Anomaly-robust time-averaged radio frequency exposure compliance continuity

Abstract

Some aspects of the present disclosure provide techniques for time-averaged radio frequency (RF) exposure compliance continuity that is robust to exceptions. A method that may be performed by a user equipment (UE) generally includes transmitting a first signal at a first transmit power based on RF exposure measurements time-averaged over a time window and storing RF exposure information associated with the time window. The method may also include detecting that an exception event associated with the UE has occurred and, in response to detecting the event, transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Provisional Patent Application No. 63 / 077,377, filed September 11, 2020, which claims priority to U.S. Application No. 17 / 392,442, filed August 3, 2021, both of which are expressly incorporated herein by reference in their entireties.

[0002] Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for providing radio frequency (RF) exposure compliance continuity. [Background technology]

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephone, video, data, messaging, and broadcast. Modern wireless communication devices (e.g., cellular telephones) are generally required to meet radio frequency (RF) exposure limits set by national and international standards and regulations. To ensure compliance with these standards, such devices must currently undergo an extensive certification process prior to being released to the market. To ensure that wireless communication devices comply with RF exposure limits, techniques have been developed to enable wireless communication devices to assess RF exposure from the wireless communication device in real time and adjust the transmit power of the wireless communication device accordingly to comply with the RF exposure limits. Summary of the Invention [Means for solving the problem]

[0004] The systems, methods, and devices of the present disclosure each have several aspects, no single aspect of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the following claims, some features will now be briefly described. After considering this discussion, and particularly after reading the section entitled "Detailed Description of the Invention," one will understand how the features of the present disclosure provide advantages, including ensuring compliance with radio frequency exposure limits after various exception events.

[0005] Some aspects of the subject matter described in this disclosure may be implemented in a method for wireless communication by a user equipment (UE). The method generally includes transmitting a first signal at a first transmit power based on radio frequency (RF) exposure measurements time-averaged over a time window and storing RF exposure information associated with the time window. The method may also include detecting that an exception event associated with the UE has occurred and, in response to detecting the event, transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information.

[0006] Some aspects of the subject matter described in this disclosure may be implemented in an apparatus for wireless communication. The apparatus generally includes a transmitter, a memory, and a processor. The transmitter is configured to transmit a first signal at a first transmit power based on RF exposure measurements time-averaged over a time window. The processor is coupled to the memory such that the processor and the memory store RF exposure information associated with the time window and are configured to detect that an exception event associated with the device has occurred. The transmitter is further configured to transmit a second signal at a second transmit power in response to detecting the event based at least in part on the stored RF exposure information.

[0007] Some aspects of the subject matter described in this disclosure may be implemented in an apparatus for wireless communication. The apparatus generally includes means for transmitting a first signal at a first transmit power based on RF exposure measurements time-averaged over a time window, means for storing RF exposure information associated with the time window, means for detecting that an exception event associated with the apparatus has occurred, and means for transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information in response to detecting the event.

[0008] Certain aspects of the present subject matter described in this disclosure may be implemented in a computer-readable medium storing instructions for transmitting a first signal at a first transmit power based on RF exposure measurements time-averaged over a time window, storing RF exposure information associated with the time window, detecting that an exception event associated with the UE has occurred, and, in response to detecting the event, transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information.

[0009] Some aspects of the subject matter described in this disclosure may be implemented in a method for wireless communication by a UE. The method generally includes transmitting a first signal at a first transmit power based on RF exposure measurements time-averaged over a time window, storing RF exposure information associated with the time window, detecting that an exception event associated with the UE has occurred, determining that a timestamp corresponding to a most recent time-averaged RF exposure measurement is not within the current time window or determining that a check value does not pass a cyclic redundancy check (CRC) of the RF exposure information, and transmitting a second signal at a second transmit power in a fail-safe mode based on the determination.

[0010] To the accomplishment of the foregoing and related ends, the one or more aspects 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 features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of the various aspects may be employed.

[0011] So that the above-mentioned features of the present disclosure may be understood in detail, a more particular description may be had by reference to embodiments, some of which are illustrated in the drawings. However, since the present description may lead to other equally effective embodiments, it should be noted that the accompanying drawings illustrate only some typical embodiments of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram conceptually illustrating an example wireless communication network, in accordance with certain aspects of the present disclosure. [Figure 2] FIG. 1 is a block diagram conceptually illustrating an example base station (BS) and user equipment (UE) design in accordance with certain aspects of the present disclosure. [Figure 3] 1 is a block diagram of an example radio frequency (RF) transceiver in accordance with certain aspects of the present disclosure. [Figure 4] FIG. 10 is a flow diagram illustrating example operations for wireless communication by a UE, in accordance with certain aspects of the present disclosure. [Figure 5] FIG. 10 illustrates time-averaged RF exposure over a time window, in accordance with some aspects of the present disclosure. [Figure 6] FIG. 1 is a block diagram illustrating a design of an example wireless communication device implementing RF exposure continuity in accordance with certain aspects of the present disclosure. [Figure 7] FIG. 10 is a signaling flow diagram illustrating example signaling for RF exposure continuity, according to an aspect of the disclosure. [Figure 8]FIG. 1 illustrates a communications device (e.g., a UE) that may include various components configured to perform operations for the techniques disclosed herein, in accordance with aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] For ease of understanding, where possible, like reference numerals have been used to designate like elements common to the figures. It is contemplated that elements disclosed in one embodiment may be advantageously utilized in other embodiments without specific recitation.

[0014] Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable media for controlling radio frequency (RF) exposure after an exception event (such as an error, reset, crash, or reboot affecting the operation of a user equipment (UE) or the UE's modem, or an event resulting in the detection or detection of a portion of time during which exposure is unknown or indeterminate). In some aspects, the UE may periodically store RF exposure information (such as time-averaged RF exposure measurements of transmit power history) in a memory that is preferably not susceptible to corruption from the exception event. When an exception event occurs (such as a UE reboot or a UE modem reset, or the UE determining that a portion of time during which exposure is unknown or indeterminate has passed), the UE may use the stored RF exposure information to determine a transmit power that complies with RF exposure limits. Techniques for providing RF exposure continuity described herein may enable the UE to remain compliant with RF exposure limits after the UE encounters an exception event, potentially without exposing the user to excessive RF fields. In other words, the techniques for providing RF exposure continuity described herein may provide a user with a safe operating state in terms of RF exposure after an exception event. The techniques for providing RF exposure continuity described herein may provide a low-power solution that consumes an allowable amount of power for storing RF exposure information without significantly impacting the battery life of the UE.

[0015] The following description provides examples of RF exposure compliance management in a communication system and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of the described elements without departing from the scope of the present disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects described herein. In addition, the scope of the present disclosure is intended to cover such apparatuses or methods practiced using other structure, functions, or structure and functions in addition to or other than the various aspects of the present disclosure described herein. It should be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of a claim. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

[0016] In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, air interface, etc. A frequency may also be referred to as a carrier, subcarrier, frequency channel, tone, subband, etc. Each frequency may support a single RAT in a given geographic area and / or may be associated with several RATs to avoid interference between wireless networks of different RATs.

[0017] The techniques described herein may be used for various wireless networks and radio technologies. Although aspects may be described herein using terminology commonly associated with 3G, 4G, and / or New Radio (e.g., 5G NR) wireless technologies, aspects of the present disclosure may be applied in other generation-based communication systems and / or according to other radio technologies (e.g., 802.11, Bluetooth, etc.).

[0018] NR access may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidths (e.g., 80 MHz or greater), millimeter wave (mmW) targeting high carrier frequencies (e.g., 24 GHz to 53 GHz or greater), massive machine-type communications (MTC) targeting non-backward compatible MTC techniques, and / or mission-critical targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet their respective quality of service (QoS) requirements. In addition, these services may coexist in the same subframe. NR supports beamforming, and the beam direction may be dynamically configured. MIMO transmission with precoding may also be supported, as may multi-layer transmission. Aggregation of multiple cells may be supported.

[0019] 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be implemented. For example, the wireless communication network 100 may be an NR system (e.g., a 5G NR network), an Evolved Universal Terrestrial Radio Access (E-UTRA) system (e.g., a 4G network), a Universal Mobile Telecommunications System (UMTS) (e.g., a 2G / 3G network), or a Code Division Multiple Access (CDMA) system (e.g., a 2G / 3G network), or may be configured for communication in accordance with an IEEE standard, such as one or more of the 802.11 standard. As shown in FIG. 1, a UE 120a includes an RF exposure manager 122 that provides RF exposure continuity (e.g., after an exception event) in accordance with aspects of the present disclosure.

[0020] As shown in FIG. 1, wireless communication network 100 may include several BSs 110a-110z (each also referred to herein individually as BS 110 or collectively as BS 110) and other network entities. BSs 110 may provide communication coverage for a particular geographic area, which may be referred to as a “cell,” and may be fixed or may move according to the location of mobile BSs 110. In some examples, BSs 110 may be interconnected to each other and / or to one or more other BSs or network nodes (not shown) within wireless communication network 100 through various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.) using any suitable transport network. In the example shown in FIG. 1, BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more cells.

[0021] The BS 110 communicates with UEs 120a-120y (each also referred to herein individually as a UE 120 or collectively as a UE 120) within the wireless communication network 100. The UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE 120 may be fixed or mobile. The wireless communication network 100 may include relay stations or repeaters (e.g., relays), which are also called relays, that receive transmissions of data and / or other information from an upstream station (e.g., the BS 110a or the UE 120r), transmit transmissions of data and / or other information to a downstream station (e.g., the UE 120 or the BS 110), or relay transmissions between the UEs 120 to facilitate communication between the devices.

[0022] The network controller 130 may be in communication with the set of BSs 110 and may provide coordination and control for these BSs 110 (e.g., via a backhaul). In some cases, the network controller 130 may include, for example, a centralized unit (CU) and / or a distributed unit (DU) in a 5G NR system. In an aspect, the network controller 130 may be in communication with a core network 132 (e.g., a 5G core network (5GC)), which provides various network functions such as access and mobility management, session management, user plane functions, policy control functions, authentication server functions, integrated data management, application functions, network exposure functions, network repository functions, and network slice selection functions.

[0023] FIG. 2 illustrates example components of a BS 110a and a UE 120a (eg, within the wireless communication network 100 of FIG. 1) that may be used to implement aspects of the present disclosure.

[0024] At the BS 110a, the transmit processor 220 may receive data from the data source 212 and control information from the controller / processor 240. The control information may be for a Physical Broadcast Channel (PBCH), a Physical Control Format Indicator Channel (PCFICH), a Physical Hybrid ARQ Indicator Channel (PHICH), a Physical Downlink Control Channel (PDCCH), a Group Common PDCCH (GC PDCCH), etc. The data may be for a Physical Downlink Shared Channel (PDSCH), etc. A Medium Access Control (MAC) Control Element (MAC-CE) is a MAC layer communication structure that may be used to control command exchanges between wireless nodes. The MAC-CE may be carried within a shared channel, such as a Physical Downlink Shared Channel (PDSCH), a Physical Uplink Shared Channel (PUSCH), or a Physical Sidelink Shared Channel (PSSCH).

[0025] The processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, such as for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a PBCH demodulation reference signal (DMRS), and a channel state information reference signal (CSI-RS). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​the data symbols, control symbols, and / or reference symbols, if applicable, and provide output symbol streams to modulators (MODs) within the transceivers 232a through 232t. Each modulator transceiver 232a through 232t may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulator transceivers 232a through 232t may be transmitted via antennas 234a through 234t, respectively.

[0026] At UE 120a, antennas 252a through 252r may receive downlink signals from BS 110a and may provide received signals to demodulators (DEMODs) within transceivers 254a through 254r, respectively. Each demodulator within transceivers 254a through 254r may condition (e.g., filter, amplify, downconvert, and digitize) its respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all demodulators within transceivers 254a through 254r, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols and provide decoded data for UE 120a to a data sink 260 and decoded control information to controller / processor 280.

[0027] On the uplink, at the UE 120a, a transmit processor 264 may receive and process data (e.g., for the Physical Uplink Shared Channel (PUSCH)) from a data source 262 and control information (e.g., for the Physical Uplink Control Channel (PUCCH)) from a controller / processor 280. The transmit processor 264 may also generate reference symbols for a reference signal (e.g., for a Sounding Reference Signal (SRS)). The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by a modulator (MOD) within the transceivers 254a through 254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At BS 110a, the uplink signal from UE 120a may be received by antenna 234, processed by modulators in transceivers 232a-232t, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120a. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller / processor 240.

[0028] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively. Scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0029] Antenna 252, processors 266, 264, and / or controller / processor 280 of UE 120a and / or antenna 234, processors 220, 230, and / or controller / processor 240 of BS 110a may be used to perform various techniques and methods described herein. As shown in FIG. 2, controller / processor 280 of UE 120a has RF exposure manager 281 that provides RF exposure continuity (e.g., after an exception event) in accordance with aspects described herein. RF exposure manager 281 may be an example of RF exposure manager 122 (FIG. 1). Although shown in a controller / processor, other components of UE 120a and BS 110a may be used to perform the operations described herein. In some embodiments, BS 110a (e.g., controller / processor 240) includes an exposure manager configured to provide RF exposure continuity to BS 110a.

[0030] NR may utilize orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP) on the uplink and downlink. NR may support half-duplex operation using time division duplexing (TDD). OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth into multiple orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. Modulation symbols are transmitted in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers may depend on the system bandwidth. The system bandwidth may also be partitioned into subbands. For example, a subband may cover multiple resource blocks (RBs).

[0031] 1 and 2 as communicating with a BS and / or within a network, the UE 120a may be configured to communicate / transmit directly with another UE 120 and / or another wireless device without relaying communications within a network. In some embodiments, the BS 110a shown in FIG. 2 and described above is an example of another UE 120.

[0032] Exemplary RF Transceiver 3 is a block diagram of an exemplary RF transceiver circuit 300 in accordance with some aspects of the present disclosure. In some embodiments, the RF transceiver circuit 300 is an example of the transceivers 232 and / or 254, or portions thereof. The RF transceiver circuit 300 includes at least one transmit (TX) path 302 for transmitting signals via one or more antennas 306 (which may be an example of the antennas 234 and / or 252) and at least one receive (RX) path 304 (also referred to as a receive chain) for receiving signals via the antenna 306. When the TX path 302 and the RX path 304 share the antenna 306, these paths may be connected to the antenna via an interface 308, which may include any of a variety of suitable RF devices, such as a switch, a duplexer, a diplexer, a multiplexer, etc.

[0033] The TX path 302, which receives an in-phase (I) or quadrature-phase (Q) baseband analog signal from a digital-to-analog converter (DAC) 310, may include a baseband filter (BBF) 312, a mixer 314, a driver amplifier (DA) 316, and a power amplifier (PA) 318. The BBF 312, the mixer 314, and the DA 316 may be included within one or more radio frequency integrated circuits (RFICs). In some embodiments, the mixer (e.g., 314), the DA 316, and / or the PA 318 may be included within an RFIC.

[0034] The BBF 312 filters the baseband signal received from the DAC 310, and the mixer 314 mixes the filtered baseband signal with a transmit local oscillator (LO) signal to convert the baseband signal to a different frequency (e.g., upconvert from baseband to radio frequency). This frequency conversion process creates sum and difference frequencies between the LO frequency and the frequency of the baseband signal. The sum and difference frequencies are called beat frequencies. The beat frequencies are generally in the RF range, such that the signal output by the mixer 314 is generally an RF signal that can be amplified by the DA 316 and / or the PA 318 before transmission by the antenna 306. Although one mixer 314 is illustrated, several mixers may be used to upconvert the filtered baseband signal to one or more intermediate frequencies (IFs) and then upconvert the intermediate frequency signals to frequencies for transmission. Additionally, although the examples discussed herein utilize I and Q signals, those skilled in the art will understand that elements of RF transceiver circuitry 300 may be configured to utilize polar modulation.

[0035] The RX path 304 may include a low noise amplifier (LNA) 324, a mixer 326, and a baseband filter (BBF) 328. The LNA 324, the mixer 326, and optionally the BBF 328 may be included in one or more RFICs, which may or may not be the same RFIC that includes the TX path components. An RF signal received via the antenna 306 may be amplified by the LNA 324, and the mixer 326 mixes the amplified RF signal with a receive local oscillator (LO) signal to convert (e.g., downconvert) the RF signal to a different baseband frequency. The baseband signal output by the mixer 326 may be filtered by the BBF 328 before being converted to a digital I or Q signal by an analog-to-digital converter (ADC) 330 for digital signal processing. Although one mixer 326 is illustrated, several mixers may be used to downconvert the amplified RF signal to one or more intermediate frequencies and then downconvert the intermediate frequency signals to baseband.

[0036] Some transceivers may employ a frequency synthesizer with a voltage-controlled oscillator (VCO) to generate a stable, tunable LO signal with a specific tuning range. Thus, a transmit LO signal may be created by the TX frequency synthesizer 320, which may be buffered or amplified by an amplifier 322 before being mixed with a baseband (or IF) signal in the mixer 314. Similarly, a receive LO signal may be created by the RX frequency synthesizer 332, which may be buffered or amplified by an amplifier 334 before being mixed with an RF (or IF) signal in the mixer 326.

[0037] The controller 336 may direct the operation of the RF transceiver circuit 300, such as transmitting signals via the TX path 302 and / or receiving signals via the RX path 304. The controller 336 may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof. The controller 336 may be an example of, or a portion of, the controller / processor 240 or 280, or may be implemented separately from the controller / processor 240, 280. The memory 338 may store data and program code for operating the RF transceiver circuit 300. The memory 338 may be an example of, or a portion of, the memory 242 or 282, or may be implemented separately from the memory 242, 282. The controller 336 and / or the memory 338 may include control logic. In some cases, the controller 336 may determine a time-averaged RF exposure measurement based on the transmit power level set by the TX path 302 (e.g., a constant level at the PA 318) to set a transmit power level over a time slot that complies with RF exposure limits set by national and international regulations, as further described herein.

[0038] Exemplary RF Exposure Measurements RF exposure can be expressed in terms of the specific absorption rate (SAR), which measures the energy absorption by human tissue per unit mass and may have units of watts per kilogram (W / kg). RF exposure also measures the energy absorption per unit area and may be expressed in mW / cm. 2In some cases, maximum permissible exposure (MPE) limits may be imposed in terms of PD for wireless communication devices using transmission frequencies above 6 GHz. MPE limits are based on area-based exposure regulatory standards, e.g., Watts per square meter (W / m), averaged over a defined area and time-averaged over a frequency-dependent time window to prevent human exposure hazards represented by tissue temperature changes. 2 ) is the energy density limit defined as the number X of

[0039] SAR may be used to assess RF exposure to transmission frequencies below 6 GHz, covering wireless communication technologies such as 2G / 3G (e.g., CDMA), 4G (e.g., LTE), 5G (e.g., NR in the 6 GHz band), IEEE 802.11ac, etc. PD may be used to assess RF exposure to transmission frequencies above 10 GHz, covering wireless communication technologies such as IEEE 802.11ad, 802.11ay, 5G in the mmWave band, etc. Thus, different criteria may be used to assess RF exposure to different wireless communication technologies.

[0040] A wireless communication device (e.g., UE 120) may simultaneously transmit signals using multiple wireless communication technologies. For example, the wireless communication device may simultaneously transmit signals using a first wireless communication technology operating at or below 6 GHz (e.g., 3G, 4G, 5G, etc.) and a second wireless communication technology operating above 6 GHz (e.g., mmWave 5G, IEEE 802.11ad, or 802.11ay in the 24 to 60 GHz band). In some aspects, the wireless communication device may simultaneously transmit signals using a first wireless communication technology whose RF exposure is measured in terms of SAR (e.g., 3G, 4G, 5G, IEEE 802.11ac, etc. in the sub-6 GHz band) and a second wireless communication technology whose RF exposure is measured in terms of PD (e.g., 5G, IEEE 802.11ad, 802.11ay, etc. in the 24 to 60 GHz band).

[0041] To assess RF exposure from transmissions using a first technology (e.g., 3G, 4G, 5G, IEEE 802.11ac, etc. in the sub-6 GHz band), the wireless communication device may include multiple SAR distributions for the first technology stored in a memory (e.g., memory 242, 282 of FIG. 2 or memory 338 of FIG. 3). The SAR distributions may each correspond to a respective one of multiple transmission scenarios supported by the wireless communication device for the first technology. The transmission scenarios may correspond to various combinations of antennas (e.g., antennas 234a through 234t, 252a through 252r of FIG. 2, or antenna 306 of FIG. 3), frequency bands, channels, and / or body positions, as discussed further below.

[0042] A SAR distribution (also called a SAR map) 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 to enable a processor (e.g., processor 240, 280 of FIG. 2 or controller 336 of FIG. 3) to assess RF exposure in real time, as discussed 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 mass, e.g., 1 g or 10 g, at the respective location.

[0043] The SAR values ​​in each SAR distribution correspond to a particular transmit power level (e.g., the transmit power level at which the SAR values ​​were measured in a test laboratory). Because the SAR scales with transmit power level, the processor may scale the SAR distribution for any transmit power level by multiplying each SAR value in the SAR distribution by the following transmit power scaler:

[0044]

number

[0045] In the formula, Tx c is the current transmit power level for each transmission scenario, and Tx SAR is the transmit power level corresponding to the SAR value in the stored SAR distribution (eg, the transmit power level at which the SAR value was measured in a test laboratory).

[0046] As discussed above, a wireless communication device may support multiple transmit scenarios for a first technology. In some aspects, a transmit scenario may be specified by a set of parameters. The set of parameters may include one or more of the following: 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 the wireless communication device relative to a user's body location (head, torso, off the body, etc.); parameters indicating whether a device cover and / or a type of device cover is located on the device; and / or other parameters. When a wireless communication device supports a large number of transmit scenarios, performing measurements for each transmit scenario in a test setting (e.g., a test lab) can be very 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 distribution for each of the remaining transmission scenarios may be generated by combining two or more of the SAR distributions for the subsets of transmission scenarios, as discussed further below.

[0047] For example, SAR measurements may be performed for each of the antennas to generate a SAR distribution for each of the antennas. In this example, a SAR distribution for a transmission scenario in which two or more of the antennas are active may be generated by combining the SAR distributions for those two or more active antennas.

[0048] 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.

[0049] In some aspects, the SAR distribution may be normalized to the SAR limit by dividing each SAR value in the SAR distribution by the SAR limit, where the normalized SAR value exceeds the SAR limit when the normalized SAR value is greater than 1 and is below the SAR limit when the normalized SAR value is less than 1. In these aspects, each of the SAR distributions stored in memory may be normalized to the SAR limit.

[0050] In some aspects, a normalized SAR distribution for a transmission scenario may be generated by combining two or more normalized SAR distributions. For example, a normalized SAR distribution for a transmission scenario in which two or more antennas are active may be generated by combining the normalized SAR distributions for those two or more active antennas. If different transmit power levels are used for the active antennas, the normalized SAR distribution for each active antenna may be scaled by the respective transmit power level before combining the normalized SAR distributions for those active antennas. The normalized SAR distribution for simultaneous transmission from multiple active antennas may be given by:

[0051]

number

[0052] In the formula, SAR lim is the SAR limit, and SAR norm_combined is the combined normalized SAR distribution for simultaneous transmission from the active antennas, i is the index for the active antenna, and SAR i is the SAR distribution for the i-th active antenna, and Tx i is the transmit power level for the i-th active antenna, and Tx SARi is the transmit power level for the SAR distribution for the i-th active antenna, and K is the number of active antennas.

[0053] Equation (2) can be rewritten as:

[0054]

number

[0055] In the formula, SAR norm_i is the normalized SAR distribution for the i-th active antenna. In the case of simultaneous transmission using multiple active antennas at the same transmission frequency (e.g., multiple-input multiple-output (MIMO)), the combined normalized SAR distribution is obtained by adding the square roots of the individual normalized SAR distributions and calculating the square of the sum, as given below:

[0056]

number

[0057] In another example, normalized SAR distributions for different frequency bands may be stored in memory. In this example, a normalized SAR distribution for a transmission scenario in which two or more frequency bands are active may be generated by combining the normalized SAR distributions for the two or more active frequency bands. If the transmit power levels for the active frequency bands are different, the normalized SAR distribution for each of the active frequency bands may be scaled by the respective transmit power levels before combining the normalized SAR distributions for the active frequency bands. In this example, the combined SAR distribution may be calculated using equation (3a), where i is an index for the active frequency band and SAR norm_i is the normalized SAR distribution for the i-th active frequency band, and Tx i is the transmit power level for the i-th active frequency band, and Tx SARi is the transmit power level for the normalized SAR distribution for the i-th active frequency band.

[0058] To assess RF exposure from transmissions using a second technology (e.g., 5G, IEEE 802.11ad, 802.11ay, etc., in the 24 GHz to 60 GHz band), the wireless communication device may include multiple PD distributions for the second technology stored in a memory (e.g., memory 242, 282 of FIG. 2 or memory 338 of FIG. 3). The PD distributions may each correspond to a respective one of multiple transmission scenarios supported by the wireless communication device for the second technology. The transmission scenarios may correspond to various combinations of antennas (e.g., antennas 234a through 234t, 252a through 252r of FIG. 2, or antenna 306 of FIG. 3), frequency bands, channels, and / or body positions, as discussed further below.

[0059] A PD distribution (also called a PD map) for each transmit scenario may be generated based on measurements (e.g., E-field measurements) performed in a test laboratory using a model of the human body. After the PD distribution is generated, it is stored in memory to enable a processor (e.g., processor 240, 280 of FIG. 2 or controller 336 of FIG. 3) to assess RF exposure in real time, as discussed further below. Each PD distribution includes a set of PD values, where each PD value may correspond to a different location (e.g., on the model of the human body).

[0060] The PD values ​​in each PD distribution correspond to a particular transmit power level (e.g., the transmit power level at which the PD values ​​were measured in a test laboratory). Because PD scales with transmit power level, the processor may scale the PD distribution for any transmit power level by multiplying each PD value in the PD distribution by the following transmit power scaler:

[0061]

number

[0062] In the formula, Tx c is the current transmit power level for each transmission scenario, and Tx PD is the transmit power level corresponding to the PD value in the PD distribution (eg, the transmit power level at which the PD value is measured in a test laboratory).

[0063] As discussed above, a wireless communication device may support multiple transmission scenarios for the second technology. In some aspects, a transmission scenario may be specified by a set of parameters. The set of parameters may include one or more of the following: 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 the wireless communication device relative to the user's body location (head, torso, off the body, etc.); parameters indicating whether a device cover and / or a type of device cover is located on the device; and / or other parameters. When a wireless communication device supports a large number of transmission scenarios, performing measurements for each transmission scenario in a test setting (e.g., a test lab) can be very time-consuming and expensive. To reduce test time, measurements may be performed for a subset of the transmission scenarios to generate PD distributions for the subset of transmission scenarios. In this example, the PD distribution for each of the remaining transmission scenarios may be generated by combining two or more of the PD distributions for the subsets of transmission scenarios, as discussed further below.

[0064] For example, PD measurements may be performed for each of the antennas to generate a PD distribution for each of the antennas. In this example, a PD distribution for a transmission scenario in which two or more of the antennas are active may be generated by combining the PD distributions for those two or more active antennas.

[0065] In another example, PD measurements may be performed for each of a plurality of frequency bands to generate a PD distribution for each of the plurality of frequency bands. In this example, a PD distribution for a transmission scenario in which two or more frequency bands are active may be generated by combining the PD distributions for the two or more active frequency bands.

[0066] In some embodiments, the PD distribution may be normalized to the PD limits by dividing each PD value in the PD distribution by the PD limit, where a normalized PD value exceeds the PD limit when the normalized PD value is greater than 1 and is below the PD limit when the normalized PD value is less than 1. In these embodiments, each of the PD distributions stored in memory may be normalized to the PD limits.

[0067] In some aspects, a normalized PD distribution for a transmission scenario may be generated by combining two or more normalized PD distributions. For example, a normalized PD distribution for a transmission scenario in which two or more antennas are active may be generated by combining the normalized PD distributions for those two or more active antennas. If different transmit power levels are used for the active antennas, the normalized PD distribution for each active antenna may be scaled by the respective transmit power level before combining the normalized PD distributions for those active antennas. The normalized PD distribution for simultaneous transmission from multiple active antennas may be given by:

[0068]

number

[0069] During the ceremony, P.D. lim is the PD limit, and PD norm_combined is the combined normalized PD distribution for simultaneous transmission from the active antennas, i is the index for the active antenna, and PD i is the PD distribution for the i-th active antenna, and Txi is the transmit power level for the i-th active antenna, and Tx PDi is the transmit power level for the PD distribution for the i-th active antenna, and L is the number of active antennas.

[0070] Equation (5) can be rewritten as:

[0071]

number

[0072] During the ceremony, P.D. norm_i is the normalized PD distribution for the i-th active antenna. In the case of simultaneous transmission using multiple active antennas at the same transmission frequency (e.g., MIMO), the combined normalized PD distribution is obtained by adding the square roots of the individual normalized PD distributions and calculating the square of the sum, as given below:

[0073]

number

[0074] In another example, normalized PD distributions for different frequency bands may be stored in memory. In this example, a normalized PD distribution for a transmission scenario in which two or more frequency bands are active may be generated by combining the normalized PD distributions for the two or more active frequency bands. If the transmit power levels for the active frequency bands are different, the normalized PD distribution for each of the active frequency bands may be scaled by the respective transmit power levels before combining the normalized PD distributions for the active frequency bands. In this example, the combined PD distribution may be calculated using equation (6a), where i is an index for the active frequency band and PD norm_i is the normalized PD distribution for the i-th active frequency band, and Tx iis the transmit power level for the i-th active frequency band, and Tx PDi is the transmit power level for the normalized PD distribution for the i-th active frequency band.

[0075] As discussed above, UE 120 may simultaneously transmit signals using a first technology and a second technology (e.g., 3G, 4G, IEEE 802.11ac, etc.) where RF exposure is measured using different criteria (e.g., SAR for the first technology or PD for the second technology) for the first technology and the second technology (e.g., 5G, IEEE 802.11ad, etc.). In this case, processor 280 may determine a first maximum allowable power level for the first technology and a second maximum allowable power level for the second technology to transmit within a time slot that complies with RF exposure limits. During the time slot, the transmit power levels for the first and second technologies are constrained (i.e., limited) by the determined first and second maximum allowable power levels, respectively, to ensure compliance with RF exposure limits, as discussed further below. In this disclosure, the term “maximum allowable power level” refers to the “maximum allowable power level” imposed by RF exposure limits, unless otherwise specified. It should be appreciated that the "maximum allowed power level" is not necessarily equal to the absolute maximum power level that complies with RF exposure limits, and may be less than the absolute maximum power level that complies with RF exposure limits (e.g., to provide a safety margin). The "maximum allowed power level" may be used to set a power level limit for transmissions at a transmitter, such that the power level of the transmission is not allowed to exceed the "maximum allowed power level" to ensure RF exposure compliance.

[0076] A processor (e.g., 240, 280, 336) may determine the first and second maximum allowable power levels as follows: The processor may determine a normalized SAR distribution for a first technology at a first transmit power level, determine a normalized PD distribution for a second technology at a second transmit power level, and combine the normalized SAR and PD distributions to generate a combined normalized RF exposure distribution (hereinafter simply referred to as the combined normalized distribution). The value at each location in the combined normalized distribution may be determined by combining the normalized SAR value at that location with the normalized PD value at that location or by another technique.

[0077] The processor may then determine whether the first and second transmit power levels comply with RF exposure limits by comparing the peak value in the combined normalized distribution to 1. If the peak value is less than or equal to 1 (i.e., the condition ≦1 is satisfied), the processor 280 may determine that the first and second transmit power levels comply with RF exposure limits (e.g., SAR limits and PD limits) and may use the first and second transmit power levels as the first and second maximum allowed power levels, respectively, during the time slot. If the peak value is greater than 1, the processor may determine that the first and second transmit power levels do not comply with RF exposure limits. The condition for RF exposure compliance for simultaneous transmission using the first and second technologies may be given by: SAR norm +PD norm <= 1 (7)

[0078] The normalized SAR distribution in equation (7) may be generated by combining two or more normalized SAR distributions as discussed above (e.g., for a transmit scenario using multiple active antennas). Similarly, the normalized PD distribution in equation (7) may be generated by combining two or more normalized PD distributions as discussed above (e.g., for a transmit scenario using multiple active antennas). In this case, the RF exposure compliance condition in equation (7) can be rewritten using equations (3a) and (6a) as follows:

[0079]

number

[0080] In the case of MIMO, equations (3b) and (6b) may be combined instead. As shown in equation (8), the combined normalized distribution may be a function of the transmit power level for the first technology and the transmit power level for the second technology. All points in the combined normalized distribution may satisfy the normalization limit of 1 in equation (8). In addition, when combining the SAR and PD distributions, the SAR and PD distributions may be spatially aligned, or their peak locations may be aligned, so that the combined distribution given by equation (8) represents the combined RF exposure for a given position on the human body.

[0081] Illustrative anomaly-robust time-averaged RF exposure compliance continuity Time-averaged RF exposure compliance (e.g., SAR or MPE / PD) can provide desirable device performance while ensuring user safety at the device. In some cases (such as normal runtime operation), a device (e.g., a UE) has an active system that constantly ensures RF exposure compliance based on various time windows of power history. When an exception condition (e.g., assert, crash, reset, etc.) causes UE operation to cease and the UE then subsequently returns to normal runtime operation, the UE may lose all of the recent RF exposure history used to ensure time-averaged RF exposure compliance. For shorter RF exposure time windows (e.g., 4 seconds for NR frequency range (FR) 2), it may be acceptable to reset the RF exposure history because the time it takes for the UE to reboot and begin normal transmission operation may be longer than the time window over which the power history would be averaged. However, for certain transmission frequencies (e.g., NR FR1 and legacy 2 / 3 / 4G wireless wide area networks (WWANs)), the time window may be longer (e.g., up to 360 seconds) depending on the regulatory standard used. A longer time window for determining RF exposure compliance for a given transmission frequency allows the UE to start anew without transmit power history. Thus, the lack of transmit power history may disrupt the operation of software / components that ensure RF exposure compliance. For example, without proper procedures, the lack of transmit power history prior to an exception condition within the time window may cause the UE to transmit data using transmit power that exceeds the RF exposure limit for the time window.

[0082] Aspects of the present disclosure provide various techniques for providing continuity of RF exposure information following various exception events (such as an error, reset, crash, or reboot that affects the operation of the UE, or in particular, the UE's modem, and / or an event that results in a portion of time during which RF exposure is unknown or indeterminate). In some aspects, the UE may periodically store RF exposure information (such as transmit power and / or time-averaged RF exposure measurements of transmit power history) in a memory that is not susceptible to corruption from exception events. When an exception event occurs (such as a UE reboot or a UE modem reset, or an event that causes the UE to experience or be detected as experiencing an amount of time during which RF exposure information is unknown or indeterminate), the UE may use the stored RF exposure information to determine a transmit power that complies with RF exposure limits. Techniques for providing RF exposure continuity described herein may enable the UE to remain compliant with RF exposure limits after the UE encounters an exception event and / or may enable the UE to transmit at a higher power in some such circumstances while maintaining safety for the user after the exception event. The techniques for providing RF exposure continuity described herein may provide a low-power solution that consumes an allowable amount of power for storing RF exposure measurements without significantly impacting the battery life of the UE. In some cases, the techniques for providing RF exposure continuity described herein may facilitate desirable power consumption, e.g., by a relatively high transmit power (e.g., above RF exposure limits) used before an exception event when taking into account stored RF exposure information. In some cases, the techniques for providing RF exposure continuity described herein may enable desirable power consumption, e.g., by a relatively low transmit power (e.g., below RF exposure limits) used before an exception event when taking into account stored RF exposure information.

[0083] Some aspects of the present disclosure may relate to using a UE's on-board power management integrated circuit (PMIC), which may include a counter. In some cases, the counter may be based on a real-time clock (RTC). The RTC may count monotonically upward even when the UE resets or when power is momentarily lost. The RTC may enable UE software to periodically take snapshots of the transmit power history using the PMIC RTC timestamp and store the transmit power history in internal static memory that is less susceptible to corruption due to exception events. Upon or immediately after reset, the UE software may check memory locations in the internal static memory against the RTC timestamp, optionally a consistency / reliability indicator (e.g., a checksum such as a cyclic redundancy check (CRC)), and data indicative of recent transmit power history (e.g., a CRC-protected set of data). If the CRC passes, for example, the current (post-reset) RTC timestamp is used to determine how old the transmit power history is, and the UE's compliance algorithm transmit power history bookkeeping is updated accordingly. The techniques described herein for providing RF exposure continuity can always ensure compliance, even against unexpected resets or other exceptional events (e.g., recent records of exposure are lost or unknown for some reason). If the CRC passes but the timestamp is old enough not to fall within the longest time averaging window, the transmit power history cannot be used. If the CRC fails, the UE can enter a failsafe mode, where transmit power is limited for the initial duration of the longest window, ensuring compliance at the expense of initial performance.

[0084] 4 is a flow diagram illustrating example operations 400 for wireless communication according to some aspects of the present disclosure. The operations 400 may be performed, for example, by a UE (e.g., UE 120a in wireless communication network 100), a BS, or customer premises equipment (CPE). The operations 400 may be implemented as software components executed and operated on one or more processors (e.g., controller / processor 240, 280 in FIG. 2 , controller 336 in FIG. 3 ). Furthermore, transmission of signals by the UE (or BS, CPE) in operations 400 may be enabled, for example, by one or more antennas (e.g., antennas 234, 252 in FIG. 2 , antenna 306 in FIG. 3 ). In some aspects, transmission and / or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller / processor 240, 280 in FIG. 2 , controller 336 in FIG. 3 ) that acquire and / or output the signals.

[0085] The operations 400 may begin at block 402, where the UE may transmit a first signal at a first transmit power based on RF exposure measurements time-averaged over a time window. At block 404, the UE may store RF exposure information associated with the time window. At block 406, the UE may detect that an exception event associated with the UE has occurred. At block 408, the UE may transmit a second signal at a second transmit power based at least in part on the stored RF exposure information in response to detecting the event.

[0086] In an aspect, a UE (e.g., using the components described in FIG. 2 and / or FIG. 3, and potentially in combination with the RF exposure manager 122, 281) may be in communication with a base station, such as the BS 110. For example, in block 402 and / or block 408, the UE may be transmitting user data on a physical uplink shared channel (PUSCH) or various uplink feedback (e.g., uplink control information or hybrid automatic repeat request (HARQ) feedback) on a physical uplink control channel (PUCCH) to the base station. In some cases, the UE may be in communication with another UE. For example, in block 402 and / or block 408, the UE may be transmitting user data and / or various feedback to the other UE on a sidelink channel.

[0087] In embodiments, the RF exposure information may include a history of transmit power and / or time-averaged RF exposure measurements. In some cases, the RF exposure information may include a sum of time-averaged RF exposure measurements, a sum of transmit power within a time window at a time corresponding to a timestamp, or an integral of transmit power over time. In some cases, the RF exposure information may include separate values ​​for each of the time-averaged RF exposure measurements or transmit power within a time window at a time corresponding to a timestamp.

[0088] In block 404, the UE (e.g., RF exposure manager 122, 281) may periodically store the RF exposure information. That is, the UE may store the RF exposure information according to a period, such as every 50 milliseconds (ms), every 500 ms, or every 1 second (s). In other words, the UE may store the RF exposure information at periodic intervals of, for example, 50 ms, 500 ms, or 1 s.

[0089] In block 404, the UE may store the RF exposure information in memory that is not susceptible to corruption from an exception event. That is, the memory may be configured to store data (e.g., RF exposure information) before or upon an exception event, where the exception event does not corrupt the stored data. In some cases, the UE may store the RF exposure information upon an exception event, for example, when the UE may still be transmitting during the exception event. For example, the memory may be a non-volatile or static memory that is separate from the memory used for the file system, as further described herein with respect to FIG. 6. In some cases, the memory used for the file system may consume too much power to provide a low-power memory solution for storing the RF exposure information. However, in some aspects, the RF exposure information may be stored within the memory used for the file system.

[0090] In block 404, the UE may store the RF exposure information along with a timestamp. The timestamp may correspond to the time (e.g., absolute or relative time) when the most recent time-averaged RF exposure measurement was generated or the most recent transmission was sent by the UE. In other words, the RF exposure information may include the most recent time-averaged RF exposure measurement or the most recent transmit power history.

[0091] In an aspect, a timestamp associated with the RF exposure information may be used to determine whether to use the RF exposure information in determining a second transmit power for the second signal. For example, in block 408, the UE may transmit the second signal at a second transmit power based at least in part on the stored RF exposure information if the timestamp of the RF exposure information is within a current time window (e.g., in response to determining that the timestamp of the RF exposure information is within the current time window), where the current time window may look back to a time starting, for example, at a current timestamp corresponding to when the UE recovers from the exception event. In other words, if the timestamp of the RF exposure information is outside the current time window, the UE may not consider the RF exposure information in determining the second transmit power for the second signal. In some cases, the UE may determine a time delta between the timestamp of the RF exposure information and a current timestamp (e.g., corresponding to when the UE recovers from the exception event), and if the time delta is greater than (or equal to) the duration of the (current or longest) time window, the UE may not consider the RF exposure information in determining the second transmit power for the second signal. Otherwise, if the time delta is less than (or equal to) the duration of the (current or longest) time window, the UE may use the RF exposure information in determining the second transmit power for the second signal. As explained above, the time window may vary based on frequency and / or regulations / standards, and thus a constant time delta may correspond in some scenarios (e.g., transmit frequency, geographic location, etc.) to the UE using the RF exposure information in determining the second transmit power for the second signal, and in other scenarios to the UE ignoring the RF exposure information.

[0092] In some aspects, storing the RF exposure information may involve obtaining a timestamp from a counter or clock. For example, the UE may obtain the timestamp from a counter that is not susceptible to corruption by an exception event. The counter may be exceptionally tolerant by being able to continue providing a timestamp independent of the exception event. That is, the counter can continue to count monotonically upward during an exception event without losing any time increments. In some cases, the counter may be based on a real-time clock.

[0093] As an example, suppose the UE reboots. When the UE returns to normal operation, the UE checks whether the timestamp of the stored RF exposure information is within the current (or longest) time window. For example, the UE may obtain the current timestamp from a counter and compare it with the timestamp of the RF exposure information. If the timestamp of the stored RF exposure information is within the current time window, the UE may use the stored RF exposure information in determining the second transmit power for the second signal. The UE may continue to use the RF exposure information to supplement the RF exposure measurement until the timestamp is outside the current time window. If the timestamp of the RF exposure information is outside the current time window (i.e., too much time has passed since the exception event), the UE cannot use the stored RF exposure information in determining the second transmit power for the second signal.

[0094] In some cases, the RF exposure information and / or timestamp may be stored with a check value or other reliability or fidelity indicator to detect data inconsistencies, such as a cyclic redundancy check (CRC) or checksum. In some cases, the check value may include a CRC remainder of the RF exposure information and / or timestamp.

[0095] In some aspects, determining whether to use the RF exposure information may depend on confirming the fidelity of the RF exposure based on a check value or reliability indicator that passes a CRC. For example, the UE may transmit a second signal at a second transmit power based on supplementing a time-averaged RF exposure measurement over the current time window with stored RF exposure information if the CRC of the RF exposure information matches the check value (e.g., in response to determining that the CRC of the RF exposure information matches the check value). In some aspects, if the CRC of the RF exposure information passes, the RF exposure information may be used to determine a second transmit power for the second signal. If the CRC of the RF exposure information fails, the UE may enter a fail-safe mode, in which a lower RF exposure limit than the standard RF exposure limit may be used to determine the transmit power for the second signal. For example, the fail-safe mode may include determining the transmit power for the second signal using an assumed previous transmit power or exposure (e.g., a maximum transmit power or exposure over the duration of a previous / previous portion of the current time window) to ensure safety for the user and compliance with any applicable exposure limits. In some cases, the fail-safe mode may be used when returning to normal operation after an exception event if the RF exposure information is outside the current time window. However, when the transmit power for the second signal is based on the stored RF exposure information, the stored RF exposure information will indicate that the previous transmit power or exposure was less than the transmit power or exposure that would have been assumed in the fail-safe mode, and therefore the transmit power for the second signal may be higher than the transmit power that would have been used in the fail-safe mode while still maintaining safe operating conditions for the user.

[0096] In some cases, the second transmit power in block 408 may be based on supplementing the time-averaged RF exposure measurements with stored RF exposure information. For example, assume the time window is 100 seconds, such that the stored RF exposure information represents 100 seconds of transmission history. If the exception event only took 10 seconds, then 90 seconds of RF exposure information is still available to supplement new RF exposure measurements made during normal operation after the exception event.

[0097] In some cases, the second transmit power in block 408 may be based at least in part on the stored RF exposure information when at least one RF exposure measurement is missing from the time window. For example, the UE may be missing an RF exposure measurement due to an exception event. That is, the UE may be unable to communicate with other wireless communication devices and transmit signals during the exception event. The UE may be missing a transmit power history during the exception event, resulting in a missing RF exposure measurement from the time window.

[0098] In aspects, the UE may detect the exception event (at block 406) through various means. For example, the UE (e.g., RF exposure manager 122, 281) may monitor certain logs, statistics, or interface states (enabled or disabled) associated with one or more wireless communication components (such as a modem) of the UE to determine whether the UE has encountered an exception event. Some messages in the logs (e.g., error messages or boot messages) may indicate that an exception event has occurred, various transmission statistics (e.g., transmitted packets or transmitted bytes) resetting to zero may indicate that an exception event has occurred, or a modem switching from an enabled state (e.g., the modem is online and operational) to a disabled state (e.g., the modem is offline) may indicate that an exception event has occurred. In some embodiments, the RF exposure manager is implemented within the modem, and the RF exposure manager may recognize that the modem has been (temporarily) disabled by examining the logs or transmission statistics mentioned above. Thus, software implemented separately from the modem may monitor the modem and / or its operation and make the determination in block 406, or the modem may monitor itself and make the determination in block 406. Such a test may be performed periodically (e.g., every 50 ms, 500 ms, or 1 s, in the same order as the storage of RF exposure information, or according to another period unrelated to the storage of RF exposure information), may be performed based on some occurrence (e.g., new data being loaded into the transmit buffer), etc.

[0099] In aspects, exception events may include various events that cause the UE to temporarily cease communication or events that result in a portion of time during which the UE's RF exposure is unknown or indeterminate. For example, exception events may include a modem stopping, a modem reset, a modem reboot, a modem crash, or a resulting modem experiencing an error. In some cases, exception events may include an error, reset, crash, or reboot that affects the operation of the UE or modem used in transmitting the first and second signals. For example, an error, reset, crash, or reboot of a modem or another component may render the UE temporarily inoperable from a wireless communication perspective or may render it temporarily inoperable from tracking RF exposure. That is, the error, reset, crash, or reboot may prevent the UE from communicating wirelessly, such as transmitting signals from the UE's antenna, or from determining RF exposure for a duration of time.

[0100] In an aspect, the second transmit power in block 408 may be based on the type of exception event and / or confidence in the possibility of transmission during the portion of the time window corresponding to the missing RF exposure measurement. For example, if the RF exposure manager determines (e.g., based on messages, logs, statistics, etc. described above) that communication (or at least transmission) stopped during the portion of the time window, the RF exposure manager may allocate zero transmit power for that portion of time when calculating the second transmit power. In other embodiments, when calculating the second transmit power, the RF exposure manager allocates a minimum transmit power (e.g., the power required to maintain a link) for the portion of the time window corresponding to the missing RF exposure measurement, e.g., during conservative operation. In other aspects, if the RF exposure manager cannot determine why the exception event occurred or that transmission stopped during the portion of the time window corresponding to the missing RF exposure measurement, the RF exposure manager may allocate a maximum allowable power level (or other predetermined transmit power) for that portion of time in order to calculate the second transmit power. In some aspects, a confidence level may be determined (e.g., based on data in a transmission buffer, a transmission log, a communication received from another device, etc.) as to whether the device was transmitting during the portion of the time window corresponding to the missing RF exposure measurement, and a second transmit power may be determined based thereon. For example, a comparison of the confidence level to a threshold may determine whether no transmit power level, a minimum transmit power level, or a maximum allowed power level (or other power level) is allocated to that portion of the time window. In some embodiments, the confidence level may be used to allocate transmit power proportionally to that portion of the time window.

[0101] In embodiments, the time-averaged RF exposure measurements (e.g., stored in block 404) may include at least one of a time-averaged SAR or a time-averaged PD. In embodiments, the time window may be in a range of 1 second to 360 seconds. For example, the time window may be 100 seconds to 360 seconds. The range of 1 second to 360 seconds is an example, and other suitable values ​​for the time window may be used. In some cases, the time window may be less than 1 second, such as 500 milliseconds. In some cases, the time window may be greater than 360 seconds, such as 600 seconds.

[0102] 5 is a chart illustrating time-averaged RF exposure over time window T1 in accordance with some aspects of the present disclosure. The UE may determine the time-averaged RF exposure using RF exposure measurements (e.g., various RF measurements corresponding to intervals (i) to (im)) time-averaged over time window T1. In some cases, the UE may determine the RF exposure measurements based on a speech model or a scaling factor between the SAR / PD and the transmit power used in each transmission interval (e.g., interval (i) to (im)).

[0103] In this example, the RF exposure measurements 502 may have been stored as RF exposure information prior to the exception event, e.g., as described herein with respect to operation 400. In an aspect, the RF exposure information may be stored as a sum of the RF exposure measurements 502 or as separate values ​​for each of the RF exposure measurements. Within time window T1, the UE may have encountered an exception event. After returning to normal operation or recovering from the exception event, the UE may use the RF exposure information in determining a time-averaged RF exposure to represent the RF exposure measurement prior to the exception event if the RF exposure information is within time window T1 (e.g., the current time window spans from im to i). In this example, the RF exposure information is within time window T1 (e.g., the current time window spans from im to i), and therefore the UE may use the RF exposure information in determining a transmit power that complies with the respective RF exposure requirement based on the time-averaged RF exposure. In some cases, the UE may use a portion of the RF exposure information in determining the time-averaged RF exposure. For example, as the UE continues to determine time-averaged RF exposure over a rotating time window T1 (e.g., the current time window may progress (i.e., shift in time) to span time intervals il to i+1), the UE may use portions of the RF exposure information corresponding to the remaining time intervals within time window T1 (e.g., intervals (i-1) and (ik)).

[0104] If the RF exposure information is outside of time window T1, the UE cannot use the RF exposure information in determining the transmit power, and in some cases, the UE may operate in a fail-safe mode, e.g., as described herein with respect to operation 400. As an example, assume that a timestamp associated with the RF exposure information places the RF exposure information outside of time window T1 in interval (in). The UE may determine that the RF exposure information is outside the time window by comparing the timestamp associated with the RF exposure information with a timestamp associated with the current interval (i). As described herein, if the time delta between the timestamp associated with the RF exposure information and the timestamp associated with the current interval (i) is greater than or equal to the duration of time window T1, the UE cannot use the RF exposure information in determining the transmit power.

[0105] 6 is a block diagram illustrating a design of an example wireless communication device 600 (e.g., UE 120, BS 110) for implementing RF exposure continuity following an exception event in accordance with certain aspects of the present disclosure. As shown, the wireless communication device 600 may include a transceiver 602 (which may be an example of a transceiver 232, 254, 300), one or more antennas 604 (which may be an example of an antenna 234, 252, 306), a modem 606, a processor 608, a memory 610 (which may be an example of a memory 242, 282, 338), and a counter 612. In some cases, the counter 612 may be integrated with or included within a PMIC 614. In some cases, the wireless communication device 600 may include an application processor 616 and a file system memory 618. In some embodiments, one or both of modem 606 and processor 608 may be implemented by or within components of Figure 2, such as 212, 220, 230, 236, 238, 239, 240, 244, 256, 258, 260, 262, 264, 266, and / or 280, and / or controller 336 of Figure 3. An RF exposure manager (e.g., 122, 281) may be implemented within modem 606 and / or processor 608.

[0106] The wireless communication device 600 may transmit various signals from a transceiver 602 and one or more antennas 604 coupled to the transceiver 602. The modem 606 may provide modulated signals to the transceiver 602 and instructions to the transceiver 602 to adjust the transmit power of the signals to comply with various RF exposure limits. For example, the modem 606 may provide instructions for a first transmit power and a second transmit power to the transceiver 602, as described herein with respect to operation 400. The processor 608 may obtain current RF exposure information from the modem 606 and periodically store the RF exposure information along with a timestamp (and CRC) in the memory 610, as described herein with respect to operation 400. In aspects, the memory 610 is tightly coupled to the modem 606 and / or the processor 608 and may provide a lower power solution for repeatedly storing RF exposure information compared to the file system memory 618. In some aspects, the memory 610 may not be susceptible to corruption by an exception event affecting the operation of the wireless communication device 600 or the modem 606 (e.g., electrically isolated from the modem 606 or some components of the modem 606). Those skilled in the art will appreciate that the exception event that triggers the use of the stored RF exposure information may be associated with other components that affect the operation of the wireless communication device 600, such as various circuits, memories, or processors. In some cases, the processor 608 and / or the memory 610 may be integrated with the modem 606.

[0107] The processor 608 may obtain a timestamp from the counter 612, which may be integrated with the PMIC 614, so that the counter 612 can continue to record time when the wireless communication device 600 shuts down or reboots, which may trigger an exception event related to the modem 606. For example, the PMIC 614 may provide power for the counter 612 to keep track of time while the wireless communication device 600 is shut down (i.e., off), resetting, or rebooting. In some cases, the counter 612 may be based on a real-time clock (RTC), which may be integrated with the PMIC. When the wireless communication device 600 returns to a normal operating state or at least recovers from the exception event, the processor 608 may obtain a current timestamp from the counter 612 and compare the current timestamp to a timestamp stored with the RF exposure information to determine whether the timestamp is within a time window associated with the RF exposure limit. If the timestamp of the RF exposure information is within the time window (e.g., T1 in FIG. 5 ), the wireless communication device 600 may use the stored RF exposure information to determine a transmit power that complies with the RF exposure limit.

[0108] The application processor 616 may be a processor included with a system-on-chip (SoC). For example, the application processor 616 may run an operating system that provides a graphical environment for a user to access various applications (e.g., a web browser, a streaming application, a social media application, etc.). The file system memory 618 may store the operating system, applications, and various user data. In aspects, the memory 610 may be a non-volatile memory separate from the file system memory 618. In some cases, the application processor 616 and the file system memory 618 may store RF exposure information instead of or in addition to the processor 608 and the memory 610. Further, in some cases, the counter 612 may be implemented on the SoC. For example, a monotonically increasing global counter on the SoC may be used when determining timestamps. In some such cases, the counter on the SoC resets when the application processor 616 crashes or otherwise stops. In these cases, the RTC in the PMIC 614 may provide an advantage because the RTC will continue to count when the application processor 616 is disabled (e.g., due to a reboot, shutdown, etc.).

[0109] 7 is a signaling flow illustrating example operations for providing RF exposure continuity following an exception event according to an aspect of the present disclosure. At 702, the UE 120 may transmit a first signal to the BS 110 at a first transmit power based on RF exposure measurements time-averaged over a time window (e.g., time window T1 of FIG. 5). At 704, the UE 120 may periodically store RF exposure information associated with the time window. At 706, the UE 120 may encounter an exception event associated with the UE or modem (e.g., modem 606). For example, the UE 120 may reboot, causing the modem to power cycle. In some cases, the modem may crash or experience an error, for example, due to a software bug or overheating. At 708, the UE 120 may detect that an exception event has occurred, as described herein with respect to operation 400. At 710, the UE 120 may transmit a second signal at a second transmit power based at least in part on the stored RF exposure information in response to detecting the event, for example, as described with respect to operation 400 herein.

[0110] 8 shows a communications device 800 (e.g., UE 120) that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as those illustrated in FIG. 4. The communications device 800 includes a processing system 802 coupled to a transceiver 808 (e.g., a transmitter and / or a receiver). The transceiver 808 is configured to transmit and receive signals for the communications device 800 via an antenna 810, such as various signals as described herein. The processing system 802 may be configured to perform processing functions for the communications device 800, including processing signals to be received and / or transmitted by the communications device 800.

[0111] Processing system 802 includes a processor 804 coupled to a computer-readable medium / memory 812 via a bus 806. In some aspects, computer-readable medium / memory 812 is configured to store instructions (e.g., computer-executable code) that, when executed by processor 804, cause processor 804 to perform operation 400 illustrated in FIG. 4 or other operations for performing various techniques described herein for providing RF exposure continuity after an exception event. In some aspects, computer-readable medium / memory 812 stores code for transmitting 814, code for storing 816, and / or code for detecting 818. In some aspects, processing system 802 has circuitry 820 configured to implement the codes stored in computer-readable medium / memory 812. In some aspects, circuitry 820 is coupled to processor 804 and / or computer-readable medium / memory 812 via bus 806. For example, circuitry 820 includes circuitry for transmitting 822, circuitry for storing 824, and / or circuitry for detecting 826. In other aspects, the circuitry 820 is integrated with the processor 804 .

[0112] Exemplary Embodiments In addition to the various aspects described above, certain combinations of aspects are within the scope of the present disclosure, some of which are detailed below.

[0113] Aspect 1: A method of wireless communication by a user equipment (UE), comprising: transmitting a first signal at a first transmit power based on radio frequency (RF) exposure measurements time-averaged over a time window; storing RF exposure information associated with the time window; detecting that an exception event associated with the UE has occurred; and, in response to detecting the event, transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information.

[0114] Aspect 2. The method of aspect 1, wherein storing the RF exposure information comprises periodically storing the RF exposure information.

[0115] Aspect 3. The method of any one of aspects 1 or 2, wherein storing the RF exposure information includes storing the RF exposure information in a memory that is not susceptible to corruption from an exception event.

[0116] Aspect 4: The method of any one of aspects 1 to 3, wherein the step of storing the RF exposure information includes the steps of storing the RF exposure information with a timestamp corresponding to when a most recent time-averaged RF exposure measurement was generated and obtaining the timestamp from a counter that is not susceptible to exception events, and the step of transmitting the second signal includes the step of transmitting the second signal at a second transmit power based at least in part on the stored RF exposure information in response to determining that the timestamp of the RF exposure information is within the time window.

[0117] Aspect 5. The method of any one of aspects 1 to 4, wherein storing the RF exposure information includes storing the RF exposure information together with a check value comprising a cyclic redundancy check (CRC) remainder of the RF exposure information.

[0118] Aspect 6: The method of aspect 5, wherein the step of transmitting the second signal includes, in response to determining that the CRC of the RF exposure information matches the check value, transmitting the second signal at a second transmit power based on supplementing the time-averaged RF exposure measurement value over the current time window with the stored RF exposure information.

[0119] Aspect 7. The method of any one of aspects 1 to 6, wherein transmitting the second signal includes transmitting the second signal at a second transmit power based on supplementing the time-averaged RF exposure measurement with the stored RF exposure information.

[0120] Aspect 8. The method of aspect 7, wherein the step of transmitting the second signal includes the step of transmitting the second signal at a second transmit power based at least in part on the stored RF exposure information when at least one RF exposure measurement is missing from the current time window.

[0121] Example 9 The method of any one of examples 1 to 8, wherein the RF exposure information comprises a sum of the time-averaged RF exposure measurements or a separate value for each of the time-averaged RF exposure measurements.

[0122] Aspect 10. The method of any one of aspects 1 to 9, wherein the exception event includes at least one of an error, a reset, a crash, or a reboot that affects operation of the UE or a modem used in transmitting the first and second signals.

[0123] Embodiment 11 The method of any one of embodiments 1 to 10, wherein the time-averaged RF exposure measurements include at least one of a time-averaged specific absorption rate (SAR) or a time-averaged power density (PD).

[0124] Example 12. The method of any one of examples 1 to 11, wherein the sending of the second signal is based on a determination of a type of the exception event.

[0125] Aspect 13. An apparatus for wireless communication, comprising: a transmitter configured to transmit a first signal at a first transmit power based on radio frequency (RF) exposure measurements time-averaged over a time window; a memory; and a processor coupled to the memory, wherein the processor and memory are configured to store RF exposure information associated with the time window and detect that an exception event associated with the apparatus has occurred; and wherein the transmitter is further configured to transmit a second signal at a second transmit power based at least in part on the stored RF exposure information in response to detecting the event.

[0126]

[0033] Aspect 14

[0034] The apparatus of aspect 13, further comprising: a modem coupled to the transmitter and the processor, the modem configured to provide instructions for the first transmit power and the second transmit power to the transmitter.

[0127] Embodiment 15 The apparatus of any one of embodiments 13 or 14, wherein the processor and memory are further configured to periodically store the RF exposure information.

[0128]

[0033] Aspect 16. The apparatus of any one of aspects 13 to 15, wherein the memory is not susceptible to corruption from an exception event.

[0129] Aspect 17. The apparatus of any one of aspects 13 to 16, further including a counter configured to provide a timestamp and to be less susceptible to exception events, wherein the processor and memory are further configured to obtain the timestamp from the counter and store the RF exposure information with the timestamp corresponding to when the most recent time-averaged RF exposure information was generated, and wherein the transmitter is further configured to transmit a second signal at a second transmit power based at least in part on the stored RF exposure information in response to determining that the timestamp of the RF exposure information is within the current time window.

[0130]

[0042] Example 18. The apparatus of any one of Examples 13 to 17, further comprising a power management integrated circuit (PMIC), wherein the counter is integrated with the PMIC.

[0131] Embodiment 19 The apparatus of any one of embodiments 13 to 18, wherein the processor and memory are further configured to store the RF exposure information along with a check value comprising a cyclic redundancy check (CRC) remainder of the RF exposure information.

[0132] Aspect 20. The apparatus of aspect 19, wherein the transmitter is further configured to, in response to determining that the CRC of the RF exposure information matches the check value, transmit a second signal at a second transmit power based on supplementing the time-averaged RF exposure measurement over the current time window with the stored RF exposure information.

[0133] Embodiment 21 The apparatus of any one of embodiments 13 to 20, wherein the transmitter is further configured to transmit a second signal at a second transmit power based on supplementing the time-averaged RF exposure measurement with the stored RF exposure information.

[0134] Aspect 22. The apparatus of aspect 21, wherein the transmitter is further configured to transmit a second signal at a second transmit power based at least in part on the stored RF exposure information when at least one RF exposure measurement is missing from the current time window.

[0135] Embodiment 23 The apparatus of any one of embodiments 13 to 22, wherein the RF exposure information comprises a sum of time-averaged RF exposure measurements or a separate value for each of the time-averaged RF exposure measurements.

[0136] Aspect 24. The apparatus of any one of aspects 13 to 23, wherein the exception event includes at least one of an error, a reset, a crash, or a reboot that affects operation of the apparatus or a modem used in transmitting the first and second signals.

[0137] Embodiment 25. The apparatus of any one of embodiments 13 to 24, wherein the time-averaged RF exposure measurements include at least one of a time-averaged specific absorption rate (SAR) or a time-averaged power density (PD).

[0138]

[0042] Embodiment 26. The apparatus of embodiment 13, configured to perform the method of any one of embodiments 1 to 12.

[0139] Embodiment 27: An apparatus for wireless communication, comprising: means for transmitting a first signal at a first transmit power based on radio frequency (RF) exposure measurements time-averaged over a time window; means for storing RF exposure information associated with the time window; means for detecting that an exception event associated with the apparatus has occurred; and means for transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information in response to detecting the event.

[0140] Embodiment 28 The apparatus of embodiment 27, further including means for generating a timestamp, wherein the means for generating the timestamp is not susceptible to exception events; the means for storing the RF exposure information includes means for obtaining the timestamp from the means for generating the timestamp and means for storing the RF exposure information with a timestamp corresponding to when a most recent time-averaged RF exposure measurement is generated; and the means for transmitting a second signal includes means for transmitting the second signal at a second transmit power based at least in part on the stored RF exposure information if the timestamp of the RF exposure information is within the time window.

[0141] Embodiment 29. The apparatus of embodiment 27, comprising means for performing the method of any one of embodiments 1 to 13.

[0142] Aspect 30. A computer-readable medium storing computer-executable code for wireless communication that, when executed by at least one processor, causes an apparatus to perform the method of any one of aspects 1-12.

[0143]

[0033] Aspect 31. The method of any one of aspects 1 to 12, wherein transmitting the second signal at the second transmit power is based on a determination of a type of exception event.

[0144]

[0033] Aspect 32. The method of any one of aspects 1 to 12, wherein the step of transmitting the second signal at the second transmit power is based on a determination that transmission from the UE has stopped during a portion of time corresponding to the exception event.

[0145] Aspect 33. The apparatus of any one of aspects 13 to 26, wherein the processor and the memory are configured to determine a type of the exception event, and wherein the transmitter is configured to transmit the second signal at a second transmit power based on the determination.

[0146] Aspect 34. The apparatus of any one of aspects 13 to 26, wherein the processor and memory are configured to determine that transmission from the UE has stopped during a portion of time corresponding to an exception event, and the transmitter is configured to transmit a second signal at a second transmit power based on the determination.

[0147] Aspect 35: A method of wireless communication by a user equipment (UE), comprising: transmitting a first signal at a first transmit power based on radio frequency (RF) exposure measurements time-averaged over a time window; storing RF exposure information associated with the time window; detecting that an exception event associated with the UE has occurred; determining that a timestamp corresponding to a most recent time-averaged RF exposure measurement is not within a current time window or determining that a check value does not pass a cyclic redundancy check (CRC) of the RF exposure information; and transmitting a second signal at a second transmit power in a fail-safe mode based on the determination.

[0148]

[0072] Aspect 36. The method of aspect 35, comprising obtaining a timestamp from a counter that is not susceptible to exception events.

[0149]

[0041] Embodiment 37. The method of any one of embodiments 35 or 36, wherein the second transmit power is based on a transmit power or exposure that is greatest over a duration of a previous portion of a current time window.

[0150] Embodiment 38. The method of any one of embodiments 35 to 37, wherein the time-averaged RF exposure measurements over the current time window are not supplemented with stored RF exposure information in a fail-safe mode.

[0151] Aspect 39: An apparatus for wireless communication, comprising: a transmitter configured to transmit a first signal at a first transmit power based on radio frequency (RF) exposure measurements time-averaged over a time window; a memory; and a processor coupled to the memory, wherein the processor and memory are configured to store RF exposure information associated with the time window; detect that an exception event associated with the apparatus has occurred; determine that a timestamp corresponding to a most recent time-averaged RF exposure measurement is not within the current time window or determine that a check value does not pass a cyclic redundancy check (CRC) of the RF exposure information; and wherein the transmitter is configured to transmit a second signal at a second transmit power in a fail-safe mode based on the determination.

[0152] Aspect 40. An apparatus for wireless communications, comprising: means for transmitting a first signal at a first transmit power based on radio frequency (RF) exposure measurements time-averaged over a time window; means for storing RF exposure information associated with the time window; means for detecting that an exception event associated with the UE has occurred; means for determining that a timestamp corresponding to a most recent time-averaged RF exposure measurement is not within a current time window or determining that a check value does not pass a cyclic redundancy check (CRC) of the RF exposure information; and means for transmitting a second signal at a second transmit power in a fail-safe mode based on the determination.

[0153] The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP® Long Term Evolution (LTE), LTE-Advanced (LTE-A), code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA), time division synchronous code division multiple access (TD-SCDMA), and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers the IS-2000, IS-95, and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are parts of the Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is a new wireless communications technology under development.

[0154] In 3GPP, the term "cell" can refer to a coverage area of ​​a Node B (NB) and / or an NB subsystem serving this coverage area, depending on the context in which the term is used. In an NR system, the terms "cell" and BS, next-generation Node B (gNB or gNodeB), access point (AP), distributed unit (DU), carrier, or transmit reception point (TRP) may be used interchangeably. A BS may provide communication coverage for a macrocell, picocell, femtocell, and / or other types of cell and / or may be configured as a CPE. A macrocell may cover a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access by UEs with service subscriptions. A picocell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions. A femtocell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.). A BS for a macrocell may be referred to as a macro BS. A BS for a picocell may be referred to as a pico BS. A BS for a femtocell may be referred to as a femto BS or a home BS.

[0155] A UE may also be called and / or configured as a mobile station, terminal, access terminal, subscriber unit, station, CPE, cellular phone, smartphone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet computer, camera, gaming device, netbook, smartbook, ultrabook, appliance, medical device or equipment, biometric sensor / device, wearable device such as smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or vehicle sensor, smart meter / sensor, industrial manufacturing equipment, global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs may be considered machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC UEs and eMTC UEs include, for example, a robot, a drone, a remote device, a sensor, a meter, a monitor, a location tag, etc. that may communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

[0156] In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication between some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, the subordinate entities utilize the resources allocated by the scheduling entity. A base station is not the only entity that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and schedule resources for one or more subordinate entities (e.g., one or more other UEs), and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network and / or in a mesh network. In the example of a mesh network, UEs may communicate directly with each other in addition to communicating with the scheduling entity.

[0157] The methods disclosed herein include one or more steps or actions for achieving the method. The steps and / or actions of the methods may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0158] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to encompass a, b, c, ab, ac, bc, and abc, as well as any combination having multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other order of a, b, and c).

[0159] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, etc. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. Also, "determining" may include resolving, selecting, choosing, establishing, etc.

[0160] The above description is provided to enable any person skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Accordingly, the claims are not limited to the embodiments set forth herein but are to be accorded the full scope consistent with the language of the claims, and references to elements in the singular shall mean "one and only one," rather than "one or more," unless expressly stated otherwise. Unless expressly stated otherwise, the term "some" refers to one or more. All structural and functional equivalents of the elements of the various embodiments described throughout this disclosure that are known or later become known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is made public, regardless of whether such disclosure is expressly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112(f) unless the element is expressly recited using the phrase "means for," or, in the case of a method claim, unless the element is recited using the phrase "step for."

[0161] The various operations of the methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and / or software components and / or modules, including, but not limited to, circuits, application specific integrated circuits (ASICs), or processors. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components that are similarly numbered.

[0162] The various example logic blocks, modules, and circuits described in connection with this disclosure may be implemented or performed using a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0163] When implemented in hardware, an exemplary hardware configuration may comprise a processing system within a wireless node. The processing system may be implemented using a bus architecture. The bus may include any number of interconnected buses and bridges, depending on the particular application of the processing system and overall design constraints. The bus may link various circuits together, including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter to the processing system via the bus, among other things. The network adapter may be used to implement PHY layer signal processing functions. In the case of a user terminal (see FIG. 1 ), a user interface (e.g., keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, etc., which are well known in the art and therefore will not be described further. The processor may be implemented using one or more general-purpose and / or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits capable of executing software. Those skilled in the art will recognize how to best implement the described functionality for a processing system depending on the particular application and the overall design constraints imposed on the overall system.

[0164] If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Software shall be broadly construed to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. A processor may be responsible for general processing, including managing a bus and executing software modules stored on the machine-readable storage medium. The computer-readable storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral to the processor. By way of example, the machine-readable medium may include a transmission line, a carrier wave modulated by data, and / or a computer-readable storage medium having instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through a bus interface. Alternatively or additionally, the machine-readable medium, or any portion thereof, may be integrated into the processor, such as may be a cache and / or general-purpose register file. Examples of machine-readable storage media may include, by way of example, RAM (random access memory), flash memory, ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable medium may be embodied in a computer program product.

[0165] A software module may include a single instruction or many instructions and may be distributed across several different code segments, among different programs, and across multiple storage media. A computer-readable medium may include several software modules. A software module includes instructions that, when executed by a device such as a processor, cause a processing system to perform various functions. A software module may include a transmitting module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. As an example, a software module may be loaded into RAM from a hard drive when a trigger event occurs. During execution of a software module, a processor may load some of the instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general-purpose register file for execution by the processor. When referring below to the functionality of a software module, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

[0166] Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of medium. As used herein, disk and disc include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically while discs reproduce data optically using lasers. Thus, in some aspects, computer-readable medium may include non-transitory computer-readable medium (e.g., tangible media). In addition, for other aspects, computer-readable media may include transitory computer-readable media (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

[0167] Accordingly, some aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and / or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein, e.g., instructions for performing the operations described herein and illustrated in FIG. 4.

[0168] Furthermore, it should be appreciated that modules and / or other suitable means for performing the methods and techniques described herein may be downloaded and / or otherwise obtained by a user terminal and / or base station, where applicable. For example, such a device may be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, the various methods described herein may be provided via storage means (e.g., a physical storage medium such as RAM, ROM, a compact disc (CD), or a floppy disk) such that the user terminal and / or base station may obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device may be utilized.

[0169] It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims. [Explanation of symbols]

[0170] 100 Wireless Communication Networks 102a Macrocell 102b Macrocell 102c Macrocell 102x picocell 102y Femtocell 102z Femtocell 110 BS, Mobile BS 110a~110z BS 110r relay station 120 UE 120a~120y UE 122 RF Exposure Manager 130 Network Controller 132 Core Network 212 Data Sources 220 Transmit Processor, Processor 230 Transmit (TX) Multiple Input Multiple Output (MIMO) Processor, Processor 232 Transceiver 232a~232t Transceiver, Modulator Transceiver 234 Antenna 234a~234t antenna 236 MIMO detector 238 Receive Processor 239 Data Sink 240 Controllers / Processors 242 memory 244 Scheduler 252 Antenna 252a~252r Antenna 254 Transceiver 254a~254r transceiver 256 MIMO detector 258 Receive Processor 260 Data Sink 262 Data Sources 264 Transmit Processor, Processor 266 TX MIMO Processor, Processor 280 Controller / Processor 281 RF Exposure Manager 282 memory 300 RF transceiver circuits, transceivers 302 TX route 304 Receive (RX) Route 306 Antenna 308 Interface 310 Digital-to-Analog Converter (DAC) 312 Baseband Filter (BBF) 314 Mixer 316 Driver Amplifier (DA) 318 Power Amplifier (PA) 320 TX Frequency Synthesizer 322 Amplifier 324 Low Noise Amplifier (LNA) 326 Mixer 328 Baseband Filter (BBF) 330 Analog-to-Digital Converter (ADC) 332 RX Frequency Synthesizer 334 Amplifier 336 Controller 338 memory 400 operations 500 wireless communication devices 502 RF Exposure Measurement 600 Wireless Communication Devices 602 Transceiver 604 Antenna 606 modem 608 processor 610 memory 612 counters 614 PMIC 616 Application Processor 618 File System Memory 800 Communication Devices 802 Processing System 804 processor 806 Bus 808 Transceiver 810 Antenna 812 Computer-readable medium / memory 814 code to send 816 Code to Remember 818 Code to Detect 820 circuits 822 Transmitting Circuit 824 Memory Circuit 826 Circuit for detecting

Claims

1. 1. A method of wireless communication by a user equipment (UE), comprising: transmitting a first signal at a first transmit power based on a radio frequency (RF) exposure measurement time-averaged over a time window; storing RF exposure information associated with the time window; detecting that an exception event associated with the UE has occurred, the exception event including an event that results in a period of uncertainty regarding RF exposure of the UE; transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information in response to the detection of the exception event; A method comprising:

2. 10. The method of claim 1, wherein storing the RF exposure information comprises periodically storing the RF exposure information.

3. 2. The method of claim 1, wherein storing the RF exposure information comprises storing the RF exposure information in a memory that is not susceptible to corruption from the exception event.

4. storing the RF exposure information storing the RF exposure information along with a timestamp corresponding to when the most recent time-averaged RF exposure measurement was generated; obtaining the timestamp from a counter that is not susceptible to the exception event; Including, Transmitting the second signal includes, in response to determining that the timestamp of the RF exposure information is within a current time window, transmitting the second signal at the second transmit power based at least in part on the stored RF exposure information. The method of claim 1.

5. 10. The method of claim 1, wherein storing the RF exposure information comprises storing the RF exposure information along with a check value comprising a cyclic redundancy check (CRC) remainder of the RF exposure information.

6. 6. The method of claim 5, wherein transmitting the second signal comprises, in response to determining that the CRC of the RF exposure information matches the check value, transmitting the second signal at the second transmit power based on supplementing a time-averaged RF exposure measurement over a current time window with the stored RF exposure information.

7. 10. The method of claim 1, wherein transmitting the second signal comprises transmitting the second signal at the second transmit power based on supplementing a time-averaged RF exposure measurement with the stored RF exposure information.

8. 8. The method of claim 7, wherein transmitting the second signal comprises transmitting the second signal at the second transmit power based at least in part on the stored RF exposure information when at least one RF exposure measurement is missing from a current time window.

9. 10. The method of claim 1, wherein the RF exposure information comprises a sum of the time-averaged RF exposure measurements or a separate value for each of the time-averaged RF exposure measurements.

10. 2. The method of claim 1, wherein the exception event includes at least one of an error, a reset, a crash, or a reboot that affects operation of the UE or a modem used in transmitting the first and second signals.

11. 10. The method of claim 1, wherein the time-averaged RF exposure measurements include at least one of a time-averaged specific absorption rate (SAR) or a time-averaged power density (PD).

12. The method of claim 1 , wherein the sending of the second signal is based on a determination of a type of the exception event.

13. An apparatus for wireless communication a transmitter configured to transmit a first signal at a first transmit power based on a radio frequency (RF) exposure measurement time-averaged over a time window; Memory and a processor coupled to the memory; wherein the processor and the memory storing RF exposure information associated with the time window; Detecting that an exception event associated with the device has occurred, the exception event including an event that results in a time period of uncertainty regarding RF exposure of the UE; configured to: The apparatus, wherein the transmitter is further configured to, in response to the detection of the exception event, transmit a second signal at a second transmit power based at least in part on the stored RF exposure information.

14. 14. The apparatus of claim 13, further comprising a modem coupled to the transmitter and the processor, the modem configured to provide instructions to the transmitter for the first transmit power and the second transmit power.

15. 14. The apparatus of claim 13, wherein the processor and the memory are further configured to periodically store the RF exposure information.

16. The apparatus of claim 13 , wherein the memory is not susceptible to corruption from the exception event.

17. a counter configured to provide a timestamp and to be immune to said exception event; the processor and the memory obtaining the timestamp from the counter; storing the RF exposure information along with the timestamp corresponding to when the most recent time-averaged RF exposure measurement was generated; further configured as follows: the transmitter is further configured, in response to determining that the timestamp of the RF exposure information is within a current time window, to transmit the second signal at the second transmit power based at least in part on the stored RF exposure information.

14. The apparatus of claim 13.

18. 20. The apparatus of claim 17, further comprising a power management integrated circuit (PMIC), wherein the counter is integrated with the PMIC.

19. 14. The apparatus of claim 13, wherein the processor and the memory are further configured to store the RF exposure information along with a check value comprising a cyclic redundancy check (CRC) remainder of the RF exposure information.

20. 20. The apparatus of claim 19, wherein the transmitter is further configured, in response to determining that the CRC of the RF exposure information matches the check value, to transmit the second signal at the second transmit power based on supplementing a time-averaged RF exposure measurement over a current time window with the stored RF exposure information.

21. 14. The apparatus of claim 13, wherein the transmitter is further configured to transmit the second signal at the second transmit power based on supplementing a time-averaged RF exposure measurement with the stored RF exposure information.

22. 22. The apparatus of claim 21, wherein the transmitter is further configured to transmit the second signal at the second transmit power based at least in part on the stored RF exposure information when at least one RF exposure measurement is missing from the time window.

23. 14. The apparatus of claim 13, wherein the RF exposure information comprises a sum of the time-averaged RF exposure measurements or a separate value for each of the time-averaged RF exposure measurements.

24. 14. The apparatus of claim 13, wherein the exception event comprises at least one of an error, a reset, a crash, or a reboot affecting operation of the apparatus or a modem used in transmitting the first and second signals, and wherein the time-averaged RF exposure measurements comprise at least one of a time-averaged specific absorption rate (SAR) or a time-averaged power density (PD).

25. 14. The apparatus of claim 13, wherein the processor and the memory are configured to determine that transmission from the UE has stopped during a portion of time corresponding to the exception event, and the transmitter is configured to transmit the second signal at the second transmit power based on the determination.

26. An apparatus for wireless communication means for transmitting a first signal at a first transmit power based on a radio frequency (RF) exposure measurement time-averaged over a time window; means for storing RF exposure information associated with said time window; means for detecting that an exception event associated with the device has occurred, the exception event including an event that results in a period of uncertainty in RF exposure of the UE; means for transmitting a second signal at a second transmit power based at least in part on the stored RF exposure information in response to the detection of the exception event; 1. An apparatus comprising:

27. 1. A method of wireless communication by a user equipment (UE), comprising: transmitting a first signal at a first transmit power based on a radio frequency (RF) exposure measurement time-averaged over a time window; storing RF exposure information associated with the time window; detecting that an exception event associated with the UE has occurred, the exception event including an event that results in a period of uncertainty regarding RF exposure of the UE; determining that a timestamp corresponding to a most recent time-averaged RF exposure measurement is not within a current time window or that a test value does not pass a cyclic redundancy check (CRC) of the RF exposure information; transmitting a second signal at a second transmit power in a fail-safe mode based on the determination, wherein the fail-safe mode uses RF exposure limits that are lower than standard RF exposure limits; A method comprising:

28. 28. The method of claim 27, comprising obtaining the timestamp from a counter that is not susceptible to the exception event.

29. 28. The method of claim 27, wherein the second transmit power is based on a transmit power or exposure that is greatest over a duration of a previous portion of the current time window.

30. 28. The method of claim 27, wherein time-averaged RF exposure measurements over the current time window are not supplemented with the stored RF exposure information in the fail-safe mode.

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