Radio Frequency Exposure Compliance

Abstract

In some aspects, a method for wireless communication includes transmitting a first transmission using a first transmitter operable according to a first radio technology and, after completion of the first transmission, transmitting a second transmission using a second transmitter operable according to a second radio technology. The method may also include, if the first radio technology is a radio frequency (RF) exposure time-averaged technology and the second radio technology is a non-time-averaged RF exposure technology, delaying transmission of the second transmission by a predetermined wait time after completion of the first transmission. The method may also include, if the first radio technology is a non-time-averaged RF exposure technology and the second radio technology is a time-averaged RF exposure technology, transmitting the second transmission using limited peak power for a predetermined time period of at least a portion of the second transmission.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This patent application claims priority to pending U.S. Non-provisional Application No. 17 / 952,166, filed September 23, 2023, assigned to the assignee of this patent application, and expressly incorporated herein by reference as if fully set forth below and for all applicable purposes. [Background technology]

[0002] [Technology] Aspects of the present disclosure relate generally to wireless devices, and more particularly to considering and limiting radio frequency (RF) exposure from wireless devices.

[0003] [background] Modern wireless devices (e.g., mobile phones) are generally required to limit a user's exposure to radio frequency (RF) radiation in accordance with RF exposure limits set by various regulations. To ensure that wireless devices comply with RF exposure limits, techniques have been developed to enable wireless devices to assess RF exposure from the wireless device in real time and adjust the transmit power of the wireless device accordingly to comply with the RF exposure limits. Summary of the Invention

[0004] The following presents a simplified summary of one or more embodiments in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated aspects, and is not intended to identify key or critical elements of all embodiments or to delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0005] A first aspect relates to a wireless device. The wireless device includes a plurality of transmitters, including a first transmitter and a second transmitter, each configured to transmit a signal according to a respective one of a plurality of wireless technologies, the plurality of wireless technologies including the first wireless technology having a time-averaged radio frequency (RF) exposure technique and the second wireless technology having a non-time-averaged RF exposure technique. The wireless device also includes a processor coupled to the plurality of transmitters. The processor is configured to cause the first transmitter to transmit a first transmission and to cause the second transmitter to transmit a second transmission after completion of the first transmission. The processor is further configured to: cause the second transmitter to transmit the second transmission following completion of a predetermined waiting time after completion of the first transmission, if the first transmitter is operable according to the first wireless technology and the second transmitter is operable according to the second wireless technology; and cause the second transmitter to transmit at least a portion of the second transmission at a limited peak power for a predetermined period of time after completion of the first transmission, if the first transmitter is operable according to the second wireless technology and the second transmitter is operable according to the first wireless technology.

[0006] A second aspect relates to a method for wireless communication, the method including: transmitting a first transmission using a first transmitter operable according to a first wireless technology; and transmitting a second transmission using a second transmitter operable according to a second wireless technology after completion of the first transmission. The method also includes, if the first wireless technology is a radio frequency (RF) exposure time-averaged technology and the second wireless technology is a non-time-averaged RF exposure technology, delaying transmission of the second transmission by a predetermined wait time after completion of the first transmission; and, if the first wireless technology is the non-time-averaged RF exposure technology and the second wireless technology is a time-averaged RF exposure technology, transmitting the second transmission using limited peak power for a predetermined time period for at least a portion of the second transmission.

[0007] A third aspect relates to a wireless device. The wireless device includes a plurality of transmitters, each configured to transmit a signal according to a respective one of a plurality of wireless technologies, the plurality of wireless technologies including a time-averaged radio frequency (RF) exposure technique and a non-time-averaged RF exposure technique. The wireless device also includes a processor coupled to the plurality of transmitters. The processor is configured to: set a transmission level limit of the non-time-averaged RF exposure technique to a predetermined back-off level during a period in which the time-averaged RF exposure technique is active over a transmission time window; determine an RF exposure profile for the non-time-averaged RF exposure technique over the transmission time window; and control transmission of one of the transmitters operable according to the time-averaged RF exposure technique based on the RF exposure profile.

[0008] A fourth aspect relates to a method for wireless communication, the method including: setting a transmission level limit of a non-time-averaged RF exposure technique to a predetermined back-off level during a time period when a time-averaged RF exposure technique is active over a transmission time window, determining an RF exposure profile for the non-time-averaged RF exposure technique over the transmission time window, and controlling transmission of a transmitter operable according to the time-averaged RF exposure technique based on the derived RF exposure profile.

[0009] To the accomplishment of the foregoing and related ends, the one or more embodiments comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the one or more embodiments. These aspects are indicative, however, of but a few of the various ways in which the principles of the various aspects may be employed, and the description is intended to include all such aspects and their equivalents. [Brief explanation of the drawings]

[0010] [Figure 1] 1 illustrates an example of a wireless device in which aspects of the present disclosure may be implemented. [Figure 2A]1 shows a graph of SAR exposure for wireless access technologies over time. [Figure 2B] 1 shows a graph of SAR exposure for one or the other of two radio access technologies over a particular time period in a system that eliminates simultaneous transmissions from the two radio access technologies to control RF exposure. [Figure 2C] 1 shows a graph of SAR exposure for a combination of at least two radio access technologies over a particular time period in a system that eliminates simultaneous transmissions from the two radio access technologies to control RF exposure. [Figure 2D] 1 illustrates an example of determining a wait time between completion of a transmission using an RF exposure time averaging technique and completion of a transmission using an RF exposure non-time averaging technique, according to some embodiments. [Figure 3] 1 shows a flow diagram illustrating a method for controlling transmission for time-averaged and non-time-averaged RF exposure techniques according to some aspects of the present disclosure. [Figure 4] 10 illustrates a flow diagram of another method for controlling transmission for time-averaged and non-time-averaged RF exposure techniques, according to some aspects of the present disclosure. [Figure 5] 10 illustrates a flow diagram of yet another method for controlling transmission for time-averaged and non-time-averaged RF exposure techniques, according to some aspects of the present disclosure. [Figure 6A] 1 illustrates a visual representation of an example normalization of WLAN exposure that takes into account WWAN transmissions, in accordance with certain aspects of the present disclosure. [Figure 6B] 1 illustrates a visual representation of an exemplary WLAN exposure considering WWAN transmissions and different WLAN transmission frequencies, according to some aspects of the present disclosure. [Figure 7] 1 is an exemplary block diagram of an apparatus for controlling a transmitter in a wireless device. [Figure 8] 1 is a flowchart illustrating an example method for wireless communication in accordance with various aspects of the present disclosure. [Figure 9]1 is a flowchart illustrating an example method for controlling transmissions in a wireless device to ensure compliance with RF exposure limits, in accordance with certain aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The Detailed Description set forth below in connection with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The Detailed Description includes specific details intended to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0012] 1 illustrates an example of a wireless device 100 in which aspects of the disclosure described herein may be implemented. Wireless device 100 may comprise a mobile wireless device (e.g., a cell phone), a laptop, a wireless access point, or some other wireless device.

[0013] In particular, wireless device 100 includes processor 110 and memory 115 coupled to processor 110. Memory 115 may store instructions that, when executed by processor 110, cause processor 110 to perform one or more of the operations described herein. Memory 115 may include random access memory (RAM), read-only memory (ROM), flash memory such as NAND storage, or any combination thereof. Processor 110 may be implemented with a general-purpose processor, a digital signal processor (DSP), a baseband modem, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate logic, discrete hardware components, or any combination thereof configured to perform one or more of the operations described herein.

[0014] Wireless device 100 also includes multiple transmitters 120-1 through 120-N, multiple antennas 122-1 through 122-N, and a bus 140 that couples processor 110 and multiple transmitters 120-1 through 120-N. In the example shown in FIG. 1 , an output of each of transmitters 120-1 through 120-N is coupled to a respective one of antennas 122-1 through 122-N and configured to output a respective RF signal to the respective one of antennas 122-1 through 122-N for transmission. Antennas 122-1 through 122-N may be arranged in a one-dimensional array, a two-dimensional array, or a three-dimensional array. Each of antennas 122-1 through 122-N may be implemented with a patch antenna or another type of antenna. Transmitters 120-1 through 120-N may also be referred to as a transmit chain or other terminology, and antennas 122-1 through 122-N may also be referred to as antenna elements.

[0015] In some aspects, transmitters 120-1 through 120-N are configured to transmit signals via respective antennas 122-1 through 122-N using one or more wireless access technologies, including, but not limited to, third-generation (3G) technology (e.g., CDMA), fourth-generation (4G) technology (also known as long-term evolution (LTE)), fifth-generation (5G) technology such as 5G NR, one or more technologies based on one or more IEEE 802.11 protocols (e.g., IEEE 802.11 ac, IEEE 802.11n, IEEE 802.11 ad, IEEE 802.11 ax, IEEE 802.11 ay, IEEE 802.15 protocols, IEEE 802.16 protocols, etc.), and / or one or more other technologies. In some aspects, wireless device 100 transmits data to another wireless device (not shown) in a multiple-input multiple-output (MIMO) transmission mode to increase throughput between wireless device 100 and the other wireless device. In the MIMO transmission mode, transmitters 120-1 through 120-N transmit multiple signals via antennas 122-1 through 122-N, with each of transmitters 120-1 through 120-N transmitting a respective one of the multiple signals via its respective antenna 122-1 through 122-N. Transmitters 120-1 through 120-N may transmit multiple signals on the same frequency. The MIMO transmission mode may use spatial multiplexing, diversity coding, precoding, beamforming, multi-user MIMO, etc. In some aspects, transmitters 120-1 through 120-N may be configured to transmit signals via antennas 122-1 through 122-N using beamforming to direct transmissions to other wireless devices (e.g., in the MIMO transmission mode). In these aspects, transmissions may be electrically steered by adjusting the relative phase and / or amplitude of the transmit signals for different antennas 122-1 through 122-N.

[0016] Processor 110 interfaces with transmitters 120-1 through 120-N via bus 140. In some aspects, bus 140 includes multiple signal lines 142-1 through 142-N between processor 110 and transmitters 120-1 through 120-N, each of signal lines 142-1 through 142-N coupled between processor 110 and an input of a respective one of transmitters 120-1 through 120-N. To transmit data, processor 110 may process the data into one or more signals (e.g., baseband signals or intermediate frequency (IF) signals). The processing performed by processor 110 may include encoding the data and modulating the encoded data (e.g., using any one of a variety of different modulation schemes including BPSK, QPSK, QAM, etc.). In a MIMO example, processor 110 may also perform MIMO precoding, spatial processing, etc. Processor 110 outputs one or more signals to transmitters 120-1 through 120-N via bus 140. In one example, the one or more signals include multiple signals, and processor 110 outputs each of the multiple signals to each of transmitters 120-1 through 120-N via a respective signal line 142-1 through 142-N. In this example, each of the multiple signals may include a respective one of multiple data streams. In another example, processor 110 may output the same signal to transmitters 120-1 through 120-N or a subset of transmitters 120-1 through 120-N.

[0017] Each of transmitters 120-1 through 120-N is configured to process a respective signal from processor 110 into a respective RF signal for transmission via a respective antenna 122-1 through 122-N. The processing performed by each of transmitters 120-1 through 120-N may include frequency upconversion, power amplification, etc. In a MIMO example, the RF signals output by transmitters 120-1 through 120-N may have the same transmit frequency.

[0018] In some aspects, processor 110 may set the transmit power level for each of antennas 122-1 through 122-N by setting the gain of the amplifier in each transmitter 120-1 through 120-N accordingly. Processor 110 may set the gain of each of the amplifiers using a respective gain control signal. In this example, processor 110 may independently set the transmit power levels for antennas 122-1 through 122-N by setting the gain of each amplifier using a respective gain control signal.

[0019] In another example, processor 110 outputs multiple signals to transmitters 120-1 through 120-N, each of the multiple signals corresponding to a respective one of antennas 122-1 through 122-N. In this example, processor 110 sets the transmit power level of each of the antennas by setting the amplitude of each signal accordingly. It should be understood that the present disclosure is not limited to the above example, and processor 110 may employ other techniques to set the transmit power levels of antennas 122-1 through 122-N.

[0020] In some aspects, processor 110 may set transmit power levels for antennas 122-1 through 122-N using an open power control loop and / or a closed power control loop. In an example of an open power control loop, wireless device 100 may receive a pilot signal from another wireless device (not shown) via a receiver (not shown). In this example, processor 110 estimates channel conditions between wireless device 100 and the other wireless device based on the received pilot signal and sets transmit power levels for antennas 122-1 through 122-N based on the estimated channel conditions. In an example of a closed power control loop, wireless device 100 receives a feedback signal from the other wireless device via a receiver (not shown), the feedback signal indicating channel conditions between wireless device 100 and the other wireless device. In this example, processor 110 sets transmit power levels for antennas 122-1 through 122-N based on the indicated channel conditions.

[0021] Additionally, processor 110 may set the transmit power levels of antennas 122-1 through 122-N to keep RF exposure from wireless device 100 within RF exposure limits set by regulators (e.g., the FCC), as described further below. In this case, the transmit power levels of antennas 122-1 through 122-N are constrained by the RF exposure limits.

[0022] For some wireless devices, such as 5G NR devices, at frequencies below 6 GHz (i.e., sub-6 GHz), the device (e.g., device 100) may require RF exposure assessment in terms of specific absorption rate (i.e., SAR in units of W / kg), as well as power density, i.e., mW / cm 2 Simultaneous transmissions at frequencies above 6 GHz (i.e., mmWave) assess exposure in terms of "PD" in units of Hz. Due to regulations regarding simultaneous exposure, this limits the maximum transmit (Tx) power of a wireless device for both frequency bands below 6 GHz and above 6 GHz. To maximize Tx power, it is known to utilize real-time RF exposure algorithms that determine time-averaged SAR and time-averaged PD exposure over a given time window in real time to determine future sub-6 GHz and mmWave antenna power limits in real time using pre-stored SAR and PD values ​​and / or distributions.

[0023] To assess RF exposure from transmissions of wireless device 100, wireless device 100 may include multiple SAR distributions (also referred to as SAR maps) stored in memory 115. Each of the SAR distributions may correspond to a respective one of multiple transmission scenarios supported by wireless device 100. The transmission scenarios may correspond to various combinations of antennas 122-1 through 122-N, frequency bands, channels, and / or body positions, as described further below.

[0024] The SAR distribution for each transmit scenario may be generated based on measurements (e.g., E-field measurements) performed in a test laboratory using a human body model. After the SAR distribution is generated, it is stored in memory 115 to enable processor 110 to assess RF exposure in real time, as described further below. Each SAR distribution includes a set of SAR values, where each SAR value may correspond to a different location (e.g., on the human body model). Each SAR value may include a SAR value averaged over a 1 g or 10 g mass at the respective location.

[0025] As previously described, wireless device 100 may support multiple transmit scenarios. In some aspects, a transmit scenario may be specified by a set of parameters. The set of parameters may include one or more of: antenna parameters indicating one or more antennas used for transmission (i.e., active antennas); frequency band parameters indicating one or more frequency bands used for transmission (i.e., active frequency bands); channel parameters indicating one or more channels used for transmission (i.e., active channels); body position parameters indicating the location of wireless device 100 relative to a user's body location (away from the body, head, torso, etc.); distance of human body tissue from the device; and / or other parameters. When wireless device 100 supports a large number of transmit scenarios, performing measurements for each transmit scenario in a test environment (e.g., a test lab) may be extremely time-consuming and expensive. To reduce test time, measurements may be performed for a subset of the transmit scenarios to generate SAR distributions for the subset of transmit scenarios. In this example, the SAR distributions for each of the remaining transmit scenarios may be generated by combining two or more of the SAR distributions for the subset of transmit scenarios. For example, SAR measurements may be performed for each of antennas 122-1 through 122-N to generate a SAR distribution for each of antennas 122-1 through 122-N. In this example, a SAR distribution for a transmission scenario in which two or more of antennas 122-1 through 122-N are active may be generated by combining the SAR distributions for the two or more active antennas.

[0026] In another example, SAR measurements may be performed for each of a plurality of frequency bands to generate a SAR distribution for each of the plurality of frequency bands. In this example, a SAR distribution for a transmission scenario in which two or more frequency bands are active may be generated by combining the SAR distributions for the two or more active frequency bands.

[0027] It should be understood that assessing RF exposure is not limited to the example of an SAR distribution. For example, RF exposure may also be assessed in some implementations using a single SAR value instead of an SAR distribution including multiple SAR values. In this example, an SAR value may be measured for each of one or more of the example scenarios described above and stored in memory 115 to enable wireless device 100 to assess RF exposure for various scenarios, as described further below. It should also be understood that wireless device 100 may also assess RF exposure based on power density (PD) and / or a combination of SAR and PD. Thus, it should be understood that the present disclosure is not limited to a particular type of RF exposure measurement, and that aspects of the present disclosure are generally applicable to other types of RF exposure measurements.

[0028] Additionally, a wireless device may be required to comply with the total time-averaged RF exposure from transmitters of all radio access technologies in the device (e.g., WWAN, 5G NR, WLAN, and BT transmitters). If any of these technologies are not part of the time-averaging, such as WLAN (e.g., WLAN third-party chips), a conventional method for achieving compliance is to statically divide or partition the overall RF exposure margin between the non-time-averaged technology (e.g., WLAN) and all other radio access technologies, which means that none of these technologies (e.g., 5G NR) can exceed this partial limit, thereby always providing less power for transmission, regardless of, for example, the current level of WLAN exposure.

[0029] Furthermore, with regard to the traditional approach to RF exposure compliance, the time-averaged RF exposure for some technologies, such as WWAN, and the RF exposure from the remaining technologies, such as WLAN, should total below the limit. In this particular example, this approach can be expressed by the following relationship: Time-averaged RF exposure for WWAN (+5G NR) + RF exposure from WLAN ≦ 100%. Compliance can then be achieved by dividing the margin into an "A" portion and a "B" portion. In particular, this can be determined based on the following condition: WWAN time-averaged RF exposure (e.g., "5G NR") ≤ A RF exposure from WLAN ≤ B A+B≦100%

[0030] This approach has the drawback that regardless of whether a particular radio technology is on or off, the margin is reduced to a set value "A" or "B", which is less than the total margin (i.e., 100%).

[0031] Another alternative for attempting to comply with RF exposure limits is to prevent simultaneous transmission of time-averaged (e.g., WWAN) and non-time-averaged (e.g., WLAN) technologies. While limiting simultaneous transmissions could theoretically provide 100% margin for each individual wireless technology (e.g., WWAN and WLAN), this does not guarantee time-averaged compliance, as explained below with respect to Figures 2A-2C.

[0032] 2A shows a graph illustrating SAR levels over time for different technologies when utilizing a technique that prevents simultaneous transmission of time-averaging (e.g., WWAN) and non-time-averaging (e.g., WLAN) technologies. The theoretical total RF exposure compliance, without considering the specific wireless technology, is shown at 202, and the SAR limit 204 is emitted over a time window (e.g., 100 seconds) specified by the regulator for averaging RF exposure. The total available SAR margin is therefore shown by time window 206.

[0033] FIG. 2B shows a graph illustrating two different scenarios 208 and 210 in which transmissions comply with exposure limits using a method of limiting simultaneous transmissions that provides an equivalent exposure as the total limit shown in FIG. 2A. In scenario 208, a time-averaging technology, such as a WWAN technology, transmits at a level 212 that exceeds the SAR limit 204, but for a time that is less than the time window (e.g., 100 seconds) shown in the example of FIG. 2A. In this example, the call is dropped at time t1 so that the total SAR exposure time window 214 is equal to the SAR exposure of FIG. 2A due to the time averaging of the WWAN technology. Note that because the wireless technology is time-averaged such that the transmission time is reduced in scenario 208, the SAR level 212 can exceed the SAR limit 204 as long as the total SAR exposure (i.e., window 214) when averaged over a time window (e.g., 100 seconds) is within the total limit (e.g., window 206 of FIG. 2A).

[0034] In another RF exposure compliance scenario 210, a non-time-averaging technology, such as WLAN, is assumed to transmit at a level 216 for a time period of 100 seconds at the SAR limit 204. Because no other technologies are simultaneously transmitting during this time, the time window 218 is equivalent to the window 206 shown in FIG. 2A . In this disclosure, the SAR limit (or 100% of the RF exposure margin) may be equal to the regulatory SAR limit set by a regulatory body (e.g., the Federal Communications Commission). In some aspects, the SAR limit may be set to a value below the regulatory SAR limit to account for device uncertainty and / or to budget sufficient SAR margin to comply with total RF exposure in simultaneous technologies with other transmitters (e.g., Bluetooth to comply with total RF exposure compliance in WWAN+Bluetooth and WLAN+Bluetooth scenarios). Thus, in this disclosure, the SAR limit may be less than or equal to the regulatory SAR limit.

[0035] 2C illustrates a scenario 240 in which two technologies (i.e., a time-averaged technology and a non-time-averaged technology) transmit at different times to attempt to comply with RF exposure limits. However, in scenario 240, although the time-averaged RF exposure of a first time-averaged technology, such as WWAN, is less than 100%, and the RF exposure of a second non-time-averaged technology, such as WLAN, is also less than 100%, the RF exposure of the system does not comply with the RF exposure limits. As seen at 242, the time-averaged technology, such as the WWAN technology, transmits at a level 244 that exceeds the SAR limit 204, but for a time less than the 100 seconds shown in the example of FIG. 2A. In this example, the WWAN call is dropped at time t1 so that the total SAR exposure time window 246 is less than 100% of the total RF exposure limit throughout the time averaging of the WWAN technology.

[0036] After transmission using a first technology (i.e., WWAN) ends at time t1, transmission using a non-time-averaged technology (e.g., WLAN) begins. In the example shown at 248, a WLAN transmission 250 within the SAR limit 204 from t1 to 100 seconds results in an RF exposure time window 252. Both the time-averaged WWAN exposure shown at 242 and the WLAN exposure shown at 248 are each less than the 100% RF exposure limit shown in FIG. 2A. However, the total RF exposure (WLAN+WWAN) exceeds 100% for the 100-second time period; therefore, the system as a whole is not in compliance with the RF exposure limit.

[0037] In light of the above approach, further methods and apparatus are disclosed herein for providing dynamic adjustment of Tx power limits for transmission of a non-time-averaged technology(ies) to optimize RF exposure margin and obtain larger RF exposure margin for active transmission of time-averaged technologies (e.g., WWAN, 5G NR, etc.) to improve overall device performance.

[0038] According to some aspects, in systems that do not allow simultaneous transmission of a time-averaged RF exposure technique (e.g., WWAN) and a non-time-averaged RF exposure technique (e.g., WLAN), a time delay may be added before switching between the time-averaged and non-time-averaged techniques. For example, if the WWAN technology is turned off, the WLAN technology is not immediately turned on but is controlled to wait until a predetermined time delay has expired before being turned on. According to further aspects, the predetermined time delay may be calculated based on the amount or level of past exposure from the time-averaged technique (e.g., WWAN). In the example shown in FIG. 2C, this would be equivalent to delaying the transmission of the non-time-averaged RF exposure technique (e.g., WLAN) between time t1 and 100 seconds (i.e., a predetermined time delay equal to 100 seconds - t1). The time delay may be calculated based on the RF exposure margin transmitted by the previous time-averaged RF exposure technique (e.g., WWAN) transmission. As used herein, a time-averaged RF exposure technology is a wireless technology that uses time averaging over a time window to ensure that RF exposure from the wireless technology complies with predefined RF exposure limits.

[0039] 3 shows a flow diagram illustrating a method 300 for controlling transmissions for time-averaged and non-time-averaged RF exposure techniques in a wireless device (e.g., device 100), according to one aspect. In method 300, a first transmitter (e.g., 120-1) transmits using a time-averaged RF exposure technique (e.g., WWAN), as shown in block 302. While the time-averaged RF exposure technique(s) is transmitting, a check is performed to determine whether the first transmitter and accompanying techniques are turned off, as shown by decision block 304. If the first transmitter is not turned off (i.e., the first transmitter is still transmitting using a time-averaged RF exposure technique (e.g., WWAN)), method 300 may loop back to block 302 until the first transmitter is turned off.

[0040] That is, if the first transmitter is turned off in decision block 304 (i.e., the first transmitter stops transmitting using a time-averaged RF exposure technique (e.g., WWAN)), flow may proceed to optional block 306, where a predetermined time period to wait is calculated based on the amount of exposure from the time-averaged RF technique that was previously transmitting in block 302. In other aspects, instead of calculating a value in block 306, a set predetermined time period may be utilized.

[0041] Regardless of whether the predetermined time period is calculated in block 306 or a set predetermined time period is utilized, flow proceeds to block 308, where the wireless device waits or delays transmitting a next technique, such as a non-time-averaged RF exposure technique, for the duration of the predetermined time period, thereby more likely ensuring that RF exposure limits will not be exceeded, such as in the scenario illustrated by Figure 2C. After the predetermined time period has elapsed in block 308, flow proceeds to block 310, where a second transmitter (e.g., 120-2) transmits using a non-time-averaged RF exposure technique (e.g., WLAN).

[0042] As described above, a predetermined time period to wait may be calculated in optional block 306. In one example, if a transmitter using a time-averaged RF technique (e.g., WWAN) transmits at the high power level 244 shown in FIG. 2C in block 302, for RF exposure compliance, the wireless device may calculate a predetermined time of one time window minus t1 (e.g., 100 seconds - t1), where t1 is the amount of time the transmitter using the time-averaged RF technique transmits at level 244. In another example, the transmitter using the time-averaged RF technique (e.g., WWAN) transmits at or below power level 207 (the power level corresponding to the SAR limit 204 shown in FIG. 2C) in block 302. In this example, a transmitter using a non-time-averaged RF technique (e.g., WLAN) does not need to wait after time t1 before transmitting because a transmitter using a non-time-averaged RF technique can transmit at or below power level 207 and still be compliant.

[0043] 2D shows another example for determining a waiting period (i.e., a time period for waiting) according to some embodiments. FIG. 2D shows a first graph of RF exposure 260 including an RF exposure profile 262 for a time averaging technique (e.g., WWAN) and an RF exposure profile 266 for a non-time averaging technique (e.g., WWAN). In this example, transmission for the time averaging technique ends at time t1. In this example, processor 110 may determine a waiting period at approximately time t1 at which processor 110 may determine RF exposure profile 266 for the time averaging technique based on a previous transmit power level for the time averaging technique known by processor 110. For example, the previous transmit power level may be stored in memory and accessed by processor 110. Also, in this example, processor 110 may assume that the non-time averaging technique transmits at a power level corresponding to an RF exposure limit (e.g., SAR limit 204).

[0044] In this example, processor 110 may select a wait time (e.g., a wait time less than time window −t1) and calculate an RF exposure profile over the time window (e.g., set by a regulator). Processor 110 may then compare the RF exposure profile over the time window to a total RF exposure margin (e.g., 206) and determine whether to use the wait time in block 308 based on the comparison (e.g., use the wait time if the RF exposure profile is less than or equal to the total RF exposure margin (e.g., 206)). In this example, the portion of the RF exposure profile includes an RF exposure profile from a time-averaging technique and an RF exposure profile from a non-time-averaging technique, with a wait time therebetween. In some embodiments, processor 110 may shift time window 268 to multiple time positions. In this regard, FIG. 2D illustrates one example of a shift 270 in which time window 268 is shifted to the right. In this example, processor 110 may calculate an RF exposure profile over time window 268 for each of the shifts, compare each of the RF exposure profiles to a total RF exposure margin (e.g., 206), and determine whether to use a wait time in block 308 based on the comparison (e.g., use a wait time if each of the RF exposure profiles is less than or equal to the total RF exposure profile). If one or more of the calculated RF exposure profiles exceeds the total RF exposure margin, processor 110 may select another wait time (e.g., a longer wait time) and repeat the above process using the other wait time.

[0045] In still further aspects, if a non-time-averaging technique (e.g., WLAN) is transmitting and then turned off, a time-averaging technique (e.g., WWAN) may be immediately turned on. However, in this case, the time-averaging technique may be operated such that the peak Tx power is limited to a maximum time-averaged Tx power level 207 (i.e., a Tx power level corresponding to the SAR limit). In some aspects, the peak Tx power of the time-averaging technique (e.g., WWAN) may be limited for a predetermined time period (e.g., to a power level corresponding to the SAR limit) to ensure RF exposure compliance of the time-averaging technique. In one example, the time period may be equal to one time window (e.g., 100 seconds). 2C , if a non-time-averaged RF exposure technology (e.g., WLAN) initially transmits at the SAR limit between 0 s and time t1, is turned off at time t1, and a time-averaged RF exposure technology (e.g., WWAN) is turned on at time t1, then in order to remain compliant with the total RF exposure, the time-averaged technology may be limited to a peak Tx power level of 207 (i.e., maximum time-averaged Tx transmit level 207 corresponding to SAR limit 204) for one time window between time t1 and t1 plus one time window (e.g., t1 + 100 seconds). In this example, the time window may correspond to the time-averaging window defined by the regulator (e.g., 100 seconds in the example of FIG. 2C ). In another example, if the time-averaged technology (e.g., WWAN) transmits at low power (i.e., below power level 207) during this time (i.e., after time t1, until a predetermined time period expires), the predetermined time period may be less than one window. For example, processor 110 may determine an RF exposure profile for a non-time averaging technique based on previous transmit power levels for the non-time averaging technique that are known by processor 110. For example, the previous transmit power levels may be stored in memory 115 and accessed by processor 110. In this example, processor 110 may determine a time period based on the RF exposure profile for the non-time averaging technique (e.g., determine a shorter time period for a lower RF exposure profile and a longer time period for a higher RF exposure profile).

[0046] In another example, processor 110 can input the RF exposure profile for a non-time-averaged technique into an algorithm that assesses RF exposure compliance over a time window for the time-averaged technique and sets a transmit power level for the time-averaged technique based on the assessment. This allows the algorithm (which may be executed by processor 110) to consider the RF exposure profile for the non-time-averaged technique when assessing RF exposure compliance over a time window. The RF exposure profile for a non-time-averaged technique may be input into an existing algorithm that assesses RF exposure compliance over a time window for the time-averaged technique, and the algorithm processes the RF exposure profile for the non-time-averaged technique in the same way as the RF exposure profile for the time-averaged technique (e.g., the algorithm does not distinguish between RF exposure from a non-time-averaged technique and an RF exposure from a time-averaged technique in assessing RF exposure compliance over a time window). In some examples, the RF exposure profile for a non-time-averaged technique that is input into an existing algorithm that assesses RF exposure compliance over a time window for the time-averaged technique assumes that the non-time-averaged technique was transmitted at maximum power for the entire time it was on.

[0047] 4 shows a flow diagram illustrating a further method 400 for controlling transmissions for time-averaged and non-time-averaged RF exposure techniques in a wireless device (e.g., device 100), according to one aspect. In method 400, a first transmitter (e.g., 120-2) transmits a signal using a non-time-averaged RF exposure technique (e.g., WLAN), as shown in block 402. After the transmission of the first transmitter is turned off as determined in decision block 404, flow proceeds to block 406, where transmission with a second transmitter using a time-averaged RF exposure technique (e.g., WWAN) is performed. Further, note that the transmission shown in block 406 includes transmission at a limited transmit peak power (e.g., peak transmit power limited to a maximum time-averaged Tx power level 207) over a predetermined time period. In some aspects, when the second transmitter transmits at low power (i.e., below power level 0, including 207 power levels representing delayed transmissions using time averaging techniques (e.g., WWAN)), the predetermined time period may be one time window (e.g., 100 seconds) or less than one time window. After expiration or lapse of the predetermined time period as determined in decision block 408, flow proceeds to block 410, where the second transmitter may be allowed to return to normal time averaging and power levels in accordance with a particular time averaging algorithm or method employed in the wireless device and / or second transmitter.

[0048] FIG. 5 shows a method 500 for controlling transmissions for time-averaged and non-time-averaged RF exposure techniques in a wireless device (e.g., device 100) according to a further aspect that incorporates features of methods 300 and 400 of both FIGS. 3 and 4. Method 500, like methods 300 and 400, is a method that may be used in systems in which non-time-averaged RF exposure techniques (e.g., WLAN) and time-averaged RF exposure techniques (e.g., WWAN) are not transmitted simultaneously. Method 500 initially includes determining whether the current transmission is from a transmitter (e.g., 120-1) using a non-time-averaged RF exposure technique or from a transmitter (e.g., 120-2) using a time-averaged RF exposure technique, as shown in decision block 502. If the current transmission is being performed using a non-time-averaged RF exposure technique (e.g., WLAN), flow proceeds to block 504, where the transmitter transmits a signal using a non-time-averaged RF exposure technique (e.g., WLAN). After the first transmitter is turned off as determined in decision block 506, flow proceeds to block 508, where a transmission is performed with a transmitter using a time-averaged RF exposure technique (e.g., WWAN). Further, note that the transmission shown in block 508 includes a transmission at a limited transmit peak power (e.g., peak transmit power limited to a maximum time-averaged Tx power level 207) over a predetermined time period. In some aspects, if the second transmitter transmits at a low power (i.e., less than power level 0, including the 207 power level representing a delayed transmission using a time-averaged technique (e.g., WWAN)), the predetermined time period may be one time window (e.g., 100 seconds) or less than one time window. After expiration of the predetermined time period in block 508, flow proceeds to block 510, where a transmitter using a time-averaged RF exposure technique may be allowed to return to a normal time-averaged and transmit power level according to a particular time-averaging algorithm or method employed in the wireless device or transmitter.

[0049] Alternatively, if a time-averaged RF exposure technique (e.g., WWAN) is currently being used to transmit signals, as determined in block 502, then flow proceeds to transmitting using a transmitter (e.g., 120-2) capable of operating in accordance with at least a radio access technology (RAT) with time averaging for RF exposure compliance, as shown in block 512. While the time-averaged RF exposure technique (or techniques) is transmitting, a check is performed to determine whether the transmitter and accompanying technology are turned off, as shown by decision block 514, and a loop back to block 512 is performed until the technology is turned off.

[0050] Flow then proceeds to block 516, where the wireless device is configured to wait or delay transmission of a next RF exposure technique, such as a non-time-averaged RF exposure technique (e.g., WLAN), for the duration of a predetermined time period, thereby more likely ensuring that RF exposure limits are not exceeded. More notably, the process of block 512 may include calculating the predetermined time period to wait based on the amount of exposure from a time-averaged RF technique (e.g., WWAN) that was previously transmitting in block 512. In other aspects, a set predetermined time period may be utilized instead of calculating a value in block 512.

[0051] After the predetermined time period in block 516 expires, flow proceeds to block 518 where transmission by a transmitter (eg, 120-1) operable according to a non-time-averaged RF exposure technique (eg, WLAN) is then performed.

[0052] In yet a further aspect, it should be noted that in connection with methods 300, 400, or 500, if a time averaging algorithm or method for a time averaging technique (e.g., WWAN) is configured to receive input information regarding whether a non-time averaging technique (e.g., WLAN) is turned on or off, the time averaging algorithm can be configured to account for the non-time averaging technique (e.g., WLAN) RF exposure by assuming that the non-time averaging technique transmits at maximum power all the time the non-time averaging technique transmitter is turned on. In this way, the time averaging algorithm can provide appropriate Tx power limits for the time averaging technique (e.g., WWAN) depending on the history of non-time averaging transmitter activity, i.e., adjust the time delay before high-power transmission for the time averaging technique transmitter. In one example, processes 406 and 508 can utilize this further method to determine the predetermined time delay.

[0053] According to further aspects, if the time averaging algorithm is configured to, for example, send a backoff or reduced power limit to a non-time averaging technique (e.g., WLAN) transmitter and has knowledge of whether the non-time averaging technique transmitter is on or off, the non-time averaging technique RF exposure can be even more accurately accounted for. In one aspect, the non-time averaging technique (e.g., WLAN) transmitter can be limited to an "x" dB backoff level whenever the time averaging technique (e.g., WWAN) transmitter is active (i.e., the maximum RF exposure from the non-time averaging technique (e.g., WLAN) will be "x" dB below level 207). In certain aspects, when normalizing RF exposure levels using the SAR limit (i.e., level 207), the non-time averaging technique normalized RF exposure can be "x" dB below level 207. -x / 10Furthermore, when the time-averaging technique (e.g., WWAN) transmitter is off and the non-time-averaging technique (e.g., WLAN) transmitter is active, the non-time-averaging technique (e.g., WLAN) transmitter is assumed to transmit at full power (i.e., the "x" decibel (dB) back-off level is 0, and therefore, the WLAN normalized RF exposure = 1). The assumption that the transmitter for the non-time-averaging technique transmits at full power (i.e., the WLAN normalized RF exposure in the simultaneous transmission scenario = 1 or = 10 -x / 10 ) represents the worst-case RF exposure and therefore represents a conservative estimate since a transmitter for a non-time-averaging technique could have transmitted at a lower power level than this worst-case assumption during this time period.

[0054] As a visual example, FIG. 6A shows timelines 602, 604, and 606 illustrating different aspects of WLAN (non-time-averaged RF exposure technique in this example) signaling over a time window (e.g., a 100-second window) occurring just prior to the current time. While the example of FIG. 6A is described with reference to WLAN and WWAN, it should be noted that these techniques are merely exemplary, and the illustrated concepts are applicable to non-time-averaged RF exposure techniques and time-averaged RF exposure techniques. More specifically, in the example of FIG. 6A , the discussion regarding WLAN generally applies to other non-time-averaged RF exposure techniques (e.g., Bluetooth technology), and the discussion regarding WWAN generally applies to other time-averaged RF exposure techniques. In yet another example, WWAN operates as a non-time-averaged technique, and WLAN and / or Bluetooth operate as time-averaged techniques. Thus, the concepts illustrated in FIG. 6A are not limited to WLAN and WWAN, but may also be applied to other non-time-averaged RF exposure techniques and time-averaged RF exposure techniques.

[0055] Furthermore, it should be understood that all exposure levels shown in FIGS. 2A, 2B, 2C, 6A, and 6B may correspond to continuous transmission (e.g., a frequency division duplex (FDD) system such as WCDMA) or may correspond to burst transmission (e.g., a time division duplex (TDD) system such as GSM). It should also be understood that a duty cycle for transmission may be implemented. As used herein, a duty cycle of a transmission may refer to a portion (e.g., 5 milliseconds) of a particular period (e.g., 500 milliseconds) during which one or more signals are transmitted. In other words, a duty cycle of a transmission may represent a percentage or fraction of a particular period during which one or more signals are transmitted. In some cases, the duty cycle may be standardized (e.g., predetermined) with a particular radio access technology and / or may vary over time due to, for example, changes in radio conditions, mobility, and / or user behavior. Duty cycles may be applicable to all exposure levels described in this application. For example, if transmissions are occurring at a duty cycle of z%, where z% is less than 100%, then the exposure level in Figures 2A, 2B, 2C, 6A, and 6B will be the exposure level at z% * 100% duty cycle. In other words, that particular radio can transmit at a higher peak Tx power level than corresponds to 1 / z% * continuous Tx power level at a 100% duty cycle.

[0056] In the example of FIG. 6A, timeline 602 illustrates specific examples of on and off periods for a WLAN transmitter that is either on or off (i.e., in the "on" or "off" state as shown on the "y" axis). Timeline 604 illustrates WLAN transmission exposure based on an exemplary series of WWAN transmission states. In particular, the values ​​on the "y" axis are WLAN normalized exposure versus time, which is on the "x" axis. The normalized exposure values ​​are expressed in dB relation 10 -x / 10, depending on the WWAN on or WWAN off state. Thus, as can be seen in timeline 604, when the WWAN is off, the normalized value for WLAN exposure is 1.0 as shown at 608 as an example, and when the WWAN is on, the normalized value for WLAN exposure is 10 for a given x dB backoff or attenuated value as shown at 610. -x / 10 is reduced to a value of

[0057] Timeline 606 is effectively a combination or composite of timelines 602 and 604 to derive a normalized WLAN transmit exposure profile that may be used, as an example, as input for a time averaging method for the WWAN. As shown, when the WWAN is off and the WLAN is on or active, the normalized WLAN transmit exposure profile will have a value of "1," as can be seen at reference numeral 612. Similarly, when the WLAN is off and the WWAN is either on or off, the normalized WLAN transmit exposure profile will have a value of "0," as can be seen at reference numerals 614 and 616, as long as the WLAN is off. During periods when both the WLAN and WWAN are on, the corresponding normalization of the WLAN signal will be 10 dB for a given x dB backoff value, as shown at reference numerals 618 and 620. -x / 10 In one aspect, the exposure profile generated in this manner may be generated by a processor (e.g., processor 110) or logic using knowledge of when the WLAN is on and off and knowledge of the x dB backoff.

[0058] The WLAN transmission exposure profile may be used by a processor (e.g., processor) to determine an amount of RF exposure margin (e.g., 206) used by a WLAN transmission over a time window. This allows the processor to consider RF exposure from the WLAN transmission in calculating transmit power level limits for the WWAN transmission. For example, the processor may combine the RF exposure profile for the WLAN over the time window with the RF exposure profile for the WWAN over the time window to obtain a combined RF exposure profile and use the combined RF exposure profile to determine a total amount of RF exposure margin (e.g., 206) used by both the WLAN and WWAN, and thus, a remaining RF exposure margin for RF exposure compliance. The processor may use the remaining RF exposure margin to determine a transmit power level limit for the WWAN transmission that provides RF exposure compliance. The processor may determine the RF exposure profile for the WWAN by tracking transmit power levels for the WWAN over the time window and using the tracked transmit power levels to determine the RF exposure profile for the WWAN.

[0059] By taking into account the backoff of WLAN transmissions when both WLAN and WWAN are active (i.e., on), the RF exposure profile shown in Figure 6A provides the processor with a more accurate representation of the RF exposure margin used by WLAN compared to blindly assuming that WLAN transmissions are transmitted at 100% (e.g., at a power level corresponding to the SAR limit), which would overestimate the RF exposure margin used for WLAN. This allows the device to utilize more RF exposure margin for active transmissions of time-averaged technologies such as WWAN or 5G NR, by way of example, thereby providing better overall device performance.

[0060] The back-off values ​​described above may be determined based on one or more factors. In one example, the back-off values ​​may be determined based on the spatial overlap between the RF exposure from the WLAN transmission and the RF exposure from the WWAN transmission. In this example, for example, when the WLAN transmitter and the WWAN transmitter transmit in the same general direction, the RF exposure overlap may be greater, and for example, when the WLAN transmitter and the WWAN transmitter transmit in different directions (e.g., the antenna for the WLAN and the antenna for the WWAN are pointed in different directions on the wireless device), the RF exposure overlap may be smaller. In this example, when the spatial overlap is greater, the back-off value may be greater. In another example, the back-off values ​​may be determined based on the priority of the WLAN and WWAN transmissions. For example, the back-off value may be greater when the WWAN transmission has a higher priority than the WLAN transmission, and the back-off value may be smaller when the WLAN transmission has a higher priority than the WWAN transmission. If the WLAN transmission has a higher priority, the peak power level of the WWAN transmission may be limited to ensure RF exposure compliance. In some aspects, simulations and / or testing may be performed to find back-off values ​​that result in RF exposure compliance for simultaneous WLAN and WWAN transmissions under one or more scenarios.

[0061] In a further aspect, it is known that a WLAN transmitter (e.g., non-time averaging technique in this example) may transmit, for example, in both the 2.4 GHz band and the 5 GHz band, and that relevant regulatory bodies (e.g., Federal Communications Commission (FCC), International Commission, etc.) mandate different respective time averaging windows for different frequency bands (i.e., 100 seconds for 2.4 GHz and 60 seconds for 5 GHz). If the time averaging algorithm has knowledge of WLAN transmitter activity, whether in the 2.4 GHz band, the 5 GHz band, or both bands (in which case it assumes a worst-case scenario in a 60-second time window), then each point in time in the determined WLAN exposure profile in timeline 606 may be described in either a 100-second time window (for 2.4 GHz transmissions only) or a 60-second time window (for 5 GHz or 2.4 GHz + 5 GHz transmissions). However, if the time averaging algorithm does not have knowledge of the transmission frequencies of the WLAN transmitters, the WLAN exposure may be divided into 2.4 GHz and 5 GHz time windows in accordance with some aspects. As an example of partitioning WLAN exposure, FIG. 6B shows an exemplary transmission timeline assuming the WLAN exposure profile shown by timeline 606 from FIG. 6A. In the example shown by FIG. 6B, a "worst-case" scenario for transmissions occurring in the past 100 seconds for the 2.4 GHz and 5.0 GHz bands over a time window of the past 100 seconds is assumed, as shown by timeline 640. In this timeline 640, transmissions in the 2.4 GHz WLAN band are assumed for 60 seconds from the past 100 seconds, as shown at 642. Similarly, transmissions in the 5.0 GHz WLAN band, as shown at 644, are assumed for the past 60 seconds prior to the current time. While this example shows transmissions partitioned in time based on FCC-mandated time averaging window times for different frequency bands, it should be noted that the disclosure is not limited to this example and other time partitions may be used.

[0062] Based on an assumed worst-case scenario during band windows 642 and 644, the WLAN exposure shown in timeline 606 is split between the 2.4 GHz band and the 5.0 GHz band, as shown in timelines 646 and 648, respectively. The time portion 650 of the WLAN exposure for time averaging in timeline 606 that coincides with window 642 (i.e., from the past 100 seconds to the past 60 seconds) is allocated as the WLAN 2.4 GHz exposure for that time period and is shown in timeline 646. Similarly, the time portion 652 of the WLAN exposure for time averaging in timeline 606 that coincides with window 644 (i.e., from the past 60 seconds to the current time) is allocated as the WLAN 5.0 GHz exposure for that time period and is shown in timeline 648.

[0063] 7 shows an example block diagram of an apparatus 700 for controlling a transmitter in a wireless device, such as device 100 of FIG. 1. Apparatus 700 includes a time averaging operator 702, a transmitter controller 704, a first transmitter 706, and a second transmitter 708. For example, time averaging operator 702 and transmitter controller 704 may be implemented by processor 110 in separate components and / or by any one or more of transmitters 120-1 through 120-N. First transmitter 706 and second transmitter 708 may be implemented in any one or more of transmitters 120-1 through 120-N.

[0064] The time averaging operator 702 may comprise hardware or other logic, or software running on a dedicated processor (not shown), and the time averaging operator 702 is configured to implement time averaging operations to provide RF exposure and / or SAR compliance for a transmitter operable in accordance with RF exposure time averaging techniques, such as, in one example, the second transmitter 708.

[0065] Transmitter controller 704 may further be implemented as hardware or logic, or software, configured to control transmitters in a wireless device, such as transmitters 706 and 708. Transmitter controller 704 may be implemented within processing circuitry of the wireless device or within RF front-end components of the wireless device. Transmitter controller 704 is communicatively coupled to transmitters 706 and 708, as represented by couplings 710 and 712, respectively. In some aspects, transmitter controller 704 may impose transmit power or signal timing restrictions, among other things, on either of transmitters 706 and 708, which may further be based on input from time averaging operator 702, as described in further detail below.

[0066] According to one aspect, assuming the first transmitter 706 is capable of operating with a non-time-averaged RF exposure technology (e.g., WLAN), information regarding whether the first transmitter 706 is on or off (and may include transmit frequency information such as 2.4 GHz and 5 GHz band activity) may be provided from the transmitter 706 to the time-averaging operator 702 via communication coupling 714. It should be noted that information regarding the on / off state of the first transmitter 706 may alternatively be provided from the transmitter controller 704 via communication coupling 716, for example, or from some other component within the wireless device, such as a main processor or digital signal processor (DSP) (not shown).

[0067] 6A and 6B, the time averaging operator 702 may be configured to send a back-off power limit to the first transmitter 706, such as via the transmitter controller 704. According to some aspects, the time averaging operator 702 may send a back-off power limit to the first transmitter 706, such as via the transmitter controller 704, as previously described. -x / 10In addition, assuming the second transmitter 708 is a time-averaged RF exposure technology such as WWAN or 5G NR, the time averaging operator 702 may impose this back-off level when the second transmitter 708 is active and transmitting.

[0068] In a further aspect, when the second transmitter 708 in this example is in an “off” state but the first transmitter 706 is active, the time averaging operator 702 may be configured to assume that the transmit level of the first transmitter 706 is at maximum power in order to anticipate a worst-case scenario to best ensure compliance with RF exposure limits when ultimately calculating the transmit power limit for the second transmitter 708 (e.g., a WWAN transmitter) based on or taking into account the transmissions by the first transmitter 706 (e.g., a WLAN transmitter). Additionally, the time averaging operator 702 may be configured to split between transmissions in the 2.4 GHz band or the 5 GHz band, as previously described with respect to FIG.

[0069] Based on worst-case RF exposure assumptions, including the on / off states of the first and second transmitters, a predetermined backoff level of the first transmitter when the second transmitter is active, and the division between different frequency bands, the time averaging operator 702 and / or the transmitter controller 704 may then dynamically control transmissions by the first transmitter 706 in the example of FIG. 7 . Specifically, the transmit power of the first transmitter 706, which is operable according to a non-time averaging technique, such as WLAN, is controlled. This allows for an RF exposure margin to be obtained, and this increased RF exposure margin may then be used for transmissions for the second transmitter 708, which is operable according to a time averaging technique (e.g., WWAN, 5G NR, etc.). As an example of this benefit, as previously described herein, a conventional approach to dividing the margin between the time-averaged RF exposure of a time-averaged technique, such as WWAN and / or 5G NR, being less than or equal to “A,” and the RF exposure of a non-time-averaged technique, such as WLAN, being less than or equal to “B,” involves ensuring that the sum A+B is less than or equal to 100%. The presently disclosed method and apparatus, for example, allows value B to be minimized and time-averaged technique value "A" to be increased or maximized when active.

[0070] It is further noted that the apparatus of Figure 7 can also implement any of the methods and accompanying processes of Figures 3-5. For example, the time averaging operator 702 and transmitter controller 704 can be used to implement the determination and application of a predetermined wait time period or delay, as shown in blocks 306, 308, or 516. Furthermore, the time averaging operator 702 and transmitter controller 704 can be used to calculate a predetermined time period and implement transmission using a time-averaged RF exposure technique with a limited Tx peak power over the predetermined time period, as shown in blocks 406 or 508. In yet another example, the time averaging operator 702 and transmitter controller 704 can be used to implement conventional time averaging algorithms and methods for time-averaged RF exposure techniques, as well as a process for returning a transmitter using time-averaged RF exposure techniques to a power level determined by the time averaging algorithm after the expiration of the predetermined time period, as shown in blocks 410 or 510.

[0071] 8 shows an example method 800 of wireless communication. Method 800 includes transmitting a first transmission with a first transmitter operable according to a first radio technology, as shown in block 802. The first transmitter may correspond to any one or more of transmitters 120-1 through 120-N, 706, and 708.

[0072] The method 800 also includes transmitting a second transmission using a second transmitter after completion of the first transmission, the second transmitter being operable according to a second wireless technology, as shown in block 804. The second transmitter may correspond to any one or more of transmitters 120-1 through 120-N, 706, and 708.

[0073] Method 800 may also include delaying transmission of the second transmission by a predetermined waiting time after completion of the first transmission if the first wireless technology is a radio frequency (RF) exposure time-averaging technology and the second wireless technology is a non-time-averaging RF exposure technology, as shown in block 806. For example, the second transmission may be delayed by processor 110, transmitter controller 704, and / or any one or more of transmitters 120-1 through 120-N, 706, and 708. The RF exposure time-averaging technology may include one or more of WWAN technology and 5G New Radio (NR) technology, and the RF exposure non-time-averaging technology may include one or more of WLAN technology and Bluetooth technology.

[0074] Method 800 may also include, if the first wireless technology is a non-time-averaged RF exposure technology and the second wireless technology is a time-averaged RF exposure technology, transmitting the second transmission at a limited peak power for a predetermined time period of at least a portion of the second transmission, as shown in block 808. For example, the second transmission may be transmitted at the limited peak power by processor 110, transmitter controller 704, and / or any one or more of transmitters 120-1 through 120-N, 706, and 708. The RF exposure time-averaged technology may include one or more of WWAN technology and 5G New Radio (NR) technology, and the RF exposure non-time-averaged technology may include one or more of WLAN technology and Bluetooth technology.

[0075] 9 illustrates an example method 900 for controlling transmissions in a wireless device to ensure compliance with RF exposure limits. Note that method 900 provides control of RF transmissions by specifically considering RF exposure from transmissions from technologies that are not part of time-averaging techniques (i.e., non-time-averaging RF exposure technologies such as WLAN) to obtain more RF exposure margin while obtaining better overall RF exposure compliance.

[0076] As shown in block 902, the method 900 for controlling transmission includes setting a transmission level limit for a non-time-averaged technique (i.e., the "first radio access technology") equal to a predetermined backoff level when a time-averaged RF exposure technique is active over a transmission time window, as described above in connection with timeline 604 of FIG. 6A. In a further aspect, the transmission level limit in the process of block 902 is set equal to a predetermined backoff level, as described above in connection with timeline 604 of FIG. -x / 10 where "x" is a predetermined back-off level in decibels. The transmit level limit may be set by, for example, the processor 110 and / or the transmitter controller 704.

[0077] Method 900 further includes determining an RF exposure profile for the non-time-averaged RF exposure technique over a transmit time window, as shown in block 904. The determination of the RF exposure profile is based on an active transmission period for the non-time-averaged RF exposure technique over the transmit time window and a determined transmission limit level during the active time of the time-averaged RF exposure technique over the transmit time window. As an example of this determination, the RF exposure profile shown in timeline 606 of FIG. 6A shows that the profile is based on a combination of the active transmission period for the non-time-averaged technique shown in timeline 602 and the determined level limit for the non-time-averaged RF exposure technique shown in timeline 604 over the transmit time window, which in the example given above is a time window of the past 100 seconds, but is not necessarily limited to such. In some aspects, the RF exposure profile may be determined based on the assumption that when the time-averaged RF exposure technology (e.g., WWAN) is inactive (i.e., off), the non-time-averaged RF exposure technology (e.g., WLAN) transmits at 100% (e.g., a power level corresponding to the SAR limit), and when the time-averaged RF exposure technology (e.g., WWAN) is active (i.e., on), the non-time-averaged RF exposure technology (e.g., WLAN) transmits at a predetermined back-off level from 100%. The RF exposure profile may be determined by the processor 110. The RF exposure profile may be determined by, for example, the processor 110, the time averaging operator 702, and / or the transmitter controller 704.

[0078] In an alternative, method 900 may further include dividing the RF exposure profile over the transmission time window according to frequency bands, as shown in block 906. In particular, the RF exposure profile may be divided based on frequency bands, such as 2.4 GHz and 5.0 GHz (or based on actual knowledge of the WLAN transmission frequencies, if the time averaging operator receives this information from the WLAN transmitter), as described above with respect to FIG. 6B , and illustrated by timelines 646 and 648. The RF exposure profile may be divided by, for example, processor 110, time averaging operator 702, and / or transmitter controller 704.

[0079] Finally, method 900 includes, at block 908, controlling transmission of a transmitter based on the RF exposure profile determined at blocks 904 and / or 906. In some aspects, controlling transmission of a transmitter (e.g., a transmitter for a time-averaged RF exposure technique) may include setting a transmit power level limit for the transmitter taking into account the RF exposure profile determined at blocks 904 and / or 906. For example, processor 110 may combine the RF exposure profile determined at blocks 904 and / or 906 with an RF exposure profile for a time-averaged RF exposure technique (e.g., WWAN) over a transmission time window to obtain a combined RF exposure profile, use the combined RF exposure profile to determine a total amount of RF exposure margin (e.g., 206) used by the non-time-averaged RF exposure technique and the time-averaged RF exposure technique, and determine a remaining RF exposure margin for RF exposure compliance. Processor 110 may use the remaining RF exposure margin to determine a transmit power level limit for WWAN transmissions that provides RF exposure compliance. The transmitter transmissions may be controlled by, for example, the processor 110 and / or the transmitter controller 704 .

[0080] In some aspects disclosed herein, processor 110 may assess time-averaged RF exposure compliance by calculating a time-averaged SAR distribution over an average time window (e.g., 60 seconds, 100 seconds, 6 minutes, 30 minutes, etc.) and then compare the peak values ​​in the time-averaged SAR distribution with the RF exposure limit to assess time-averaged RF exposure compliance. If the peak values ​​are less than or equal to the RF exposure limit, processor 110 may determine time-averaged RF exposure compliance. If the time-averaged SAR distribution is normalized, the RF exposure limit may be 1.

[0081] It should be understood that processor 110 is not limited to the above examples for assessing time-averaged RF exposure compliance. For example, processor 110 may assess time-averaged RF exposure compliance (e.g., at a single location) by calculating a time-averaged SAR value (e.g., at that location) over an average time window and then comparing the time-averaged SAR value to the RF exposure limit to assess time-averaged RF exposure compliance. If the time-averaged SAR value is less than or equal to the RF exposure limit, processor 110 may determine time-averaged RF exposure compliance. It should also be understood that processor 110 can assess RF exposure based on power density (PD) and / or a combination of SAR and PD. Thus, it should be understood that processor 110 is not limited to a particular type of RF exposure measurement for assessing time-averaged RF exposure and may use other types of RF exposure measurements.

[0082] Although aspects of the present disclosure have been described above using the example of WLAN as a non-time-averaged RF exposure technology and the example of WWAN as a time-averaged RF exposure technology, it should be understood that aspects of the present disclosure are more generally applicable to non-time-averaged RF exposure technologies and time-averaged RF exposure technologies. More specifically, aspects described above using the example of WLAN as a non-time-averaged RF exposure technology generally apply to other non-time-averaged RF exposure technologies (e.g., Bluetooth technology), and aspects described above using the example of WWAN as a time-averaged RF exposure technology generally apply to other time-averaged RF exposure technologies. In yet another example, WWAN may be operated as a non-time-averaged technology, and WLAN and / or Bluetooth may be operated as time-averaged technologies.

[0083] In some other aspects, memory 115 may include a computer-readable medium storing instructions that, when executed by processor 110, cause processor 110 to perform the methods and operations described herein. The computer-readable medium may include, by way of example, a RAM (random access memory), flash memory, a ROM (read-only memory), a PROM (programmable read-only memory), an EPROM (erasable programmable read-only memory), an EEPROM (electrically erasable programmable read-only memory), registers, a magnetic disk, an optical disk, a hard drive, or any other tangible non-transitory storage medium, or any combination thereof.

[0084] Example implementations are described in the following numbered clauses.

[0085] Clause 1. A wireless device comprising: a plurality of transmitters including a first transmitter and a second transmitter, each of the plurality of transmitters configured to transmit signals according to a respective wireless technology of a plurality of wireless technologies, the plurality of wireless technologies including a first wireless technology comprising a time-averaged radio frequency (RF) exposure technique and a second wireless technology comprising a non-time-averaged RF exposure technique; a processor coupled to the plurality of transmitters, the processor comprising: causing a first transmitter to transmit a first transmission; causing the second transmitter to transmit a second transmission after completion of the first transmission; if the first transmitter is operable according to a first wireless technology and the second transmitter is operable according to a second wireless technology, causing the second transmitter to transmit a second transmission following completion of a predetermined waiting time after completion of the first transmission; 1. A wireless device configured to: when a first transmitter is operable according to a second radio technology and a second transmitter is operable according to the first radio technology, cause the second transmitter to transmit at least a portion of the second transmission using limited peak power for a predetermined period of time after completion of a first transmission.

[0086] Clause 2. The wireless device of clause 1, wherein the processor is further configured to determine the predetermined wait time based on an amount of RF exposure resulting from the first transmission by the first transmitter.

[0087] Clause 3. The wireless device of clause 1 or 2, wherein the processor is further configured to determine the predetermined time period based on an amount of RF exposure resulting from the first transmission by the first transmitter.

[0088] Clause 4. A wireless device as described in any one of clauses 1 to 3, wherein the processor is configured to cause the second transmitter to transmit according to the first radio technology at a normal power level determined by time averaging after expiration of a predetermined time period.

[0089] Clause 5: A wireless device as described in any one of clauses 1 to 4, wherein the first wireless technology includes one or more of a wide area network (WWAN) technology and a 5G new radio (NR) technology, and the second wireless technology includes one or more of a wireless local area network (WLAN) technology and a Bluetooth technology.

[0090] Clause 6 If the Processor: receiving information regarding the on and off states of a transmitter operable according to a second wireless technology; A wireless device as described in any one of clauses 1 to 5, further configured to set a transmit power limit for one or more transmitters operable according to the first radio technology based on information regarding the on and off states of transmitters operable according to the second radio technology.

[0091] Clause 7 If the Processor: determining a history of the transmitter operable according to the second wireless technology based on the received information regarding the on-state and off-state of the transmitter operable according to the second wireless technology; The wireless device of clause 6, further configured to adjust at least one of a transmit power level and a predetermined time period for one or more transmitters operable according to the first radio technology based on the determined history.

[0092] Clause 8 A method for wireless communication comprising: Transmitting a first transmission using a first transmitter operable according to a first wireless technology; transmitting a second transmission using a second transmitter after completion of the first transmission, the second transmitter operable according to a second wireless technology; delaying transmission of the second transmission by a predetermined waiting time after completion of the first transmission, if the first wireless technology is a radio frequency (RF) exposure time-averaged technology and the second wireless technology is a non-time-averaged RF exposure technology; and if the first wireless technology is a non-time-averaged RF exposure technology and the second wireless technology is a time-averaged RF exposure technology, transmitting a second transmission at a limited peak power for a predetermined time period for at least a portion of the second transmission.

[0093] Clause 9. The method of clause 8, further comprising, when the first wireless technology includes a time-averaged RF exposure technique, determining the predetermined waiting time based on an amount of RF exposure resulting from the first transmission by the first transmitter.

[0094] Clause 10. The method of clause 8 or 9, further comprising determining the predetermined time period based on an amount of RF exposure resulting from the first transmission by the first transmitter when the first wireless technology includes a non-time-averaged RF exposure technology.

[0095] Clause 11. The method of any one of clauses 8 to 10, further comprising transmitting at least a portion of the second transmission using the second transmitter when the second wireless technology is a time-averaged RF exposure technology at a normal power level determined by time averaging after expiration of a predetermined time period.

[0096] Clause 12: The method of any one of clauses 8 to 11, wherein the time-averaged RF exposure technology includes one or more of a wireless wide area network (WWAN) technology and a 5G new radio (NR) technology, and the radio frequency (RF) exposure non-time-averaged technology includes one or more of a wireless local area network (WLAN) technology and a Bluetooth technology.

[0097] Article 13 receiving information regarding on-state and off-state of a transmitter operable according to a non-time-averaged RF exposure technique; 13. The method of any one of clauses 8 to 12, further comprising: setting a transmit power limit for one or more transmitters operable according to a time-averaged RF exposure technique based on information about the on and off states of the transmitters operable according to a non-time-averaged RF exposure technique.

[0098] Article 14 determining a history of transmitters operable according to the non-time-averaged RF exposure technique based on the received information regarding on and off states of transmitters operable according to the second wireless technology; 14. The method of claim 13, further comprising: adjusting at least one of a transmit power level and a predetermined time period for an operable transmitter according to a time-averaged RF exposure technique based on the determined history.

[0099] Clause 15. A wireless device comprising: a plurality of transmitters, each of the plurality of transmitters configured to transmit signals according to a respective one of a plurality of wireless technologies, the plurality of wireless technologies including a time-averaged radio frequency (RF) exposure technique and a non-time-averaged RF exposure technique; a processor coupled to the plurality of transmitters, the processor comprising: setting a transmit level limit of a non-time-averaged RF exposure technique to a predetermined back-off level during a period when the time-averaged RF exposure technique is active over a transmit time window; determining an RF exposure profile for a non-time-averaged RF exposure technique over a transmit time window; The wireless device is configured to control transmission of one of the operable transmitters according to a time-averaged RF exposure technique based on the RF exposure profile.

[0100] Clause 16. The wireless device of clause 15, wherein the non-time-averaged RF exposure technique transmits using multiple frequency bands, and the processor is further configured to divide the RF exposure profile over the transmit time window based on the multiple frequency bands.

[0101] Clause 17. The wireless device of clause 16, wherein the plurality of frequency bands includes a 2.4 GHz band and a 5.0 GHz band.

[0102] Clause 18. The wireless device of clause 16 or 17, wherein the RF exposure profile is divided into a first portion and a second portion corresponding to a first time portion and a second time portion, respectively, of the transmission time window.

[0103] Clause 19. The wireless device of clause 18, wherein the RF exposure profile is divided into a first portion and a second portion based on received information of active frequency bands of a non-time-averaged RF exposure technique.

[0104] Article 20 The Processor shall -x / 10 20. The wireless device of any one of clauses 15 to 19, further configured to determine the predetermined back-off level based on x, where x is a back-off value in decibels.

[0105] Clause 21. The wireless device of any one of clauses 15 to 20, wherein the processor is further configured to determine the RF exposure profile by assuming a set transmit level limit during an inactive period of the time-averaged RF exposure technique is a maximum transmit power.

[0106] Clause 22: A wireless device as described in any one of clauses 15 to 21, wherein the time-averaged RF exposure technologies include one or more of Wireless Wide Area Network (WWAN) technology and 5G New Radio (NR) technology, and the non-time-averaged RF exposure technologies include one or more of Wireless Local Area Network (WLAN) technology and Bluetooth technology.

[0107] Article 23 If the processor: receiving information regarding the on and off states of a transmitter operable according to a non-time-averaged RF exposure technique; 23. The wireless device of any one of clauses 15 to 22, further configured to determine an RF exposure profile for a non-time-averaged RF exposure technique based further on the received information regarding the on state and the off state.

[0108] Clause 24. The wireless device of clause 23, wherein the RF exposure profile is divided into a first portion and a second portion based on received information of active frequency bands of a non-time-averaged RF exposure technique.

[0109] Clause 25. The wireless device of any one of clauses 15 to 24, wherein the processor is configured to set a transmission level limit for the non-time-averaged RF exposure technique RF exposure technique to a power level during a period when the time-averaged RF exposure technique is inactive over a transmission time window, the backoff level being equal to the power level reduced by a backoff value.

[0110] Article 26 A method for wireless communication comprising: setting a transmit level limit of a non-time-averaged RF exposure technique to a predetermined back-off level during a period when the time-averaged RF exposure technique is active over a transmit time window; determining an RF exposure profile for a non-time-averaged RF exposure technique over a transmit time window; and controlling transmission of an operable transmitter according to a time-averaged RF exposure technique based on the derived RF exposure profile.

[0111] Clause 27. The method of clause 26, further comprising dividing the RF exposure profile over the transmit time window based on multiple frequency bands that the non-time-averaged RF exposure technique may transmit.

[0112] Clause 28. The method of clause 27, wherein the plurality of frequency bands includes a 2.4 GHz band and a 5.0 GHz band.

[0113] Clause 29. The method of clause 27 or 28, wherein the RF exposure profile is divided into a first portion and a second portion corresponding to a first time portion and a second time portion, respectively, of the transmit time window.

[0114] Article 30 Relation 10 -x / 10 30. The method of any one of clauses 26 to 29, further comprising determining the predetermined back-off level based on x, where x is a back-off value in decibels.

[0115] Clause 31. The method of any one of clauses 26 to 30, wherein determining the RF exposure profile includes assuming a set transmit level limit during an active period of the time-averaged RF exposure technique is a maximum transmit power.

[0116] Clause 32 The method of any one of clauses 26 to 31, wherein the time-averaged RF exposure technology includes one or more of a wireless wide area network (WWAN) technology and a 5G new radio (NR) technology, and the non-time-averaged RF exposure technology includes one or more of a wireless local area network (WLAN) technology and a Bluetooth technology.

[0117] Article 33 receiving information regarding the on and off states of a transmitter operable according to a non-time-averaged RF exposure technique; 33. The method of any one of clauses 26 to 32, further comprising: determining an RF exposure profile for a non-time-averaged RF exposure technique further based on the received information regarding the on state and the off state.

[0118] Clause 34. The method of clause 33, wherein the RF exposure profile is divided into a first portion and a second portion based on received information of an active frequency band of a non-time-averaged RF exposure technique.

[0119] Clause 35. The method of any one of clauses 26 to 34, further comprising setting a transmission level limit for the non-time-averaged RF exposure technique RF exposure technique to a power level during a period when the time-averaged RF exposure technique is inactive over a transmission time window, the back-off level being equal to the power level reduced by a back-off value.

[0120] It should be understood that the present disclosure is not limited to the exemplary terminology used above to describe aspects of the present disclosure. For example, it should be understood that a distribution may be referred to as a map, a scan, or other term. For another example, it should be understood that an antenna may be referred to as an antenna element or other term. For yet another example, it should be understood that a maximum allowed power level may be referred to as a power level limit or other term.

[0121] The term "about" as used herein in connection with a stated value or property is intended to indicate within 10% of the stated value or property.

[0122] Any reference herein to an element using a designation such as "first," "second," etc. generally does not limit the quantity or order of those elements. Rather, these designations are used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must precede the second element.

[0123] Within the scope of this disclosure, the word "exemplary" is used to mean "serving as an example, instance, or illustration." Any implementation or aspect described herein as "exemplary" should not necessarily be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term "aspect" does not require that all aspects of the disclosure include the described feature, advantage, or mode of operation.

[0124] The above description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the embodiments described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. A wireless device, comprising: a plurality of transmitters including a first transmitter and a second transmitter, each of the plurality of transmitters configured to transmit signals according to a respective wireless technology of a plurality of wireless technologies, the plurality of wireless technologies including a first wireless technology comprising a time-averaged radio frequency (RF) exposure technique and a second wireless technology comprising a non-time-averaged RF exposure technique; a processor coupled to the plurality of transmitters, the processor comprising: causing the first transmitter to transmit a first transmission; causing the second transmitter to transmit a second transmission after completion of the first transmission; if the first transmitter is operable according to the first wireless technology and the second transmitter is operable according to the second wireless technology, causing the second transmitter to transmit the second transmission following completion of a predetermined waiting time after completion of the first transmission; 1. A wireless device configured to, when the first transmitter is capable of operating according to the second radio technology and the second transmitter is capable of operating according to the first radio technology, cause the second transmitter to transmit at least a portion of the second transmission using limited peak power for a predetermined period of time after completion of the first transmission.

2. 10. The wireless device of claim 1, wherein the processor is further configured to determine the predetermined wait time based on an amount of RF exposure resulting from the first transmission by the first transmitter.

3. 10. The wireless device of claim 1, wherein the processor is further configured to determine the predetermined time period based on an amount of RF exposure resulting from the first transmission by the first transmitter.

4. 2. The wireless device of claim 1, wherein the processor is configured to cause the second transmitter to transmit according to the first radio technology at a normal power level determined by time averaging after expiration of the predetermined time period.

5. 10. The wireless device of claim 1, wherein the first wireless technology comprises one or more of a wireless wide area network (WWAN) technology and a 5G new radio (NR) technology, and the second wireless technology includes one or more of a wireless local area network (WLAN) technology and a Bluetooth technology.

6. the processor: receiving information regarding the on and off states of a transmitter operable according to the second wireless technology; 10. The wireless device of claim 1, further configured to: set transmit power limits for one or more transmitters operable according to the first radio technology based on the information regarding the on and off states of the transmitters operable according to the second radio technology.

7. the processor: determining a history of the transmitter operable according to the second wireless technology based on the received information regarding the on-state and the off-state of the transmitter operable according to the second wireless technology; 7. The wireless device of claim 6, further configured to adjust at least one of the transmit power level and the predetermined time period for the one or more transmitters operable according to the first radio technology based on the determined history.

8. 1. A method for wireless communication, comprising: Transmitting a first transmission using a first transmitter operable according to a first wireless technology; transmitting a second transmission using a second transmitter after completing the first transmission, the second transmitter operable according to a second wireless technology; if the first wireless technology is a radio frequency (RF) exposure time-averaged technology and the second wireless technology is a non-time-averaged RF exposure technology, delaying transmission of the second transmission by a predetermined waiting time after completion of the first transmission; and if the first wireless technology is a non-time-averaged RF exposure technology and the second wireless technology is a time-averaged RF exposure technology, transmitting the second transmission at a limited peak power for a predetermined time period for at least a portion of the second transmission.

9. 10. The method of claim 8, further comprising, when the first wireless technology comprises the time-averaged RF exposure technique, determining the predetermined wait time based on an amount of RF exposure resulting from the first transmission by the first transmitter.

10. 10. The method of claim 8, further comprising, when the first wireless technology includes the non-time-averaged RF exposure technology, determining the predetermined time period based on an amount of RF exposure resulting from the first transmission by the first transmitter.

11. 10. The method of claim 8, further comprising transmitting at least a portion of the second transmission using the second transmitter when the second wireless technology is the time-averaged RF exposure technology at a normal power level determined by time averaging after expiration of the predetermined time period.

12. 10. The method of claim 8, wherein the time-averaged RF exposure technology comprises one or more of a wireless wide area network (WWAN) technology and a 5G new radio (NR) technology, and the non-time-averaged RF exposure technology includes one or more of a wireless local area network (WLAN) technology and a Bluetooth technology.

13. 1. A method comprising: receiving information regarding on-state and off-state of a transmitter operable according to the non-time-averaged RF exposure technique; 9. The method of claim 8, further comprising: setting transmit power limits for one or more transmitters operable according to the time-averaged RF exposure technique based on the information regarding the on and off states of the transmitters operable according to the non-time-averaged RF exposure technique.

14. 1. A method comprising: determining a history of the transmitters operable according to the non-time-averaged RF exposure technique based on the received information regarding the on and off states of the transmitters operable according to the second wireless technology; 14. The method of claim 13, further comprising: adjusting at least one of the transmit power level and the predetermined time period for transmitters operable according to the time-averaged RF exposure technique based on the determined history.

15. 1. A wireless device, comprising: a plurality of transmitters, each of the plurality of transmitters configured to transmit signals according to a respective one of a plurality of wireless technologies, the plurality of wireless technologies including a time-averaged radio frequency (RF) exposure technique and a non-time-averaged RF exposure technique; a processor coupled to the plurality of transmitters, the processor comprising: setting a transmit level limit of the non-time-averaged RF exposure technique to a predetermined back-off level during a period when the time-averaged RF exposure technique is active over a transmit time window; determining an RF exposure profile for the non-time-averaged RF exposure technique over the transmit time window; a wireless device configured to control transmission of one of the transmitters operable according to the time-averaged RF exposure technique based on the RF exposure profile.

16. 16. The wireless device of claim 15, wherein the non-time-averaged RF exposure technique transmits using multiple frequency bands, and the processor is further configured to divide the RF exposure profile over the transmission time window based on the multiple frequency bands.

17. 17. The wireless device of claim 16, wherein the multiple frequency bands include a 2.4 GHz band and a 5.0 GHz band.

18. 17. The wireless device of claim 16, wherein the RF exposure profile is divided into first and second portions corresponding to first and second time portions, respectively, of the transmit time window.

19. 20. The wireless device of claim 18, wherein the RF exposure profile is divided into the first and second portions based on received information of active frequency bands of the non-time-averaged RF exposure technique.

20. The processor －ｘ／１０ 16. The wireless device of claim 15, further configured to determine the predetermined back-off level based on x, where x is a back-off value in decibels.

21. 16. The wireless device of claim 15, wherein the processor is further configured to determine the RF exposure profile by assuming the set transmit level limit during inactive periods of the time-averaged RF exposure technique is a maximum transmit power.

22. 16. The wireless device of claim 15, wherein the time-averaged RF exposure technology comprises one or more of a wireless wide area network (WWAN) technology and a 5G new radio (NR) technology, and the non-time-averaged RF exposure technology includes one or more of a wireless local area network (WLAN) technology and a Bluetooth technology.

23. the processor: receiving information regarding on-state and off-state of a transmitter operable according to the non-time-averaged RF exposure technique; 16. The wireless device of claim 15, further configured to determine the RF exposure profile for the non-time-averaged RF exposure technique further based on the received information regarding the on state and the off state.

24. 24. The wireless device of claim 23, wherein the RF exposure profile is divided into a first portion and a second portion based on received information of active frequency bands of the non-time-averaged RF exposure technique.

25. 16. The wireless device of claim 15, wherein the processor is configured to set the transmission level limit of the non-time-averaged RF exposure technique to a power level during periods when the time-averaged RF exposure technique is inactive over the transmission time window, the back-off level being equal to the power level reduced by a back-off value.

26. 1. A method for wireless communication, comprising: setting a transmission level limit for a non-time-averaged RF exposure technique to a predetermined back-off level during a period when the time-averaged RF exposure technique is active over a transmission time window; determining an RF exposure profile for the non-time-averaged RF exposure technique over the transmit time window; and and controlling transmission of a transmitter operable according to the time-averaged RF exposure technique based on the RF exposure profile.

27. 27. The method of claim 26, further comprising dividing the RF exposure profile over the transmit time window based on a plurality of frequency bands over which the non-time-averaged RF exposure technique may transmit.

28. Relationship 10 －ｘ／１０ 27. The method of claim 26, further comprising determining the predetermined back-off level based on x, where x is a back-off value in decibels.

29. 27. The method of claim 26, wherein determining the RF exposure profile includes assuming the set transmit level limit is a maximum transmit power during an active period of the time-averaged RF exposure technique.

30. 27. The method of claim 26, further comprising setting the transmit level limit of the non-time-averaged RF exposure technique to a power level during periods when the time-averaged RF exposure technique is inactive over the transmit time window, wherein the back-off level is equal to the power level reduced by a back-off value.

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