PATENT DOCUMENT

Publication Number: US-11438023-B1
Application Number: US-202117318927-A
Country: US
Kind Code: B1

Title: Electronic devices with hierarchical management of radio-frequency exposure

Abstract:
An electronic device may include a first set of radios subject to a specific absorption rate (SAR) limit and a second set of radios subject to a maximum permissible exposure (MPE) limit over an averaging period. Control circuitry may dynamically adjust radio-frequency (RF) exposure metric budgets provided to the radios over the averaging period, based on feedback reports from the radios identifying the amount of SAR and MPE consumed by the radios during different subperiods of the averaging period. The control circuitry may distribute and adjust SAR budgets and MPE budgets across the radios based on the feedback reports, distribution policies, radio statuses, transmit activity factors, and/or usage ratios associated with the radios. This may provide efficient utilization of the total available SAR and MPE budget, thereby leading to increased uplink coverage and throughput relative to scenarios where the SAR and MPE budgets remain static.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a first radio configured to wirelessly transmit first radio-frequency signals during a sub-period of an averaging period and pursuant to a first radio-frequency (RF) exposure metric budget, wherein the first radio is configured to generate a first report indicative of an amount of a first RF exposure metric consumed by the first radio during the sub-period; 
 a second radio configured to wirelessly transmit second radio-frequency signals during the sub-period and pursuant to a second RF exposure metric budget, wherein the second radio is configured to generate a second report indicative of an amount of a second RF exposure metric consumed by the second radio during the sub-period, the second RF exposure metric being different from the first RF exposure metric; and 
 one or more processors configured to
 receive the first report from the first radio and the second report from the second radio, and 
 update the first RF exposure metric budget based at least in part on the amount of the second RF exposure metric consumed by the second radio during the sub-period, wherein the first radio is configured to transmit third radio-frequency signals during a subsequent sub-period of the averaging period and pursuant to the updated first RF exposure metric budget. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the first radio is configured to wirelessly transmit the first radio-frequency signals at a frequency less than 6 GHz, the second radio is configured to wirelessly transmit the second radio-frequency signals at a frequency greater than 6 GHz, the first RF exposure metric comprises specific absorption rate (SAR), and the second RF exposure metric comprises maximum permissible exposure (MPE). 
     
     
       3. The electronic device of  claim 1 , wherein the first radio is configured to wirelessly transmit the first radio-frequency signals at a frequency greater than 6 GHz, the second radio is configured to wirelessly transmit the second radio-frequency signals at a frequency less than 6 GHz, the first RF exposure metric comprises maximum permissible exposure (MPE), and the second RF exposure metric comprises specific absorption rate (SAR). 
     
     
       4. The electronic device of  claim 1 , wherein the one or more processors is further configured to update the second RF exposure metric budget based at least in part on the amount of the first RF exposure metric consumed by the first radio during the sub-period, the second radio being configured to transmit fourth radio-frequency signals during the subsequent sub-period and pursuant to the updated second RF exposure metric budget. 
     
     
       5. The electronic device of  claim 1 , further comprising:
 a third radio configured to wirelessly transmit fourth radio-frequency signals during the sub-period and pursuant to a third RF exposure metric budget, wherein the third radio is configured to generate a third report indicative of an amount of the first RF exposure metric consumed by the third radio during the sub-period, the one or more processors being further configured to
 receive the third report from the third radio, 
 generate an overall exposure metric budget based at least on the amount of the first RF exposure metric consumed by the first radio during the sub-period, the amount of the second RF exposure metric consumed by the second radio during the sub-period, and the amount of the first RF exposure metric consumed by the third radio during the sub-period, and 
 update the first RF exposure metric budget and the third RF exposure metric budget by distributing the overall exposure metric budget between at least the first radio and the third radio, wherein the third radio is configured to transmit fifth radio-frequency signals during the subsequent sub-period and pursuant to the updated third RF exposure metric budget. 
 
 
     
     
       6. The electronic device of  claim 5 , wherein the one or more processors is configured to distribute the overall exposure metric budget between at least the first radio and the third radio based at least in part on a first transmit activity factor included in the first report by the first radio and a second transmit activity factor included in the third report by the third radio. 
     
     
       7. The electronic device of  claim 5 , wherein the one or more processors is configured to distribute the overall exposure metric budget between at least the first radio and the third radio based at least in part on a first usage ratio included in the first report by the first radio and a second usage ratio included in the third report by the third radio. 
     
     
       8. A method of operating an electronic device having one or more processors and a set of radios, the method comprising:
 with the set of radios, transmitting first radio-frequency signals during a first subperiod of an averaging period and identifying an amount of a radio-frequency (RF) exposure metric consumed by the set of radios during the first subperiod; 
 with the one or more processors, generating an average RF exposure metric value by averaging the amount of the RF exposure metric consumed by the set of radios with an amount of the RF exposure metric consumed by the set of radios during at least a second subperiod of the averaging period that is prior to the first subperiod; 
 with the one or more processors, generating an overall budget for the RF exposure metric based at least in part on the average RF exposure metric value; 
 with the one or more processors, distributing the overall budget for the RF exposure metric into respective RF exposure metric budgets for the radios in the set of radios; and 
 with the set of radios, transmitting second radio-frequency signals during a third subperiod of the averaging period and pursuant to the RF exposure metric budgets, the third subperiod being subsequent to the first subperiod. 
 
     
     
       9. The method of  claim 8 , further comprising:
 with the one or more processors, generating a remaining RF exposure metric value based on the average RF exposure metric value and a limit on consumption of the RF exposure metric for the averaging period; 
 with the one or more processors, comparing the remaining RF exposure metric value to the overall budget for the RF exposure metric; 
 distributing the overall budget for the RF exposure metric into the RF exposure metric budgets in response to the remaining RF exposure metric value exceeding the overall budget for the RF exposure metric; and 
 distributing the remaining RF exposure metric value into the RF exposure metric budgets in response to the overall budget for the RF exposure metric being greater than or equal to the remaining RF exposure metric value. 
 
     
     
       10. The method of  claim 9 , wherein the electronic device comprises an additional set of radios and the method further comprises:
 with the additional set of radios, transmitting third radio-frequency signals during the first subperiod and identifying an amount of an additional RF exposure metric consumed by the additional set of radios during the first subperiod, the additional RF exposure metric being different from the RF exposure metric; 
 with the one or more processors, generating an additional average RF exposure metric value by averaging the amount of the additional RF exposure metric consumed by the additional set of radios with an amount of the additional RF exposure metric consumed by the additional set of radios during at least the second subperiod; and 
 with the one or more processors, generating a total exposure ratio (TER) value based on the average RF exposure metric value, the additional average RF exposure metric value, the limit on consumption of the RF exposure metric value for the averaging period, and a limit on consumption of the additional RF exposure metric value for the averaging period, wherein generating the overall budget for the RF exposure metric comprises generating the overall budget for the RF exposure metric based on the TER value and a split policy between the RF exposure metric and the additional RF exposure metric. 
 
     
     
       11. The method of  claim 10 , further comprising:
 with the one or more processors, generating an overall budget for the additional RF exposure metric based on the TER value and the split policy between the RF exposure metric and the additional RF exposure metric; 
 with the one or more processors, distributing the overall budget for the additional RF exposure metric into respective additional RF exposure metric budgets; and 
 with the additional set of radios, transmitting fourth radio-frequency signals during the third subperiod and pursuant to the additional RF exposure metric budgets. 
 
     
     
       12. The method of  claim 11 , further comprising:
 with the one or more processors, generating an additional remaining RF exposure metric value based on the additional average RF exposure metric value and the limit on consumption of the additional RF exposure metric for the averaging period; 
 with the one or more processors, comparing the additional remaining RF exposure metric value to the overall budget for the additional RF exposure metric; 
 distributing the overall budget for the additional RF exposure metric into the additional RF exposure metric budgets in response to the additional remaining RF exposure metric value exceeding the overall budget for the additional RF exposure metric; and 
 distributing the additional remaining RF exposure metric value into the additional RF exposure metric budgets in response to the overall budget for the additional RF exposure metric being greater than or equal to the additional remaining RF exposure metric value. 
 
     
     
       13. The method of  claim 12 , wherein the first radio-frequency signals and the second radio-frequency signals are at frequencies less than 6 GHz, the third radio-frequency signals and the fourth radio-frequency signals are at frequencies greater than 6 GHz, the RF exposure metric comprises specific absorption rate (SAR), and the additional RF exposure metric comprises maximum permissible exposure (MPE). 
     
     
       14. The method of  claim 8 , wherein the first radio-frequency signals and the second radio-frequency signals are at frequencies less than 6 GHz and the RF exposure metric comprises specific absorption rate (SAR). 
     
     
       15. The method of  claim 8 , wherein the first radio-frequency signals and the second radio-frequency signals are at frequencies greater than 6 GHz and the RF exposure metric comprises maximum permissible exposure (MPE). 
     
     
       16. The method of  claim 8 , wherein distributing the overall budget for the RF exposure metric into respective RF exposure metric budgets for the radios in the set of radios comprises:
 distributing the overall budget for the RF exposure metric based at least in part on which radios in the set of radios are inactive during the first subperiod. 
 
     
     
       17. The method of  claim 8 , wherein distributing the overall budget for the RF exposure metric into respective RF exposure metric budgets for the radios in the set of radios comprises:
 distributing the overall budget for the RF exposure metric based at least in part on radio usage ratios associated with transmission by the set of radios during the first subperiod. 
 
     
     
       18. The method of  claim 8 , wherein distributing the overall budget for the RF exposure metric into respective RF exposure metric budgets for the radios in the set of radios comprises:
 distributing the overall budget for the RF exposure metric based at least in part on transmit activity factors associated with transmission by the set of radios during the first subperiod. 
 
     
     
       19. An electronic device comprising:
 a first radio configured to wirelessly transmit first radio-frequency signals at a frequency less than 6 GHz during a first sub-period of an averaging period; 
 a second radio configured to wirelessly transmit second radio-frequency signals at a frequency greater than 6 GHz during the first sub-period; and 
 one or more processors configured to
 generate an average specific absorption rate (SAR) consumed by at least the first radio during the first sub-period and during at least a second sub-period of the averaging period, the second sub-period being prior to the first sub-period, 
 generate an average maximum permissible exposure (MPE) consumed by at least the second radio during the first sub-period and during at least the second sub-period, 
 generate a total exposure ratio (TER) value based on the average SAR, the average MPE, a first limit on an amount of SAR consumed by the electronic device over the averaging period, and a second limit on an amount of MPE consumed by the electronic device over the averaging period, 
 generate a SAR budget based at least on the TER value, the first radio being configured to transmit third radio-frequency signals during a third sub-period of the averaging period and pursuant to the SAR budget, the third sub-period being after the first sub-period, and 
 generate an MPE budget based on the TER value, the second radio being configured to transmit fourth radio-frequency signals during the third sub-period and pursuant to the MPE budget. 
 
 
     
     
       20. The electronic device of  claim 19 , wherein the one or more processors is further configured to:
 generate an overall SAR budget by multiplying the TER value by a SAR allocation according to an SAR/MPE split policy; 
 generate an overall MPE budget by multiplying the TER value by an MPE allocation according to the SAR/MPE split policy; 
 generate the SAR budget as a portion of the overall SAR budget; and 
 generate the MPE budget as a portion of the overall MPE budget.

Description:
FIELD 
     This disclosure relates generally to electronic devices and, more particularly, to electronic devices with wireless circuitry. 
     BACKGROUND 
     Electronic devices are often provided with wireless capabilities. An electronic device with wireless capabilities has wireless circuitry that includes one or more antennas. The antennas transmit radio-frequency signals. During transmission, the radio-frequency signals are sometimes incident upon nearby external objects such as the body of a user or another person. 
     Electronic devices with wireless capabilities are typically operated in geographic regions that impose regulatory limits on the amount of radio-frequency exposure produced by the electronic device in transmitting radio-frequency signals. It can be challenging to design electronic devices that meet these regulatory limits. In addition, it can be difficult to efficiently operate the wireless circuitry in multiple different radio-frequency bands while continuing to meet the regulatory limits. 
     SUMMARY 
     An electronic device may include wireless circuitry controlled by one or more processors. The wireless circuitry may include radios that transmit radio-frequency signals using at least one antenna. The radios may include a first set of one or more radios that transmit radio-frequency signals at frequencies less than 6 GHz. The radios may include a second set of one or more radios that transmit radio-frequency signals at frequencies greater than 6 GHz. The first set of radios may be subject to a regulatory specific absorption rate (SAR) limit over a regulatory averaging period. The second set of radios may be subject to a regulatory maximum permissible exposure (MPE) limit over the regulatory averaging period. 
     The wireless circuitry may include a radio-frequency (RF) exposure metric manager. The RF exposure metric manager may dynamically adjust RF exposure metric budgets provided to the first and second sets of radios over the averaging period based on feedback reports from the first and second sets of radios. For example, the first set of radios may generate feedback reports identifying the amount of SAR consumed by the radios during a first subperiod of the averaging period. The second set of radios may generate feedback reports identifying the amount of MPE consumed by the radios during the first subperiod. The RF exposure metric manager may generate an average SAR value based on the amount of SAR consumed by the first set of radios during the first subperiod and any prior subperiods of the averaging period. The RF exposure metric manager may generate an average MPE value based on the amount of MPE consumed by the second set of radios during the first subperiod and any prior subperiods of the averaging period. The RF exposure metric manager may generate a total exposure ratio (TER) value based on the average SAR value and the average MPE value. The RF exposure metric manager may generate a remaining SAR value based on the average SAR value and the regulatory SAR limit, a remaining MPE value based on the average MPE value and the regulatory MPE limit, and a remaining TER value based on the TER value. 
     The RF exposure manager may generate an overall SAR budget and an overall MPE budget based on the remaining TER value and a SAR allocation from a SAR/MPE split policy. The RF exposure manager may distribute the overall MPE budget into MPE budgets for the second set of radios when the overall MPE budget is less than the remaining MPE value. The RF exposure manager may distribute the remaining MPE value into MPE budgets for the second set of radios when the overall MPE budget is greater than or equal to the remaining MPE value. The RF exposure manager may distribute the overall SAR budget into SAR budgets for the first set of radios when the overall SAR budget is less than the remaining SAR value. The RF exposure manager may distribute the remaining SAR value into SAR budgets for the first set of radios when the overall SAR budget is greater than or equal to the remaining SAR value. The distribution may be made based on distribution policies, radio statuses, transmit activity factors, and/or usage ratios associated with the radios. This may result in more efficient utilization of the total available SAR and MPE budget, thereby leading to increased uplink coverage and throughput relative to scenarios where the SAR and MPE budgets remain static. 
     An aspect of the disclosure provides an electronic device. The electronic device can include a first radio configured to wirelessly transmit first radio-frequency signals during a sub-period of an averaging period and pursuant to a first radio-frequency (RF) exposure metric budget. The first radio can be configured to generate a first report indicative of an amount of a first RF exposure metric consumed by the first radio during the sub-period. The electronic device can include a second radio configured to wirelessly transmit second radio-frequency signals during the sub-period and pursuant to a second RF exposure metric budget. The second radio can be configured to generate a second report indicative of an amount of a second RF exposure metric consumed by the second radio during the sub-period. The second RF exposure metric can be different from the first RF exposure metric. The electronic device can include one or more processors. The one or more processors can be configured to receive the first report from the first radio and the second report from the second radio. The one or more processors can be configured to update the first RF exposure metric budget based at least in part on the amount of the second RF exposure metric consumed by the second radio during the sub-period. The first radio can be configured to transmit third radio-frequency signals during a subsequent sub-period of the averaging period and pursuant to the updated first RF exposure metric budget. 
     An aspect of the disclosure provides a method of operating an electronic device having one or more processors and a set of radios. The method can include, with the set of radios, transmitting first radio-frequency signals during a first subperiod of an averaging period and identifying an amount of a radio-frequency (RF) exposure metric consumed by the set of radios during the first subperiod. The method can include, with the one or more processors, generating an average RF exposure metric value by averaging the amount of the RF exposure metric consumed by the set of radios with an amount of the RF exposure metric consumed by the set of radios during at least a second subperiod of the averaging period that is prior to the first subperiod. The method can include, with the one or more processors, generating an overall budget for the RF exposure metric based at least in part on the average RF exposure metric value. The method can include, with the one or more processors, distributing the overall budget for the RF exposure metric into respective RF exposure metric budgets for the radios in the set of radios. The method can include, with the set of radios, transmitting second radio-frequency signals during a third subperiod of the averaging period and pursuant to the RF exposure metric budgets, the third subperiod being subsequent to the first subperiod. 
     An aspect of the disclosure provides an electronic device. The electronic device can include a first radio configured to wirelessly transmit first radio-frequency signals at a frequency less than 6 GHz during a first sub-period of an averaging period. The electronic device can include a second radio configured to wirelessly transmit second radio-frequency signals at a frequency greater than 6 GHz during the first sub-period. The electronic device can include one or more processors. The one or more processors can be configured to generate an average specific absorption rate (SAR) consumed by at least the first radio during the first sub-period and during at least a second sub-period of the averaging period, the second sub-period being prior to the first sub-period. The one or more processors can be configured to generate an average maximum permissible exposure (MPE) consumed by at least the second radio during the first sub-period and during at least the second sub-period. The one or more processors can be configured to generate a total exposure ratio (TER) value based on the average SAR, the average MPE, a first limit on an amount of SAR consumed by the electronic device over the averaging period, and a second limit on an amount of MPE consumed by the electronic device over the averaging period. The one or more processors can be configured to generate a SAR budget based at least on the TER value. The first radio can be configured to transmit third radio-frequency signals during a third sub-period of the averaging period and pursuant to the SAR budget, the third sub-period being after the first sub-period. The one or more processors can be configured to generate an MPE budget based on the TER value. The second radio can be configured to transmit fourth radio-frequency signals during the third sub-period and pursuant to the MPE budget. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an illustrative electronic device having wireless circuitry with multiple radios and a radio-frequency (RF) exposure metric manager in accordance with some embodiments. 
         FIG. 2  is a block diagram of an illustrative RF exposure metric manager having a total RF exposure calculation engine and an RF exposure metric budget calculation and distribution engine in accordance with some embodiments. 
         FIG. 3  is a circuit block diagram of an illustrative total RF exposure calculation engine in accordance with some embodiments. 
         FIG. 4  is a circuit block diagram of an illustrative RF exposure metric budget calculation and distribution engine in accordance with some embodiments. 
         FIG. 5  is a flow chart of illustrative operations involved in using an RF exposure metric manager to dynamically adjust RF exposure metric budgets provided to different radios over time based on RF exposure metric feedback from the radios in accordance with some embodiments. 
         FIG. 6  is a flow chart of illustrative operations involved in using a total RF exposure calculation engine to generate RF exposure metric values for calculating updated RF exposure metric budgets in accordance with some embodiments. 
         FIG. 7  is a flow chart of illustrative operations involved in using an RF exposure metric budget calculation and distribution engine to generate updated RF exposure metric budgets for different radios in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic device  10  of  FIG. 1  may be a computing device such as a laptop computer, a desktop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a wireless internet-connected voice-controlled speaker, a home entertainment device, a remote control device, a gaming controller, a peripheral user input device, a wireless base station or access point, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     As shown in the functional block diagram of  FIG. 1 , device  10  may include components located on or within an electronic device housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, metal alloys, etc.), other suitable materials, or a combination of these materials. In some situations, parts or all of housing  12  may be formed from dielectric or other low-conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may include control circuitry  14 . Control circuitry  14  may include storage such as storage circuitry  16 . Storage circuitry  16  may include hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Storage circuitry  16  may include storage that is integrated within device  10  and/or removable storage media. 
     Control circuitry  14  may include processing circuitry such as processing circuitry  18 . Processing circuitry  18  may be used to control the operation of device  10 . Processing circuitry  18  may include on one or more processors, microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), etc. Control circuitry  14  may be configured to perform operations in device  10  using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device  10  may be stored on storage circuitry  16  (e.g., storage circuitry  16  may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry  16  may be executed by processing circuitry  18 . 
     Control circuitry  14  may be used to run software on device  10  such as satellite navigation applications, internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  14  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  14  include internet protocols, wireless local area network (WLAN) protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network (WPAN) protocols, IEEE 802.11ad protocols (e.g., ultra-wideband protocols), cellular telephone protocols (e.g., 3G protocols, 4G (LTE) protocols, 5G protocols, etc.), antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), antenna-based spatial ranging protocols (e.g., radio detection and ranging (RADAR) protocols or other desired range detection protocols for signals conveyed at millimeter and centimeter wave frequencies), or any other desired communications protocols. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol. 
     Device  10  may include input-output circuitry  20 . Input-output circuitry  20  may include input-output devices  22 . Input-output devices  22  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  22  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  22  may include touch sensors, displays (e.g., touch-sensitive and/or force-sensitive displays), light-emitting components such as displays without touch sensor capabilities, buttons (mechanical, capacitive, optical, etc.), scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, audio jacks and other audio port components, digital data port devices, motion sensors (accelerometers, gyroscopes, and/or compasses that detect motion), capacitance sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to a display to detect pressure applied to the display), temperature sensors, etc. In some configurations, keyboards, headphones, displays, pointing devices such as trackpads, mice, and joysticks, and other input-output devices may be coupled to device  10  using wired or wireless connections (e.g., some of input-output devices  22  may be peripherals that are coupled to a main processing unit or other portion of device  10  via a wired or wireless link). 
     Input-output circuitry  20  may include wireless circuitry  24  to support wireless communications and/or radio-based spatial ranging operations. Wireless circuitry  24  may include one or more antennas  34 . Wireless circuitry  24  may also include n+1 radios  28  (e.g., a first radio  28 - 0 , a second radio  28 - 1 , an (n+1)th radio  28 - n , etc.). Each radio  28  may include circuitry that operates on signals at baseband frequencies (e.g., baseband processor circuitry), signal generator circuitry, modulation/demodulation circuitry (e.g., one or more modems), radio-frequency transceiver circuitry (e.g., radio-frequency transmitter circuitry, radio-frequency receiver circuitry, mixer circuitry for downconverting radio-frequency signals to baseband frequencies or intermediate frequencies between radio and baseband frequencies and/or for upconverting signals at baseband or intermediate frequencies to radio-frequencies, etc.), amplifier circuitry (e.g., one or more power amplifiers and/or one or more low-noise amplifiers (LNAs)), analog-to-digital converter (ADC) circuitry, digital-to-analog converter (DAC) circuitry, control paths, power supply paths, signal paths (e.g., radio-frequency transmission lines, intermediate frequency transmission lines, baseband signal lines, etc.), switching circuitry, filter circuitry, and/or any other circuitry for transmitting and/or receiving radio-frequency signals using antenna(s)  34 . The components of each radio  28  may be mounted onto a respective substrate or integrated into a respective integrated circuit, chip, package, or system-on-chip (SOC). If desired, the components of multiple radios  28  may share a single substrate, integrated circuit, chip, package, or SOC. 
     Antenna(s)  34  may be formed using any desired antenna structures. For example, antenna(s)  34  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antennas, dipoles, hybrids of these designs, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and/or other antenna tuning components may be adjusted to adjust the frequency response and wireless performance of antenna(s)  34  over time. 
     Transceiver circuitry in radios  28  may convey radio-frequency signals using one or more antennas  34  (e.g., antenna(s)  34  may convey the radio-frequency signals for the transceiver circuitry). The term “convey radio-frequency signals” as used herein means the transmission and/or reception of the radio-frequency signals (e.g., for performing unidirectional and/or bidirectional wireless communications with external wireless communications equipment). Antenna(s)  34  may transmit the radio-frequency signals by radiating the radio-frequency signals into free space (or to free space through intervening device structures such as a dielectric cover layer). Antenna(s)  34  may additionally or alternatively receive the radio-frequency signals from free space (e.g., through intervening devices structures such as a dielectric cover layer). The transmission and reception of radio-frequency signals by antenna(s)  34  each involve the excitation or resonance of antenna currents on an antenna resonating element in the antenna by the radio-frequency signals within the frequency band(s) of operation of the antenna. 
     Each radio  28  may be coupled to one or more antennas  34  over one or more radio-frequency transmission lines  31 . Radio-frequency transmission lines  31  may include coaxial cables, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Radio-frequency transmission lines  31  may be integrated into rigid and/or flexible printed circuit boards if desired. One or more radio-frequency lines  31  may be shared between radios  28  if desired. Radio-frequency front end (RFFE) modules may be interposed on one or more radio-frequency transmission lines  31 . The Radio-frequency front end modules may include substrates, integrated circuits, chips, or packages that are separate from radios  28  and may include filter circuitry, switching circuitry, amplifier circuitry, impedance matching circuitry, radio-frequency coupler circuitry, and/or any other desired radio-frequency circuitry for operating on the radio-frequency signals conveyed over radio-frequency transmission lines  31 . 
     Radios  28  may use antenna(s)  34  to transmit and/or receive radio-frequency signals within different frequency bands at radio frequencies (sometimes referred to herein as communications bands or simply as a “bands”). The frequency bands handled by radios  28  may include wireless local area network (WLAN) frequency bands (e.g., Wi-Fi® (IEEE 802.11) or other WLAN communications bands) such as a 2.4 GHz WLAN band (e.g., from 2400 to 2480 MHz), a 5 GHz WLAN band (e.g., from 5180 to 5825 MHz), a Wi-Fi® 6E band (e.g., from 5925-7125 MHz), and/or other Wi-Fi® bands (e.g., from 1875-5160 MHz), wireless personal area network (WPAN) frequency bands such as the 2.4 GHz Bluetooth® band or other WPAN communications bands, cellular telephone frequency bands (e.g., bands from about 600 MHz to about 5 GHz, 3G bands, 4G LTE bands, 5G New Radio Frequency Range  1  (FR1) bands below 10 GHz, 5G New Radio Frequency Range  2  (FR2) bands between 20 and 60 GHz, etc.), other centimeter or millimeter wave frequency bands between 10-300 GHz, near-field communications (NFC) frequency bands (e.g., at 13.56 MHz), satellite navigation frequency bands (e.g., a GPS band from 1565 to 1610 MHz, a Global Navigation Satellite System (GLONASS) band, a BeiDou Navigation Satellite System (BDS) band, etc.), ultra-wideband (UWB) frequency bands that operate under the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols, communications bands under the family of 3GPP wireless communications standards, communications bands under the IEEE 802.XX family of standards, and/or any other desired frequency bands of interest. 
     Each radio  28  may transmit and/or receive radio-frequency signals according to a respective radio access technology (RAT) that determines the physical connection methodology for the components in the corresponding radio. One or more radios  28  may implement multiple RATs if desired. As just one an example, the radios  28  in device  10  may include a UWB radio  28 - 0  for conveying UWB signals using one or more antennas  34 , a Bluetooth (BT) radio  28 - 1  for conveying BT signals using one or more antennas  34 , a Wi-Fi radio  28 - 3  for conveying WLAN signals using one or more antennas  34 , a cellular radio  28 - 4  for conveying cellular telephone signals using one or more antennas  34  (e.g., in 4G frequency bands, 5G FR1 bands, and/or 5G FR2 bands), an NFC radio  28 - 5  for conveying NFC signals using one or more antennas  34 , and a wireless charging radio  28 - 6  for receiving wireless charging signals using one or more antennas  34  for charging a battery on device  10 . This example is merely illustrative and, in general, radios  28  may include any desired combination of radios for covering any desired combination of RATs. 
     Radios  28  may use antenna(s)  34  to transmit and/or receive radio-frequency signals to convey wireless communications data between device  10  and external wireless communications equipment (e.g., one or more other devices such as device  10 , a wireless access point or base station, etc.). Wireless communications data may be conveyed by radios  28  bidirectionally or unidirectionally. The wireless communications data may, for example, include data that has been encoded into corresponding data packets such as wireless data associated with a telephone call, streaming media content, internet browsing, wireless data associated with software applications running on device  10 , email messages, etc. Radios  28  may also use antenna(s)  34  to perform spatial ranging operations (e.g., for identifying a distance between device  10  and an external object such as external object  8 ). Radios  28  that perform spatial ranging operations may include radar circuitry if desired (e.g., frequency modulated continuous wave (FMCW) radar circuitry, OFDM radar circuitry, FSCW radar circuitry, a phase coded radar circuitry, other types of radar circuitry). 
     During radio-frequency signal transmission, some of the radio-frequency signals transmitted by antenna(s)  34  may be incident upon external objects such as external object  8 . External object  8  may be, for example, the body of the user of device  10  or another human or animal. In these scenarios, the amount of radio-frequency energy exposure at external object  8  may be characterized by one or more radio-frequency (RF) exposure metrics. The RF exposure metrics may include specific absorption rate (SAR) for radio-frequency signals at frequencies less than 6 GHz (in units of W/kg), maximum permissible exposure (MPE) for radio-frequency signals at frequencies greater than 6 GHz (in units of mW/cm 2 ), and total exposure ratio (TER), which combines SAR and MPE. 
     Regulatory requirements often impose limits on the amount of RF energy exposure permissible for external object  8  within the vicinity of antenna(s)  34  over a specified time period (e.g., an SAR limit and an MPE limit over a corresponding averaging period). Radios  28  that handle radio-frequency signals at frequencies greater than 6 GHz are sometimes referred to herein as MPE radios  28  because these radios  28  may be subject to MPE limits. Radios  28  that handle radio-frequency signals at frequencies less than 6 GHz are sometimes referred to herein as SAR radios  28  because these radios  28  may be subject to SAR limits. Radios  28  that handle signals greater than 6 GHz and signals less than 6 GHz (e.g., a cellular telephone radio  28 ) are subject to both SAR and MPE limits and are therefore both a SAR radio and an MPE radio. 
     Wireless circuitry  24  may include RF exposure metric manager  26  for ensuring that radios  28  comply with these regulatory requirements. The components of RF exposure metric manager  26  may be implemented in hardware (e.g., one or more processors, circuit components, logic gates, diodes, transistors, switches, arithmetic logic units (ALUs), registers, application-specific integrated circuits, field-programmable gate arrays, etc.) and/or software on device  10 . RF exposure metric manager  26  may sometimes be referred to herein as RF exposure manager  26 , RF exposure managing engine  26 , RF exposure metric management circuitry  26 , RF exposure metric management engine  26 , or RF exposure metric management processor  26 . RF exposure metric manager  26  may be coupled to each radio  28  over a respective control path  30  (e.g., control path  30 - 0  may couple RF exposure metric manager  26  to radio  28 - 0 , control path  30 - 1  may couple RF exposure metric manager  26  to radio  28 - 1 , control path  30 - n  may couple RF exposure metric manager  26  to radio  28 - n , etc.). 
     RF exposure metric manager  26  may generate RF exposure budgets BGT for radios  28  (e.g., a first RF exposure budget BGT 0  for radio  28 - 0 , a second RF exposure budget BGT 1  for radio  28 - 1 , an (n+1)th RF exposure budget BGTn for radio  28 - n , etc.). RF exposure metric manager  26  may provide RF exposure budgets BGT to radios  28  over control paths  30 . Each RF exposure budget BGT may include a corresponding SAR budget and/or a corresponding MPE budget (e.g., depending on whether the radio subject to that budget is subject to SAR and/or MPE limits). Each RF exposure budget BGT may specify the amount of SAR and/or MPE that may be generated by the corresponding radio  28  in transmitting radio-frequency signals over the regulatory averaging period while still satisfying the overall SAR and MPE regulatory limits. The circuitry in radios  28  may adjust the maximum transmit (TX) power level of its transmitted radio-frequency signals to ensure that the RF exposure budget BGT for that radio remains satisfied over the averaging period (e.g., using look-up tables on the radios that map the RF exposure budget to transmit power levels to use). 
     In some scenarios, each radio or RAT in device  10  is assigned a fixed SAR/MPE budget, such that the distribution of the total available RF exposure budget across RATs remains static over time to meet the overall SAR/MPE regulatory limits on the operation of device  10  (e.g., over the averaging period). In these scenarios, each radio uses look-up tables to derive the maximum transmit power levels allowed for its fixed SAR/MPE budget and then maintains its transmit power level below that maximum transmit power level to satisfy the SAR/MPE limits. However, assigning static SAR/MPE budgets to the radios in this way without considering the radio needs for the current operating state/environment of device  10  results in sub-optimal budget distribution between the radios/RATs. For example, the part of the overall RF exposure budget that is not used by one radio cannot be re-assigned to another radio that may urgently need to transmit at a higher power level or increased duty cycle. 
     In order to mitigate these issues, RF exposure metric manager  26  may dynamically allocate SAR and MPE budgets to radios  28  over time (e.g., over the averaging period). RF exposure metric manager  26  may dynamically allocate SAR and MPE budgets to radios  28  based on feedback from radios  28 . For example, as shown in  FIG. 1 , each radio  28  may be coupled to RF exposure metric manager  26  over feedback path  32 . Each radio  28  may generate a SAR/MPE report RPT that identifies the amount of the assigned SAR and/or MPE budget that was consumed by that radio during different sub-periods (sometimes referred to herein as instantaneous periods) of the averaging period. SAR/MPE reports RPT may sometimes also be referred to herein as SAR/MPE feedback reports RPT, feedback reports RPT, SAR/MPE feedback RPT, feedback RPT, SAR/MPE feedback signals RPT, or feedback signals RPT. Radios  28  may send the SAR/MPE reports RPT to RF exposure metric manager  26  over feedback path  32  (e.g., radio  28 - 0  may send SAR/MPE report RPT 0  to RF exposure metric manager  26 , radio  28 - 1  may send SAR/MPE report RPT 1  to RF exposure metric manager  26 , radio  28 - n  may send SAR/MPE report RPTn to RF exposure metric manager  26 , etc.). RF exposure metric manager  26  may receive each SAR/MPE report through the active transmission of the reports by radios  28  (e.g., as control signals or other control data) or by querying or retrieving the reports from radios  28  (e.g., by transmitting control signals or commands to the radios instructing the radios to transmit the corresponding report to RF exposure metric manager  26 ). RF exposure metric manager  26  may generate updated RF exposure budgets BGT for radios  28  based on the received SAR/MPE reports RPT and based on the current or expected communication needs of device  10  to ensure that radios  28  can continue to transmit radio-frequency signals to meet the active and dynamic needs of device  10  while still satisfying the SAR and MPE limits imposed on device  10  over the averaging period. In this way, RF exposure metric manager  26  may assign SAR/MPE budgets across RATs while ensuring an SAR/MPE compliant overall RF exposure across the RATs. 
     The example of  FIG. 1  is merely illustrative. While control circuitry  14  is shown separately from wireless circuitry  24  in the example of  FIG. 1  for the sake of clarity, wireless circuitry  24  may include processing circuitry (e.g., one or more processors) that forms a part of processing circuitry  18  and/or storage circuitry that forms a part of storage circuitry  16  of control circuitry  14  (e.g., portions of control circuitry  14  may be implemented on wireless circuitry  24 ). As an example, some or all of RF exposure metric manager  26  may form a part of control circuitry  14 . In addition, wireless circuitry  24  may include any desired number of antennas  34 . Some or all of the antennas  34  in wireless circuitry  24  may be arranged into one or more phased antenna arrays (e.g., for conveying radio-frequency signals over a steerable signal beam). If desired, antenna(s)  34  may be operated using a multiple-input and multiple-output (MIMO) scheme and/or using a carrier aggregation (CA) scheme. 
       FIG. 2  is a block diagram of RF exposure metric manager  26  of  FIG. 1 . As shown in  FIG. 2 , RF exposure metric manager  26  may include RF exposure rule database  42 , total RF exposure calculation engine  36 , and budget calculation and distribution engine  38 . Total RF exposure calculation engine  36  may sometimes also be referred to herein as total RF exposure calculation circuitry  36 , total RF exposure calculation processor  36 , or total RF exposure calculator  36 . Similarly, budget calculation and distribution engine  38  may sometimes also be referred to herein as budget calculation and distribution circuitry  38 , budget calculation and distribution processor  38 , or budget calculator and distributor  38 . RF exposure rule database  42  may be coupled to total RF exposure calculation engine  36  over control paths  44  and  45  and may be coupled to budget calculation and distribution engine  38  over control path  45 . 
     RF exposure rule database  42  may be hard-coded or soft-coded into RF exposure metric manager  26  (e.g., in storage circuitry  16  of  FIG. 1 ) and may include a database, data table, or any other desired data structure. RF exposure rule database  42  may store RF exposure rules associated with the operation of wireless circuitry  24  within different geographic regions. RF exposure rule database  42  may, for example, store regulatory SAR limits SAR LIMIT , regulatory MPE limits MPE LIMIT , and averaging periods T AVG  for SAR limits SAR LIMIT  and MPE limits MPE LIMIT  for one or more geographic regions (e.g., countries, continents, states, localities, municipalities, provinces, sovereignties, etc.) that impose regulatory limits on the amount of RF energy exposure permissible for external object  8  within the vicinity of antenna(s)  34 . As an example, RF exposure rule database  42  may store a first SAR limit SAR LIMIT , a first MPE limit MPE LIMIT , and a first averaging period T AVG  imposed by the regulatory requirements of a first country, a second SAR limit SAR LIMIT , a second MPE limit MPE LIMIT , and a second averaging period T AVG  imposed by the regulatory requirements of a second country, etc. The entries of RF exposure rule database  42  may be stored upon manufacture, assembly, testing, and/or calibration of device  10  and/or may be updated during the operation of device  10  over time (e.g., periodically or in response to a trigger condition such as a software update or the detection that device  10  has entered a new country for the first time). 
     Total RF exposure calculation engine  36  may have an input coupled to feedback path  32 . Total RF exposure calculation engine  36  may have an output coupled to budget calculation and distribution engine  38  over path  40 . Total RF exposure calculation engine  36  may receive SAR/MPE reports RPT from radios  28  over feedback path  32 . Each SAR/MPE report RPT may include a corresponding SAR report and/or a corresponding MPE report. For example, the SAR/MPE report RPT 0  produced by radio  28 - 0  of  FIG. 1  may include a first SAR report SAR 0  and a first MPE report MPE 0 , the SAR/MPE report RPT 1  produced by radio  28 - 1  may include a second SAR report SAR 1  and a second MPE report MPE 1 , the SAR/MPE report RPTn produced by radio  28 - n  may include an (n+1)th SAR report SAR n  and an (n+1)th MPE report MPE n , etc. For radios  28  that do not operate at frequencies greater than 6 GHz (e.g., SAR radios  28 ), the MPE report generated by that radio may be null or empty or that radio  28  may omit an MPE report from its SAR/MPE report RPT. Similarly, for radios  28  that do not operate at frequencies less than 6 GHz (e.g., MPE radios  28 ), the SAR report generated by that radio may be null or empty or that radio  28  may omit a SAR report from its SAR/MPE report RPT. 
     Total RF exposure calculation engine  36  may generate (e.g., compute, calculate, identify, produce, etc.) an average consumed SAR value SAR AVG , an average consumed MPE value MPE AVG , and a consumed total exposure ratio value TERV based on the SAR/MPE reports RPT received over feedback path  32 , the averaging period T AVG  received from RF exposure rule database  42  over control path  44 , and the SAR limit SAR LIMIT  and the MPE limit MPE LIMIT  received from RF exposure rule database  42  over control path  45 . RF exposure rule database  42  may identify a particular averaging period T AVG , a particular SAR limit SAR LIMIT , and a particular MPE limit MPE LIMIT  to send to total RF exposure calculation engine  36  based on the current geographic location of device  10 . 
     Total RF exposure rule database  42  may, for example, receive a control signal dev_loc (e.g., from other portions of control circuitry  14  of  FIG. 1 ) that identifies the current location of device  10 . Total RF exposure rule database  42  may use control signal dev_loc to identify the averaging period T AVG , SAR limit SAR LIMIT , and MPE limit MPE LIMIT , imposed by the corresponding regulatory body for the current location of device  10 , and may provide the identified T AVG , SAR LIMIT , and MPE LIMIT  values to total RF exposure calculation engine  36  to use in generating values SAR AVG , MPE AVG , and TERV. Control circuitry  14  ( FIG. 1 ) may generate control signal dev_loc based on the current GPS location of device  10 , sensor data such as compass or accelerometer data, a location of device  10  as identified by a base station or access point in communication with device  10 , and/or any other desired information indicative of the geographic location of device  10 . 
     Total RF exposure calculation engine  36  may generate average SAR value SAR AVG  based on the SAR reports in the SAR/MPE reports RPT received over feedback path  32 . Average SAR value SAR AVG  may be indicative of the average amount of the current SAR budgets consumed by all of the radios  28  in wireless circuitry  24  during the current averaging period T AVG . Similarly, total RF exposure calculation engine  36  may generate average MPE value MPE AVG  based on the MPE reports in the SAR/MPE reports RPT received over feedback path  32 . Average MPE value MPE AVG  may be indicative of the average amount of the current MPE budgets consumed by all of the radios  28  in wireless circuitry  24  during the current averaging period T AVG . Total exposure ratio value TERV may be indicative of the combined SAR and MPE consumption by all of the radios  28  in wireless circuitry  24  during the current averaging period T AVG . 
     Budget calculation and distribution engine  38  may generate updated RF exposure budgets BGT for each radio  28  in wireless circuitry  24  based on the average SAR value SAR AVG  received over path  40 , the average MPE value MPE AVG  received over path  40 , the total exposure ratio value TERV received over path  40 , the SAR limit SAR LIMIT  received over path  45 , and the MPE limit MPE LIMIT  received over path  45 . Budget calculation and distribution engine  38  may also generate the updated RF exposure budgets BGT while taking into account which radios may or may not need to perform more or less transmission at any given time. The updated RF exposure budgets BGT may serve to dynamically adjust the amount of SAR/MPE budget provided to each radio within the current averaging period T AVG  and/or across multiple averaging periods T AVG . 
     Budget calculation and distribution engine  38  may provide each RF exposure budget BGT to the corresponding radio  28  to be subjected to that RF exposure budget over control paths  30 . Each RF exposure budget BGT may include a corresponding SAR budget and/or a corresponding MPE budget. For example, the RF exposure budget BGT 0  provided to radio  28 - 0  of  FIG. 1  may include a first SAR budget BGT 0   SAR  and a first MPE budget BGT 0   MPE , the RF exposure budget BGT 1  provided to radio  28 - 1  may include a second SAR budget BGT 1   SAR  and a second MPE budget BGT 1   MPE , the RF exposure budget BGTn provided to radio  28 - n  may include an (n+1)th SAR budget BGTn SAR  and an (n+1)th MPE budget BGTn MPE , etc. For radios  28  that do not operate at frequencies greater than 6 GHz (e.g., SAR radios  28 ), the MPE budget generated for that radio may be null or empty or budget calculation and distribution engine  38  may omit an MPE budget from the RF exposure budget for that radio. Similarly, for radios  28  that do not operate at frequencies less than 6 GHz (e.g., MPE radios  28 ), the SAR budget generated for that radio may be null or empty or budget calculation and distribution engine  38  may omit an SAR budget from the RF exposure budget for that radio. 
     Radios  28  may use the updated RF exposure budgets produced by budget calculation and distribution engine  38  to transmit radio-frequency signals. The radios may produce SAR/MPE reports RPT associated with the transmission of radio-frequency signals using the updated RF exposure budgets. This process may iterate to continue to update the RF exposure budgets provided to each radio over time, thereby allowing RF exposure metric manager  26  to dynamically adjust the amount of SAR and MPE budget provided to each radio based on feedback from previous transmissions by the radio, the SAR and MPE limits imposed by the corresponding regulatory body, and the current or future communications needs of device  10 . 
       FIG. 3  is a circuit block diagram of total RF exposure calculation engine  36  of  FIG. 2 . As shown in  FIG. 3 , total RF exposure calculation engine  36  may include SAR averaging circuitry  46 , MPE averaging circuitry  48 , and TER calculation circuitry  73 . SAR averaging circuitry  46  may sometimes also be referred to herein as SAR averager  46  or SAR averaging engine  46 . MPE averaging circuitry  48  may sometimes also be referred to herein as MPE averager  48  or MPE averaging engine  48 . TER calculation circuitry  73  may sometimes also be referred to herein as TER calculation engine  73  or TER calculator  73 . The components of SAR averaging circuitry  46 , MPE averaging circuitry  48 , and TER calculation circuitry  73  may be implemented in hardware (e.g., one or more processors, circuit components, logic gates, diodes, transistors, switches, arithmetic logic units (ALUs), registers, application-specific integrated circuits, field-programmable gate arrays, etc.) and/or software on device  10 . 
     MPE averaging circuitry  48  and SAR averaging circuitry  46  may be coupled in parallel between feedback path  32  and TER calculation circuitry  73 . TER calculation circuitry  73  may be coupled in series between MPE averaging circuitry  48  and path  40 . TER calculation circuitry  73  may also be coupled in series between SAR averaging circuitry  46  and path  40 . SAR averaging circuitry  46  may include addition logic such as adder  50 , time domain averaging circuitry such as time domain averager  54 , and a SAR value database such as SAR value database  56 . The output of adder  50  may be coupled to the input of time domain averager  54  and SAR value database  56  over path  52 . SAR value database  56  may also be coupled to time domain averager  54  over path  58 . 
     Similarly, MPE averaging circuitry  48  may include addition logic such as adder  64 , time domain averaging circuitry such as time domain averager  70 , and an MPE value database such as MPE value database  66 . The output of adder  64  may be coupled to the input of time domain averager  70  and MPE value database  66  over path  62 . MPE value database  66  may also be coupled to time domain averager  54  over path  68 . SAR value database  56  and MPE value database  66  may be databases, data tables, or any other desired data structures (e.g., on storage circuitry  16  of  FIG. 1 ). While shown in  FIG. 3  as separate databases, SAR value database  56  and MPE value database  66  may be formed from respective portions of the same database or data structure if desired. 
     Time domain averager  54  and time domain averager  70  may each receive averaging period T AVG  from RF exposure rule database  42  ( FIG. 2 ) over control path  44 . The output of time domain averager  54  may be coupled to a first input of TER calculation circuitry  73  over path  60 . The output of time domain averager  70  may be coupled to a second input of TER calculation circuitry  73  over path  72 . TER calculation circuitry  73  may also have a third input coupled to RF exposure rule database  42  over control path  45 . The input of adder  50  and the input of adder  64  may be coupled to feedback path  32 . 
     Averaging period T AVG  is determined by the regulatory body governing the current location of device  10  and is stored in RF exposure rule database  42  of  FIG. 2 . The regulatory body may, for example, allow the SAR or MPE of device  10  to temporarily or instantaneously exceed SAR limit SAR LIMIT  or MPE limit MPE LIMIT , so long as the average SAR and MPE of device  10  does not to exceed SAR limit SAR LIMIT  or MPE limit MPE LIMIT  over averaging period T AVG . Averaging period T AVG  may be, for example, between 1 and 60 seconds (e.g., 1 seconds, 4 seconds, 10 seconds, 30 seconds, 60 seconds, etc.). Averaging period T AVG  may also sometimes be referred to herein as averaging window T AVG . 
     Averaging period T AVG  may be divided into a series of instantaneous periods (sometimes referred to herein as sub-windows or subperiods of averaging period T AVG ). While referred to herein as “instantaneous” periods, the instantaneous periods have a finite duration that is less than the duration of averaging period T AVG . Each instantaneous period may be, for example, 1 second, between 1 and 10 seconds, 100 ms, between 100 ms and 10 seconds, between 100 ms and 1 second, less than 100 ms, 10 ms, between 1 and 100 ms, etc. The duration of the instantaneous period may be configurable (adjustable) if desired. For example, RF exposure metric manager  26  may adjust the duration of the instantaneous period to scale according to the applicable use case. 
     Adder  50  in SAR averaging circuitry  46  may receive, over feedback path  32 , the SAR reports SAR 0 , SAR 1 , . . . , SAR n  in the SAR/MPE reports RPT produced by radios  28 . SAR reports SAR 0 , SAR 1 , . . . , SAR n  may be generated during the immediately previous instantaneous period of averaging period T AVG  (e.g., each SAR report may be indicative of the amount of SAR consumed by the corresponding radio during the previous instantaneous period of averaging period T AVG ). Adder  50  may add SAR reports SAR 0 , SAR 1 , . . . , SAR n  together to produce an instantaneous SAR value SAR INST . Instantaneous SAR value SAR INST  (in units of W/kg) may correspond to the overall SAR consumed by all radios  28  while transmitting radio-frequency signals during the current instantaneous period. 
     Adder  50  may pass instantaneous SAR value SAR INST  to time domain averager  54  and SAR value database  56  over path  52 . SAR value database  56  may store instantaneous SAR value SAR INST  for future processing. SAR value database  56  may store the instantaneous SAR values SAR INST  produced during all of the previous instantaneous periods in the current averaging period T AVG  and may, if desired, store instantaneous SAR values SAR INST  from previous averaging periods T AVG . SAR value database  56  may provide each of the instantaneous SAR values SAR INST  produced during previous instantaneous periods of the current averaging period T AVG  to time domain averager  54  over path  58 . 
     Time domain averager  54  may generate (e.g., compute, calculate, identify, produce, etc.) average SAR value SAR AVG  based on the instantaneous SAR value SAR INST  generated by adder  50  for the current instantaneous period, each instantaneous SAR value SAR INST  generated for all previous instantaneous periods of the current averaging period T AVG  (e.g., as provided by SAR value database  56 ), and the duration of averaging period T AVG  (e.g., by averaging the instantaneous SAR values SAR INST  in the time domain over averaging period T AVG ). In other words, time domain averager  54  may generate average SAR value SAR AVG  according to equation 1. 
                     S   ⁢   A   ⁢     R   AVG       =         ∑     i   =   0       i   =   x             SAR   INST         T   AVG               (   1   )               
In equation 1, “i” is an index value and x is the number of samples applied for averaging (e.g., the number of instantaneous periods), which may depend on the sampling rate and the duration of the averaging period. Time domain averager  54  may pass average SAR value SAR AVG  to TER calculation circuitry  73  over path  60 .
 
     At the same time, adder  64  in MPE averaging circuitry  48  may receive, over feedback path  32 , the MPE reports MPE 0 , MPE 1 , . . . , MPE n  in the SAR/MPE reports RPT produced by radios  28 . MPE reports MPE 0 , MPE 1 , . . . , MPE n  may be generated during the immediately previous instantaneous period of averaging period T AVG  (e.g., each MPE report may be indicative of the amount of MPE consumed by the corresponding radio during the previous instantaneous period of averaging period T AVG ). Adder  64  may add MPE reports MPE 0 , MPE 1 , . . . , MPE n  together to produce an instantaneous MPE value MPE INST . Instantaneous MPE value MPE INST  (in units of mW/cm 2 ) may correspond to the overall MPE produced by all radios  28  while transmitting radio-frequency signals during the current instantaneous period. 
     Adder  64  may pass instantaneous MPE value MPE INST  to time domain averager  70  and MPE value database  66  over path  62 . MPE value database  66  may store instantaneous MPE value MPE INST  for future processing. MPE value database  66  may store the instantaneous MPE values MPE INST  produced during all of the previous instantaneous periods in the current averaging period T AVG  and may, if desired, store instantaneous MPE values MPE INST  from previous averaging periods T AVG . MPE value database  66  may provide each of the instantaneous MPE values MPE INST  produced during previous instantaneous periods of the current averaging period T AVG  to time domain averager  70  over path  68 . 
     Time domain averager  70  may generate (e.g., compute, calculate, identify, produce, etc.) average MPE value MPE AVG  based on the instantaneous MPE value MPE INST  generated by adder  64  for the current instantaneous period, each instantaneous MPE value MPE INST  generated for all previous instantaneous periods of the current averaging period T AVG  (e.g., as provided by MPE value database  66 ), and the duration of averaging period T AVG  (e.g., by averaging the instantaneous MPE values MPE INST  in the time domain over averaging period T AVG ). In other words, time domain averager  70  may generate average MPE value MPE AVG  according to equation 2. 
                     M   ⁢   P   ⁢     E   AVG       =         ∑     i   =   0       i   =   x         MPE   INST         T   AVG               (   2   )               
Time domain averager  70  may pass average MPE value MPE AVG  to TER calculation circuitry  73  over path  72 . MPE averaging circuitry  48  may generate average MPE value MPE AVG  and SAR averaging circuitry  46  may generate average SAR value SAR AVG  in parallel (e.g., concurrently or simultaneously).
 
     TER calculation circuitry  73  may generate (e.g., compute, calculate, identify, produce, etc.) total exposure ratio value TERV based on the SAR limit SAR LIMIT  and the MPE limit MPE LIMIT  received over control path  45  (e.g., the SAR limit and MPE limit corresponding to averaging period T AVG  as dictated by the regulatory body of the geographic region in which device  10  is located), the average MPE value MPE AVG  received over path  72 , and the average SAR value SAR AVG  received over path  60 . TER calculation circuitry  73  may, for example, generate total exposure ratio value TERV according to equation 3. 
                     T   ⁢   E   ⁢   R   ⁢   V     =         S   ⁢   A   ⁢     R   AVG         S   ⁢   A   ⁢     R   LIMIT         +       M   ⁢   P   ⁢     E   AVG         M   ⁢   P   ⁢     E   LIMIT                   (   3   )               
TER calculation circuitry  50  may, for example, include one or more adders and one or more dividers for generating total exposure ratio value TERV. TER calculation circuitry  73  may pass average MPE value MPE AVG , average SAR value SAR AVG , and total exposure ratio value TERV to budget calculation and distribution engine  38  ( FIG. 2 ) over path  40  for further processing. Total RF exposure calculation engine  36  may continue to generate SAR AVG , MPE AVG , and TERV values for each instantaneous period of averaging period T AVG  and during subsequent averaging periods T AVG .
 
       FIG. 4  is a circuit block diagram of budget calculation and distribution engine  38  of  FIG. 2 . As shown in  FIG. 4 , budget calculation and distribution engine  38  may include remaining budget calculation circuitry  74 , SAR/MPE budget splitting circuitry  76 , SAR budget distribution circuitry  78 , and MPE budget distribution circuitry  80 . Remaining budget calculation circuitry  74  may sometimes also be referred to herein as remaining budget calculation engine  74  or remaining budget calculator  74 . SAR/MPE budget splitting circuitry  76  may sometimes also be referred to herein as SAR/MPE budget splitting engine  76  or SAR/MPE budget splitter  76 . SAR budget distribution circuitry  78  may sometimes also be referred to herein as SAR budget distribution engine  78  or SAR budget distributor  78 . MPE budget distribution circuitry  80  may sometimes also be referred to herein as MPE budget distribution engine  80  or MPE budget distributor  80 . The components of remaining budget calculation circuitry  74 , SAR/MPE budget splitting circuitry  76 , SAR budget distribution circuitry  78 , and MPE budget distribution circuitry  80  may be implemented in hardware (e.g., one or more processors, circuit components, logic gates, diodes, transistors, switches, arithmetic logic units (ALUs), registers, application-specific integrated circuits, field-programmable gate arrays, etc.) and/or software on device  10 . 
     Remaining budget calculation circuitry  74  may have a first input coupled to path  40  and a second input coupled to control path  45 . The output of remaining budget calculation circuitry  74  may be coupled to the input of SAR/MPE budget splitting circuitry  76  over paths  88  and  90 . The output of SAR/MPE budget splitting circuitry  76  may be coupled to the input of SAR budget distribution circuitry  78  over path  108  and to the input of MPE budget distribution circuitry  80  over path  110 . The outputs of SAR budget distribution circuitry  78  and MPE budget distribution circuitry  80  may be coupled to radios  28  ( FIG. 1 ) over control paths  30 . In other words, remaining budget calculation circuitry  74  may be coupled in series between path  40  and SAR/MPE budget splitting circuitry  76 . SAR/MPE budget splitting circuitry  76  may be coupled in series between remaining budget calculation circuitry  74  and SAR budget distribution circuitry  78 . SAR/MPE budget splitting circuitry  76  may also be coupled in series between remaining budget calculation circuitry  74  and MPE budget distribution circuitry  80 . SAR budget distribution circuitry  78  and MPE budget distribution circuitry  80  may be coupled in parallel between SAR/MPE budget splitting circuitry  76  and control paths  30  (radios  28 ). 
     Remaining budget calculation circuitry  74  may include subtraction logic such as a first subtractor  82 , a second subtractor  84 , and a third subtractor  86 . Subtractors  82 ,  84 , and  86  may sometimes also be referred to herein as subtraction circuits and may include logic gates (e.g., AND gates, XOR gates, etc.), inverters, and/or other components for outputting the difference between first and second inputs. Subtractors  82 ,  84 , and  86  may be coupled in parallel between path  40  and SAR/MPE budget splitting circuitry  76 . Subtractor  82  may have a first input coupled to path  40 , a second input coupled to control path  45 , and an output coupled to SAR/MPE budget splitting circuitry  76  over path  88 . Subtractor  82  may receive SAR limit SAR LIMIT  from RF exposure rule database  42  ( FIG. 2 ) over control path  45 . Subtractor  82  may receive average SAR value SAR AVG  over path  40 . Subtractor  84  may also have a first input coupled to path  40 , a second input coupled to control path  45 , and an output coupled to SAR/MPE budget splitting circuitry  76  over path  88 . Subtractor  84  may receive MPE limit MPE LIMIT  from RF exposure rule database  42  ( FIG. 2 ) over control path  45 . Subtractor  84  may receive average MPE value MPE AVG  over path  40 . Subtractor  86  may have a first input coupled to path  40 , a second input that receives the integer 1, and an output coupled to SAR/MPE budget splitting circuitry  76  over path  90 . 
     Subtractor  82  may generate (e.g., calculate, compute, identify, produce, etc.) a remaining SAR value SAR REM  on path  88  by subtracting average SAR value SAR AVG  from SAR limit SAR LIMIT . Remaining SAR value SAR REM  may correspond to the amount of unused SAR budget that has not yet been consumed by radios  28  during the current averaging period T AVG . Similarly, subtractor  84  may generate (e.g., calculate, compute, identify, produce, etc.) a remaining MPE value MPE REM  on path  88  by subtracting average MPE value MPE AVG  from MPE limit MPE LIMIT . Remaining MPE value MPE REM  may correspond to the amount of unused MPE budget has not yet been consumed by radios  28  during the current averaging period T AVG . Subtractor  86  may generate (e.g., calculate, compute, identify, produce, etc.) a remaining total exposure ratio value TER REM  on path  90  by subtracting total exposure ratio value TER from the integer 1. Remaining total exposure ratio value TER REM  may correspond to the amount of unused total exposure ratio consumed by radios  28  during the current averaging period T AVG . 
     SAR/MPE budget splitting circuitry  76  may include an SAR/MPE split policy  92 , verification circuitry  94  and multiplication logic such as multipliers  96  and  98   
     Multiplier  96  may have a first input that receives remaining TER value TER REM  over path  90 , a second input that receives an SAR allocation SAR POR  from SAR/MPE split policy  92  (over path  100 ), and an output coupled to verification circuitry  94  over path  104 . Multiplier  98  may have a first input that receives remaining TER value TER REM  over path  90 , a second input that receives an MPE allocation MPE POR  from SAR/MPE split policy  92  (over path  102 ), and an output coupled to verification circuitry  94  over path  106 . SAR/MPE split policy  92  may be predetermined for device  10  or produced by RF exposure metric manager  26  ( FIG. 1 ) and may dictate how much RF exposure budget should be allocated to the SAR radios  28  relative to the MPE radios  28 . SAR/MPE split policy  92  may depend on which radios  28  are needed for transmitting and/or receiving desired data for applications running on device  10 . SAR/MPE split policy  92  may, for example, be an initial assumption of the amount of SAR or MPE budget needed by each radio, which may be defined for device  10  during manufacture, assembly, testing, or calibration. For example, radios such as radios operating under a cellular RAT may be assumed to need more SAR and/or more MPE budget than other radios such as a Bluetooth radio, which does not need any MPE budget. SAR allocation SAR POR  may form a weighting factor indicative of the amount of the RF exposure budget that is to be allocated to SAR radios  28  and MPE allocation MPE POR  may form a weighting factor indicative of the amount of RF exposure budget that is to be allocated to MPE radios  28 . SAR allocation SAR POR  and MPE allocation MPE POR  may help to ensure that each radio  28  receives a desired minimum amount of exposure budget to begin transmission. 
     Multiplier  96  may generate (e.g., calculate, compute, identify, produce, etc.) an updated overall SAR budget BGT* SAR  by multiplying remaining TER value TER REM  by SAR allocation SAR POR . Multiplier  96  may pass overall SAR budget BGT* SAR  to verification circuitry  94  over path  104 . Multiplier  98  may generate (e.g., calculate, compute, identify, produce, etc.) an updated overall MPE budget BGT* MPE  by multiplying remaining TER value TER REM  by MPE allocation MPE POR . Multiplier  98  may pass overall MPE budget BGT* MPE  to verification circuitry  94  over path  104 . 
     Verification circuitry  94  may receive remaining SAR value SAR REM  and remaining MPE value MPE REM  over path  88 . Verification circuitry  94  may determine whether overall SAR budget BGT* SAR  exceeds remaining SAR value SAR REM . Verification circuitry  94  may include one or more comparators, for example. If overall SAR budget BGT* SAR  does not exceed remaining SAR value SAR REM , verification circuitry  94  may transmit overall SAR budget BGT* SAR  to SAR budget distribution circuitry  78  over path  108  and SAR budget distribution circuitry  78  may distribute (divide) overall SAR budget BGT* SAR  across radios  28  (e.g., as SAR budgets BGT 0   SAR , . . . , BGTn SAR ). If overall SAR budget BGT* SAR  exceeds remaining SAR value SAR REM , verification circuitry  94  may replace overall SAR budget BGT* SAR  with remaining SAR value SAR REM  and may transmit remaining SAR value SAR REM  to SAR budget distribution circuitry  78  over path  108  for distribution across radios  28  (e.g., as SAR budgets BGT 0   SAR , . . . , BGTn SAR ). 
     Similarly, verification circuitry  94  may determine whether overall MPE budget BGT* MPE  exceeds remaining MPE value MPE REM . If overall MPE budget BGT* MPE  does not exceed remaining MPE value MPE REM , verification circuitry  94  may transmit overall MPE budget BGT* MPE  to MPE budget distribution circuitry  80  over path  110  and MPE budget distribution circuitry  80  may distribute (divide) overall MPE budget BGT* MPE  across radios  28  (e.g., as MPE budgets BGT 0   MPE , . . . , BGTn MPE ). If overall MPE budget BGT* MPE  exceeds remaining MPE value MPE REM , verification circuitry  94  may replace overall MPE budget BGT* MPE  with remaining MPE value MPE REM  and may transmit remaining MPE value MPE REM  to MPE budget distribution circuitry  80  over path  110  for distribution across radios  28  (e.g., as MPE budgets BGT 0   MPE , . . . , BGTn MPE ). 
     SAR budget distribution circuitry  78  may track and store information related to the activity and operation of each of the SAR radios  28  in wireless circuitry  24 . For example, SAR budget distribution circuitry  78  may store information identifying a SAR distribution policy such as SAR distribution policy  114 , SAR radio transmit (TX) activity factors such as SAR radio TX factors  118 , SAR radio statuses such as SAR radio statuses  116 , and SAR radio usage ratios such as SAR radio usage ratios  120 . SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and SAR radio usage ratios  120  may be stored on storage circuitry  16  of  FIG. 1 , for example. SAR budget distribution circuitry  78  may update SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and/or SAR radio usage ratios  120  over time (e.g., as the operating conditions, operating environment, software application needs, and/or communications needs of device  10  change over time). As an example, information for SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and/or SAR radio usage ratios  120  may be provided to SAR budget distribution circuitry  78  in the feedback reports RPT produced by radios  28  and/or by software applications running on device  10 . 
     SAR budget distribution circuitry  78  may distribute the overall SAR budget BGT* SAR  received from SAR/MPE budget splitting circuitry  76  between SAR radios  28  according to (based on) SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and/or SAR radio usage ratios  120 . In other words, SAR budget distribution circuitry  78  may distribute overall SAR budget BGT* SAR  across/between the SAR budgets BGT 0   SAR , . . . , BGTn SAR  provided to radios  28  such that some of the SAR budgets BGT 0   SAR , . . . , BGTn SAR  are allocated more of the overall SAR budget BGT* SAR  than others (or such that each radio receives the same SAR budget). For the current instantaneous period, the SAR budget allocated to any given SAR radio  28  may be different than the SAR budget allocated to that same SAR radio  28  during the previous instantaneous period (e.g., because RF exposure metric manager  26  dynamically adjusts the SAR budget based on the feedback reports RPT generated by radios  28  during previous instantaneous periods and based on SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and SAR radio usage ratios  120 ). In scenarios where SAR/MPE budget splitting circuitry  76  provides remaining SAR value SAR REM  to SAR budget distribution circuitry  78 , SAR budget distribution circuitry  78  may distribute the remaining SAR value SAR REM  between the SAR budgets BGT 0   SAR , . . . , BGTn SAR  provided to radios  28  (e.g., based on SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and/or SAR radio usage ratios  120 ). 
     SAR distribution policy  114  may identify which SAR radios  28  require SAR budget at a current point in time (e.g., because the radios already have a wireless connection established with external communication equipment). The SAR radios  28  that are actively communicating with external communications equipment and conveying a relatively large amount of data may, for example, require more SAR budget and may be allocated more SAR budget than the SAR radios  28  that are not actively communicating with the external communications equipment or that are conveying a relatively low amount of data. SAR radio statuses  116  may identify which SAR radios  28  are active or in an idle or sleep mode at any given time. SAR radios  28  that are active may, for example, require more SAR budget than SAR radios that are idle, inactive, or asleep. SAR radio TX activity factors  118  may identify the amount of transmit activity being used or expected to be used by each SAR radio  28 . SAR radios  28  that have a high amount of actual or expected transmit activity may, for example, require more SAR budget than SAR radios that have a relatively small amount of actual or expected transmit activity. SAR radio usage ratios  120  may identify how much of past SAR budgets was actually used by each SAR radio  28 . A SAR radio  28  that used all or most of its allocated SAR budget during one or more of the previous instantaneous periods and/or averaging periods may, for example, require more SAR budget during the next instantaneous period than SAR radios  28  that used relatively little of its SAR budget during the previous instantaneous periods. 
     Once SAR budget distribution circuitry  78  has generated (e.g., calculated, allocated, distributed, computed produced, etc.) SAR budgets BGT 0   SAR , . . . , BGTn SAR , SAR budget distribution circuitry  78  may transmit SAR budgets BGT 0   SAR , . . . , BGTn SAR  to radios  28  over control paths  30 . Radios  28  may then transmit radio-frequency signals during a subsequent instantaneous period in accordance with its SAR budget as allocated/distributed by SAR budget distribution circuitry  78 . 
     Similarly, MPE budget distribution circuitry  80  may track and store information related to the activity and operation of each of the MPE radios  28  in wireless circuitry  24 . For example, MPE budget distribution circuitry  80  may store information identifying a MPE distribution policy such as MPE distribution policy  122 , MPE radio transmit (TX) activity factors such as MPE radio TX factors  126 , MPE radio statuses such as MPE radio statuses  124 , and MPE radio usage ratios such as MPE radio usage ratios  128 . MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and MPE radio usage ratios  128  may be stored on storage circuitry  16  of  FIG. 1 , for example. MPE budget distribution circuitry  80  may update MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and/or MPE radio usage ratios  128  over time (e.g., as the operating conditions, operating environment, software application needs, and/or communications needs of device  10  change over time). As an example, information for MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and/or MPE radio usage ratios  128  may be provided to MPE budget distribution circuitry  80  in the feedback reports RPT produced by radios  28  and/or by software applications running on device  10 . 
     MPE budget distribution circuitry  80  may distribute the overall MPE budget BGT* MPE  received from SAR/MPE budget splitting circuitry  76  between MPE radios  28  according to (based on) MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and/or MPE radio usage ratios  128 . In other words, MPE budget distribution circuitry  80  may distribute overall MPE budget BGT* MPE  across/between the MPE budgets BGT 0   MPE , . . . , BGTn MPE  provided to radios  28  such that some of the MPE budgets BGT 0   MPE , . . . , BGTn MPE  are allocated more of the overall MPE budget BGT* MPE  than others (or such that each radio  28  is allocated the same MPE budget). For the current instantaneous period, the MPE budget allocated to any given MPE radio  28  may be different than the MPE budget allocated to that same MPE radio  28  during the previous instantaneous period (e.g., because RF exposure metric manager  26  dynamically adjusts the MPE budget based on the feedback reports RPT generated by radios  28  during previous instantaneous periods and based on MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and MPE radio usage ratios  128 ). In scenarios where SAR/MPE budget splitting circuitry  76  provides remaining MPE value MPE REM  to MPE budget distribution circuitry  80 , MPE budget distribution circuitry  80  may distribute the remaining MPE value MPE REM  between the MPE budgets BGT 0   MPE , . . . , BGTn MPE  provided to radios  28  (e.g., based on MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and/or MPE radio usage ratios  128 ). 
     MPE distribution policy  122  may identify which MPE radios  28  require MPE budget at a current point in time (e.g., because the radios already have a wireless connection established with external communication equipment). The MPE radios  28  that are actively communicating with external communications equipment and conveying a relatively large amount of data may, for example, require more MPE budget and may be allocated more MPE budget than the MPE radios  28  that are not actively communicating with the external communications equipment or that are conveying a relatively low amount of data). MPE radio statuses  124  may identify which MPE radios  28  are active or in an idle or sleep mode at any given time. MPE radios  28  that are active may, for example, require more MPE budget than MPE radios that are idle, inactive, or asleep. MPE radio TX activity factors  126  may identify the amount of transmit activity being used or expected to be used by each MPE radio  28 . MPE radios  28  that have a high amount of actual or expected transmit activity may, for example, require more MPE budget than MPE radios that have a relatively small amount of actual or expected transmit activity. MPE radio usage ratios  128  may identify how much of past MPE budgets was actually used by MPE radios  28 . An MPE radio  28  that used all or most of its allocated MPE budget during one or more of the previous instantaneous periods and/or averaging periods may, for example, require more MPE budget during the next instantaneous period than MPE radios  28  that used relatively little of its MPE budget during the previous instantaneous periods. 
     Once MPE budget distribution circuitry  80  has generated (e.g., calculated, allocated, distributed, computed produced, etc.) MPE budgets BGT 0   MPE , . . . , BGTn MPE , MPE budget distribution circuitry  80  may transmit MPE budgets BGT 0   MPE , . . . , BGTn MPE  to radios  28  over control paths  30 . Radios  28  may then transmit radio-frequency signals during a subsequent instantaneous period in accordance with its MPE budget as allocated/distributed by MPE budget distribution circuitry  80 . 
       FIG. 5  is a flow chart of illustrative operations that may be performed by RF exposure metric manager  26  to iteratively and dynamically adjust the SAR budgets BGT 0   SAR , . . . , BGTn SAR  and the MPE budgets BGT 0   MPE , . . . , BGTn MPE  provided to radios  28  over time. 
     At operation  130 , RF exposure metric manager  26  may identify the averaging period T AVG , the SAR limit SAR LIMIT , and the MPE limit MPE LIMIT  that are currently applicable to device  10  from RF exposure rule database  42  ( FIG. 2 ), based on its current geographic location (e.g., based on control signal dev_loc). SAR limit SAR LIMIT  and MPE limit MPE LIMIT  may be provided to total RF exposure calculation engine  36  over control path  45 . Averaging period T AVG  may be provided to total RF exposure calculation engine  36  over control path  44 . 
     At operation  132  (e.g., during a first or initial iteration of the operations of  FIG. 5 ), RF exposure metric manager  26  may generate initial SAR budgets BGT 0   SAR , . . . , BGTn SAR  and initial MPE budgets BGT 0   MPE , . . . , BGTn MPE  for radios  28 . RF exposure metric manager  26  may provide the initial SAR budgets BGT 0   SAR , . . . , BGTn SAR  and the initial MPE budgets BGT 0   MPE , . . . , BGTn MPE  to radios  28  over control paths  30  (e.g., within RF exposure budgets BGT 0 , . . . , BGTn of  FIGS. 1 and 2 ). The initial instantaneous period of averaging period T AVG  begins at operation  134 . 
     At operation  136 , radios  28  may transmit radio-frequency signals according to (based on) the initial SAR budgets BGT 0   SAR , . . . , BGTn SAR  and the initial MPE budgets BGT 0   MPE , . . . , BGTn MPE . This transmission occurs during the current instantaneous period of averaging period T AVG  (e.g., during the initial instantaneous period and during a first iteration of the operations of  FIG. 5 ). For example, the SAR radios  28  in wireless circuitry  24  may transmit radio-frequency signals at transmit power levels that are capped at maximum transmit power levels determined by the SAR radios from the corresponding initial SAR budget received from RF exposure metric manager  26 . Similarly, the MPE radios  28  in wireless circuitry  24  may transmit radio-frequency signals at transmit power levels that are capped at maximum transmit power levels determined by the MPE radios from the corresponding initial MPE budget received from RF exposure metric manager  26 . 
     At operation  138 , radios  28  may generate SAR reports SAR 0 , . . . , SAR n . ( FIG. 2 ) and MPE reports MPE 0 , . . . , MPE n  from the radio-frequency signals transmitted during the current instantaneous period. The SAR reports may be indicative of the amount of the current SAR budget consumed during the instantaneous period by each SAR radio. The MPE reports may be indicative of the amount of the current MPE budget consumed during the instantaneous period by each MPE radio. Radios  28  may provide the SAR reports SAR 0 , . . . , SAR n  and the MPE reports MPE 0 , . . . , MPE n  to total RF exposure calculation engine  36  in RF exposure metric manager  26  over feedback path  32  (e.g., as SAR/MPE reports RPT of  FIGS. 1 and 2 ). 
     At operation  140 , RF exposure metric manager  26  may dynamically adjust the SAR budgets and MPE budgets for radios  28  by generating updated SAR budgets BGT 0   SAR , . . . , BGTn SAR  and updated MPE budgets BGT 0   MPE , . . . , BGTn MPE  for radios  28  to use during the next instantaneous period of the averaging period. RF exposure metric manager  26  may generate updated SAR budgets BGT 0   SAR , . . . , BGTn SAR  and updated MPE budgets BGT 0   MPE , . . . , BGTn MPE  based on the SAR reports SAR 0 , . . . , SAR n  and the MPE reports MPE 0 , . . . , MPE n  produced by radios  28  during the current instantaneous period and, when available, the SAR reports SAR reports SAR 0 , . . . , SAR n  and the MPE reports MPE 0 , . . . , MPE n  and the MPE reports MPE 0 , . . . , MPE n  produced by radios  28  during each prior instantaneous period of the averaging period (e.g., during previous iterations of the operations of  FIG. 5 ). RF exposure metric manager  26  may also generate SAR budgets BGT 0   SAR , . . . , BGTn SAR  and updated MPE budgets BGT 0   MPE , . . . , BGTn MPE  based on SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , SAR radio usage ratios  120 , MPE distribution policy  122 , MPE radio statuses  124 , MPE radio TX activity factors  126 , and/or MPE radio usage ratios  128  of  FIG. 4 . 
     If additional instantaneous periods remain in the current averaging period T AVG , processing may proceed to operation  144  via path  142 . At operation  144 , the subsequent instantaneous period of the current averaging period T AVG  begins. Processing then loops back to operation  136  (e.g., where the subsequent instantaneous period becomes the current instantaneous period). In this way words, RF exposure metric manager  26  may adjust the relative SAR budgets and MPE budgets across radios of different RATs based on the amount of previous SAR and MPE budgets consumed by radios  28  during each previous instantaneous period of the current averaging period, and based on SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , SAR radio usage ratios  120 , MPE distribution policy  122 , MPE radio statuses  124 , MPE radio TX activity factors  126 , and/or MPE radio usage ratios  128 . 
     Once no additional instantaneous periods remain in the current averaging period T AVG , processing may proceed from operation  140  to operation  150  via path  148 . At operation  150 , the initial instantaneous period of a subsequent averaging period T AVG  begins. Processing then loops back to operation  136  so RF exposure metric manager  26  can dynamically update the SAR and MPE budgets for radios  28  over the subsequent averaging period T AVG . Processing may continue to iterate in this way to allow device  10  to continue to ensure that SAR and MPE budgets are efficiently allocated to radios as needed during device operation over time, while ensuring that the applicable regulatory limits (e.g., SAR LIMIT  and MPE LIMIT ) continue to be met over each regulatory averaging period T AVG . Processing may revert to operation  130  when device  10  moves to a geographic location having a different averaging period T AVG , a different SAR limit SAR LIMIT , and/or a different MPE limit MPE LIMIT , or in response to any other desired trigger condition. 
       FIG. 6  is a flow chart of illustrative operations that may be performed by total RF exposure calculation engine  36  ( FIG. 3 ) in RF exposure metric manager  26  to generate average SAR value SAR AVG , average MPE value MPE AVG , and total exposure ratio value TERV based on SAR reports SAR 0 , . . . , SAR n , MPE reports MPE 0 , . . . , MPE n , averaging period T AVG , SAR limit SAR LIMIT  and MPE limit MPE LIMIT . The operations of  FIG. 6  may, for example, be performed during a given iteration of operation  140  of  FIG. 5  (e.g., during a current instantaneous period of a current averaging period T AVG ). 
     At operation  152 , SAR averaging circuitry  46  ( FIG. 3 ) may generate average SAR value SAR AVG  based on the SAR reports SAR 0 , . . . , SAR n  received from radios  28  over feedback path  32  for the current instantaneous period and based on averaging period T AVG . Adder  50  may add SAR reports SAR 0 , . . . , SAR n  together to generate instantaneous SAR value SAR INST , which is provided to time domain averager  54  and is stored at SAR value database  56  for future processing. SAR value database  56  may provide the instantaneous SAR value SAR INST  produced by adder  50  for each previous instantaneous period of the current averaging period T AVG  to time domain averager  54 . Time domain averager  54  may average each instantaneous SAR value SAR INST  produced during the current averaging period T AVG  (e.g., for each previous instantaneous period of the current averaging period T AVG ) over the duration of the current averaging period T AVG  to produce average SAR value SAR AVG  (e.g., according to equation 1). SAR averaging circuitry  46  may provide average SAR value SAR AVG  to TER calculation circuitry  73 . 
     At operation  154 , MPE averaging circuitry  48  may generate average MPE value MPE AVG  based on the MPE reports MPE 0 , . . . , MPE n  received from radios  28  over feedback path  32  for the current instantaneous period and based on averaging period T AVG . Adder  64  may add MPE reports MPE 0 , . . . , MPE n  together to generate instantaneous MPE value MPE INST , which is provided to time domain averager  70  and is stored at MPE value database  66  for future processing. MPE value database  66  may provide the instantaneous MPE value MPE INST  produced by adder  64  for each previous instantaneous period of the current averaging period T AVG  to time domain averager  70 . Time domain averager  70  may average each instantaneous MPE value MPE INST  produced during the current averaging period T AVG  (e.g., for each previous instantaneous period of the current averaging period T AVG ) over the duration of the current averaging period T AVG  to produce average MPE value MPE AVG  (e.g., according to equation 2). MPE averaging circuitry  48  may provide average MPE value MPE AVG  to TER calculation circuitry  73 . 
     At operation  156 , TER calculation circuitry  73  may generate total exposure ratio value TERV based on average MPE value MPE AVG , average SAR value SAR AVG , SAR limit SAR LIMIT , and MPE limit MPE LIMIT  (e.g., according to equation 3). 
     At operation  158 , TER calculation circuitry  73  may provide total exposure ratio value TERV, average MPE value MPE AVG , and average SAR value SAR AVG  to budget calculation and distribution engine  38  ( FIG. 2 ). The example of  FIG. 6  is merely illustrative. In practice, operations  152  and  154  may be performed concurrently or in reverse order if desired. 
       FIG. 7  is a flow chart of illustrative operations that may be performed by budget calculation and distribution engine  38  ( FIG. 2 ) in RF exposure metric manager  26  to generate (updated) SAR budgets BGT 0   SAR , . . . , BGTn SAR  and (updated) MPE budgets BGT 0   MPE , . . . , BGTn MPE  for use by radios  28  in transmitting radio-frequency signals during the next instantaneous period. 
     At operation  160 , remaining budget calculation circuitry  74  ( FIG. 4 ) may generate remaining SAR value SAR REM , remaining MPE value MPE REM , and remaining TER value TER REM  based on average SAR value SAR AVG , average MPE value MPE AVG , total exposure ratio value TERV, SAR limit SAR LIMIT , and MPE limit MPE LIMIT . For example, subtractor  82  may generate remaining SAR value SAR REM  by subtracting average SAR value SAR AVG  from SAR limit SAR LIMIT . Subtractor  84  may generate remaining MPE value MPE REM  by subtracting average MPE value MPE AVG  from MPE limit MPE LIMIT . Subtractor  86  may generate remaining TER value TER REM  by subtracting total exposure ratio value TERV from the integer 1. Remaining budget calculation circuitry  74  may provide remaining SAR value SAR REM  and remaining MPE value MPE REM  to verification circuitry  94  in SAR/MPE budget splitting circuitry  76  over path  88 . Remaining budget calculation circuitry  74  may provide remaining TER value TER REM  to multipliers  96  and  98  in SAR/MPE budget splitting circuitry  76  over path  90 . 
     At operation  162 , multiplier  96  may generate overall SAR budget BGT* SAR  by multiplying SAR allocation SAR POR  (e.g., from SAR/MPE split policy  92 ) by remaining TER value TER REM . Multiplier  98  may concurrently generate overall MPE budget BGT* MPE  by multiplying MPE allocation MPE POR  by remaining TER value TER REM . Verification circuitry  94  may receive overall SAR budget BGT* SAR  over path  104  and may receive overall MPE budget BGT* MPE  over path  94 . Processing may subsequently proceed to operation  166  via path  164  and operation  178  via path  176 . Operations  166 - 174  may be performed concurrently with operations  178 - 186  or these operations may be performed in any desired sequence. 
     At operation  166 , verification circuitry  94  may determine or identify whether overall SAR budget BGT* SAR  exceeds remaining SAR value SAR REM . If overall SAR budget BGT* SAR  does not exceed (e.g., is less than) remaining SAR value SAR REM , verification circuitry  94  may provide overall SAR budget BGT* SAR  to SAR budget distribution circuitry  78  for allocation between SAR radios  28 , and processing may proceed to operation  170  via path  168 . 
     At operation  170 , SAR distribution circuitry  78  may allocate overall SAR budget BGT* SAR  across radios  28  by generating SAR budgets BGT 0   SAR , . . . , BGTn SAR  for each radio  28  based on overall SAR budget BGT* SAR , SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and SAR radio usage ratios  120 . SAR budget distribution circuitry  78  may provide a respective SAR budget to each corresponding radio  28  for transmission during the next instantaneous period (e.g., at operation  136  of  FIG. 5 ). 
     If overall SAR budget BGT* SAR  exceeds (e.g., is greater than or equal to) remaining SAR value SAR REM  (at operation  166 ), verification circuitry  94  may provide remaining SAR value SAR REM  to SAR budget distribution circuitry  78  for allocation between SAR radios  28 , and processing may proceed to operation  174  via path  172 . 
     At operation  174 , SAR budget distribution circuitry  78  may allocate remaining SAR value SAR REM  across radios  28  by generating SAR budgets BGT 0   SAR , . . . , BGTn SAR  for each radio  28  based on remaining SAR value SAR REM , SAR distribution policy  114 , SAR radio TX activity factors  118 , SAR radio statuses  116 , and SAR radio usage ratios  120 . SAR budget distribution circuitry  78  may provide a respective SAR budget to each corresponding radio  28  for transmission during the next instantaneous period (e.g., at operation  136  of  FIG. 5 ). 
     At operation  178 , verification circuitry  94  may determine or identify whether overall MPE budget BGT* MPE  exceeds remaining MPE value MPE REM . If overall MPE budget BGT* MPE  does not exceed remaining MPE value MPE REM , verification circuitry  94  may provide overall MPE budget BGT* MPE  to MPE budget distribution circuitry  80  for allocation between MPE radios  28 , and processing may proceed to operation  182  via path  180 . 
     At operation  182 , MPE budget distribution circuitry  80  may allocate overall MPE budget BGT* MPE  across radios  28  by generating MPE budgets BGT 0   MPE , . . . , BGTn MPE  for each radio  28  based on overall MPE budget BGT* MPE , MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and MPE radio usage ratios  128 . MPE budget distribution circuitry  80  may provide a respective MPE budget to each corresponding radio  28  for transmission during the next instantaneous period (e.g., at operation  136  of  FIG. 5 ). 
     If overall MPE budget BGT* MPE  exceeds remaining MPE value MPE REM  (at operation  178 ), verification circuitry  94  may provide remaining MPE value MPE REM  to MPE budget distribution circuitry  80  for allocation between MPE radios  28 , and processing may proceed to operation  186  via path  184 . 
     At operation  186 , MPE budget distribution circuitry  80  may allocate remaining MPE value MPE REM  across radios  28  by generating MPE budgets BGT 0   MPE , . . . , BGTn MPE  for each radio  28  based on remaining MPE value MPE REM , MPE distribution policy  122 , MPE radio TX activity factors  126 , MPE radio statuses  124 , and MPE radio usage ratios  128 . MPE budget distribution circuitry  80  may provide a respective MPE budget to each corresponding radio  28  for transmission during the next instantaneous period (e.g., at operation  136  of  FIG. 5 ). 
     By dynamically adjusting SAR and MPE budgets across radios  28 , RF exposure metric manager  26  may enable dynamic, cross-technology, SAR and MPE budget sharing such that the SAR and MPE budgets for each radio can be dynamically adjusted as required for each specific use case or scenario. SAR or MPE budget not used during a previous instantaneous period can be reassigned and used in future instantaneous periods either by the same radio or by a different radio. This may result in improved utilization of the total available SAR and MPE budget. This may in turn lead to increased uplink coverage relative to scenarios where static SAR/MPE budgets are used, as the total available SAR and MPE budget is utilized to a larger extent, allowing for higher average TX power and less TX power back-off required by the radios. Increased TX power applied by the radio also leads to better uplink coverage for the radio relative to scenarios where static SAR/MPE budgets are used. In addition, device  10  may be able to increase its duty cycle and thus exhibit increased uplink throughput relative to scenarios where static SAR/MPE budgets are used. 
     The methods and operations described above in connection with  FIGS. 1-7  (e.g., the operations of  FIGS. 5-7 ) may be performed by the components of device  10  using software, firmware, and/or hardware (e.g., dedicated circuitry or hardware). Software code for performing these operations may be stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media) stored on one or more of the components of device  10  (e.g., storage circuitry  16  of  FIG. 1 ). The software code may sometimes be referred to as software, data, instructions, program instructions, or code. The non-transitory computer readable storage media may include drives, non-volatile memory such as non-volatile random-access memory (NVRAM), removable flash drives or other removable media, other types of random-access memory, etc. Software stored on the non-transitory computer readable storage media may be executed by processing circuitry on one or more of the components of device  10  (e.g., processing circuitry  18  of  FIG. 1 , etc.). The processing circuitry may include microprocessors, central processing units (CPUs), application-specific integrated circuits with processing circuitry, or other processing circuitry. The components of  FIGS. 1-4  may be implemented using hardware (e.g., circuit components, digital logic gates, one or more processors, etc.) and/or using software where applicable. While databases are sometimes described herein as providing data to other components (see, e.g., SAR value database  56  of  FIG. 3 , MPE value database  66  of  FIG. 6 , RF exposure rule database  42  of  FIG. 2 , etc.), one or more processors, memory controllers, or other components may actively access the databases, may retrieve the stored data from the database, and may pass the retrieved data to the other components for corresponding processing. The regulatory SAR limit, MPE limit, and averaging times described herein need not be imposed by a government or regulatory body and may additionally or alternatively be imposed by a network operator, base station, or access point of a wireless network in which device  10  operates, by device  10  itself, by the manufacturer or designer of some or all of device  10 , by wireless industry standards, protocols, or practices, by software running on device  10 , etc. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20210512
Publication Date: 20220906
Grant Date: 20220906
Priority Date: 20210512
Inventors: SAMBHWANI, SHARAD
JADHAV, DIGVIJAY A.
NICKISCH, DIRK
KATZIR, GIL
PILLUTLA, LAXMINARAYANA
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B1/3838", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W24/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3838", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/3838", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W24/08", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 83149862