Proximity-Independent SAR Mitigation

Abstract

The present application relates to a communication device with proximity-independent SAR mitigation. A radio frequency (RF) power regulator includes a forward RF power detection circuit for detecting the forward RF power supplied by an RF transmitter circuit to an RF transmit antenna. An RF power sampler is coupled to the forward RF power detector circuit and provides an RF power sample of the supplied forward RF power. A plurality of filters are coupled to receive the RF power samples. Each filter filters the received forward power samples differently to apply a different average power period. Each filter activates an RF power adjustment trigger signal when the time-averaged forward RF power supplied to the RF transmit antenna satisfies the forward RF power adjustment condition of the filter's average power period. The forward RF power adjustment logic is coupled to the filter and is operable to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal.

Description

[0001] This invention patent application is a divisional application of the invention patent application with international application number PCT / US2018 / 024232, international application date March 26, 2018, application number 201880023232.5 entering the Chinese national phase, and name “Proximity-Independent SAR Mitigation”. background

[0002] Communications devices often utilize proximity detection to determine when to consider specific absorption rate (SAR) radio frequency (RF) power limits. Such devices determine whether to perform RF transmit power adjustments (e.g., reductions) when proximity of an object is detected. However, proximity detection may involve sensors that occupy valuable device space in the communications device (e.g., in a display bezel).

[0003] Overview

[0004] The various implementations described and claimed herein solve the above problems by providing a radio frequency (RF) power regulator. The RF power regulator includes a forward RF power detection circuit that is operable to detect the forward RF power supplied to the RF transmit antenna by the RF transmitter circuit. The RF power sampler is coupled to the forward RF power detector circuit and provides an RF power sample of the supplied forward RF power. A plurality of filters are coupled to receive the RF power samples. Each filter filters the received forward power samples differently to apply different average power periods. Each filter activates an RF power adjustment trigger signal when the time-averaged forward RF power supplied to the RF transmit antenna satisfies the forward RF power adjustment condition of the filter's average power period. The forward RF power adjustment logic is coupled to the filter and is operable to adjust the forward RF power supplied to the RF transmit antenna by the RF transmitter circuit based on the RF power adjustment trigger signal.

[0005] Other implementations are also described and illustrated herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 An example communications device that provides SAR mitigation independent of proximity detection is illustrated.

[0007] Figure 2 An example communication device diagram for providing proximity independent SAR mitigation is illustrated.

[0008] Figure 3 An example circuit schematic of a communication subsystem implementation for providing proximity-independent SAR mitigation is illustrated.

[0009] Figure 4 An example circuit schematic of another communication subsystem implementation for providing proximity-independent SAR mitigation is illustrated.

[0010] Figure 5 An example circuit schematic diagram of yet another communication subsystem implementation for providing proximity-independent SAR mitigation is illustrated.

[0011] Figure 6 An example circuit schematic diagram of yet another communication subsystem implementation for providing proximity-independent SAR mitigation is illustrated.

[0012] Figure 7 An example circuit schematic diagram of yet another communication subsystem implementation for providing proximity-independent SAR mitigation is illustrated.

[0013] Figure 8 An example circuit schematic for multi-band transmission in a communication subsystem implementation providing proximity-independent SAR mitigation is illustrated.

[0014] Fig. 9 An example detector emission function is illustrated.

[0015] Fig.10 Illustrated is an oscilloscope plot of LTE transmissions detected from an LTE device using a VOIP call at normal talking speeds.

[0016] Fig.11 Illustrated is an oscilloscope plot of detected LTE transmissions from an LTE device uploading a file via email.

[0017] Fig.12 Example operations for detecting RF power and implementing proximity-independent SAR mitigation are illustrated.

[0018] Fig.13 A framework that illustrates example proximity-independent SAR mitigation is illustrated.

[0019] Fig.14 Example attenuation curves that may be used by control logic for proximity-independent SAR mitigation are illustrated.

[0020] Fig.15 Example attenuation curves that may be used by control logic for proximity-independent SAR mitigation using a moderate-speed filter are illustrated.

[0021] Fig.16 Example attenuation curves that may be used by control logic for proximity-independent SAR mitigation using a fast filter are illustrated.

[0022] Fig.17 Example attenuation curves that may be used by control logic for proximity-independent SAR mitigation using a slow filter are illustrated.

[0023] Fig.18An example system is illustrated that can be used to implement the described techniques. DETAILED DESCRIPTION

[0024] Consumer electronic devices may be equipped with wireless communication circuitry that may transmit radio frequency (RF) electromagnetic fields that may be absorbed by human tissue located proximate to the wireless communication circuitry. For example, the wireless communication circuitry may transmit and receive RF signals in mobile phone RF bands, LTE RF bands, WiFi network RF bands, and GPS RF bands. In order to protect humans from harmful levels of RF radiation when using such devices, government agencies have imposed regulations that limit the RF transmission power from certain wireless electronic devices, such as tablet computers and mobile phones.

[0025] In some jurisdictions, the Specific Absorption Rate (SAR) standard sets a maximum time-averaged energy absorption limit for electronic device manufacturers. These standards impose limits on the amount of time-averaged electromagnetic radiation that can be transmitted during a rolling time window within a given distance of a transmitting radio frequency (RF) antenna. Special attention is given to radiation limits at a distance of a few centimeters (e.g., 0-3 cm) from the device (where the user may place a human body part close to the transmitting antenna). For example, the Federal Communications Commission (FCC) of the United States imposes the following regulations: According to the regulations, the average SAR level obtained on the body (containing 1 gram of tissue) that is absorbing the most signals for phones sold in the United States is at or below 1.6 watts per kilogram (W / kg). Different regulations may be imposed for different types of devices (e.g., phones, tablet computers), and for different body parts (e.g., torso, hands, legs) adjacent to the RF transmitting antenna. Such limits can be met by reducing the strength of the transmitted RF signal when a dielectric body (e.g., a human body part) is detected in the vicinity of the transmitting antenna. Such proximity detection can be performed in a variety of ways, such as capacitive sensing or other means of measuring signal interference.

[0026] Although reducing the transmitted RF signal strength can enhance user safety and / or compliance with local safety regulations, a significant reduction in the transmitted carrier signal strength can result in reduced device communication performance, including but not limited to lost connections (e.g., dropped calls) and / or delays in the transfer of information. Additionally, proximity detection typically involves sensors that occupy scarce space within a computing device.

[0027] The disclosed technology manages transmit RF signal strength to maintain device communication performance independently of proximity detection, while controlling the transmit energy of the electronic device to keep it (averaged over a rolling time window) below a predetermined safety threshold. The application of transmit RF power detection and intelligent attenuation triggering enables the technology to provide effective, proximity-independent SAR mitigation in a communication device. As a result, the communication device provides improved SAR mitigation without the need to allocate valuable space for proximity sensing structures, while maintaining effective RF signal strength for communication during a variety of signaling conditions and use cases.

[0028] Figure 1 An example communication device 100 that provides SAR mitigation independent of proximity detection is illustrated. The communication device 100 may include, but is not limited to, a tablet computer, a mobile phone, a laptop computer, a networked device (e.g., an Internet of Things (“IoT”) device). Figure 1 In , the communication device 100 includes a display 102, although other implementations may or may not include such a display component.

[0029] The communication device 100 also includes a radio frequency (RF) transmit antenna 104 that transmits a transmitted RF signal 106. Certain SAR regulations limit the time-averaged amount of transmitted RF signal energy that can be absorbed by human tissue 108 in the vicinity of the RF transmit antenna 104 over a rolling time window. In the described techniques, SAR regulations can be met by applying fine control to the time-averaged transmitted RF signal power, regardless of any proximity conditions. In other words, the communication device 100 meets the SAR requirements regardless of whether human tissue is in the vicinity, thereby allowing the proximity detection component in the communication device 100 to be omitted.

[0030] Meeting the SAR requirements is managed by a forward RF power regulator 110 coupled to the RF transmit antenna 104. The forward RF power regulator 110 monitors and manages the time-averaged amount of forward RF power supplied to the RF transmit antenna 104 within a rolling time window specified by the SAR regulations. The forward RF power regulator 110 intelligently allocates the forward RF power available within the SAR limit (or some other relevant threshold) and the rolling time window to maintain SAR standard compliance and device performance during operation in the time following the rolling time window.

[0031] When the forward RF power regulator 110 determines that the forward RF power should be attenuated to comply with the SAR limit, the forward RF power regulator 110 triggers a forward RF power adjustment event and sends a signal to the modem 112 (e.g., including an RF transmitter circuit), which is coupled to supply the forward RF power to the RF transmit antenna 104 to reduce the supplied power. Similarly, when the forward RF power regulator 110 determines that the forward RF power should be increased when additional forward RF power is available within the rolling time window, the forward RF power regulator 110 triggers a forward RF power adjustment event and sends a signal to the modem 112 to supply the forward RF power to the RF transmit antenna 104 to increase the supplied power.

[0032] Figure 2 A schematic diagram of an example communication device 200 for providing SAR mitigation is illustrated. The communication device 200 determines and implements a forward RF power adjustment or attenuation function to manage the total forward RF average power so as not to exceed a predetermined average power threshold (e.g., a SAR limit). The communication device 200 may be, but is not limited to, a tablet computer, a laptop computer, a mobile phone, a personal digital assistant, a cellular phone, a smart phone, a Blu-ray player, a gaming system, a wearable computer, a home or enterprise device, or any other device that includes a wireless communication circuit system for transmission of an RF carrier. The communication device 200 includes an RF transmit antenna 202 that transmits an RF carrier. In one implementation, the carrier has a frequency in the range of mobile phone RF transmissions (e.g., several hundred megahertz (MHz)). Other implementations are also contemplated. In the illustrated implementation, the communication device 200 represents a tablet computer with mobile phone RF capabilities.

[0033] The modem 204 (e.g., including RF transmitter circuitry) supplies forward RF power to the RF transmit antenna 202 to generate an RF carrier from the communication device 200. The modem 204 may transmit at various different power levels in response to receiving power adjustment instructions from a base station (not shown), and may vary the forward RF power supplied to the RF transmit antenna 202. For example, the base station may instruct the communication device 200 to transmit at different power levels based on the location of the communication device 200 relative to the base station or based on signal conditions (such as an upcoming handoff to another base station). In various situations, for example, when the communication device 200 is in close proximity to the base station, a low power level may be suitable for communication, while when the communication device 200 is further away from the base station, a higher or maximum power level may be requested by the base station.

[0034] The forward RF power regulator 206 also monitors the forward RF power supplied to the RF transmit antenna 202 and can change the forward RF power supplied to the RF transmit antenna 202 in response to detecting that the forward RF power adjustment condition is satisfied. The high directivity power monitoring circuitry results in the detection of power that is substantially the forward RF power supplied by the modem 204 to the RF transmit antenna 202. In this manner, the detected power is substantially uncontaminated by reflected power directed back to the modem 204 due to imperfect antenna termination impedance. Various example high directivity monitoring circuits are described herein, however other examples may also be employed.

[0035] Typically, the forward RF power regulator 206 monitors the forward RF power supplied to the RF transmit antenna 202 and adjusts the forward RF power (upward or downward) when a forward RF power adjustment condition is met. In one implementation, the adjustment may be made by instructing the modem 204 to adjust its output RF power to the RF transmit antenna 202. In another implementation, the output RF power from the modem 204 may be attenuated at different levels based on power adjustment instructions from the forward RF power regulator 206 to a power attenuator located at the coupling between the modem 204 and the RF transmit antenna 202. Other adjustment controls may be employed.

[0036] "Forward RF power adjustment condition" refers to a condition related to the average transmit RF power supplied to the RF transmit antenna 202 and its relationship to the SAR limit. In one implementation, the forward RF power adjustment condition presents an average forward RF power limit for a given rolling time window (such as a time period set by SAR regulations). The average transmit RF power limit under the condition can be set to or below the SAR limit. Setting the average transmit RF power limit below the SAR limit provides some tolerance to reduce SAR mitigation failures, although there are other ways to avoid SAR mitigation failures (e.g., a worst-case adjustment condition that terminates transmission for a period of time if the average transmit RF power approaches or reaches the SAR limit).

[0037] One implementation of the described technology employs multiple filter banks to monitor the forward RF power supplied to the RF transmit antenna 202. Each filter bank filters at a different cutoff frequency than the other filter banks and therefore applies a different average power period to the samples. If the average forward RF power is within the average power period of the filter bank (referred to as a "filter"), the filter activates an RF power adjustment trigger signal. If the control logic selects a trigger filter based on inputs such as network conditions and / or transmit requirements, the trigger point control logic initiates a transmit RF power adjustment event.

[0038] As described above, the forward RF power regulator 206 monitors the forward RF power supplied to the RF transmit antenna 202 and varies the supplied power to maintain the average transmit power below the SAR limit over a rolling time window. The forward RF power regulator 206 may evaluate various signaling condition inputs to determine when and how to adjust the supplied power, including, but not limited to, transmit frequency, transmit band, modulation scheme, GPS location of the communication device 200, channel conditions (e.g., conditions related to quality and interference in signal communications with base stations), predetermined channel activity, current channel activity, mobility characteristics of the communication device 200 (such as relative to base stations, shielding, etc.), current transmit power, distance from base stations or cell towers, etc. Thus, the evaluation is a prediction of the signaling conditions that the communication device 200 is expected to experience.

[0039] Additionally, the forward RF power regulator 206 may evaluate various transmit requirement inputs to determine when and how to adjust the supplied power, including, but not limited to, the level of transmit activity that the communication device 200 is experiencing and expects to experience (e.g., uploading a large data file indicates a high level of transmit activity, while downloading a large data file or handling a VOIP call indicates a low level of transmit activity), the importance of a successful transmission to a critical transmission (e.g., an upcoming handoff to a new base station or cell tower or an emergency 911 call), etc. Thus, the evaluation is a prediction of recently experienced transmit activity and the expected transmit requirements of the communication device 200.

[0040] An example operating characteristic of the forward RF power regulator 206 is shown in view 212. The SAR limit represents a regulation limit for the time-averaged transmit power within a rolling time window. In various implementations, satisfaction of the forward RF power adjustment condition is achieved when the time-averaged forward RF power exceeds an average power threshold that is less than or equal to the SAR limit. It should be understood that the average power threshold of the example forward RF power adjustment condition may vary depending on network conditions, transmission requirements, selected filter banks, etc.

[0041] As adjusted by the RF power regulator 206, the actual transmit power 214 is displayed in view 212. Also shown are average power monitoring results for three filter banks (fast filter 216, medium filter 218, and slow filter 220), where the fast filter 216 detects the satisfaction of the forward RF power adjustment condition at multiple points in time (reflected by the fast filter 216 graph satisfying the forward RF power adjustment condition (e.g., the average power exceeds the threshold within the filter average power period)). Each detected satisfaction of the forward RF power adjustment condition within the filter's average power period results in the issuance of an RF power adjustment trigger signal. If the trigger point control logic selects a trigger filter based on inputs such as network conditions and / or transmit requirements, the control logic initiates a transmit RF power adjustment event, represented in view 212 as a reduction in the actual transmit power 214.

[0042] Figure 3 An example circuit schematic of a communication subsystem implementation 300 for providing proximity-independent SAR mitigation is illustrated. The communication subsystem implementation 300 includes a modem 302 (e.g., an RF transmitter circuit), an RF transmit antenna 304, and a forward RF power regulator 320 including a forward RF power detection circuit 306. In the illustrated communication subsystem implementation 300, the forward RF power detection circuit 306 includes a directional coupler 307. The forward RF power regulator 320 also includes a detector 308, an analog-to-digital converter (ADC) 310, and a SAR controller 312. The modem 302 may include an LTE modem, a Wi-Fi radio, or other transmitting radio that benefits from RF transmit power monitoring and SAR compliance reduction.

[0043] The forward RF power regulator 320 may be implemented in the form of a system on a chip (SOC), an application specific integrated circuit (ASIC), a discrete circuit system, etc., which may be implemented with existing / future modems / antennas or integrated into such components. The directional coupler 307 may be located next to or may be inserted next to the antenna RF transmit line coupling (e.g., RF transmit line coupling 314). In one implementation, the directional coupler 307 exhibits the simultaneous characteristics of low insertion loss and high directivity on the RF transmit line coupling 314 (antenna to modem). The high directivity enables the detected power to be substantially the forward RF power transmitted from the modem 302 to the RF transmit antenna 304, and is substantially uncontaminated by reflected power directed back to the modem 302 due to imperfect antenna termination impedance.

[0044] The output of directional coupler 307 (e.g., a lower amplitude replica of the transmit RF power output of modem 302) is fed to a detector circuit (e.g., detector 308), which may be a root mean square (RMS) detector circuit. The detector circuit generates an output signal that conforms to both:

[0045] is proportional to the duty cycle of the transmit signal of modem 302, and

[0046] Proportional to the amplitude of the transmitted signal of modem 302.

[0047] The low frequency output signal from the detector circuit (e.g., detector 308) may be moved into the digital domain for signal processing via ADC 310, which may be a low cost ADC. SAR controller 312 monitors the digitized low frequency output signal and instructs modem 302 to perform power adjustment for SAR compliance when appropriate (e.g., when forward RF power adjustment conditions are met). Logarithmic calculations may be applied to meet applicable regulatory SAR paradigms. SAR controller 312 may include hardware and / or software stored in a processor readable medium storing processor executable instructions for reading RF power input from ADC 310 and determining whether transmit RF power adjustment is required. SAR controller 312 may include one or more processors, processing cores, microprocessors, etc.

[0048] Specifically, SAR is a time-averaged measurement. Although some periods of signal transmission will be at transmit power levels that exceed the permitted regulatory limits for body SAR (0 mm of space, or small spaces, such as 5 mm or 10 mm for certain device form factors), Figure 3 The circuit configuration in can be used to accurately monitor the average RF power over time. The near real-time calculation provides legal compliance for the time-averaged SAR. If the legal limit is about to be reached, the logic signal output from the SAR controller 312 will trigger a transmit RF power adjustment event in the modem 302 or associated circuitry (e.g., an attenuation circuit at the output of the modem 302).

[0049] Figure 4 An example circuit diagram of another communication subsystem implementation 400 for providing SAR mitigation is illustrated. The communication subsystem implementation 400 includes a modem 402 (e.g., RF transmitter circuit), an RF transmit antenna 404, and a forward RF power regulator 420 including a forward RF power detection circuit 406. Specifically, Figure 4 A hardware variant is illustrated in which the forward RF power detection circuit (e.g., Figure 3408. Forward RF power regulator 420 also includes detector 408, analog-to-digital converter (ADC) 410, and SAR controller 412. Modem 402 may include an LTE modem, a Wi-Fi radio, or other transmitting radio that benefits from RF transmit power monitoring and SAR compliance reduction.

[0050] The output of capacitor tap 407 (e.g., a lower amplitude replica of the transmit RF power output of modem 402) is fed to a detector circuit (e.g., detector 408), which may be a root mean square (RMS) detector circuit. The detector circuit generates an output signal that conforms to the following:

[0051] is proportional to the duty cycle of the transmit signal of modem 402, and

[0052] Proportional to the amplitude of the transmitted signal of modem 402.

[0053] The location of the capacitor tap 407 (e.g., protected by a circulator 409 that directs the reflected RF power to ground through an inductor 411) substantially eliminates the risk of measurement errors associated with reflected power and imperfect antenna termination impedance. The capacitor tap 407, detector 408, analog-to-digital converter (ADC) 410, SAR controller 412, circulator 409, and / or inductor 411 may be part of a system on a chip (SOC), an application specific integrated circuit (ASIC), a discrete circuit system, etc., which may be located on the RF transmit line coupling 414 (antenna to modem) to detect the forward RF power supplied by the modem 402 to the RF transmit antenna 404 and to direct the modem 402 to perform forward RF power adjustment when a forward RF power adjustment condition is met (e.g., when the average power during a rolling window reaches a SAR legal limit or some related limit).

[0054] Figure 5 An example circuit schematic diagram of another communication subsystem implementation 500 for providing proximity-independent SAR mitigation is illustrated. The communication subsystem implementation 500 includes a modem 502 (e.g., RF transmitter circuit), an RF transmit antenna 504, and a forward RF power regulator 520 including a forward RF power detection circuit 506. Specifically, Figure 5A hardware variant is illustrated in which the forward RF power detection circuit (e.g., Figure 3 The forward RF power detection circuit 306 of the embodiment of the present invention is replaced by a forward RF power detection circuit 506, which includes a directional coupler 507, a circulator 509, and an inductor 511 connected to ground. The forward RF power regulator 520 also includes a detector 508, an analog-to-digital converter (ADC) 510, and a SAR controller 512. The modem 502 may include an LTE modem, a Wi-Fi radio, or other transmitting radio that benefits from RF transmit power monitoring and SAR compliance reduction.

[0055] The location of the directional coupler 507 (e.g., protected by a circulator 509, which directs the reflected RF power to ground through an inductor 511) substantially eliminates the risk of measurement errors associated with reflected power and imperfect antenna termination impedance. The forward RF power regulator 520 can be implemented in the form of a system on a chip (SOC), an application specific integrated circuit (ASIC), a discrete circuit system, etc., which can be implemented with existing / future modems / antennas or integrated into such components. The directional coupler 507 can be located next to the antenna RF transmission line coupling (e.g., RF transmission line coupling 514) or can be inserted next to the antenna RF transmission line coupling. In one implementation, the directional coupler 507 exhibits the simultaneous characteristics of low insertion loss and high directivity on the RF transmission line coupling 514 (antenna to modem). The high directivity makes the detected power essentially the forward RF power transmitted from the modem 502 to the RF transmission antenna 504, and is substantially not contaminated by the reflected power directed back to the modem 502 due to the imperfect antenna termination impedance.

[0056] The output of directional coupler 507 (e.g., a lower amplitude replica of the transmit RF power output of modem 502) is fed to a detector circuit (e.g., detector 508), which can be a root mean square (RMS) detector circuit. The detector circuit produces an output signal that conforms to the following at the same time:

[0057] is proportional to the duty cycle of the transmit signal of modem 502, and

[0058] Proportional to the amplitude of the transmitted signal of modem 502.

[0059] The low frequency output signal from the detector circuit (e.g., detector 508) may be moved into the digital domain for signal processing via ADC 510, which may be a low cost ADC. SAR controller 512 monitors the digitized low frequency output signal and instructs modem 502 to perform power adjustment for SAR compliance when appropriate (e.g., when forward RF power adjustment conditions are met). Logarithmic calculations may be applied to meet applicable regulatory SAR paradigms. SAR controller 512 may include hardware and / or software stored in a processor readable medium storing processor executable instructions for reading RF power input from ADC 510 and determining whether transmit RF power adjustment is required. SAR controller 512 may include one or more processors, processing cores, microprocessors, etc.

[0060] Specifically, SAR is a time-averaged measurement. Although some periods of signal transmission will be at transmit power levels that exceed the permitted regulatory limits for body SAR (0 mm of space, or small spaces, such as 5 mm or 10 mm for certain device form factors), Figure 5 The circuit configuration in can be used to accurately monitor the average RF power over time. The near real-time calculation provides legal compliance for the time-averaged SAR. If the legal limit is about to be reached, the logic signal output from the SAR controller 512 will trigger a transmit RF power adjustment event in the modem 502 or associated circuitry (e.g., an attenuation circuit at the output of the modem 502).

[0061] Figure 6 An example circuit schematic diagram of another communication subsystem implementation 600 for providing proximity-independent SAR mitigation is illustrated. The communication subsystem implementation 600 includes a modem 602 (e.g., RF transmitter circuit), an RF transmit antenna 604, and a forward RF power regulator 620 including a forward RF power detection circuit 606. Specifically, Figure 6 A hardware variant is illustrated in which the forward RF power detection circuit (e.g., Figure 3 608. Forward RF power regulator 620 also includes detector 608, analog-to-digital converter (ADC) 610, and SAR controller 612. Modem 602 may include an LTE modem, a Wi-Fi radio, or other transmitting radio that benefits from RF transmit power monitoring and SAR compliance reduction.

[0062] The output of capacitor tap 607 (e.g., a lower amplitude replica of the transmit RF power output of modem 602) is fed to a detector circuit (e.g., detector 608), which may be a root mean square (RMS) detector circuit. The detector circuit generates an output signal that conforms to the following:

[0063] is proportional to the duty cycle of the transmit signal of modem 602, and

[0064] Proportional to the amplitude of the transmitted signal of modem 602.

[0065] The location of the capacitor tap 607 (e.g., protected by the isolator 609) substantially eliminates the risk of measurement errors associated with reflected power and imperfect antenna termination impedance. The capacitor tap 607, the detector 608, the analog-to-digital converter (ADC) 610, the SAR controller 612, and / or the isolator 609 may be part of a system on a chip (SOC), an application specific integrated circuit (ASIC), a discrete circuit system, etc., which may be located on the RF transmit line coupling 614 to detect the forward RF power supplied by the modem 602 to the RF transmit antenna 604, and to direct the modem 602 to perform forward RF power adjustment when a forward RF power adjustment condition is met (e.g., when the average power during the rolling window reaches the SAR legal limit or some related limit).

[0066] Figure 7 An example circuit diagram of another communication subsystem implementation 700 for providing proximity-independent SAR mitigation is illustrated. The communication subsystem implementation 700 includes a modem 702 (e.g., RF transmitter circuit), an RF transmit antenna 704, and a forward RF power regulator 720 including a forward RF power detection circuit 706. Specifically, Figure 7 A hardware variant is illustrated in which the forward RF power detection circuit (e.g., Figure 3 706) is replaced by a forward RF power detection circuit 706 that includes a directional coupler 707 and an isolator 709. The forward RF power regulator 720 also includes a detector 708, an analog-to-digital converter (ADC) 710, and a SAR controller 712. The modem 702 may include an LTE modem, a Wi-Fi radio, or other transmitting radio that benefits from RF transmit power monitoring and SAR compliance reduction.

[0067] The location of the directional coupler 707 (e.g., protected by the isolator 709) substantially eliminates the risk of measurement errors associated with reflected power and imperfect antenna termination impedance. The forward RF power regulator 720 can be implemented in the form of a system on a chip (SOC), an application specific integrated circuit (ASIC), a discrete circuit system, etc., which can be implemented with existing / future modems / antennas or integrated into such components. The directional coupler 707 can be located next to the antenna RF transmission line coupling (e.g., the RF transmission line coupling 714) or can be inserted next to the antenna RF transmission line coupling. In one implementation, the directional coupler 707 exhibits the simultaneous characteristics of low insertion loss and high directivity on the RF transmission line coupling 714. The high directivity makes the detected power essentially the forward RF power transmitted from the modem 702 to the RF transmission antenna 704, and is substantially not contaminated by the reflected power directed back to the modem 702 due to the imperfect antenna termination impedance.

[0068] The output of directional coupler 707 (e.g., a lower amplitude replica of the transmit RF power output of modem 702) is fed to a detector circuit (e.g., detector 708), which may be a root mean square (RMS) detector circuit. The detector circuit generates an output signal that conforms to the following at the same time:

[0069] is proportional to the duty cycle of the transmit signal of modem 702, and

[0070] Proportional to the amplitude of the transmitted signal of modem 702.

[0071] The low frequency output signal from the detector circuit (e.g., detector 708) may be moved into the digital domain for signal processing via ADC 710, which may be a low cost ADC. SAR controller 712 monitors the digitized low frequency output signal and instructs modem 702 to perform power adjustment for SAR compliance when appropriate (e.g., when forward RF power adjustment conditions are met). Logarithmic calculations may be applied to meet applicable regulatory SAR paradigms. SAR controller 712 may include hardware and / or software stored in a processor readable medium storing processor executable instructions for reading RF power input from ADC 710 and determining whether transmit RF power adjustment is required. SAR controller 712 may include one or more processors, processing cores, microprocessors, etc.

[0072] Specifically, SAR is a time-averaged measurement. Although some periods of signal transmission will be at transmit power levels that exceed the permitted regulatory limits for body SAR (0 mm of space, or small spaces, such as 5 mm or 10 mm for certain device form factors), Figure 7The circuit configuration in can be used to accurately monitor the average RF power over time. The near real-time calculation provides legal compliance for the time-averaged SAR. If the legal limit is about to be reached, the logic signal output from the SAR controller 712 will trigger a transmit RF power adjustment event in the modem 702 or associated circuitry (e.g., an attenuation circuit at the output of the modem 702).

[0073] Figure 8 An example circuit schematic 800 is illustrated for providing multi-band transmission in a communication subsystem implementation for proximity-independent SAR mitigation. Specifically, Figure 8 Illustrated are low-band circuits 840 for RF power detection and SAR control and medium / high-band circuits 842 for RF power detection and SAR control. The number of circuits depends on the type / quantity of the transmit port of the cellular modem. For example, some modems use low / medium / high-band ports, and therefore, a single circuit can be used for RF power detection and SAR control. In other implementations, the modem can have a low / medium-band port and a high-band port. In this way, a certain RF power detection and SAR control circuit can correspond to a low / medium-band port, and a certain RF power detection and SAR control circuit can correspond to a high-band port.

[0074] exist Figure 8 In the illustrated implementation, the low-band circuit 840 includes a modem low-band transmit (Tx) port 802, which outputs an RF signal to a low-band antenna 808 through an RF test connector 804. A directional coupler 806 (or a capacitor tap) receives some RF transmit power from the RF signal output from the modem low-band Tx port 802. The RF signal received at the directional coupler 806 is output to a 10 dB pad 810 (or another dB pad). An RMS detector 812 receives a signal from the 10 dB pad and outputs the low-frequency signal to an analog-to-digital converter (ADC) 814. The ADC 814 outputs a digital signal to a SAR controller 816. The SAR controller 816 compares the detected RF power (in the form of a digital signal) with a stored pattern to determine a transmission context. Based on the determined transmission context, the SAR controller 816 determines an average scheme to determine the average RF power over time. Based on the determined average RF power, the SAR controller 816 may recommend RF power adjustments to the modem including the modem low-band Tx port 802 .

[0075] The mid / high band circuit 842 includes a modem mid / high band transmission (Tx) port 820, which outputs an RF signal to a low band antenna 826 through an RF test connector 822. A directional coupler 824 (or a capacitor tap) receives some RF transmission power from the RF signal output from the mid / high band Tx port 820. The RF signal received at the directional coupler is output to a 10 dB pad 828 (or other dB pads). An RMS detector 830 receives a signal from the 10 dB pad 828 and outputs a low frequency signal to an analog-to-digital converter (ADC) 832. The ADC 832 outputs a digital signal to a SAR controller 834. The SAR controller 834 compares the detected RF power (in the form of a digital signal) with the stored pattern to determine the transmission context. Based on the determined transmission context, the SAR controller 834 determines an average scheme to determine the average RF power over time. Based on the determined average RF power, the SAR controller 834 can recommend RF power adjustment to the modem including the mid / high band Tx port 820 of the modem.

[0076] In various implementations, the 10 dB shims (e.g., 10 dB shims 810 and 828) are optional and depend on the type / characteristics of the RMS detector connected. In some implementations, the shims are not included, and in other implementations, the characteristics of the shims are different. In some implementations, the SAR controllers 816 and 834 can be a single processing unit in which the determination / averaging algorithm is running and the signals are being monitored and SAR adjustment recommendations are made. The circuits (e.g., low band circuit 840 and mid / high band circuit 842) can include isolators and / or circulators as described above.

[0077] Fig. 9 An example detector emission function 900 is illustrated. Specifically, Fig. 9 A detector in an LTE mobile device (eg, Figure 3-7 Figure 1 shows an example output graph of a detector). An LTE mobile device operates and accepts instructions for transmit power levels from the cellular network. The cellular tower will instruct the mobile device to transmit at a higher RF power level when far away from the tower and at a lower RF power level when close to the tower. This translates into a requirement for the monitoring circuit (e.g., detector circuit) to be able to produce an accurate output for a wide range of input RF amplitudes. Fig. 9 It shows that it is entirely possible to accurately monitor a wide range of input RF amplitudes and produce a proportional detection output signal. The detector circuit is also wideband, operating over the frequency ranges of both LTE and Wi-Fi.

[0078] Fig.10An oscilloscope graph 1000 is illustrated of LTE transmissions detected from an LTE device using a VOIP call at normal conversation speeds. The duty cycle was measured to be 27%. The detector circuit (see Figure 3-7 ) was used to monitor LTE transmissions from a tablet device operating on a cellular network under various device usage conditions. When the tablet was making a VOIP call at "normal" voice call speeds, the transmit duty cycle was approximately 27%. Under this operating condition, the modem was unable to transmit continuously. An oscilloscope was used to monitor the detector output signal under this operating condition.

[0079] Fig.10 Discontinuous transmission occurs during a VOIP call, and averaging techniques that include periods of no transmission have the potential to allow long phone calls to be sent without fully applying power regulation while fully complying with safety requirements. The details (distance from the cell tower and the averaging window specified by the regulatory authority) will affect the implementation. For example, the transmission context (e.g., VOIP call) can be determined based on a comparison of detected transmission power levels over time, and the averaging scheme can be determined based on the transmission context (e.g., signal conditions). The selected averaging scheme can offset periods of high transmission (e.g., period 1004) with periods of low / zero transmission (e.g., period 1002) when it is determined that the transmission power over time meets the SAR legal limit.

[0080] Fig.11 An oscilloscope graph 1100 of detected LTE transmissions from an LTE device uploading a file via email is illustrated. The device is transmitting a large file from a tablet (as an email attachment). The transmission duty cycle is approximately 100%.

[0081] In situations where a mobile device is uploading a very large file for a long period of time while the mobile device is far away from a cellular tower (hence high transmit power) (e.g., a transmit context), Fig.11 The RF output is illustrated to be nearly continuous (over a period of time) and of large amplitude. Computational techniques applied to this signal can easily predict when the average exposure limit is approached. When the modem transmit power is restored, the modem's transmit behavior can be reduced to a safe low power level for the duration required to maintain safe limits. Fig.11 The illustrated transmit context selects a fast averaging scheme. Thus, any small changes in transmit power level will be used to determine the average transmit power to meet SAR legal limits over time.

[0082] Averaging techniques (e.g., fast averaging) using more advanced algorithmic approaches can invoke smaller, less drastic power adjustments before approaching the "brick wall" back-off required to observe safety limits. This more gradual application of power adjustments combines the advantages of observing safe emission levels and providing a better customer user experience.

[0083] The detector output waveform (e.g. Fig.10 or Fig.11 ) is a representation of the RF input waveform. The detector outputs a low frequency signal that is ideal for low cost signal processing to evaluate the RF transmit duty cycle and RF transmit power level.

[0084] The FCC discusses SAR limits as an average over a permitted time period. The implementation described herein removes the need to instantaneously apply SAR backoff (e.g., using proximity detection techniques) when an object is nearby. This allows for assurance of safety without proximity detection and more reliance on intelligent averaging that can be adaptively and dynamically adjusted to satisfy the FCC while eliminating the need for proximity sensors.

[0085] Fig.12 Example operations 1200 for detecting RF power and implementing proximity-independent SAR control are illustrated. These operations may be performed by an RF power detector and / or a SAR controller implemented on a system on chip (SOC), an application-specific integrated circuit, a microprocessing unit (MU), etc. Instructions for operation 1200 may be implemented in instructions stored on a processor-readable storage medium. Setting operation 1202 sets an RF transmit power limit in a mobile device. The RF transmit power limit may be set independently of the proximity of the detected object to the antenna of the device. The limit may be static and / or dependent on a SAR legal limit threshold. Detection operation 1204 detects the RF transmit signal power of an RF signal transmitted from a modem to an antenna of a mobile device. Detection operation 1204 may be performed by a detector that may utilize a capacitive tap or a directional coupler. It should be understood that the forward power from the modem to the antenna is detected, rather than the reflected power generated by the impedance mismatch between the antenna and the transmission line. Conversion operation 1206 converts the detected RF signal power into a digital signal. Conversion operation 1206 may be performed by an analog-to-digital converter (ADC).

[0086] A monitoring operation 1208 monitors the converted digital signal. A determining operation 1210 determines a transmit signal condition (e.g., context) of the mobile device. The determining operation 1210 may be performed by comparing the detected (converted) RF signal power with a stored transmit power context. Such transmit power contexts may include a high transmit power context (e.g., file transmission), a medium transmit power context (e.g., VOIP call), and a low transmit power context (e.g., passive transmission). An averaging operation 1212 time-averages the monitored digital signal using a selected averaging scheme.

[0087] The selection operation 1214 selects a time-averaged filter based on the determined transmit signal condition. The time-averaged scheme corresponds to the determined context. For example, a fast averaging scheme can be used to time-average a high transmit power context in order to utilize multiple dips in the transmit power. A slow averaging scheme can be utilized in a low transmit power context in order to utilize a period of low (e.g., almost zero) transmit power. The selection of an averaging scheme may include selecting a filter / filter coefficient. An initiation operation 1216 initiates adjustment of the RF transmit power of the mobile device based on the time-averaged signal (according to the selected filter) and the RF transmit power limit. The initiation operation 1216 may utilize the current time-averaged transmit power to determine if / when the transmit power may exceed the set RF transmit power limit. In addition, the number of buffers in the RF transmit power may be considered. Operation 1200 may be performed in real time, and therefore, the time-averaged and RF transmit powers may be determined based on a moving time window.

[0088] The transmit context may include different transmit modes (which may consist of a set of signal transmission characteristics combined based on pre-stored knowledge of the transmit technology (e.g., LTE)) to determine how to best generate an attenuation curve that is best suited for OTA wireless operation while keeping FCC averages met. The results (e.g., the determined context) are then used to determine which type of filter averaging will be used for the next set of attenuation decisions, the type of filter used and its associated filter coefficients. In addition to generating adjustment values, the combinatorial logic of such overall operations also takes into account reserving a certain transmit budget, which can be intelligently reserved for anticipating future needs that may require high power periods.

[0089] It should be understood that the described operations 1204, 1206, 1208, 1210, 1212 and 1214 may be performed continuously or periodically, repeating as transmit power monitoring continues. In addition, operation 1216 may be performed whenever the average signal and RF transmit power trigger an RF transmit power adjustment instruction.

[0090] Fig.13 A framework 1300 for example proximity-independent SAR mitigation is illustrated. A forward RF power detection circuit 1302 monitors the forward RF power supplied by an RF transmit circuit 1328 (e.g., in a modem) to an RF transmit antenna 1330 via an RF transmit line coupling 1303. An RF power sampler 1304 samples the monitored forward RF power and provides forward power sample samples to a filter 1306, which includes filter bank 0 through filter bank N. Each filter bank filters at a different cutoff frequency than the other filter banks and therefore applies a different average power period to the samples (e.g., averages the forward RF power over a different average power period).

[0091] Filter 1306 issues a trigger for each filter that meets the forward RF power adjustment condition. Trigger point logic 1308 receives the triggers and selects one or more triggers based on various inputs including, but not limited to, network conditions 1310 and / or transmission requirements 1312. Control logic 1314 of trigger point logic 1308 processes the various inputs and passes the processed inputs to filter selector 1316, which selects the filter from which to receive the trigger at any particular point in time based on the processed inputs. Additionally, override logic 1309 can override the filtered trigger (e.g., if the unfiltered sample of the monitored forward RF power is at risk of violating the SAR limit within the adjustment rolling time window, the override logic 1309 can simply trigger an immediate adjustment without considering any filter-based average power period).

[0092] Decay curve logic 1320 receives a trigger from the selected filter and applies a decay curve that specifies the decay duration and possible incremental decay events and magnitudes during the decay duration based on inputs including, but not limited to, network conditions 1310 and transmission requirements 1312. See, e.g. Figure 14-17 1320. The control logic 1322 of the attenuation curve logic 1320 processes the input and passes the processed input to the curve selector 1324, which selects an appropriate attenuation curve for the processed input. For example, the attenuation curve may be more dramatic and / or abrupt in a high transmit activity scenario (e.g., file download) than in a low transmit activity scenario (e.g., VOIP call). The curve selector 1324 also sends a power adjustment instruction to the RF transmit circuit 1328 to adjust the power supplied to the RF transmit antenna 1330.

[0093] Additionally, the override logic 1326 may override the input-dependent attenuation curve (eg, if the monitored forward RF power is at risk of violating SAR limits within the regulation rolling time window, the override logic 1326 may simply terminate the transmit power for a period of time).

[0094] Fig.14An example attenuation curve 1402 that can be used by the control logic for proximity-independent SAR mitigation is illustrated. In one implementation, a time-averaging scheme relies on monitoring the power level at the antenna(s) over an averaging period. Various filters can be used to filter the monitored power level, with each filter (or filter bank) averaging over its own average power period. By averaging the power samples received from the detector using a set of dynamically selected filters, backoff decisions (e.g., power attenuation decisions) can be determined based on total transmit time, total power average, signal conditions, SAR limits, technical factors, reserved SAR margin, filter refresh based on SAR time average (e.g., within a rolling time window allowed by the FCC), and many other relevant variables using a variable filter tap mix. The reserved SAR margin is considered for the total power budget expenditure to account for and guarantee criticality of over-the-air (OTA) transmission events.

[0095] In some implementations, a recursive averaging technique is used. In such implementations, a slow averaging filter (e.g., passing lower frequency samples) is used in low transmit modes (e.g., VOIP calls), while a fast averaging filter (e.g., also passing higher frequency samples) is used in high transmit modes (e.g., uploading large data files). The filter buffer can be refreshed at selected time periods (e.g., when a maximum averaging period is reached or other system conditions require). In both slow and fast averaging, SAR margin can be reserved by periodically forcing transmit power adjustments if conditions permit (e.g., more likely in fast averaging). Many other averaging filters can be employed within the range of "fast" and "slow" averaging filter settings.

[0096] A decision counter, which may include a portion of the SAR controller described above, determines a transmission context (e.g., based on one or more signal conditions) based on a predetermined pattern and a dynamically determined pattern. For example, predetermined patterns for file uploads, VOIP calls, web browsing, passive data transmission, and other types of data transmission contexts may be stored in a memory. Dynamically determined patterns may include, but are not limited to, patterns learned based on feedback about signal conditions from base stations, etc. These patterns may vary based on the distance between the device and the tower, which may be known by the device / system disclosed herein. The decision counter may compare the power detected on the modem to the antenna transmission line coupling with a predetermined power to determine the transmission context. Based on the determined context, an averaging scheme (e.g., a filter) is selected to determine the average transmit power.

[0097] A slow averaging scheme is selected for a low transmit context (e.g., "good" signal conditions, low transmit activity). A "medium" averaging scheme is selected for a determined medium transmit context. A fast averaging scheme is selected for a high transmit context (e.g., "bad" signal conditions, high transmit activity). It should be understood that more than three example transmit contexts may be determined, and different averaging schemes may correspond to such contexts. Furthermore, it should be understood that the system may determine changes in context in real time, and therefore the averaging scheme (e.g., the filter applied) may change.

[0098] As discussed, different attenuation curves may be applied to forward RF power adjustment events at any particular time, depending on inputs such as network conditions and / or transmission requirements. Schematic diagram 1400 depicts actual RF transmit power (depending on different levels of attenuation) over time.

[0099] Attenuation curve 1402 depicts the incremental level of attenuation applied to the actual RF transmit power over time in response to the triggering of the forward RF power adjustment event and the selection of the attenuation curve. Edge 1404 generally depicts the incremental increase in attenuation level over time, resulting in a decrease in the level of the actual RF transmit power spike over time. Edge 1406 generally depicts the incremental decrease in attenuation level over time, resulting in an increase in the level of the actual RF transmit power spike over time.

[0100] Fig.15 Example attenuation curves that may be used by control logic for proximity-independent SAR mitigation using a medium-speed filter are illustrated. As discussed, different attenuation curves may be applied to the forward RF power adjustment event at any particular time, depending on inputs such as network conditions and / or transmit requirements. Schematic 1500 depicts actual RF transmit power over time for high transmit activity (depending on different levels of attenuation). Line 1502 depicts the average power on the modem-to-antenna transmit line coupling as monitored by the medium-speed averaging filter. Fig.15 In the scenario shown, the fast averaging filter exhibits an average power period that is less than the rolling time window specified by the SAR regulations.

[0101] Attenuation curve 1504 depicts the incremental level of attenuation applied to the actual RF transmit power over time in response to the medium-speed averaging filter triggering a forward RF power adjustment event and selecting an attenuation curve. In the illustrated scenario, when the average power monitored by the medium-speed averaging filter during the average power period exceeds a threshold value (e.g., -35 dBm in this scenario), the RF power adjustment trigger signal is activated to adjust the RF power supplied to the antenna. Edge 1506 generally depicts an incremental increase in the attenuation level over time, resulting in a decrease in the level of the actual RF transmit power spike over time. Edge 1508 generally depicts an incremental decrease in the attenuation level over time, resulting in an increase in the level of the actual RF transmit power spike over time.

[0102] In some implementations, hysteresis is introduced when the average power exceeds a threshold. The hysteresis delays the RF power adjustment trigger signal to allow confirmation that the activity exceeding the threshold is not an abnormal event. For example, if the average power monitored by the medium-speed averaging filter during the average power period still exceeds the threshold at the end of the hysteresis delay, the trigger condition is confirmed and the RF power adjustment trigger is activated to adjust the RF power supplied to the antenna. Hysteresis can also be applied to the reduction in attenuation, so that the start of attenuation is delayed until the average power transmitted during the averaging period is confirmed to be reduced below the threshold.

[0103] Fig.16 Example attenuation curves that may be used by control logic for proximity-independent SAR mitigation using a fast filter are illustrated. As discussed, different attenuation curves may be applied to the forward RF power adjustment event at any particular time, depending on inputs such as network conditions and / or transmit requirements. Schematic 1600 depicts actual RF transmit power over time for high transmit activity (depending on different levels of attenuation). Line 1602 depicts the average power on the modem-to-antenna transmit line coupling as monitored by the high speed averaging filter. Fig.16 In the scenario shown, the fast averaging filter exhibits an averaging power period that is smaller than the rolling time window specified by SAR regulations, and is also smaller than the averaging power periods of the slow and medium averaging filters.

[0104] Attenuation curve 1604 depicts the incremental level of attenuation applied to the actual RF transmit power over time in response to the fast average filter triggering a forward RF power adjustment event and selecting an attenuation curve. In the illustrated scenario, when the average power monitored by the fast average filter during the average power period exceeds a threshold value (e.g., -35 dBm in this scenario), the RF power adjustment trigger signal is activated to adjust the RF power supplied to the antenna. Edge 1606 generally depicts an incremental increase in the attenuation level over time, resulting in a decrease in the level of the actual RF transmit power spike over time. Edge 1608 generally depicts an incremental decrease in the attenuation level over time, resulting in an increase in the level of the actual RF transmit power spike over time.

[0105] In some implementations, hysteresis is introduced when the average power exceeds a threshold. The hysteresis delays the RF power adjustment trigger signal to allow confirmation that the activity exceeding the threshold is not an abnormal event. For example, if the average power monitored by the medium-speed averaging filter during the average power period still exceeds the threshold at the end of the hysteresis delay, the trigger condition is confirmed and the RF power adjustment trigger is activated to adjust the RF power supplied to the antenna. Hysteresis can also be applied to the reduction in attenuation, so that the start of attenuation is delayed until the average power transmitted during the averaging period is confirmed to be reduced below the threshold.

[0106] Fig.17 Example attenuation curves that may be used by control logic for proximity-independent SAR mitigation using a slow filter are illustrated. As discussed, different attenuation curves may be applied to the forward RF power adjustment event at any particular time, depending on inputs such as network conditions and / or transmit requirements. Schematic 1700 depicts actual RF transmit power over time for high transmit activity (depending on different levels of attenuation). Line 1702 depicts the average power on the modem-to-antenna transmit line coupling monitored by the slow averaging filter. Fig.17 In the scenario shown, the slow averaging filter exhibits an averaging power period approximately equal to the rolling time window specified by the SAR regulations.

[0107] Attenuation curve 1704 depicts the incremental level of attenuation applied to the actual RF transmit power over time in response to the slow average filter triggering a forward RF power adjustment event and selecting an attenuation curve. In the illustrated scenario, when the average power monitored by the fast average filter during the average power exceeds a threshold value (e.g., -35 dBm in this scenario), the RF power adjustment trigger signal is activated to adjust the RF power supplied to the antenna. Edge 1706 generally depicts an incremental increase in attenuation level over time, resulting in a decrease in the level of the actual RF transmit power spike over time. Edge 1708 generally depicts an incremental decrease in attenuation level over time, resulting in an increase in the level of the actual RF transmit power spike over time.

[0108] In some implementations, hysteresis is introduced when the average power exceeds a threshold. The hysteresis delays the RF power adjustment trigger signal to allow confirmation that the activity exceeding the threshold is not an abnormal event. For example, if the average power monitored by the medium-speed averaging filter during the average power period still exceeds the threshold at the end of the hysteresis delay, the trigger condition is confirmed and the RF power adjustment trigger is activated to adjust the RF power supplied to the antenna. Hysteresis can also be applied to the reduction in attenuation, so that the start of attenuation is delayed until the average power transmitted during the averaging period is confirmed to be reduced below the threshold.

[0109] It should be appreciated that RF transmit power limits or thresholds, decay curves, hysteresis values, averaging power periods, rolling time windows, etc. may be programmable or otherwise adjustable prior to or during operation of the SAR mitigation process.

[0110] Fig.18 An example system (labeled as communication device 1800) that can be used to implement the described techniques is illustrated. Communication device 1800 can be a client device, such as a laptop, mobile device, desktop, tablet, or server / cloud device. Communication device 1800 includes one or more processors 1802 and memory 1804. Memory 1804 generally includes both volatile memory (e.g., RAM) and non-volatile memory (e.g., flash memory). Operating system 1810 resides in memory 1804 and is executed by processor(s) 1802.

[0111] One or more application 1812 modules or sections, such as antenna module(s) 1848, SAR controller(s) 1850, and / or detector(s) 1852, are loaded into memory 1804 and / or storage 1820 and executed by processor(s) 1802. Data, such as signal context patterns, SAR RF power thresholds, conditions, etc., may be stored in memory 1804 or storage 1820 and may be retrieved by processor(s) 1802 for use in antenna module(s) 1848, SAR controller(s) 1850, detector(s) 1852, etc. Storage 1820 may be local to communication device 1800, or may be remote to and communicatively connected to communication device 1800, and may include another server. Storage 1820 may store resources that may be requested by a client device (not shown).

[0112] The communication device 1800 includes a power supply 1816 that is powered by one or more batteries or other power sources and that provides power to the other components of the communication device 1800. The power supply 1816 may also be connected to an external power source that overrides or recharges the internal batteries or other power sources.

[0113] The communication device 1800 may include one or more communication transceivers 1830, which may be connected to one or more antenna assemblies 1832 to provide network connectivity (e.g., mobile phone networks, The communication device 1800 may further include a network adapter 1836, which is a type of communication device. The communication device 1800 may use the adapter and any other type of communication device to establish a connection on a wide area network (WAN) or a local area network (LAN). It should be understood that the network connection shown is exemplary and other communication devices and means for establishing a communication link between the communication device 1800 and other devices may be used. One or more antenna assemblies 1832 may include isolators, circulators, capacitor taps, detectors, pads, analog-to-digital converters, etc.

[0114] The communication device 1800 may include one or more input devices 1834 (e.g., a keyboard or mouse) so that a user can enter commands and information. These and other input devices may be coupled to a server via one or more interfaces 1838 such as a serial port interface, a parallel port, a universal serial bus (USB), etc. The communication device 1800 may further include a display 1822, such as a touch screen display.

[0115] The communication device 1800 may include a variety of tangible processor-readable storage media and intangible processor-readable communication signals. Tangible processor-readable storage may be embodied by any available medium that can be accessed by the communication device 1800, and includes both volatile and non-volatile storage media, removable and non-removable storage media. Tangible processor-readable storage media do not include intangible communication signals, but rather include volatile and non-volatile, removable and non-removable storage media implemented in any method or technology for storing information such as processor-readable instructions, data structures, program modules or other data. Tangible processor-readable media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical storage, cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other tangible medium that can be used to store the desired information and can be accessed by the processing system. In contrast to tangible processor-readable storage media, intangible processor-readable communication signals may embody processor-readable instructions, data structures, program modules or other data using modulated data signals such as carrier waves or other signal transmission mechanisms. The term "modulated data signal" means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, intangible communication signals include signals propagated through wired media (such as a wired network or direct-wired connection) and wireless media (such as acoustic, RF, infrared and other wireless media).

[0116] Some implementations may include articles of manufacture. Articles of manufacture may include tangible storage media storing logic. Examples of storage media may include one or more types of processor-readable storage media capable of storing electronic data, including volatile or non-volatile memory, removable or non-removable memory, erasable or non-erasable memory, writable or rewritable memory, etc. Examples of logic may include various software elements, such as software components, programs, applications, computer programs, applications, system programs, machine programs, operating system software, middleware, firmware, software modules, routines, subroutines, operation segments, methods, processes, software interfaces, application program interfaces (APIs), instruction sets, computing codes, computer codes, code segments, computer code segments, text, values, symbols, or any combination thereof. For example, in one implementation, an article of manufacture may store executable computer program instructions that, when executed by a computer, cause the computer to perform methods and / or operations according to the described implementations. Executable computer program instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, etc. Executable computer program instructions can be implemented according to a predefined computer language, manner or syntax for instructing a computer to perform a specific operation segment. These instructions can be implemented using any suitable high-level, low-level, object-oriented, visual, compiled, and / or interpreted programming language.

[0117] An example method adjusts forward radio frequency (RF) power supplied by an RF transmitter circuit to an RF transmit antenna, and includes detecting the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna, and receiving forward RF power samples of the supplied forward RF power at a plurality of filters. Each filter filters the received forward power samples differently to apply a different average power period. Each filter further activates an RF power adjustment trigger signal when the time-averaged forward RF power supplied to the RF transmit antenna satisfies a forward RF power adjustment condition of the filter's average power period. The example method also adjusts the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal.

[0118] Another example method of any of the foregoing methods further includes selecting a filter from a plurality of filters to output the RF power adjustment trigger signal.

[0119] Another example method of any of the foregoing methods is provided, wherein the selecting operation selects a filter of the plurality of filters based on at least one of a network condition and a transmission requirement.

[0120] Another example method of any of the foregoing methods further includes applying an attenuation curve while the RF power adjustment trigger signal is activated, and the adjustment operation adjusts the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna according to the attenuation curve.

[0121] Another example method of any of the foregoing methods is provided, wherein the attenuation curve specifies a magnitude of an incremental adjustment in forward RF power supplied by the RF transmitter circuit to the RF transmit antenna.

[0122] Another example method of any of the foregoing methods is provided, wherein the decay curve specifies a duration of an incremental adjustment in forward RF power supplied by the RF transmitter circuit to the RF transmit antenna.

[0123] Another example method of any of the foregoing methods is provided, wherein the detecting operation includes isolating forward RF power from reflected RF power in a power coupling between an RF transmitter circuit and an RF transmit antenna.

[0124] An example radio frequency (RF) power regulator includes a forward RF power detection circuit that is operable to detect the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna. An RF power sampler is coupled to the forward RF power detection circuit and provides an RF power sample of the supplied forward RF power. A plurality of filters are coupled to receive the RF power samples. Each filter filters the received forward power samples differently to apply a different average power period. Each filter further activates an RF power adjustment trigger signal when the time-averaged forward RF power supplied to the RF transmit antenna satisfies the forward RF power adjustment condition of the filter's average power period. The forward RF power adjustment logic is coupled to the filter and is operable to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal.

[0125] Another example RF power regulator of any of the previous regulators further includes a filter selector coupled to the plurality of filters and operable to select a filter from the plurality of filters to output the RF power adjustment trigger signal.

[0126] Another example RF power regulator of any previous regulator is provided, wherein a filter selector is operable to select one of a plurality of filters based on at least one of a network condition and a transmission requirement.

[0127] Another example RF power regulator of any of the previous regulators further includes an attenuation curve controller operable to apply the attenuation curve while activating the RF power adjustment trigger signal and adjust the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna according to the attenuation curve.

[0128] Another example RF power regulator of any of the previous regulators is provided, wherein a decay curve specifies a magnitude of an incremental adjustment in forward RF power supplied by an RF transmitter circuit to an RF transmit antenna.

[0129] Another example RF power regulator of any of the previous regulators is provided, wherein a decay curve specifies a duration of an incremental adjustment in forward RF power supplied by an RF transmitter circuit to an RF transmit antenna.

[0130] Another example RF power regulator of any previous regulator is provided, wherein the forward RF power detection circuit includes a forward RF power isolation circuit system coupled between the RF transmitter circuit and the RF transmit antenna and operable to isolate the forward RF power from the reflected RF power in the power coupling between the RF transmitter circuit and the RF transmit antenna.

[0131] Another example RF power regulator of any of the previous regulators is provided wherein the forward RF power isolator circuitry includes a directional coupler operable to detect forward RF power from power coupling between the RF transmitter circuitry and the RF transmit antenna.

[0132] Another example RF power regulator of any of the previous regulators is provided wherein the forward RF power isolator circuitry includes a directional coupler operable to detect forward RF power from power coupling between an RF transmitter circuit and an RF transmit antenna, and a circulator coupled between the directional coupler and the RF transmit antenna.

[0133] Another example RF power regulator of any of the previous regulators is provided wherein the forward RF power isolator circuitry includes a capacitor tap operable to detect forward RF power from a power supply coupled between an RF transmitter circuit and an RF transmit antenna, and a circulator coupled between the capacitor tap and the RF transmit antenna.

[0134] Another example RF power regulator of any of the previous regulators is provided, wherein the forward RF power isolator circuitry includes a directional coupler operable to detect forward RF power from power coupling between an RF transmitter circuit and an RF transmit antenna, and an isolator coupled between the directional coupler and the RF transmit antenna.

[0135] Another example RF power regulator of any of the previous regulators is provided, wherein the forward RF power isolator circuit system includes a capacitor tap operable to detect forward RF power from a power supply coupled between an RF transmitter circuit and an RF transmit antenna, and an isolator coupled between the capacitor tap and the RF transmit antenna.

[0136] An example communication device includes: a radio frequency (RF) transmit antenna, an RF transmitter circuit coupled to supply forward RF power to the RF transmit antenna, a forward RF power detection circuit operable to detect the forward RF power supplied to the RF transmit antenna by the RF transmitter circuit, an RF power sampler coupled to the forward RF power detection circuit and providing an RF power sample of the supplied forward RF power, and a plurality of filters coupled to receive the RF power samples. Each filter filters the received forward power samples differently to apply a different average power period. Each filter further activates an RF power adjustment trigger signal when the time-averaged forward RF power supplied to the RF transmit antenna satisfies a forward RF power adjustment condition of the filter's average power period. A filter selector is coupled to the plurality of filters and is operable to select a filter from the plurality of filters to output an RF power adjustment trigger signal based on at least one of a network condition and a transmission requirement. A forward RF power adjustment logic is coupled to the filter selector and is operable to adjust the forward RF power supplied to the RF transmit antenna by the RF transmitter circuit based on the RF power adjustment trigger signal output from the selected filter.

[0137] An example system regulates forward radio frequency (RF) power supplied by an RF transmitter circuit to an RF transmit antenna, and includes means for detecting the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna, and means for receiving forward RF power samples of the supplied forward RF power at a plurality of filters. Each filter filters the received forward power samples differently to apply a different average power period. Each filter further activates an RF power adjustment trigger signal when the time-averaged forward RF power supplied to the RF transmit antenna satisfies a forward RF power adjustment condition for an average power period of the filter. The example system also includes means for adjusting the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal.

[0138] Another example system of any of the foregoing systems further includes means for selecting a filter from a plurality of filters to output the RF power adjustment trigger signal.

[0139] Another example system of any of the foregoing systems is provided, wherein the means for selecting selects a filter of a plurality of filters based on at least one of a network condition and a transmission requirement.

[0140] Another example system of any of the foregoing systems further includes means for applying the attenuation curve while activating the RF power adjustment trigger signal. The means for adjusting adjusts the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna according to the attenuation curve.

[0141] Another example system of any of the foregoing systems is provided, wherein the attenuation curve specifies a magnitude of an incremental adjustment in forward RF power supplied by the RF transmitter circuit to the RF transmit antenna.

[0142] Another example system of any of the foregoing systems is provided, wherein the decay curve specifies a duration of an incremental adjustment in forward RF power supplied by the RF transmitter circuit to the RF transmit antenna.

[0143] Another example system of any of the foregoing systems is provided, further comprising: wherein the means for detecting includes means for isolating forward RF power from reflected RF power in a power coupling between an RF transmitter circuit and an RF transmit antenna.

[0144] The implementations described herein may be implemented as logical steps in one or more computer systems. Logical operations may be implemented as: (1) a sequence of processor-implemented steps executed in one or more computer systems; and (2) interconnected machine or circuit modules within one or more computer systems. The implementation is a matter of choice depending on the performance requirements of the computer systems being utilized. Accordingly, the logical operations that make up the implementations described herein may also be referred to as operations, steps, objects, or modules. Furthermore, it should be understood that the logical operations may be performed in any order unless explicitly stated or the claim language inherently requires a particular order.

Claims

1. A method of regulating forward RF power supplied by a radio frequency (RF) transmitter circuit to an RF transmit antenna, the method comprising: detecting the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna; monitoring RF power samples of the supplied forward RF power over at least one average power period; activating an RF power adjustment trigger signal while the time-averaged forward RF power supplied to the RF transmit antenna satisfies the forward RF power adjustment condition of the at least one average power period, the forward RF power adjustment condition specifying a relationship between the time-averaged forward RF power supplied to the RF transmit antenna during the at least one average power period and a first predetermined time-averaged power threshold, wherein the relationship is that the time-averaged forward RF power supplied to the RF transmit antenna reaches, exceeds or is less than the first predetermined time-averaged power threshold; and adjusting the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal; Wherein the at least one average power period comprises a plurality of average power periods, wherein the monitoring operation is performed at a plurality of filters, each filter filtering the monitored RF power samples differently to apply a different average power period of the plurality of average power periods.

2. The method according to claim 1, characterized in that Further including: A filter is selected from the plurality of filters to output the RF power adjustment trigger signal.

3. The method according to claim 2, characterized in that The selecting a filter from the plurality of filters to output the RF power adjustment trigger signal selects a filter from the plurality of filters based on at least one of a network condition and a transmission requirement.

4. The method according to claim 1, characterized in that Further including: An attenuation curve is applied while the RF power adjustment trigger signal is activated, and the adjusting the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna adjusts the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna according to the attenuation curve.

5. The method according to claim 4, characterized in that The attenuation curve specifies the magnitude of an incremental adjustment in forward RF power supplied by the RF transmitter circuit to the RF transmit antenna.

6. The method according to claim 5, characterized in that The decay curve specifies the duration of an incremental adjustment in forward RF power supplied by the RF transmitter circuit to the RF transmit antenna.

7. The method according to claim 1, characterized in that The detection operation includes: The forward RF power is isolated from reflected RF power in a power coupling between the RF transmitter circuit and the RF transmit antenna.

8. A radio frequency (RF) power regulator, comprising: a forward RF power detection circuit configured to detect forward RF power supplied by the RF transmitter circuit to the RF transmit antenna; an RF power sampler coupled to the forward RF power detection circuit, the RF power sampler configured to provide RF power samples of the supplied forward RF power over at least one average power period; at least one filter for monitoring the RF power samples, the at least one filter activating an RF power adjustment trigger signal when the time-averaged forward RF power supplied to the RF transmit antenna satisfies a forward RF power adjustment condition of the at least one filter, the forward RF power adjustment condition specifying a relationship between the time-averaged forward RF power supplied to the RF transmit antenna during the at least one average power period and a first predetermined time-averaged power threshold, wherein the relationship is that the time-averaged forward RF power supplied to the RF transmit antenna reaches, exceeds, or is less than the first predetermined time-averaged power threshold; as well as forward RF power adjustment logic coupled to the at least one filter and configured to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal; Wherein the at least one filter comprises a plurality of filters, wherein each filter of the plurality of filters filters the monitored RF power samples differently to apply a different averaging power period.

9. The RF power regulator according to claim 8, characterized in that The power regulator further comprises: A filter selector is coupled to the plurality of filters and configured to select a filter from the plurality of filters to output the RF power adjustment trigger signal.

10. The RF power regulator according to claim 9, characterized in that The filter selector is configured to select one of the plurality of filters based on at least one of a network condition and a transmission requirement.

11. The RF power regulator according to claim 8, characterized in that Further including: an attenuation curve controller configured to apply an attenuation curve while the RF power adjustment trigger signal is activated and to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna according to the attenuation curve.

12. The RF power regulator according to claim 11, wherein: The decay curve specifies a magnitude of an incremental adjustment or a duration of an incremental adjustment in forward RF power supplied by the RF transmitter circuit to the RF transmit antenna.

13. The RF power regulator according to claim 8, characterized in that The forward RF power detection circuit comprises: A forward RF power isolation circuit system is coupled between the RF transmitter circuit and the RF transmit antenna and is configured to isolate the forward RF power from reflected RF power in the power coupling between the RF transmitter circuit and the RF transmit antenna.

14. The RF power regulator according to claim 13, wherein: The forward RF power isolator circuit system comprises: A directional coupler is configured to detect the forward RF power coupled from the power supply between the RF transmitter circuit and the RF transmit antenna.

15. The RF power regulator according to claim 13, wherein: The forward RF power isolator circuit system comprises: a directional coupler configured to detect the forward RF power coupled from the power supply between the RF transmitter circuit and the RF transmit antenna; and A circulator is coupled between the directional coupler and the RF transmit antenna.

16. The power conditioner according to claim 8, characterized in that Wherein the forward RF power adjustment logic is configured to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna by reducing the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal.

17. A power regulator as described in claim 8, characterized in that and wherein the forward RF power adjustment logic is configured to adjust the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna by increasing the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal.

18. The power conditioner according to claim 8, characterized in that The first predetermined time-average power threshold is selected to be smaller than a second predetermined time-average power threshold to limit the time-average forward RF power supplied to the RF transmit antenna to not exceed the second predetermined time-average power threshold.

19. One or more tangible processor-readable storage media containing instructions for executing a process on one or more processors and circuits of a computing device, the process comprising: detecting RF power supplied by a forward radio frequency (RF) transmitter circuit to an RF transmitting antenna; monitoring RF power samples of the supplied forward RF power over at least one average power period; activating an RF power adjustment trigger signal while the time-averaged forward RF power supplied to the RF transmit antenna satisfies the forward RF power adjustment condition of the at least one average power period, the forward RF power adjustment condition specifying a relationship between the time-averaged forward RF power supplied to the RF transmit antenna during the at least one average power period and a first predetermined time-averaged power threshold, wherein the relationship is that the time-averaged forward RF power supplied to the RF transmit antenna reaches, exceeds or is less than the first predetermined time-averaged power threshold; and adjusting the forward RF power supplied by the RF transmitter circuit to the RF transmit antenna based on the RF power adjustment trigger signal; Wherein the at least one average power period comprises a plurality of average power periods, wherein the monitoring operation is performed at a plurality of filters, each filter filtering the monitored RF power samples differently to apply a different average power period of the plurality of average power periods.

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