake-up sensitivity to a value at which at least one beacon is received.

Certain embodiments disclosed herein also include a wake-up circuit for detecting a wake-up signal and operable in a low-power wireless device. The wake-up circuit includes: a wake-up receiver configured to detect a wake-up signal from an RF signal received at an antenna of the wireless device; and an antenna tuner configured to tune the frequency of the antenna of the wireless device; and a controller configured to control the wake-up receiver to at least calibrate the sensitivity of the wake-up receiver and tune the frequency of the antenna to allow rapid detection of the wake-up signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter disclosed herein is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification.The foregoing and other objects, features and advantages of the disclosed embodiments will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram of a wake-up circuit according to an embodiment.

2A and 2B are graphs of received signal energy and integrated voltage over time according to an embodiment.

3 is a graph of received signal energy versus frequency for different sensitivity functions, according to an embodiment.

FIG. 4 is a flow chart of a method for calibrating wake-up sensitivity according to an embodiment.

FIG. 5 is a flow chart illustrating a method of optimizing antenna frequency settings by receiving antenna frequency scanning according to an embodiment.

6 is a schematic graph of received signal energy and corresponding receive antenna tuning over time according to an embodiment.

FIG. 7 is an example signal diagram illustrating a wake-up procedure according to one embodiment.

Detailed ways

It is important to note that the embodiments disclosed herein are merely examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed embodiments. In addition, some statements may apply to some inventive features but not to other inventive features. In general, unless otherwise stated, singular elements may be plural and vice versa without loss of generality. In the accompanying drawings, the same numerals refer to the same parts through the multiple views.

Various disclosed embodiments include a system and method for effectively waking up a wireless device in a low-power wireless device without the need for a reference clock. To this end, the disclosed embodiments utilize a wake-up circuit to perform a wake-up process while maximizing the probability of activating (or waking up) the device system through a specific target signal of interest. Example target signals of interest are BLE advertising event signals of beacons on channel 37 (2402MHz), channel 38 (2426MHz), and channel 39 (2480MHz). More specifically, the disclosed embodiments utilize the frequency allocation and time pattern of these signals to identify a signal energy envelope that matches the expected energy envelope. The wake-up circuit is configured to detect the rising and falling edges of the received signal. It should be noted that the wake-up process disclosed herein is optimized to monitor and search for the rising and falling edges of the received signal.

The disclosed embodiments provide improved sensitivity and selectivity for detecting target signals within the 2.4 GHz ISM radio frequency band. The sensitivity of the system can be optimized for the surroundings of an Internet of Things (IoT) tag to further eliminate detection of non-beacon BLE signals, which in turn enables efficient management of stored energy. In addition, it has been found that a reference clock including a crystal oscillator is typically implemented on a wireless IoT tag to provide a sufficiently accurate and stable time and/or frequency reference. However, the disclosed embodiments eliminate the crystal oscillator by utilizing a signal for the wake-up process. This removal of the crystal oscillator not only reduces the overall cost, but also reduces the very desirable size of a wireless device (e.g., an IoT tag).

1 is an example block diagram of a wake-up circuit 100 according to an embodiment. The wake-up circuit 100 includes a tuner circuit 130, a wake-up receiver 140, and a microcontroller 150. The wake-up circuit 100 is coupled to an antenna interface 110 and an antenna 120. The antenna 120 is composed of a transmit/receive antenna for transmitting and receiving signals from an energy source 101.

According to the disclosed embodiments, the wake-up circuit 100 is designed for a small, low-power wireless IoT tag 102 with high sensitivity and selectivity. To this end, the wake-up receiver 140 is designed to have low power computing and high sensitivity to allow fast and accurate detection of the wake-up signal. In a further embodiment, the IoT tag 102 uses an over-the-air signal as a reference clock. That is, the IoT tag 102 does not include a crystal or any physical source to provide a reference clock, which may increase the cost, size, and power consumption of the wireless IoT device. The over-the-air signal is used for calibration to allow transmission and reception of signals, such as BLE signals. Example techniques for IoT tags 102 for calibration and from over-the-air signals are described in more detail in U.S. Patent No. 10,886,929 to Yehezkely et al., assigned to a common assignee, the contents of which are incorporated herein by reference. In an embodiment, the IoT tag 102 operates with the BLE communication protocol.

It should be understood that since the calibration operation occurs after the wake-up event, given the limited duration of the incident signal, the wake-up event (or signal) must be detected very quickly, for example, within tens of microseconds from the moment the RF signal is received. In an embodiment, a wake-up event is defined as the correct reception of at least one BLE advertising beacon on at least one BLE advertising channel. In an embodiment, in order to remove false detections, a wake-up event is triggered when consecutive BLE advertising beacons are received on at least two BLE advertising beacons.

The wake-up signal may be detected from an RF signal transmitted by the energy source 101. In an example embodiment, the energy source 101 may be electromagnetic energy that may be obtained from an existing wireless signal present in the environment. Such wireless signals may conform to known wireless standards, such as Wi-Fi (IEEE 802.11) operating in the 2.4 GHz and 5-6 GHz bands, BLE protocols operating in the 2.400-2.4835 GHz band, Wi-Gig operating in the 60 GHz band, cellular signals conforming to cellular standards (e.g., 2G, 3G, LTE, 4G, 5G, 5G millimeter wave, etc.), and industrial, scientific, and medical (ISM) frequency bands (e.g., sub-1 GHz), frequency modulation (FM) radio signals, etc. In an embodiment, the antenna 120 may include multiple antennas.

The tuner circuit 130 is configured with an antenna frequency controller to calibrate a local oscillator (LO (local oscillator), not shown), thereby calibrating the receiving antenna of the antenna interface 110. Calibration of the LO frequency tunes the receiving antenna frequency and can effectively detect electromagnetic signals with frequency matching. In an embodiment, the antenna frequency controller can be a digital controller oscillator (DCO).

The wake-up receiver 140 is configured to detect a wake-up signal that activates the IoT tag 102. Here, the wake-up receiver 140 monitors ambient energy signals from the surrounding environment and identifies the presence of a target signal of interest. In particular, the sensitivity and selectivity of the wake-up mechanism are very important for efficient activation and deactivation and, therefore, saving energy in the wireless IoT tag. Examples of such target signals are mentioned below.

In an embodiment, the wake-up receiver 140 may share a common interface with the antenna interface 110. In this configuration, tuning of the wake-up receiver 140 for a target signal may be performed through a chain of events. In an embodiment, the receive antenna first needs to be calibrated to tune the antenna 120. Due to the shared common interface, tuning of the antenna 120 also tunes the wake-up receiver 140. Typically, calibration of the receive antenna requires a reference clock generated by a crystal within the wireless device, but the disclosed embodiments avoid this configuration to reduce the cost and size of the wireless device. More specifically, multiple target signals for the wake-up mechanism may be measured to obtain a ratio of the measured frequency to a known absolute frequency.

Once the absolute frequency of a given signal is determined, the wake-up receiver 140 can measure the frequency of the internal clock to determine the frequency of the signal. In an embodiment, the determined frequency can be used in system calibration processes, such as calibrating the LO to tune the frequency of the antennas used for transmission and reception, and calibrating the symbol clock that times the symbol data in the transmitted data packets. In another embodiment, the internal clock frequency can be dynamically temperature compensated before the receive antenna calibration.

In an embodiment, the target signal of interest may be one or more of the three beacons of a BLE advertising event in the 2.4 GHz ISM radio frequency band, and are represented as channel 37 (2402 MHz), channel 38 (2426 MHz), and channel 39 (2480 MHz). The BLE advertising beacon includes a triplet of these beacons that are sent continuously, where the duration of the beacon is typically between 120 μs and 376 μs, the interval between beacons is typically between 150 μs and 800 μs, and the BLE advertising beacon is repeated every 30 ms to 150 ms. These signals are distinguishable from beacons from other sources with independent timing patterns. To this end, this frequency allocation and time energy pattern can be used to identify the signal energy envelope of the BLE advertising beacon to effectively wake up the IoT tag 102. In an embodiment, the wake-up circuit 100 can dynamically learn the energy duration and interval time of the beacon in each BLE advertising event to better identify the BLE advertising beacon.

A method for dynamically learning the energy duration and interval time of a beacon of a BLE advertising beacon is to set an upper limit on the energy duration of the beacon and another upper limit on the interval duration. The wake-up receiver 140 then searches for BLE advertising beacons as beacon triplets, ignoring beacons with durations longer than the upper limit or beacon triplets with intervals greater than the upper limit. Once a valid beacon triplet is identified and it is detected that the frequency ratio of the beacons in the found beacon triplet matches the frequency ratio of the beacon of the BLE advertising beacon, the wake-up receiver 140 can then consider the found triplet to be a BLE advertising beacon, measure the beacon duration and interval time, and then use this knowledge to further filter subsequent beacon triplets that do not match the found beacon duration and interval time.

In an embodiment, the wake-up receiver 140 includes at least one radio frequency to direct current (RF-DC) converter configured to output a DC voltage level in response to an RF signal received at the antenna 120. Each RF-DC converter is coupled to a switch that can reset or disconnect the converter. The wake-up receiver 140 includes a detector configured to output a wake-up signal when the DC voltage level output by the RF-DC converter is higher than a reference voltage signal. In an embodiment, the reference voltage can be tuned to determine the initial sensitivity of the wake-up receiver 140.

In an embodiment, in order to allow rapid detection of the wake-up signal and control the sensitivity of the detection, the frequency of the antenna is calibrated and the receiver sensitivity is optimized. These processes are performed under the control of the microcontroller 150. Compared to, for example, using a separate microprocessor, the microcontroller 150 provides the ability to control various devices with a reduced size unit. A microcontroller typically includes a processor, memory, and input/output peripherals, and typically also includes non-volatile memory (NVM) such as flash memory.

2A and 2B are example graphs of received signal energy 200 and integrated voltage 210 over time according to an embodiment. The graph 200 of received signal energy over time shows the energy envelope of a BLE advertising event signal. Three separate energy envelopes 201-1 to 201-3 (hereinafter referred to as energy envelopes 201, respectively, and collectively referred to as energy envelopes 201) indicate signals from channels 37, 38, and 39 of a BLE advertising event beacon, respectively. The received signal energy measured in decibel milliwatts (dBm) is a function of the transmitted signal power from the energy source (101 of FIG. 1), the signal channel between the energy source and the receiver (e.g., antenna 101 of FIG. 1), and the energy dissipation between them. The graph 210 represents the integrated voltage of the received signal energy over time, with a rising edge 211 and a falling edge 212 on each of the energy envelopes 201.

The wake-up circuit is a clock mechanism that, when activated, integrates and cleans up the received signal energy to detect the rising edge 211 and the falling edge 212 of the received signal. In an embodiment, the rising edge 211 and the falling edge 212 of the detection envelope are required to monitor the energy envelope 201 of the received signal. In an embodiment, a detection threshold may be predefined to modify the sensitivity and/or selectivity of the wake-up circuit and determine the presence of a target signal. In an example embodiment, a higher detection threshold may result in a less sensitive wake-up mechanism, but in turn may allow a more selective wake-up mechanism under given conditions.

3 is an example graph 300 of received signal energy 310 at frequencies 315 of different sensitivity functions, according to an embodiment. The curves in graph 300 show received signal energy 310 at the same antenna frequency with variations in sensitivity functions such as signal attenuation 301, signal integration 302, and receive antenna gain 303. It should be noted that measuring lower received signal energy 310 indicates higher sensitivity of the wake-up mechanism (i.e., curve 303 shows the condition of highest sensitivity). Curve 301 shows a measurement with high signal attenuation and short signal integration. In an example embodiment, the wake-up mechanism gain chain can be used to amplify the received energy signal, where more elements in the gain chain increase the sensitivity.

Curves 302-1 to 302-3 respectively show measurements of received signal energy 310 as signal integration increases from short to long, where better sensitivity is achieved at long signal integration 302-3. In addition, curve 303 shows measurements under long signal integration and high receive antenna gain to produce a narrower 3dB bandwidth than the curve without high receive antenna gain 302-3. As described above, the wake-up circuit is coupled to a transmit/receive antenna (e.g., antenna 120 of FIG. 1). In an embodiment, the gain of the receive antenna can be increased by performing antenna quality factor enhancement. Therefore, a more sensitive wake-up circuit and a more selective antenna can be achieved with a higher receive antenna gain.

In an embodiment, the wake-up circuit sensitivity can be further modified by the antenna frequency setting, where the sensitivity is preferably highest when the receiving antenna (e.g., antenna 120 of Figure 1) is tuned to match the frequency of the target signal. Larger frequency mismatches may reduce target signal detection, thereby reducing the sensitivity of the wake-up mechanism. In addition, the selectivity of the wake-up mechanism can also be increased by matching the antenna frequency setting, because the receiving antenna will effectively detect signals with matching frequencies. For example, when detecting a beacon on channel 37, the receiving antenna should be tuned to 2402MHz for optimal sensitivity and selectivity of the wake-up circuit. It should be noted that the sensitivity of the wake-up circuit can be adjusted by the above-mentioned functions, such as detection threshold, signal attenuation, signal integration, receiving antenna gain, and antenna frequency setting.

In an embodiment, a high sensitivity wake-up circuit may allow detection of weaker signals, but with a trade-off between an increase in detectable signal density and resulting detection of undesired non-target signals. In this case, the sensitivity may be limited to reduce the probability of unnecessary false signal detection. In an example embodiment, in the presence of two BLE advertising event beacon sources, the sensitivity may be limited to detect only the stronger of the two beacon sources to reduce such false detections. It should be noted that both the sensitivity and selectivity of the wake-up circuit determine the effectiveness of the circuit and the wake-up point of the wireless device. At this point, once the wake-up sensitivity is calibrated, the wake-up circuit may be configured for higher selectivity, for example, by increasing the receive antenna gain and a reduction in signal integration or an increase in the detection threshold, to maintain sensitivity and filter out undesired signals.

4 is an example flow chart 400 illustrating a method for calibrating wake-up sensitivity according to an embodiment. In an embodiment, the method is performed at the wake-up circuit 100 (FIG. 1) under the control of the microcontroller 150.

At S410, assuming a strong beacon signal, the wake-up sensitivity is initialized to minimum. In a scenario with a strong beacon, a high wake-up sensitivity may result in incomplete clearing of the received signal energy during integration and clearing. As a result, the rising and falling edges of the received signal may not be identified as required by the wake-up mechanism. For this purpose, the wake-up sensitivity may be set to minimum.

At S420, the wake-up circuit searches for an event beacon. The event beacon may include a BLE advertising event beacon. In an embodiment, a timeout timer may be used for beacon searching, where multiple occurrences of timeouts indicate a lack of sensitivity of the wake-up mechanism. In an embodiment, a time period for the timeout timer may be predetermined.

At S430, it is checked whether the beacon of the event is found or whether the maximum sensitivity is reached. If so, the wake-up circuit sensitivity calibration is good, or the wake-up circuit has reached its maximum sensitivity, so the operation ends. Otherwise, execution continues to S440.

At S440, the wake-up sensitivity is increased, and execution continues to S420 to search for event beacons at a higher wake-up sensitivity. This sensitivity increase can be performed by adjusting the sensitivity function described above, such as but not limited to detection threshold, signal attenuation, signal integration, receive antenna gain, and antenna frequency settings. In an embodiment, in order to obtain optimal performance of the wake-up mechanism, the wake-up sensitivity can be periodically reinitialized and recalibrated.

5 is an example flow chart 500 illustrating a method for optimizing antenna frequency settings by receiving antenna frequency scanning according to an embodiment. In an embodiment, the method is performed at the wake-up circuit 100 (FIG. 1) under the control of the microcontroller 150.

At S510, the antenna settings are set to transmit at a first channel. In an embodiment, the first channel is channel number 37 of the BLE advertising event.

At S520, the antenna settings are offset from the calibrated transmit settings to enable reception of the first channel. This offset takes into account small deviations of the receive frequency settings from the transmit frequency settings. Initially, the offset of the antenna settings that enables reception at the first channel is a rough estimate of the actual offset setting, so the receiver antenna scanning mechanism is used to find the actual offset.

At S530, the wake-up circuit and the receiver scanning mechanism are activated. The receiver scanning mechanism enables the antenna tuner to repeatedly scan the antenna setting value from the lower antenna frequency to the higher antenna frequency with the offset reception setting of S520 as the center. Here, the antenna setting for waking up the system is identified as the antenna setting value required for the target channel and its frequency.

At S540 , once awakened, the wake-up circuit is reactivated by the antenna setting value identified at the target channel.

At S550, it is checked whether the received beacon (signal) is on the target channel. If yes, execution continues to S560. If not, execution returns to S510, where the antenna settings may be calibrated for reception at a different channel.

At S560, the antenna setting values of the identified target channel are stored. In an embodiment, the antenna setting values may be stored in an external memory or an on-tag memory (not shown) (eg, non-volatile memory (NVM)) for future reference.

At S570, it is checked whether there are more channels. If not, execution terminates. If yes, execution returns to S530. Once returned to S530, the antenna settings remain at the previous antenna settings until the previous signal ends. Then, the receiver scanning mechanism is activated for the next channel.

In an embodiment, the method of FIG. 5 may include iterations of three channels. In an example embodiment, more channels may include channels 38 and 39 for BLE advertising events. It should be understood that identifying and setting the antenna frequency for each of the target channels will maximize receive sensitivity and allow antenna hopping between beacons receiving BLE advertising events.

It should be noted that careful calibration and optimization of the wake-up circuit increases the probability of detecting the target signal, thereby effectively waking up the system only at the target signal, which in turn allows for efficient management and saving of the power stored in the wireless IoT tag.

6 is an example diagram of received signal energy 600 and corresponding receive antenna tuning 610 over time according to an embodiment. The example received signal energy graph 600 shows the energy envelopes from three BLE beacons on channels 37, 38, and 39. In order to effectively detect such signals, it is desirable to perform receive antenna tuning for each of the BLE advertising event beacons. To this end, the wake-up mechanism can perform a jump in the receive antenna tuning, as shown in the example receive antenna tuning graph 610.

The receive antenna tuning is initially tuned to 2402 MHz to detect a signal on channel 37. Once the falling edge of the beacon is detected, the receive antenna tuning is changed to 2426 MHz to detect the beacon on channel 38. Similarly, the falling edge of the signal from the beacon on channel 38 changes the receive antenna tuning to 2480 MHz to detect the beacon on channel 39. This receive antenna frequency hopping can be used to effectively detect the target signal from dense electromagnetic ambient energy. It should be noted that the effective detection of the target signal increases the sensitivity and selectivity of the wake-up circuit to improve its performance.

FIG. 7 is an example signal diagram 700 illustrating a wake-up process according to one embodiment. The wake-up mechanism diagram 710 illustrates an active search period of the wake-up mechanism from a search start point 711 to a system wake-up point 712, which is when the search ends. The RF medium diagram 720 illustrates radio frequency signals in the 2.4 GHz ISM band in the surrounding environment. In the example diagram 720, the first BLE advertising event 750-1 is followed by WiFi 760, and then the second BLE advertising event 750-2.

Each of the BLE advertising events occurs consecutively in a triplet of signals including beacons from channels 37, 38, and 39. In particular, these three energy envelopes have nominally the same energy duration and interval duration between them. At this point, the wake-up mechanism can use this characteristic of the BLE advertising event to identify and subsequently trigger the wake-up of the system. When the detected energy envelope does not match the expected energy envelope, the wake-up mechanism can reset and continue searching until the expected energy envelope is detected.

In an example embodiment, the wake-up circuit is configured to wake up the wireless IoT tag once a BLE beacon on channel 39 is detected, more specifically, upon detecting the third rising edge (e.g., 712) of the BLE advertising event. As shown in the wake-up mechanism diagram 710, the search start point 711 is after the rising edge of the first energy envelope (channel 37) of the first BLE advertising event 750-1, and therefore, the second energy envelope (channel 38) is marked as the first rising edge 713. The wake-up circuit is configured to monitor the rising and falling edges of each of the envelopes, as well as their energy duration and interval duration, to search for the third rising edge. A violation of the interval duration 715-1 is determined based on the absence of the expected third rising edge at the first BLE advertising event 750-1; and the search is reset.

In addition, a violation of the energy duration 715-2 is determined to reset the search. The violation of the energy duration 715-2 occurs due to the absence of the expected falling edge in the BLE energy envelope, thereby allowing the bypass of non-target signals, in this example, WiFi 760. After resetting at the violation 715-2, the wake-up mechanism continues its search for the first rising edge 713 and the third rising edge 712 while monitoring the energy duration and the interval duration. When the third rising edge 712 is detected, the wake-up mechanism can stop the search and wake up the system to process the signal.

It should be noted that the example embodiment demonstrates the process of the wake-up mechanism at an example target signal. However, the wake-up circuit can be configured to detect other target signals, such as but not limited to other BLE advertising event signals, such as beacons from channel 37 and channel 38.

In yet another embodiment, the wake-up circuit may be configured to detect a silent period in the ISM 2.4 GHz band and wake up the system when no energy is detected. The wake-up circuit may monitor both rising and falling edges of the energy envelope, but search for an extended silent period after such a signal. In an embodiment, a valid silent period may be predefined so that the system is woken only when the predefined silent period time has passed after the falling edge of the energy envelope. In an embodiment, the silent period may be used for, but is not limited to, calibration and carrier conflict assessment prior to transmission of a BLE packet.

It should be noted that computer-readable instructions can be broadly interpreted to mean any type of instructions, whether referring to software, firmware, middleware, microcode, hardware description language, or other. The instructions may include code, such as source code format, binary code format, executable code format, or any other suitable code format. When the instructions are executed by the circuit, the circuit is caused to perform the various processes described herein.

The various embodiments disclosed herein can be implemented as hardware, firmware, software or any combination thereof. In addition, the software is preferably implemented as an application program tangibly embodied in a program storage unit or a computer-readable medium, which is composed of a combination of components or certain devices and/or devices. The application program can be uploaded to a machine including any suitable architecture and executed by it. Preferably, the machine is implemented on a computer platform with hardware such as one or more central processing units (CPU), memory and input/output interfaces. The computer platform may also include an operating system and microinstruction codes. The various processes and functions described herein may be part of a microinstruction code or part of an application program or any combination thereof, which may be executed by a CPU, whether or not such a computer or processor is explicitly shown. In addition, various other peripheral units may be connected to a computer platform, such as an additional data storage unit and a printing unit. In addition, a non-transitory computer-readable medium is any computer-readable medium other than a signal that is temporarily propagated.

It should be understood that any reference to an element using the names "first", "second" etc. herein will not generally limit the quantity or order of these elements. On the contrary, these names are generally used as a convenient method to distinguish two or more elements or element instances in this article. Therefore, the reference to the first element and the second element does not mean that only two elements can be used there, or that the first element must be before the second element in some way. In addition, unless otherwise stated, a group of elements includes one or more elements.

As used herein, the phrase "at least one of" followed by a list of items means that any of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a system is described as including "at least one of A, B, and C," the system may include A alone; include B alone; include C alone; include a combination of A and B; include a combination of B and C; include a combination of A and C; or include a combination of A, B, and C.

All examples and conditional language listed herein are intended for teaching purposes to help the reader understand the principles of the disclosed embodiments and the concepts contributed by the inventors to further advance the art, and should be interpreted as not being limited to these specifically listed examples and conditions. In addition, all statements describing the principles, aspects and embodiments of the disclosed embodiments and their specific examples herein are intended to cover their structural and functional equivalents. In addition, it is intended that such equivalents include currently known equivalents and equivalents developed in the future, that is, any element that performs the same function, regardless of the structure.

Claims (18)

1. A method for waking up a low power wireless device, comprising: Initializing a wake-up sensitivity to a minimum value of a wake-up circuit of the wireless device; searching, by the wake-up circuit, for at least one beacon; When the at least one beacon is not found, increasing the wake-up sensitivity of the wake-up circuit; and The wake-up sensitivity is set to a value received by the at least one beacon. 2. The method according to claim 1, further comprising: calibrating an antenna setting of the wireless device to transmit signals on a first channel; offsetting the calibrated antenna setting to allow reception of the at least one beacon; Repeatedly scan antenna settings from low frequency to high frequency; upon receiving the at least one beacon, checking whether the received beacon is on the first channel; and The antenna setting for the first channel is stored. 3. The method according to claim 2, further comprising: calibrating an antenna setting of the wireless device to transmit signals on any of the second channel and the third channel when the at least one beacon is not received; upon receiving the at least one beacon, checking whether the received beacon is on any one of the second channel and the third channel; and The antenna settings for receiving the at least one beacon are stored. The method of claim 3 , wherein the first channel and the second channel are BLE advertising channels. 5. The method according to claim 4, further comprising: The antenna setting of the at least one beacon is set at an edge of the received beacon channel. The method of claim 1 , wherein scanning the antenna settings causes the wake-up circuit to tune. 7. The method of claim 2, wherein the receiving of the at least one beacon further comprises: A temporary reference clock is set to receive the at least one beacon, wherein the temporary reference clock is predetermined and dynamically temperature compensated. 8. A wake-up circuit for detecting a wake-up signal and capable of operating in a low power wireless device, comprising: a wake-up receiver configured to detect a wake-up signal from an RF signal received at an antenna of the wireless device; and an antenna tuner configured to tune a frequency of an antenna of the wireless device; and A controller is configured to control the wake-up receiver to at least calibrate a sensitivity of the wake-up receiver and tune a frequency of the antenna to allow rapid detection of a wake-up signal. 9 . The wake-up circuit of claim 8 , wherein the wake-up circuit is coupled to an antenna interface of the wireless device. 10. The wake-up circuit according to claim 9, wherein the controller is configured to: Initializing a wake-up sensitivity to a minimum value of a wake-up receiver of the wireless device; searching, by the wake-up circuit, for at least one beacon; When the at least one beacon is not found, increasing the wake-up sensitivity of the wake-up circuit; and The wake-up sensitivity is set to a value received by the at least one beacon. 11. The wake-up circuit according to claim 10, wherein the controller is further configured to: calibrating an antenna of the wireless device to transmit a signal on a first channel; offsetting the calibrated antenna setting to allow reception of at least one beacon of the first channel; repeatedly scanning the antenna setting values from low frequency to high frequency; upon receiving the at least one beacon, checking whether the received beacon is on the first channel; and The antenna setting for the first channel is stored. 12. The wake-up circuit according to claim 10, wherein the controller is further configured to: calibrating the antenna arrangement to transmit signals on either of the second channel and the third channel when the at least one beacon is not received; upon receiving the at least one beacon, checking whether the received beacon is on any one of the second channel and the third channel; and The antenna settings for receiving the at least one beacon are stored. 13 . The wake-up circuit of claim 12 , wherein the first channel and the second channel are BLE advertising channels. 14. The wake-up circuit according to claim 10, wherein the controller is further configured to: The antenna setting of the at least one beacon is set at an edge of the received beacon channel. 15. The wake-up circuit of claim 10, wherein scanning the antenna settings causes the wake-up circuit to tune. 16 . The wake-up circuit according to claim 10 , wherein the low-power wireless device is at least an IoT tag capable of operating under a BLE communication protocol. 17 . The wake-up circuit of claim 16 , wherein the wake-up signal is output when a BLE advertising beacon is detected on a BLE advertising channel. 18 . The wake-up circuit of claim 17 , wherein the wake-up signal is output when at least two consecutive BLE advertising beacons are detected on at least two consecutive BLE advertising channels.