Time-averaged radio frequency (RF) exposure over an organization and / or body location

Abstract

Certain aspects of the present disclosure provide techniques for operating a wireless communication device in accordance with radio frequency (RF) exposure over an organization and / or body location. Exemplary methods of wireless communication by a wireless device generally include tracking multiple RF exposures over time across multiple locations associated with a human body. The method further includes transmitting a signal at a transmit power determined at least in part based on a time-averaged RF exposure limit and the tracked RF exposure.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit and priority of U.S. Application No. 18 / 326,822, filed May 31, 2023, which claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 365,696, filed Jun. 1, 2022, the entire contents of which are incorporated herein by reference.

Background Art

[0002] Field of Disclosure Aspects of the present disclosure relate to wireless communication and, more particularly, to radio frequency (RF) exposure over an organizational and / or body location.

[0003] Description of Related Art Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, etc. Modern wireless communication devices (such as cellular phones) generally need to meet the radio frequency (RF) exposure limits set by national and international standards and regulations. To ensure compliance with the standards, such devices are currently subject to an extensive authentication process before being shipped to the market. To ensure that wireless communication devices comply with RF exposure limits, techniques have been developed that enable wireless communication devices to assess RF exposure from the device and adjust the transmission power of the wireless communication device accordingly to comply with the RF exposure limits.

Summary of the Invention

[0004] The systems, methods, and devices of the present disclosure each have several aspects, none of which alone serves a role for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the following claims, several features are described herein briefly. After considering this description, and particularly after reading the section entitled "DETAILED DESCRIPTION", those skilled in the art will understand how the features of the present disclosure provide advantages, including, for example, evaluating radio frequency (RF) exposure over tissue and / or body locations for each exposure scenario and / or category.

[0005] Some aspects provide a method of wireless communication by a wireless device. The method includes tracking over time a plurality of RF exposures over a plurality of locations associated with a human body. The method further includes transmitting a signal with a transmit power determined at least in part based on a time-averaged RF exposure limit and the tracked RF exposure.

[0006] Some aspects provide an apparatus for wireless communication. The apparatus includes a memory and a processor coupled to the memory. The processor is configured to track over time a plurality of RF exposures over a plurality of locations associated with a human body and to transmit a signal with a transmit power determined at least in part based on a time-averaged RF exposure limit and the tracked RF exposure.

[0007] Some aspects provide an apparatus for wireless communication. The apparatus includes means for tracking over time a plurality of RF exposures over a plurality of locations associated with a human body and means for transmitting a signal with a transmit power determined at least in part based on a time-averaged RF exposure limit and the tracked RF exposure.

[0008] Some aspects provide a non-transitory computer-readable recording medium. The computer-readable recording medium stores instructions that, when executed by a device, cause the device to implement a method. The method includes tracking over time a plurality of RF exposures across a plurality of locations associated with a human body. The method further includes transmitting a signal at a transmission power determined at least in part based on a time-averaged RF exposure limit and the tracked RF exposure.

[0009] To achieve the above object and related objects, one or more aspects include features that are fully described below and particularly pointed out in the claims. The following description and the accompanying drawings detail certain illustrative features of one or more aspects. However, these features are only a small part of the various ways in which the principles of the various aspects can be employed.

[0010] To better understand the above-described features of the present disclosure, a more specific description, briefly summarized above, can be obtained by referring to aspects shown in the drawings. However, it should be noted that the accompanying drawings show only certain exemplary aspects of the present disclosure and, therefore, the description should not be considered as limiting the scope of the present disclosure as it can be incorporated into other equally effective aspects.

Brief Description of the Drawings

[0011]

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[0012] For ease of understanding, as far as possible, the same reference numerals are used to designate the same elements common to the figures. It is intended that elements disclosed in one aspect can be beneficially utilized in other aspects without being specifically detailed.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Aspects of the present disclosure provide an apparatus, a method, a processing system, and a computer-readable recording medium for complying with radio frequency (RF) exposure limits. The RF exposure may be determined and / or tracked across different tissues and / or locations of a user's body. Certain examples comply with RF exposure limits for one or more exposure scenarios and / or exposure categories.

[0014] In some cases, a wireless communication device may evaluate a time-averaged RF exposure over a time window when the wireless communication device encounters different exposure scenarios during that time window. For example, during a first portion of the time window, the wireless communication device may be in a head exposure scenario (e.g., exp1), and during a second portion of the time window, the wireless communication device may be in a body-worn exposure scenario (e.g., exp2). In these cases, the different exposures may be correlated over the time window of the time-averaged RF exposure limit such that the different exposures are evaluated in the same time-averaging function (e.g., f(exp1, exp2, t)) for determining an available transmit power margin. Such a technique for determining an available transmit power margin may result in a degradation of wireless communication performance, for example, due to applying the same RF exposure settings to the time-averaging function despite different RF exposure scenarios.

[0015] Aspects of the present disclosure provide techniques and apparatus for evaluating time-averaged RF exposure for each RF exposure scenario and / or RF exposure category. When the exposure scenario changes from head to body-worn or vice versa, for example, due to exposure from an active radio, the same tissue may not be exposed to RF energy, and thus, a wireless communication device may or may not take into account the change in the exposure scenario when evaluating time-averaged RF exposure compliance. As an example, in some configurations, the time-averaged RF exposure encountered in a head exposure scenario may be evaluated separately from the time-averaged RF exposure encountered in a limb exposure scenario, such that an RF exposure history for each RF exposure scenario is tracked and / or assessed separately, as further described herein. RF exposure time averaging may be performed for each exposure scenario or exposure category that may include one or more exposure scenarios, as further described herein.

[0016] The apparatus and techniques for implementing RF exposure compliance (e.g., for each exposure scenario / category) described herein may enable a desired transmit power for a particular radio, antenna, and / or antenna group, for example, due to the different exposures each encounters. The desired transmit power may provide desired wireless communication performance, such as an increase in data rate, a reduction in latency, and / or an increase in transmission range.

[0017] The following description provides examples of RF exposure compliance in a communication system and is not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made to the functions and arrangements of the described elements without departing from the scope of the disclosure. Various embodiments may omit, replace, or add various procedures or components as necessary. For example, the described method 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 embodiments can be combined with those of some other embodiments. For example, an apparatus may be implemented or a method may be practiced using any number of aspects described herein. Additionally, the scope of the disclosure is intended to cover such apparatuses or methods practiced using other structures, functions, or structures and functions in addition to or other than the various aspects of the disclosure described herein. It should be understood that any aspect of the disclosure disclosed herein can be embodied by one or more elements of the claims. The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" should not necessarily be construed as preferred or advantageous over other aspects.

[0018] In general, any number of wireless networks can be deployed in a given geographical area. Each wireless network can support a particular radio access technology (RAT) and operate on one or more frequencies. RATs may also be referred to as wireless technologies, air interfaces, etc. Frequencies may also be referred to as carriers, subcarriers, frequency channels, tones, subbands, etc. Each frequency may support a single RAT or multiple RATs in a given geographical area to avoid interference between wireless networks of different RATs.

[0019] The techniques described in this specification can be used in various wireless networks and wireless technologies. Although aspects may be described herein using terms commonly associated with 3G, 4G, and / or new radio (e.g., 5G NR) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems and / or to wireless technologies such as 802.11, 802.15, etc.

[0020] NR access can support various wireless communication services such as enhanced mobile broadband (eMBB) targeting wide bandwidths (e.g., 80 MHz or more), millimeter wave (mmWave) targeting high carrier frequencies (e.g., from 24 GHz to 53 GHz or more), massive machine type communications MTC (mMTC) 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 can be dynamically configured. Multiple-input, multiple-output (MIMO) transmission using precoding is supported and multi-layer transmission may also be supported. Aggregation of multiple cells may be supported.

[0021] Exemplary Wireless Communication Networks and Devices FIG. 1 shows an exemplary wireless communication network 100 in which aspects of the present disclosure may be implemented. For example, the wireless communication network 100 may be a New Radio (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 according to an IEEE standard, such as one or more of the 802.11 standards. As shown in FIG. 1, UE 120a includes an RF exposure manager 122 that enforces RF exposure compliance (for each exposure scenario / category), as further described herein with respect to FIGS. 11-20. In some examples, RF exposure is managed among mutually exclusive antenna groups assigned to a particular exposure scenario / category in accordance with aspects of the present disclosure.

[0022] As shown in FIG. 1, the wireless communication network 100 may include several base stations (BSs) 110a-110z (each is also individually referred to as BS 110 or collectively as BSs 110 herein), and other network entities. BS 110 can provide communication coverage to a specific geographic area, sometimes called a "cell", which may be stationary or may move according to the location of a mobile BS. In some examples, BSs 110 are interconnected via various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.) using any suitable transport network, and / or may be interconnected to one or more other BSs or network nodes (not shown) within the wireless communication network 100. In the example shown in FIG. 1, BSs 110a, 110b, and 110c may be macro BSs of macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS of pico cell 102x. BSs 110y and 110z may be femto BSs of femto cells 102y and 102z, respectively. A BS may support one or more cells.

[0023] BSs 110 communicate with UEs 120a-120y (each is also individually referred to as UE 120 or collectively as UEs 120 herein) within the wireless communication network 100. UEs 120 (e.g., 120x, 120y, etc.) may be distributed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. The wireless communication network 100 may also include a relay station (e.g., relay station 110r), which is also called a relay, etc., receives the transmission of data and / or other information from an upstream station (e.g., BS 110a or UE 120r), and sends the transmission of data and / or other information to a downstream station (e.g., UE 120 or BS 110), or relays the transmission between UEs 120 to facilitate communication between devices.

[0024] The network controller 130 can communicate with a set of BSs 110 and 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 can communicate with a core network 132 (5G Core Network, 5GC) that provides various network functions, such as access and mobility management, session management, user plane function, policy control function, authentication server function, integrated data management, application function, network exposure function, network repository function, network slice selection function, etc.

[0025] FIG. 2 shows exemplary components of BS110a and UE120a (e.g., the wireless communication network 100 of FIG. 1) that can be used to implement aspects of the present disclosure.

[0026] In BS110a, the transmission processor 220 can receive data from the data source 212 and control information from the controller / processor 240. The control information can be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data can be for the physical downlink shared channel (PDSCH), etc. The medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that can be used for the exchange of control commands between wireless nodes. The MAC-CE can be carried within a shared channel such as the PDSCH, physical uplink shared channel (PUSCH), or physical sidelink shared channel (PSSCH).

[0027] Processor 220 can process data and control information (e.g., encoding and symbol mapping) to obtain data symbols and control symbols respectively. The transmit processor 220 can also generate reference symbols for, e.g., 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 can perform spatial processing (e.g., precoding) on data symbols, control symbols, and / or reference symbols, if applicable, and provide an output symbol stream to the modulators (MODs) within transceivers 232a - 232t. Each modulator within transceivers 232a - 232t can process its respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each of transceivers 232a - 232t can further process the output sample stream (e.g., analog conversion, amplification, filtering, and upconversion) to obtain a downlink signal. The downlink signals from transceivers 232a - 232t can be transmitted via antennas 234a - 234t respectively.

[0028] In UE120a, antennas 252a to 252r may receive downlink signals from BS110a and may provide the received signals to transceivers 254a to 254r respectively. Transceivers 254a to 254r may each adjust (e.g., filter, amplify, down-convert, and digitize) the respective received signals to obtain input samples. Each demodulator (DEMOD) within transceivers 232a to 232t may further process the input samples (e.g., for OFDM etc.) to obtain received symbols. MIMO detector 256 may obtain received symbols from all demodulators within transceivers 254a to 254r, perform MIMO detection on the received symbols if applicable, and provide the detected symbols. Receiving processor 258 may process the detected symbols (e.g., demodulate, de-interleave, and decode), provide the decoded data for UE120a to data sink 260, and provide the decoded control information to controller / processor 280.

[0029] On the uplink, in UE120a, transmission processor 264 may receive and process data from data source 262 (e.g., for the physical uplink shared channel (PUSCH)) and control information from controller / processor 280 (e.g., for the physical uplink control channel (PUCCH)). Transmission processor 264 may also generate reference symbols for reference signals (e.g., for the sounding reference signal (SRS)). Symbols from transmission processor 264 may be precoded by TX MIMO processor 266, if applicable, and further processed by modulators (MODs) within transceivers 254a - 254r (e.g., for SC - FDM) and transmitted to BS110a. At BS110a, the uplink signal from UE120a is received by antenna 234, processed by demodulators within transceivers 232a - 232t, detected by MIMO detector 236, if applicable, and further processed by receive processor 238 to obtain the decoded data and control information sent by UE120a. Receive processor 238 may provide the decoded data to data sink 239 and the decoded control information to controller / processor 240.

[0030] Memories 242 and 282 may store data and program code for BS110a and UE120a, respectively. Scheduler 244 may schedule the UE for data transmission on the downlink and / or uplink.

[0031] The antenna 252, processors 266, 258, 264, and / or controller / processor 280 of UE120a, and / or the antenna 234, processors 220, 230, 238, and / or controller / processor 240 of BS110a may be used to implement the various techniques and methods described herein. As shown in FIG. 2, the controller / processor 280 of UE120a has an RF exposure manager 281 that enforces RF exposure compliance. In some examples, according to the aspects described herein, RF exposure is achieved among mutually exclusive antenna groups assigned to specific exposure scenarios / categories. Although shown in the controller / processor, other components of UE120a and BS110a may be used to implement the operations described herein.

[0032] NR may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on both the uplink and downlink. NR may support half-duplex operation using time division duplexing (TDD). OFDM and single-carrier frequency division multiplexing (SC-FDM) divide the system bandwidth into a plurality of orthogonal subcarriers, which are generally also referred to as tones, bins, etc. Each subcarrier may be modulated with data. Modulation symbols may be sent using OFDM in the frequency domain and SC-FDM in the time domain. 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 divided into subbands. For example, a subband may cover a plurality of resource blocks (RBs).

[0033] Regarding FIGS. 1 and 2, UE120a is described as communicating with the BS and / or within the network. However, UE120a can be configured to communicate directly with another UE120 / transmit directly to another UE120, or communicate directly with another wireless device / transmit directly to another wireless device without relaying the communication through the network. In some aspects, BS110a shown in FIG. 2 and described above is an example of another UE120.

[0034] Exemplary RF transceiver FIG. 3 is a block diagram of an exemplary RF transceiver circuit 300 according to certain aspects of the present disclosure. The RF transceiver circuit 300 includes at least one transmit (TX) path 302 (also referred to as a transmit chain) for transmitting signals via one or more antennas 306, and at least one receive (RX) path 304 (also referred to as a receive chain) for receiving signals via the antennas 306. When the TX path 302 and the RX path 304 share the antenna 306, these paths can be connected to the antenna via an interface 308 that can include any of various suitable RF devices such as switches, duplexers, diplexers, multiplexers, etc.

[0035] The TX path 302 that receives an in-phase (I) or quadrature (Q) baseband analog signal from a digital-to-analog converter (DAC) 310 can 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 can be included within one or more radio frequency integrated circuits (RFICs). The PA 318 can be external to the RFIC(s) in some implementations.

[0036] BBF312 filters the baseband signal received from DAC310, and mixer 314 mixes the filtered baseband signal with a transmit local oscillator (LO) signal to convert the target baseband signal to a different frequency (e.g., up-convert from baseband to radio frequency). This frequency conversion process generates a sum frequency and a difference frequency between the LO frequency and the frequency of the target baseband signal. The sum frequency and the difference frequency are called beat frequencies. Since the beat frequencies are generally within the RF range, the signal output by mixer 314 is generally an RF signal and can be amplified by DA316 and / or PA318 before being transmitted by antenna 306. Although one mixer 314 is shown, several mixers can be used to up-convert the filtered baseband signal to one or more intermediate frequencies and then up-convert the intermediate frequency signal to the frequency for transmission.

[0037] RX path 304 may include a low noise amplifier (LNA) 324, a mixer 326, and a baseband filter (BBF) 328. LNA 324, mixer 326, and BBF 328 may be included within one or more RFICs, and the one or more RFICs may or may not be the same RFIC that includes the TX path components. The RF signal received via antenna 306 is amplified by LNA 324, and mixer 326 can mix the amplified RF signal with a receive local oscillator (LO) signal to convert the target RF signal to a different baseband frequency (e.g., down-convert). The baseband signal output by mixer 326 can be filtered by BBF 328 before being converted to a digital I or Q signal by an analog-to-digital (ADC) 330 for digital signal processing.

[0038] A particular transceiver may employ a frequency synthesizer with a voltage-controlled oscillator (VCO) to generate a stable, tunable LO with a particular tuning range. Thus, the transmit LO may be generated by the TX frequency synthesizer 320 and may be buffered or amplified by the amplifier 322 before being mixed with the baseband signal in the mixer 314. Similarly, the receive LO may be generated by the RX frequency synthesizer 332 and may be buffered or amplified by the amplifier 334 before being mixed with the RF signal in the mixer 326.

[0039] 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 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 gates or transistor logic, discrete hardware components, or any combination thereof. The memory 338 may store data and program code for operating the RF transceiver circuit 300. The controller 336 and / or the memory 338 may include control logic. In some cases, the controller 336 may determine the time-averaged RF exposure based on the transmit power level applied to the TX path 302 (e.g., a certain level of gain in the PA 318) to set the transmit power level that complies with the RF exposure limits defined by domestic regulations and international standards, as further described herein.

[0040] Exemplary RF Exposure RF exposure can be measured as the energy absorption per unit mass by human tissue and can be expressed in units of specific absorption rate (SAR) which can have units of watts per kilogram (W / kg). RF exposure can also be measured as the energy absorption per unit area and can be expressed in units of power density (PD) which can have units of mW / cm 2 . It may be the case that for wireless communication devices using transmission frequencies above 6 GHz, maximum permissible exposure (MPE) limits are imposed in PD units. The MPE limits are regulatory standards for area-based exposure, e.g., an energy density limit defined as a numerical value X of watts per square meter (W / m 2 ) averaged over a defined area and time-averaged over a frequency-dependent time window to prevent the risk of human exposure represented by tissue temperature changes.

[0041] SAR can be used to assess RF exposure for 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), IEEE802.11ac. PD can be used to assess RF exposure for transmission frequencies higher than 6 GHz covering wireless communication technologies such as IEEE802.11ad, 802.11ay, 5G in the millimeter wave band. Thus, various metrics can be used to assess the RF exposure of different wireless communication technologies.

[0042] A wireless communication device (e.g., UE120) may transmit signals simultaneously using multiple wireless communication technologies. For example, the wireless communication device may transmit signals simultaneously using a first wireless communication technology operating below 6 GHz (e.g., 3G, 4G, 5G, etc.) and a second wireless communication technology operating above 6 GHz (e.g., millimeter wave 5G within the 24 - 60 GHz band, IEEE802.11ad or 802.11ay). In some aspects, the wireless communication device may transmit signals simultaneously using a first wireless communication technology (e.g., 3G, 4G, 5G within the sub - 6 GHz band, IEEE802.11ac, etc.) where RF exposure is measured in SAR units and a second wireless communication technology (e.g., 5G within the 24 - 60 GHz band, IEEE802.11ad, 802.11ay, etc.) where RF exposure is measured in PD units. As used herein, the sub - 6 GHz band may, in some examples, include a frequency band of 300 - 6000 MHz, and in some examples, may include a band within the range of 6000 MHz and / or 7000 MHz.

[0043] To assess the RF exposure from transmissions using a first technology (e.g., 3G, 4G, 5G within the sub - 6 GHz band, IEEE802.11ac, etc.), the wireless communication device may include a plurality of SAR values and / or distributions for the first technology stored in a memory (e.g., memory 282 of FIG. 2 or memory 338 of FIG. 3). Each of the SAR values and / or distributions may correspond to one of a plurality of transmission scenarios supported by the wireless communication device for the first technology. The transmission scenarios may correspond to various combinations of an antenna (e.g., antennas 252a - 252r of FIG. 2 or antenna 306 of FIG. 3), frequency band, channel, and / or body position, as further described below. In some examples, the stored SAR includes a single value (e.g., a peak value determined based on the following description, or the sum of peak values).

[0044] The SAR value and / or distribution (also referred to as a SAR map) for each transmission scenario can be generated based on measurements (e.g., E-field measurements) performed at a test laboratory using a model of the human body. After being generated, they are stored in memory to enable a processor (e.g., processor 280 of FIG. 2 or controller 336 of FIG. 3) to assess RF exposure in real time, as further described below. Each SAR distribution may include a set of SAR values, and each SAR value may correspond to a different location (e.g., on a model of the human body). Each SAR value may include the SAR value averaged over a 1 g or 10 g mass at each respective location.

[0045] The SAR values within each SAR distribution correspond to a particular transmission power level (e.g., the transmission power level used when the SAR values were measured in the test laboratory). Since SAR scales with the transmission power level, the processor can scale the SAR value or distribution for any transmission power level by multiplying each SAR value (e.g., within the SAR distribution) by the following transmission power scaler.

Number

[0046] As described above, the wireless communication device may support multiple transmission scenarios for a first technology. In some embodiments, the transmission scenario may be specified by a set of parameters. The set of parameters may include, for example, antenna parameters indicating one or more antennas (i.e., active antennas) used for transmission, frequency band parameters indicating one or more frequency bands (i.e., active frequency bands) used for transmission, channel parameters indicating one or more channels (i.e., active channels) used for transmission, body position parameters indicating the location of the wireless communication device relative to the user's body location (such as head, torso, away from the body, etc.) (e.g., device state index (DSI)), exposure category, and / or one or more of other parameters. When the wireless communication device supports a large number of transmission scenarios, it may be very time-consuming and costly to perform measurements for each transmission scenario within a test setup (e.g., a test laboratory). To shorten the test time, the measurements may be performed on a subset of the transmission scenarios to generate SAR values and / or distributions for the subset of the transmission scenarios. In this example, the SAR values and / or distributions for each of the remaining transmission scenarios may be generated by combining two or more of the SAR values and / or distributions for the subset of the transmission scenarios, as further described below.

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

[0049] In some aspects, the SAR distribution may be normalized with respect to the SAR limit by dividing each SAR value within the SAR distribution by the SAR limit. In this case, 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 SAR distribution stored in memory may be normalized with respect to the SAR limit. Similarly, a single or individual SAR value may be normalized with respect to the SAR limit.

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

Equation

[0051] Equation (2) can be rewritten as follows.

Number

Number

[0052] In another example, the normalized SAR values or distributions for different frequency bands can be stored in memory. In this example, the normalized SAR distribution for a transmission scenario where two or more frequency bands are active can be generated by combining the normalized SAR distributions for those two or more active frequency bands. If the transmission power levels for the active frequency bands are different, the normalized SAR values or distributions for each of those active frequency bands can be scaled by their respective transmission power levels before combining the normalized SAR values or distributions for those active frequency bands. In this example, the combined SAR value or distribution may also be calculated using Equation (3a), where i is the index for the active frequency band, and SAR norm_i is the normalized SAR value or distribution for the i-th active frequency band, Tx iis the transmission power level for the i-th active frequency band, Tx SARi is the transmission power level for the normalized SAR value or distribution for the i-th active frequency band.

[0053] To assess RF exposure from transmissions using a second technology (e.g., 5G, IEEE802.11ad, 802.11ay, etc. in the 24 - 60 GHz band), a wireless communication device may include a plurality of PD values and / or distributions for the second technology stored in a memory (e.g., memory 282 of FIG. 2 or memory 338 of FIG. 3). Each PD value or distribution may correspond to one of a plurality of 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 252a - 252r of FIG. 2 or antenna 306 of FIG. 3), frequency bands, channels, and / or body positions, as further described below. In some examples, the stored PDs may include a single value (e.g., a peak value determined based on the following description, or the sum of peak values).

[0054] The PD values and / or distributions (also referred to as PD maps) for each transmission 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 being generated, they are stored in a memory so that a processor (e.g., processor 280 of FIG. 2 or controller 336 of FIG. 3) can assess RF exposure in real time, as further described below. Each PD distribution may include a set of PD values, and each PD value may correspond to a different location (e.g., on a model of the human body).

[0055] The PD values within each PD distribution correspond to a specific transmission power level (e.g., the transmission power level used when the PD values were measured in the test laboratory). Since PD scales with the transmission power level, the processor may scale the PD values or distributions for any transmission power level by multiplying each PD value (e.g., within a PD distribution) by the following transmission power scaler. [Number] In the formula, Tx c is the current transmission power level for each transmission scenario, and Tx PD is the transmission power level corresponding to the PD value (for example, the transmission power level used when the PD value is measured in a test laboratory).

[0056] As described above, the wireless communication device may support multiple transmission scenarios for a second technology. In some embodiments, the transmission scenario may be specified by a set of parameters. The set of parameters may include, for example, antenna parameters indicating one or more antennas (i.e., active antennas) used for transmission, frequency band parameters indicating one or more frequency bands (i.e., active frequency bands) used for transmission, channel parameters indicating one or more channels (i.e., active channels) used for transmission, body position parameters (e.g., DSI) indicating the location of the wireless communication device relative to the user's body location (such as head, torso, away from the body, etc.), exposure categories, and / or one or more of other parameters. When the wireless communication device supports a large number of transmission scenarios, it may be very time-consuming and costly to perform measurements for each transmission scenario within a test setup (e.g., a test laboratory). To shorten the test time, the measurements may be performed on a subset of the transmission scenarios to generate PD values and / or distributions for the subset of the transmission scenarios. In this example, the PD value and / or distribution for each of the remaining transmission scenarios may be generated by combining two or more of the PD values and / or distributions for the subset of the transmission scenarios, as further described below.

[0057] For example, PD measurements can be performed for each of the antennas to generate PD values or distributions for each of the antennas. In this example, the PD value or distribution for a transmission scenario in which two or more of the antennas are active can be generated by combining the PD values or distributions for those two or more active antennas.

[0058] In another example, PD measurements can be performed for each of a plurality of frequency bands to generate PD values or distributions for each of the plurality of frequency bands. In this example, the PD value or distribution for a transmission scenario in which two or more of the frequency bands are active can be generated by combining the PD values or distributions for those two or more active frequency bands.

[0059] In some aspects, the PD distribution can be normalized with respect to a PD limit by dividing each PD value within the PD distribution by the PD limit. In this case, the 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 aspects, each of the PD distributions stored in memory can be normalized with respect to the PD limit. Similarly, a single or individual PD value can be normalized with respect to the PD limit.

[0060] In some aspects, the normalized PD value or distribution for a transmission scenario can be generated by combining two or more normalized PD values or distributions. For example, the normalized PD value or distribution for a transmission scenario in which two or more antennas are active can be generated by combining the normalized PD values or distributions for those two or more active antennas. If different transmission power levels are used for the active antennas, the normalized PD value or distribution for each active antenna can be scaled by its respective transmission power level before combining the normalized PD values or distributions for those active antennas. The normalized PD value or distribution for simultaneous transmission from a plurality of active antennas can be given as follows.

Number

[0061] Equation (5) can be rewritten as follows.

Number

Number

[0062] In another example, the normalized PD values or distributions for different frequency bands can be stored in memory. In this example, the normalized PD values or distributions for a transmission scenario where two or more frequency bands are active can be generated by combining the normalized PD distributions for those two or more active frequency bands. If the transmission power levels for the active frequency bands are different, the normalized PD values or distributions for each of those active frequency bands can be scaled by their respective transmission power levels before combining the normalized PD values or distributions for those active frequency bands. In this example, the combined PD value or distribution may also be calculated using Equation (6a), where i is an index for the active frequency band, PD norm_i is the normalized PD value or distribution for the i-th active frequency band, Tx i is the transmission power level for the i-th active frequency band, and Tx PDi is the transmission power level for the normalized PD value or distribution for the i-th active frequency band.

[0063] Exemplary RF Exposure Combinations As described above, the UE 120 simultaneously transmits signals using a first technology (e.g., 3G, 4G, IEEE802.11ac, etc.) and a second technology (e.g., 5G, IEEE802.11ad, etc.), where RF exposure can be measured using various metrics for the first technology (e.g., SAR in the case of the first technology) and the second technology (e.g., PD in the case of the second technology). In this case, the processor 280 can determine a first maximum allowable power level for the first technology and a second maximum allowable power level for the second technology that comply with the RF exposure limit for transmission in a future time slot. During the future time slot, the transmission power levels for the first and second technologies are constrained (i.e., limited) by the first and second maximum allowable power levels determined respectively to ensure compliance with the RF exposure limit, as further described below. In the present disclosure, the term "maximum allowable power level" refers to the "maximum allowable power level" imposed by the RF exposure limit, unless otherwise stated. It should be understood that the "maximum allowable power level" is not necessarily equal to the absolute maximum power level that complies with the RF exposure limit and may be less than the absolute maximum power level that complies with the RF exposure limit (e.g., to provide a safety margin). The "maximum allowable power level" can be used to set the power level limit for transmission in a transmitter so that the power level of the transmission does not exceed the "maximum allowable power level" to ensure RF exposure compliance. Certain examples below (in this section and other sections) are described with respect to SAR distributions and / or PD distributions. However, it will be understood that distributions may not be used and individual SAR or PD values may be utilized in most such examples.

[0064] Processor 280 may determine the first and second maximum allowable power levels as follows. The processor determines a normalized SAR distribution for the first technology at the first transmission power level, determines a normalized PD distribution for the second technology at the second transmission power level, and may combine the normalized SAR distribution and the normalized PD distribution to generate a combined normalized RF exposure distribution (hereinafter simply referred to as the combined normalized distribution). The value at each location within 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.

[0065] Processor 280 may then determine whether the first and second transmission power levels comply with the RF exposure limits by comparing the peak value within the combined normalized distribution to 1. If the peak value is less than or equal to 1 (i.e., the condition ≤1 is satisfied), processor 280 determines that the first and second transmission power levels comply with the RF exposure limits (e.g., the SAR limit and the PD limit), and may use the first and second transmission power levels as the first and second maximum allowable power levels, respectively, during a future time slot. If the peak value exceeds 1, processor 280 may determine that the first and second transmission power levels do not comply with the RF exposure limits. The condition for RF exposure compliance for simultaneous transmission using the first and second technologies may be given by the following equation.

Equation

[0066] FIG. 4 is a diagram showing a normalized SAR distribution 410 and a normalized PD distribution 420, and a combined normalized distribution 430 is generated by combining the normalized SAR distribution 410 and the normalized PD distribution 420. FIG. 4 also shows the condition for RF exposure compliance that the peak value in the combined normalized distribution 430 is less than or equal to 1. Although each of the distributions 410, 420, and 430 is shown as a two-dimensional distribution in FIG. 4, it should be understood that the present disclosure is not limited to this example.

[0067] As described above, the normalized SAR distribution in Equation (7) can be generated by combining two or more normalized SAR distributions (e.g., in the case of a transmission scenario using multiple active antennas). Similarly, the normalized PD distribution in Equation (7) can be generated by combining two or more normalized PD distributions (e.g., in the case of a transmission scenario using multiple active antennas). In this case, the RF exposure compliance condition of Equation (7) can be rewritten using Equations (3a) and (6a) as follows.

Number

[0068] Exemplary RF Exposure Measurements As described above, the UE 120 can transmit signals simultaneously using the first technology and the second technology, where the RF exposure is measured using various metrics (e.g., SAR for the first technology and PD for the second technology) for the first technology (e.g., 3G, 4G, IEEE 802.11ac, etc.) and the second technology (e.g., 5G, IEEE 802.11ad, etc.). The RF exposure measurements are performed separately for each transmission scenario and can include, for example, electric field measurements using a human body model. The RF exposure distribution (simulation and / or measurement) can then be generated for each transmission antenna / configuration (beam) over all evaluation surfaces / locations at all locations (as described above).

[0069] FIG. 5 is a diagram illustrating an exemplary system 500 for measuring RF exposure values or distributions according to certain aspects of the present disclosure. As shown, the RF exposure measurement system 500 includes a processing system 502, a robotic RF probe 504, and a human body model 506. The RF exposure measurement system 500 can perform RF measurements in various transmission scenarios and / or exposure scenarios associated with the UE 120. In some examples, these measurements can be used to assess appropriate back-off factors for the transmit power of one or more antennas 252 that comply with one or more RF exposure limits. In other words, the UE 120 may emit electromagnetic radiation via one or more antennas 252 at various transmit powers, and the RF exposure measurement system 500 can perform RF measurements via the robotic RF probe 504 (e.g., to determine a back-off factor for the one or more antennas 252).

[0070] The processing system 502 can include a processor 508 coupled to a memory 510 via a bus 512. The processing system 502 can be a computing device such as a computer. The processor 508 can include a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gates or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor 508 can communicate with the robotic RF probe 504 via an interface 514 (such as a computer bus interface) such that the processor 508 can obtain RF measurement values obtained, for example, by the robotic RF probe 504 and control the position of the robotic RF probe 504 relative to the human body model 506.

[0071] Memory 510 can be configured to store instructions (e.g., computer-executable code) that, when executed by processor 508, cause processor 508 to perform various operations. For example, memory 510 can store instructions for obtaining RF exposure distributions associated with various RF exposure / transmission scenarios and / or for adjusting the position of robot RF probe 504.

[0072] Robot RF probe 504 can include an RF probe 516 coupled to a robotic arm 518. In an aspect, RF probe 516 can be a dosimetry probe capable of measuring RF exposure at various frequencies such as the sub-6 GHz band and / or the millimeter wave band. RF probe 516 can be positioned by robotic arm 518 at various locations (indicated by dashed arrows) to capture electromagnetic radiation emitted by the antenna(s) 252 of UE 120. Robotic arm 518 can be a 6-axis robot capable of performing precise movements to position RF probe 516 at the location of the maximum electromagnetic field (on human body model 506) generated by UE 120. In other words, robotic arm 518 can provide six degrees of freedom when positioning RF probe 516 with respect to the antenna(s) 252 of UE 120 and / or human body model 506.

[0073] Human body model 506 can be a special anthropomorphic mannequin with simulated human tissues. For example, human body model 506 can include one or more liquids that simulate human tissues of the head, torso, and / or limbs. Human body model 506 can simulate human tissues to determine the maximum allowable transmit power of antenna(s) 252 that comply with various RF exposure limits.

[0074] The example shown in FIG. 5 is described herein with respect to obtaining RF exposure values or distributions using a robotic RF probe for ease of understanding, but aspects of the present disclosure may also be applied to other suitable RF probe architectures such as using a plurality of fixed RF probes arranged at various locations along a human body model 506.

[0075] Exemplary Transmitter Antenna Grouping A multi-mode / multi-band UE has a plurality of transmit antennas that can transmit simultaneously in both the sub-6 GHz band and a band above 6 GHz such as the millimeter wave band. As described herein, the RF exposure in the sub-6 GHz band may be evaluated in terms of SAR, and the RF exposure in a band above 6 GHz may be evaluated in terms of PD. Due to regulations on simultaneous exposure, a wireless communication device may limit the maximum transmit power for both the sub-6 GHz band and the band above 6 GHz.

[0076] In some cases, the antennas may be located at different locations across the UE, but the time averaging algorithm for RF exposure compliance may assume that all transmit antennas are collocated at the central location of the UE. Under such an assumption, the total transmit power of all transmit antennas may be limited regardless of the actual exposure scenario of individual antennas (e.g., head exposure, torso exposure, or limb exposure). For example, assume that while the user's hand covers the location of the collocation model, a particular antenna is not covered by the user's hand. That is, the antennas may contribute differently to RF exposure depending on the location of exposure. Enforcing the collocation model may actually limit the transmit power of a particular antenna that is not covered by the user's hand. That is, the assumption that the transmit antennas are collocated for RF exposure compliance may supply an unnecessarily low transmit power, which may affect uplink performance such as uplink data rate, uplink carrier aggregation, and / or uplink connection at the edge of the cell.

[0077] Aspects of the present disclosure provide various techniques for grouping antennas, for example, to determine group-based RF exposure compliance. In an aspect, antenna groups can be defined and / or operated to be mutually exclusive with respect to RF exposure. RF exposure compliance and corresponding transmit power levels can be determined separately for each antenna group. The antenna grouping described herein can enable a relatively high transmit power for a particular antenna group. Antenna grouping can refer to the specific assignment (or grouping) of antennas to separate antenna groups. The higher transmit power can provide desirable uplink performance such as a desirable uplink data rate, uplink carrier aggregation, and / or uplink connection at the edge of a cell.

[0078] In some aspects, a plurality of antenna groups are defined. Each antenna group can include one or more antennas. For example, antenna 252a may be classified into a first antenna group, and antenna 252t may be classified into a second antenna group. In some aspects, each antenna array (e.g., each phased array) is divided into different groups. The groups can be defined manually, for example, by a designer or a test operator, or in an automated manner by an algorithm that operates, for example, prior to initialization of the device, at initialization, or during operation of the device. The groups can be established based on, for example, physical location, operating frequency, form factor, associated RF exposure calculation method, etc. (as described in more detail below).

[0079] FIG. 6 is a flowchart illustrating exemplary operation 600 for grouping antennas for RF exposure compliance according to certain aspects of the present disclosure. Operation 600 may be performed by a processing system including, for example, a UE (e.g., UE120a within wireless communication network 100), an RF exposure measurement system (e.g., RF exposure measurement system 500), and / or a computing device such as a computer. Operation 600 may be implemented as software components executed on one or more processors (e.g., controller / processor 280 of FIG. 2 and / or processor 508 of FIG. 5). Further, transmission and / or reception of signals by the UE or RF exposure test system in operation 600 may be enabled by, for example, one or more antennas (e.g., antenna 252 of FIG. 2 and / or RF probe 516 of FIG. 5). In some aspects, transmission and / or reception of signals by the UE may be performed via a bus interface of one or more processors (e.g., controller / processor 280) that acquire and / or output the signals.

[0080] Operation 600 may begin at block 602, where the processing system may determine (e.g., generate and / or receive) an RF exposure profile for each transmit antenna configuration of a plurality of transmit antennas of a wireless communication device (such as UE120 shown in FIG. 5). At block 604, the processing system may assign the plurality of transmit antennas to a plurality of antenna groups based on the RF exposure profile. Optionally, at block 606, the UE and / or the processing system may determine a back-off factor for at least one of the plurality of antenna groups associated with a particular exposure / transmission scenario. At block 608, the UE may transmit from at least one antenna in at least one of the plurality of antenna groups using a transmit power level based on the back-off factor.

[0081] In some aspects, in block 604, assigning the plurality of transmit antennas to a plurality of antenna groups may involve, for example, as further described herein with respect to FIG. 8, the processing system determining a back-off factor for each of the antenna groups. As used herein, the back-off factor may be a specific number representing a fractional part (or portion) of the maximum transmit power level supported by the UE, such as a number in the range from 0 to 1. For example, the processing system may generate a normalized distribution of the RF exposure distribution, generate a normalized composite map of the normalized distribution for each of the antenna groups, and generate a sum of the normalized composite maps for all of the antenna groups based on the back-off factor associated with each of the antenna groups.

[0082] In some aspects, the normalized distribution may be generated by dividing the RF exposure distribution by the maximum RF exposure value for the corresponding transmit antenna configuration, as described herein with respect to block 802. In some aspects, the normalized composite map may be generated by selecting the maximum distribution among the normalized distributions as the normalized composite map for each of the antenna groups, as described herein with respect to block 804.

[0083] In some aspects, generating the sum of the normalized composite maps may involve, for example, as described herein with respect to block 808, multiplying the normalized composite map for each antenna group by the associated back-off factor to generate a weighted normalized composite map for each antenna group and adding the weighted normalized composite maps together. In some aspects, at least one of the back-off factors may be adjusted and applied to calculating the sum of the normalized composite maps until the sum of the normalized composite maps is below a first threshold (e.g., 1.0). That is, the back-off factor associated with each antenna group may be updated and applied to the calculation of the normalized composite maps until the sum of the normalized composite maps is below the first threshold.

[0084] In some cases, the processing system may assign each of the plurality of transmit antennas to one of the plurality of antenna groups based on the RF exposure distribution such that there are no transmit antennas included within the plurality of antenna groups. In some cases, the processing system may assign each of the plurality of transmit antennas to one of the plurality of antenna groups based on the RF exposure distribution such that at least one transmit antenna is included within the plurality of antenna groups.

[0085] In an aspect, at block 604, for example, as further described herein with respect to FIG. 9, the plurality of transmit antennas may be assigned to the plurality of antenna groups based on the determined value of the backoff factor. The transmit antennas may be redistributed or regrouped if one of the backoff factors is less than a second threshold (e.g., 0.5). For example, the processing system may determine a backoff factor for a first grouping of antenna groups, as described herein with respect to FIG. 8, and if at least one of the backoff factors for the first grouping is less than a second threshold (e.g., 0.5), the transmit antennas may be assigned to a second grouping of antenna groups. In some cases, the first grouping may include a separate antenna group for each transmit antenna, and the second grouping may include at least one antenna group having a plurality of transmit antennas. That is, a first iteration of the antenna grouping procedure may involve determining a backoff factor for each antenna and determining which transmit antennas should be grouped together based on the backoff factor, and subsequent iterations may improve or adjust the assignment of antennas to specific antenna groups, for example, based on the determined backoff factor.

[0086] The processing system may determine a back-off coefficient and repeat assigning the transmission antennas to antenna groups until all of the back-off coefficients are greater than a second threshold. For example, the processing system may determine a back-off coefficient for a second grouping of antenna groups (e.g., by repeating the operations described herein with respect to FIG. 8), and if at least one of the back-off coefficients for the second grouping is less than the threshold, the transmission antennas may be assigned to a third grouping of antenna groups. In some cases, the third grouping may include at least two antenna groups each having a plurality of transmission antennas within each of the at least two antenna groups. That is, the assignment of the third grouping may further refine the antenna groups to include a plurality of antennas within three or more antenna groups.

[0087] In some aspects, the antenna groups may include hybrid-mode antennas (e.g., a sub-6 GHz antenna and a millimeter-wave antenna). For example, at least one of the antenna groups may include a first antenna configured to transmit in a first mode and a second antenna configured to transmit in a second mode. The first mode may be a transmission mode in the sub-6 GHz band, and the second mode may be a transmission mode in the millimeter-wave band. In other words, the first mode may transmit at one or more frequencies below 6 GHz (e.g., from 300 MHz to 6 GHz), and the second mode may transmit at one or more frequencies above 6 GHz (e.g., from 24 GHz to 53 GHz or higher frequencies). That is, the first mode may include a first antenna operable at one or more frequencies below 6 GHz, and the second mode may include a second antenna operable at one or more frequencies above 6 GHz.

[0088] In an aspect, the transmit antenna configuration may include a transmit beam configuration of a particular antenna or an antenna module having a plurality of antennas. In an aspect, at least one of the transmit antennas is part of an antenna module having a plurality of antennas. As an example, in block 602, for each antenna among the plurality of antennas and / or for each transmit beam configuration supported by the antenna module among the plurality of antennas, an RF exposure distribution may be generated (and / or an indication thereof may be received). In an aspect, the transmit beam configuration may refer to a transmit radiation pattern from an antenna or an antenna module in a particular azimuth direction and / or elevation direction that may be realized through beamforming. The transmit beam configuration may have a particular transmit power spread (e.g., a power angle spread associated with the emission angle) in the azimuth direction and / or elevation direction.

[0089] In some cases, antenna grouping may be used to determine RF exposure compliance and corresponding transmit power levels. For example, a UE may transmit a signal at a transmit power level based on enforcement of RF exposure compliance for at least one of the antenna groups. In some aspects, enforcing RF exposure compliance may include the UE transmitting a signal at a transmit power level that meets a particular RF exposure limit (e.g., a SAR limit of 1.6 watts per kilogram (1.6 W / kg) and / or a PD limit of 1.0 milliwatt per square centimeter (1.0 mW / cm 2 ²)).

[0090] In an aspect, ensuring RF exposure compliance may include evaluating RF exposure compliance with respect to time-averaged RF exposure such as time-averaged SAR or time-averaged PD over a time window. In an aspect, the time window may range from 1 second to 360 seconds. For example, the time window may be 100 seconds or 360 seconds. The range of 1 second to 360 seconds is an example, and other suitable values may be used for the time window. In some cases, the time window may be less than 1 second, such as 500 milliseconds. In some cases, the time window may exceed 360 seconds, such as 600 seconds.

[0091] In an aspect, the UE may communicate with a base station such as BS110. For example, in block 608, the UE may transmit user data to the base station on a Physical Uplink Shared Channel (PUSCH) or various uplink feedbacks (e.g., uplink control information or hybrid automatic repeat request (HARQ) feedback) on a Physical Uplink Control Channel (PUCCH). In some cases, the UE may communicate with another UE. For example, in block 608, the UE may transmit user data and / or various feedbacks to another UE on a sidelink channel.

[0092] FIG. 7 is a block diagram showing an exemplary grouping of a plurality of antennas of a wireless communication device 700 according to certain aspects of the present disclosure. In this example, the wireless communication device 700 (e.g., a UE 120 such as a smartphone or any of the wireless communication devices described herein) includes a first antenna 702a, a second antenna 702b, a third antenna 702c, a fourth antenna 702d, a fifth antenna 702e, a sixth antenna 702f, and a seventh antenna 702g. In this example, antennas 702a - 702g are divided into three antenna groups 704, 706, 708 that generally correspond to the top, bottom, and sides of the device 700 when the device 700 is held in an upright position. Those skilled in the art will understand that more than seven or fewer than seven antennas may be implemented and / or more than three or fewer than three antenna groupings may be defined. Each of the illustrated antennas 702a - 702g may represent a single antenna, an array of antennas (e.g., a phased array), or a module that includes one or more antennas. Each of the antenna groups 704, 706, 708 may include one or more antennas configured to transmit in a particular frequency band (e.g., very high (e.g., millimeter wave band), high (e.g., 6 - 7 GHz band), intermediate (e.g., 3 - 6 GHz band), or low (e.g., 400 MHz - 3 GHz band)), or each antenna group may include one or more antennas configured to transmit in multiple frequency bands.

[0093] In an aspect, the antenna grouping described herein can be assigned to various antenna groupings (such as millimeter-wave grouping, sub-6 GHz grouping, low-band grouping (e.g., 400 MHz - 3 GHz band), mixed-mode grouping (e.g., millimeter-wave and sub-6 GHz grouping), etc.) for different transmission scenarios. As an example, under millimeter-wave grouping, each millimeter-wave module (e.g., the first antenna 702a, the third antenna 702c, and the fifth antenna 702e) may be treated as a separate antenna group, and each millimeter-wave module may have a plurality of antenna elements (e.g., 64 dual-polarized antenna elements) arranged in one or more arrays. The millimeter-wave module may be capable of transmitting various beams via a predefined antenna configuration, and the beams may form a codebook. Under sub-6 GHz grouping, the sub-6 GHz antennas can be grouped into separate groups. For example, the second antenna 702b and the fourth antenna 702d may be assigned to one group, and the sixth antenna 702f and the seventh antenna 702g may be assigned to another group. In some cases, the antennas 702a - 702g may be assigned to a mixed-mode grouping such as three antenna groups 704, 706, 708, etc.

[0094] The groups can be defined and / or operated to be mutually exclusive with respect to RF exposure. In some aspects, the (normalized) sum of all antenna group exposures, or the exposure of overlapping RF exposure distributions, can have the transmission power of one or more of the groups (or one or more of the antennas within one or more of the groups) reduced so as to be less than a particular value (e.g., 1.0). For example, a back-off factor can be determined and applied for one or more groups, or one or more antennas within one or more groups, to limit the transmission power of the antenna(s) and / or group.

[0095] As an example, the back-off factor bf can be between [0, 1] for each antenna group such that the maximum allowable transmission power for each antenna group is equal to the transmission power limit of the antenna group multiplied by their respective back-off factors (e.g., bf * Tx_power_limit), where bf = 1 represents no back-off, where bf = 0.3 means operating the antenna group at 30% of the transmission power limit, and where the transmission power limit can be the maximum transmission power supported by that particular antenna and / or antenna group.

[0096] FIG. 8 is a flowchart illustrating exemplary operation 800 for determining a back-off factor for an antenna group according to certain aspects of the present disclosure. Operation 800 may be performed, for example, by a UE (e.g., UE120a within wireless communication network 100), an RF exposure measurement system (e.g., RF exposure measurement system 500), and / or a processing system. To determine such a back-off factor, at block 802, an RF exposure distribution (simulation and / or measurement) may be generated for each transmit antenna / configuration (beam) over all evaluation surfaces / locations at all locations, for example, using a processing system and / or the RF exposure measurement system 500 (as described above). In some aspects, the RF exposure distribution may be generated via simulations such as simulations of various exposure / transmission scenarios using a model of a human body exposed to electromagnetic radiation from a wireless communication device. As previously described herein, the RF exposure distribution may include RF exposure associated with various transmission scenarios corresponding to human body positions for a particular frequency band and / or antenna. For example, the RF exposure distribution may be represented by the formula RFexp(s,x,y,z,i), where s represents a particular surface or location, (x,y,z) represents a given location, and i represents a particular transmission configuration such as a particular antenna or transmit beam. In some cases, since a transmit antenna may support multiple bands, multiple RF exposure distributions may be available for each band / channel (low / mid / high) for a particular transmit antenna. In such a case, the RF exposure distribution for a particular transmit antenna may represent the maximum exposure at each location / exposure surface from all technologies / bands / channels supported by the transmit antenna.

[0097] Next, in block 804, a normalized distribution (map) can be calculated by collecting the exposure on all surfaces / positions for each transmission antenna / beam and dividing by the corresponding maximum value. For example, the normalized distribution can be represented by the following equation: normalized.map(s,x,y,z,i) = {RFexp(1,x,y,z,i); RFexp(2,x,y,z,i);...; RFexp(s,x,y,z,i)} / maxRFexp(i).

[0098] Thereafter, in block 806, for example, a normalized composite map for each antenna group can be calculated based on the maximum distribution of the normalized distributions within the group. That is, generating the normalized composite map can include selecting the maximum normalized distribution from among the normalized distributions within a particular antenna group. For example, the normalized composite map can be given by the equation:

Equation

[0099] Furthermore, in block 808, for example, a total normalized composite map can be calculated for all antenna groups based on the sum of all of the normalized composite maps. As an example, the total normalized composite map can be given by the following equation.

Equation

[0100] In some embodiments, at block 810, it may be determined whether the total normalized composite map is less than a threshold (e.g., 1.0). If this condition is not met, the expected or potential power for one or more antennas (or one or more antenna groups) may be reduced using the updated back-off factor. Antenna groups may contribute to RF exposure at different levels, for example, due to the location of the antennas within the group, the supported bands of the antennas within the group, the maximum transmit power of the antennas within the group, etc. The contribution of an antenna group to RF exposure (e.g., based on the total normalized composite map where overlapping maps are at the peak) can be adjusted using the back-off factor for the antenna group. At block 812, for example, the back-off factor(s) may be adjusted (increased or decreased) for one or more of the antenna groups, and the total normalized composite map may be recalculated using the updated back-off factor from block 808. The back-off factor for each antenna and / or group may be adjusted (or updated) until the condition at block 810 is met (e.g., the total normalized composite map is below the threshold), and the total normalized composite map may be recalculated using the adjusted back-off factor. In some examples, the back-off factor for each transmitter (or antenna, or group of antennas or transmitters) may be determined based on the ratio of the RF exposure due to each transmitter at a (e.g., peak) location to the desired amount of reduction in exposure. In some examples, the back-off factor may be determined based on the priority of the transmitter coupled to the antenna. In some examples, the back-off factor for the antenna that contributes the most to RF exposure at a (e.g., peak) is the largest back-off factor compared to the back-off factors for other antennas or groups. In some examples, the back-off factor is determined such that the transmit power levels of each of several antennas or groups contribute approximately equally to the RF exposure at the location. The back-off factor may be determined or applied uniformly to the antennas within a group or may vary across the antennas within a group.

[0101] In block 814, if the total normalized composite map is less than a threshold value (e.g., 1.0), the antenna groups are considered mutually exclusive with respect to RF exposure, and in block 816, a final back-off factor for each antenna group can be obtained. The back-off factor may be used to determine the transmission power level of a particular antenna group, as further described herein, or may be used for other purposes such as determining actual or potential interference.

[0102] FIG. 9 is a flow diagram illustrating exemplary operation 900 for assigning antennas to groups based on a back-off factor (e.g., determined in operation 800) according to a particular aspect of the present disclosure. Operation 900 may be performed by a processing system and / or an RF exposure measurement system (e.g., RF exposure measurement system 500) including, for example, a UE (e.g., UE120a within wireless communication network 100).

[0103] For example, after completing a particular antenna grouping operation 800, in block 902, a back-off factor(s) for each antenna group can be obtained. For example, operation 800 may first be performed using separate groups for each antenna / beam, and in block 902, a back-off factor for an individual antenna can be obtained.

[0104] In block 904, it can be determined whether each of the back-off factors is greater than or equal to a threshold value (e.g., 0.5). If this condition is not met, then in block 906, the antennas can be re-assigned or re-distributed among the antenna groups. In some cases, for antennas / antenna groups with low back-off factors (e.g., back-off factor < 0.5), some of the antennas can be grouped together into the same antenna group based on their spatial distribution, and as a result, the number of antenna groups can be reduced. For example, in the first iteration, assume that separate groups are used for each antenna, and antennas 1 to 7 are included in antenna groups AG1 to AG7 respectively. The corresponding back-off factors are

Number

[0105] The antenna grouping operations described herein can be determined and / or applied for each exposure category indicating a device state index (DSI) and / or an exposure scenario of the device (e.g., head exposure, torso exposure, or limb exposure). For example, head exposure may have four exposure positions (right cheek, right tilt, left cheek, left tilt), and these four positions can be collected together (e.g., collected as a normalized map at block 804). In some cases, the value of s may range from [1,4] to correspond to the four exposure positions, where s represents a particular surface or position). Torso exposure may have two exposure positions (front and back), and these two exposure positions can be collected together (e.g., at block 804). Limb exposure may have six exposure positions (front, back, left, right, top, and bottom of the device) with a separation distance of 0 mm, and these six positions can be collected together (e.g., at block 804).

[0106] In some aspects, the antenna grouping operations described herein can be combined with existing techniques for some exposure configurations. For example, if the absolute sum of the maximum RF exposure values for all antenna groups (e.g., the total normalized composite map) is less than the regulatory limit, the above procedure for adjusting the power / back-off factor may be skipped.

[0107] The examples provided in this specification are described with respect to various operations performed by a UE when determining antenna grouping. However, aspects of the present disclosure may also be applied to scenarios where the antenna grouping and backoff coefficient derivation operations are performed in a laboratory facility (e.g., using an RF exposure measurement system 500), and certain calculations or simulations are performed outside of the UE by a separate processing system (e.g., a processing system 502). That is, it is not necessary for the UE to perform various functions related to antenna grouping and backoff coefficient derivation operations itself, but the UE may be configured to store / access / utilize specific information derived from the antenna grouping operation, such as a backoff coefficient and an antenna grouping assignment. For example, the antenna grouping assignment and corresponding backoff coefficient may be developed using a wireless communication device (prototype) within a laboratory facility (e.g., an RF exposure measurement system 500) to simulate various exposure / transmission scenarios during an RF exposure compliance certification process with a regulatory agency, and the UE may be configured to store / access / utilize the backoff coefficient associated with a specific antenna grouping derived from the antenna grouping operation performed within the laboratory facility.

[0108] As an example, the UE may store and access various backoff coefficients associated with specific antenna groups and / or transmission beam configurations according to various RF exposure limits associated with exposure / transmission scenarios (such as head exposure, torso exposure, and / or limb exposure in a particular frequency band). The backoff coefficients associated with a specific antenna group and / or transit beam configuration may be developed, for example, according to the operations for assigning antenna groups as described herein using a UE prototype within an RF exposure test laboratory. The backoff coefficients associated with a specific antenna group may be configured in a data structure, such as a table or database of backoff coefficients, associated with a specific antenna grouping and / or a specific exposure / transmission scenario in a particular frequency band.

[0109] The examples provided in this specification are described with respect to a UE implementing RF exposure compliance by antenna grouping, but aspects of the present disclosure are not limited to RF exposure use cases. For example, stored values derived from antenna grouping operations (e.g., back-off factors and / or antenna grouping assignments) can be used in any number of applications. One application example further described below is to evaluate RF exposure compliance using back-off factors and / or antenna grouping. Another application example can be to determine self-interference during antenna grouping based on transmission power levels. Other purposes are also possible.

[0110] In some cases, an antenna may not meet the exclusion criteria with another antenna group, and in such cases, that antenna can be incorporated into other antenna groups. In some cases, this may result in all antennas being combined into a single antenna group, which implies that RF exposure from all antennas is collocated and does not utilize spatial diversity due to the antenna placement. One way to avoid this is to force the antenna to meet the exclusion criteria by applying a higher persistent back-off(s) to one or more antennas.

[0111] Aspects of the present disclosure relate to assigning antennas to a plurality of antenna groups within a particular antenna grouping. For example, if an antenna does not meet the exclusion criteria with another antenna group, the antenna may be assigned to multiple antenna groups, thereby avoiding the need to apply a persistent back-off to all of the antennas. The antenna grouping described herein can enable flexibility in meeting desired transmission power for a particular antenna group and / or RF exposure limits for each antenna group.

[0112] Aspects of the present disclosure relate to, for example, allocating one or more antennas to a plurality of sets of antenna groups for a separate transmission scenario (i.e., a plurality of antenna groupings). For example, a processing system may develop antenna groupings for a particular country or region due to separate RF exposure limits for that country or region, which may be identified, for example, by a public land mobile network (PLMN) code and / or a mobile country code (MCC). In some cases, the processing system may develop antenna groupings for particular exposure scenarios, such as head exposure, torso exposure, limb exposure, and / or hot spot exposure (e.g., when a wireless communication device is in the immediate vicinity of human tissue), and / or may develop antenna groupings based on one or more operating conditions (e.g., whether MIMO is being utilized for a particular band when a particular high-priority application or transmission may be active). Antenna grouping for each transmission scenario (such as a particular region and / or exposure scenario) may provide the wireless communication device with flexibility to switch between antenna groupings in response to the transmission scenarios encountered by the wireless communication device.

[0113] Returning to FIG. 6, operation 600 may further involve the processing system (e.g., a UE, an RF exposure measurement system, a computer separate from the UE, and / or any other device configured to perform the operations described herein) assigning at least one of the transmit antennas to two or more of the antenna groups at block 604. For example, the processing system may assign an antenna to multiple antenna groups due to the antenna not meeting the exclusion criteria with other antenna groups. At block 604, the processing system may identify that at least one of the transmit antennas does not meet the mutual exclusion criteria with at least two of the antenna groups, and the processing system may assign at least one of the transmit antennas to at least two of the antenna groups in response to the identification.

[0114] In some cases, an antenna may be assigned to multiple antenna groups based on the maximum time-average power limit (P limit ) associated with the antenna. The maximum time-average power limit may refer to the maximum constant transmit power that an antenna can transmit continuously throughout the period of a time window associated with an RF exposure limit that complies with the RF exposure limit. For example, if a particular antenna has a relatively low P limit compared to other antennas, the processing system may refrain from repeatedly assigning that particular antenna to multiple antenna groups in order to avoid consuming the RF exposure margin within those antenna groups. As an example, if a particular antenna has a relatively high P limit , the processing system may assign that particular antenna to multiple antenna groups. Here, a low or high P limit for a particular antenna (and a particular technology / frequency band) may be quantified by comparing P max to P limit . In such a scenario, the peak-to-average-power ratio (PAPR) is P limitcan be used as a metric to determine whether it is relatively low or high. The PAPR in dB is given by P max -P limit and may be given by, where P max and P limit can be in units of dBm. For example, if the PAPR is positive (e.g., a few dB, e.g., 2 dB, 3 dB, or 6 dB), for that particular technology / band / antenna, P limit can be considered low. Similarly, if the PAPR is less than or negative than one of these exemplary values, P limit can be considered high. With respect to operation 600, the processing system may identify a maximum time-average power limit associated with each of the transmit antennas, and the processing system may assign at least one of the transmit antennas to at least two of the antenna groups based at least in part on the maximum time-average power limit associated with at least one of the transmit antennas.

[0115] In some aspects, the processing system may generate multiple antenna groupings. The antenna groupings can be deployed for separate transmission scenarios, such as when the wireless communication device is located in a particular region and / or when the wireless communication device encounters a particular exposure scenario. With respect to operation 600, the processing system may assign the transmit antennas to a first grouping of antenna groups for a first transmission scenario (e.g., when the UE is located in the United States), and assign the transmit antennas to a second grouping of antenna groups for a second transmission scenario (e.g., when the UE is located in the European Union).

[0116] In some embodiments, the first grouping may differ from the second grouping in the arrangement of the transmit antennas into a plurality of antenna groups. At least one of the transmit antennas is present in both the first grouping and the second grouping. For example, referring to FIG. 7, antennas 702a-702g may be assigned to the first grouping, and the first antenna 702a, the second antenna 702b, the third antenna 702c, the fourth antenna 702d, and the fifth antenna 702e may be assigned to the first group, and the fifth antenna 702e, the sixth antenna 702f, and the seventh antenna 702g may be assigned to the second group. The first group may be spatially separated from the second group to provide a mutually exclusive relationship with respect to RF exposure. In this first grouping, the fifth antenna 702e is assigned to two different antenna groups (i.e., the first group and the second group). Since the fifth antenna 702e is located between the set of upper antennas and the set of lower antennas (702a-d, 702f, and 702g), it may be difficult to separate the fifth antenna 702e into mutually exclusive groups. For example, the fifth antenna 702e may interact with the other antennas (702a-d, 702f, and 702g), and in order to avoid applying a restrictive persistent backoff, the fifth antenna 702e may be assigned to the first group and the second group.

[0117] For example, referring to FIG. 7, antennas 702a to 702g may be assigned to the second grouping. The first antenna 702a, the second antenna 702b, the third antenna 702c, and the fourth antenna 702d are assigned to the third group, the sixth antenna 702f and the seventh antenna 702g are assigned to the fourth group, and the fourth antenna 702d, the fifth antenna 702e, and the seventh antenna 702g are assigned to the fifth group. In this second grouping, the fourth antenna 702d is assigned to two different antenna groups (i.e., the third and fifth groups), and the sixth antenna 702g is assigned to two different antenna groups (i.e., the fourth and fifth groups). In this second grouping, the fifth antenna 702e may also be difficult to assign to a separate group, and the fifth antenna 702e can be grouped with antennas such as the fourth antenna 702d and the seventh antenna 702g that are spatially arranged on the same side of the wireless communication device 700.

[0118] In some cases, the first transmission scenario may be associated with a first country or region (e.g., the United States), and the second transmission scenario may be associated with a second country or region (e.g., China or the European Union). That is, the first and second transmission scenarios may be region-dependent in order to comply with the specific RF exposure limits of the particular region where the UE is located. When the UE is located in its particular region (determined, for example, based on the PLMN code and / or MCC given to the UE), the UE may use a particular antenna grouping associated with that region.

[0119] In some cases, the first transmission scenario may be associated with a first exposure scenario (e.g., head exposure), and the second transmission scenario may be associated with a second exposure scenario (e.g., torso exposure). That is, the first and second transmission scenarios may depend on specific exposure scenarios such as head exposure, torso exposure, limb exposure, and / or hotspot exposure. When the UE encounters a specific exposure scenario, the UE may use a certain antenna grouping associated with that exposure scenario.

[0120] In some cases, the transmission scenario may be associated when a certain antenna is used for simultaneous transmission. For example, assume that the fourth antenna 702d and the seventh antenna 702g will generally be used for simultaneous transmission. The processing system may allocate these antennas to different groups to facilitate the efficient use of the RF exposure margins of these antennas. As an example, the processing system may develop a first grouping that allows the application of separate backoffs for these antennas for when the fourth antenna 702d and the seventh antenna 702g are used for simultaneous transmission, as described herein with respect to FIG. 7.

[0121] Regarding operation 600, the UE may transmit from at least one transmitting antenna in the first grouping during the first transmission scenario, and the UE may transmit from at least one transmitting antenna in the second grouping during the second transmission scenario. In other words, the UE may select which antenna grouping to use for a specific transmission scenario, and the UE may switch between antenna groupings when there is a change in the transmission scenario, such as when the UE moves from one area to another, as further described herein with respect to FIG. 10.

[0122] Exemplary time-averaged RF exposure for each transmitting antenna group Aspects of the present disclosure provide various techniques for determining time-average RF exposure compliance for each transmission antenna group. Since the antenna grouping described herein can provide mutually exclusive antenna groups with respect to RF exposure, the RF exposure compliance for each antenna group can be determined separately. In some cases, the RF exposure compliance for the antenna groups can be performed in parallel (e.g., simultaneously). The group-based RF exposure compliance described herein can enable a desired transmit power for a particular antenna group, for example, due to different exposure scenarios that each antenna group encounters. The desired transmit power can result in desired uplink performance such as a desired uplink data rate, uplink carrier aggregation, and / or uplink connection at the edge of the cell.

[0123] FIG. 10 is a flowchart illustrating an exemplary operation 1000 for wireless communication according to certain aspects of the present disclosure. Operation 1000 can be performed, for example, by a UE (e.g., UE 120a within wireless communication network 100). Operation 1000 can be implemented as a software component that runs on one or more processors (e.g., controller / processor 280 of FIG. 2). Further, transmission of signals by the UE in operation 1000 can be enabled, for example, by one or more antennas (e.g., antenna 252 of FIG. 2). In some aspects, transmission and / or reception of signals by the UE can be performed via a bus interface of one or more processors (e.g., controller / processor 280) that acquire and / or output the signals.

[0124] Operation 1000 may start in block 1002, and the UE may access the backoff factor associated with and stored for an antenna group (e.g., antenna group 704) among a plurality of antenna groups (e.g., antenna groups 704, 706, 708). In block 1004, the UE may transmit a signal from at least one transmit antenna (e.g., antenna 702a) within the antenna group at a transmit power level based on the backoff factor that complies with the RF exposure limit.

[0125] In some cases, the grouping of transmit antennas may not explicitly indicate which antennas are included within a particular group. In an aspect, the grouping of transmit antennas may be implicitly indicated by the various backoff factors assigned to the transmit antennas for a particular exposure / transmission scenario. That is, the antenna grouping and the assignment of antenna groups associated with the antenna grouping may be represented by the backoff factors. For example, some antennas may share the same backoff factor, such that in an aspect where these antennas are implicitly assigned to the same antenna group among a plurality of antenna groups, the transmit power level may be at least partially based on at least one of the backoff factors.

[0126] In some aspects, the transmit power level may be determined based on the sum of RF exposure being below a threshold (e.g., 1.0). For example, the UE may transmit a signal at a transmit power level based on the sum of RF exposure for each of the antenna groups being below the threshold. In some such scenarios, this is achieved by applying the backoff factor(s) described above to the transmit power level.

[0127] In some aspects, the transmission power level may be determined based on the time-averaged RF exposure being less than a threshold. For example, the UE may transmit a signal at a transmission power level based on the sum of the time-averaged RF exposure for each of the antenna groups being below a threshold (e.g., 1.0). The back-off factor may be applied to the RF exposure for each of the antenna groups, in the case of the sum of RF exposures or the sum of the time-averaged RF exposures.

[0128] In an aspect, the UE may determine the time-averaged RF exposure for each of the antenna groups and use the group-based time-averaged RF exposure when determining RF exposure compliance. For example, the UE may transmit a signal at a transmission power level based on each of the time-averaged RF exposures being below a threshold. In some cases, since the antenna groups may be mutually exclusive with respect to RF exposure, the UE may determine the time-averaged RF exposure for each of the antenna groups simultaneously. In other words, the mutual exclusivity of the antenna groups may enable the UE to determine the time-averaged RF exposure for each of the antenna groups in parallel (e.g., independently) of each other. Stated differently, the UE may use parallel (or simultaneous) processing to determine the time-averaged RF exposure for each or a portion of the antenna groups. For example, the UE may determine the time-averaged RF exposure associated with a first antenna group (e.g., antenna group 704) and simultaneously determine the time-averaged RF exposure associated with a second antenna group (e.g., antenna group 706), and the UE may determine the transmission power compliant with the RF exposure limit for each of the first and second antenna groups based on the respective time-averaged RF exposures and the respective back-off factors. In some cases, the UE may transmit a signal at a transmission power level based on enforcing RF exposure compliance for one of the plurality of antenna groups, where one of the plurality of antenna groups has a lower transmission power limit than another one of the plurality of antenna groups. That is, the minimum value of the plurality of transmission power limits may be enforced by the transmitter to ensure overall time-averaged RF exposure compliance.

[0129] In an aspect, the antenna may have various antenna groupings, as described herein with respect to operation 600 for example. As an example, the UE may have a back-off coefficient associated with an antenna group for the millimeter wave band, an antenna group for the sub-6 GHz band, and / or an antenna group for a hybrid mode band (sub-6 GHz band and millimeter wave band). In some cases, the antenna grouping may be derived using operation 600, 800, or 900. For example, at least one of the antenna groups may include a first antenna configured to transmit in a first mode and a second antenna configured to transmit in a second mode. In some cases, the first mode may be sub-6 GHz and the second mode may be millimeter wave. That is, the first mode may transmit in the sub-6 GHz band and the second mode may transmit in the millimeter wave band. In an aspect, the first mode may include a first antenna operable in the sub-6 GHz band and the second mode may include a second antenna operable in the millimeter wave band.

[0130] In some embodiments, the transmitting antenna may include one or more first antennas configured to transmit in a first mode and one or more second antennas configured to transmit in a second mode. The first antenna(s) may be separately assigned to antenna groups. That is, in a particular antenna grouping, some of the first antennas may be included in the same group, but the first antennas may be divided into groups such that one of the first antennas is not assigned to more than two groups. The second antennas may be included in each or some of the antenna groups. In some cases, each of the antenna groups may have all of the second antennas. In some cases, the first mode may transmit at one or more frequencies below 6 GHz (e.g., in the sub-6 GHz band), and the second mode may transmit at one or more frequencies above 6 GHz (e.g., in the millimeter wave band). In other cases, the first mode may transmit at one or more frequencies above 6 GHz, and the second mode may transmit at one or more frequencies below 6 GHz.

[0131] In an embodiment, the transmitting antennas are grouped such that each antenna group is mutually exclusive from all other antenna groups with respect to RF exposure. The mutual exclusivity of the antenna groups can be achieved using various techniques or criteria. For example, in a system of N antennas grouped into k antenna groups, the initially obtained normalized RF exposure distribution of each of the N antennas from i = 1 to N on all exposed surfaces represented in block 804 is equal to normalized.map(s,x,y,z,i), and the maximum value of the RF exposure distribution among all surfaces is max{normalized.map(s,x,y,z)} = 1.0. Next, obtain the composite map from all n antennas within antenna group k as shown in block 806 = normalized.composite.map.AG k(s, x, y, z) = max{normalized.map(s, x, y, z, i = 1 to n)} = normRFexposure(k, s, x, y, z). This normalized composite map is called the normalized RF exposure for antenna group k. For example, mutual exclusivity of antenna groups can be given if the sum of the RF exposures of all antenna groups (k = 1 to M) < 1.0 satisfies the following equation.

Number

[0132] Since the antenna groups are mutually exclusive with respect to RF exposure, the (real-time) averaging of RF exposure can be performed for each antenna group using the method described above or using one or more other methods (e.g., regardless of other antenna groups). For example, the RF exposure of a given antenna at any time t can be proportional to the transmit power of the antenna at t. Thus, the RF exposure of antenna i at time t belonging to antenna group k can be given by the following equation. [Number]

[0133] The time-averaged RF exposure over a time window T of all n antennas and / or antenna configurations within antenna group k can be given by the following equation. [Number] The predefined backoff can be the backoff coefficient bf described herein.

[0134] When there are antennas and / or groups of antennas within an antenna group that use different mechanisms (e.g., SAR or PD) to calculate RF exposure, the exposures can be combined as described herein or using one or more other methods or calculations.

[0135] Thus, the transmission (power) using the antennas within an antenna group can be controlled (e.g., by processor 280) such that each group individually meets the exposure limits defined by regulatory authorities, domestic or foreign. In some embodiments, as a result of this, the total power transmitted across all of the antenna groups can be higher than if the antennas were not divided into mutually exclusive groups.

[0136] In some cases, multiple sets of antenna groups (e.g., multiple antenna groupings) can be defined and used to determine settings (e.g., transmit power and / or backoff factor) for multiple transmitters and / or antennas. That is, a UE can be composed of multiple antenna groupings, where each antenna grouping can have antenna groups defined differently from other antenna groupings. For example, referring to FIG. 7, the first antenna 702a, the third antenna 702c, and the fifth antenna 702e can be antenna modules having an antenna array configured to transmit in one or more millimeter wave bands (e.g., from about 24 GHz to 53 GHz or higher). The other antennas 702b, 702d, 702f, 702g can be configured to transmit in a sub-6 GHz band (e.g., 6 GHz or less).

[0137] The first antenna grouping (M1) may include three antenna groups, and the second antenna grouping (M2) may include two antenna groups. The antenna groups of the first antenna grouping (M1) can include a first antenna group (AG1) having all of the sub-6 GHz antennas 702b, 702d, 702f, 702g and the first antenna 702a, a second antenna group (AG2) having all of the sub-6 GHz antennas 702b, 702d, 702f, 702g and the third antenna 702c, and a third antenna group (AG3) having all of the sub-6 GHz antennas 702b, 702d, 702f, 702g and the fifth antenna 702e. In an aspect, the first antenna grouping (M1) can be represented as follows. AG1: {All sub-6 GHz antennas, the first millimeter wave module} AG2: {All sub-6 GHz antennas, the second millimeter wave module} AG3: {All sub-6 GHz antennas, the third millimeter wave module}

[0138] The antenna groups for the second antenna grouping (M2) can include a fourth antenna group (AG4) having the second antenna 702b, the fourth antenna 702d, and all of the millimeter-wave antennas 702a, 702c, and 702e, and a fifth antenna group (AG5) having the sixth antenna 702f, the seventh antenna 702g, and all of the millimeter-wave antennas 702a, 702c, and 702e. The second antenna grouping can be represented as follows. AG4: {First subgroup of sub-6 GHz antennas, all millimeter-wave modules} AG5: {Second subgroup of sub-6 GHz antennas, all millimeter-wave modules} The first subgroup may include sub-6 GHz antennas (such as the second antenna 702b and the fourth antenna 702d) disposed at the upper part of the UE, and the second subgroup of sub-6 GHz may include sub-6 GHz antennas (such as the sixth antenna 702f and the seventh antenna 702g) disposed at the lower part of the UE.

[0139] In some aspects, the RF exposure of sub-6 GHz (e.g., frequency range 1 (FR1)) may be calculated by measurement, and the RF exposure of millimeter-wave (e.g., frequency range 2 (FR2)) (in the case of beams in the codebook) may be calculated by simulation (e.g., as described above). In such cases, as described above, the sub-6 GHz antennas may be grouped into M2 groups (each having all millimeter-wave modules within each group), and the millimeter-wave antennas may be grouped into M1 groups (each having all sub-6 GHz antennas within each group).

[0140] Those skilled in the art will understand that the groupings M1 and M2 are merely examples for grouping antennas for ease of understanding. Aspects of the present disclosure may also be applied to configuring antennas into additional or alternative groups, such as the groupings described above with respect to allocating antennas to multiple groups. For example, all of either FR1 or FR2 radio can be allocated to all of the antenna groups, and the other of FR1 or FR2 radio can be diffused non-uniquely among the antenna groups. In one such example, an antenna grouping (M3) can include an additional antenna group (AG6) having all of the second antenna 702b, the sixth antenna 702f, the millimeter wave antennas 702a, 702c, and 702e, in addition to a fourth antenna group AG4 and a fifth antenna group AG5. In another such example, an antenna grouping (M4) can include a fourth antenna group AG4 and a seventh antenna group (AG7) having all of the second antenna 702b, the sixth antenna 702f, the seventh antenna 702g, and the millimeter wave antennas 702a, 702c, and 702e.

[0141] In these examples, two or more time averages (e.g., one or more back-off values defined for a set, e.g., at least one for each set) can be performed. The processor 280 can determine to apply a transmission setting to an antenna based on the results of two or more determinations. In some aspects, the minimum value of the transmission power limit across multiple antenna groupings (e.g., M1 vs. M2, or M1 vs. M3 and / or M4) can be selected and achieved by the processor 280, e.g., to ensure compliance with the overall time-averaged RF exposure.

[0142] In some cases, as described herein, the UE may access the stored backoff factor and transmit a signal from at least one antenna using a transmit power level based on the backoff factor that complies with the radio frequency exposure limit. The backoff factor may correspond to at least one antenna group among a plurality of antenna groups, and at least one antenna is included within the at least one antenna group.

[0143] Exemplary selection and switching between sets of antenna groups Aspects of the present disclosure relate to selecting a set of antenna groups (also referred to herein as "grouping") for operation by a wireless communication device (e.g., UE 120). Operating with a particular set of antenna groups can be beneficial in certain wireless transmission scenarios (e.g., by providing higher performance). For example, when operating using the antenna groups (AG1, AG2, and AG3) of the first antenna grouping (M1), each mmW module can obtain up to 100% RF exposure margin in this scenario (depending on how much margin the sub6 antenna consumes), so the mmW module can obtain more combined total RF exposure margin. Thus, when operating in NR using LTE and frequency range 2 (FR2) (e.g., using an LTE+FR2 link), it may be beneficial to operate according to the grouping of M1. In contrast, when operating using only the sub6 GHz band (e.g., in NR using LTE and frequency range 1 (FR1), such as in an LTE+FR1 link), it may be beneficial to operate according to one of, for example, the M2 grouping (having AG4 and AG5) or the M3 grouping and the M4 grouping.

[0144] Aspects of the present disclosure also relate to switching between sets of antenna groups when a wireless communication device (e.g., UE 120) changes its operating parameters. For example, when switching from one antenna grouping to another (e.g., for performance benefits), the grouping assumptions may change, so RF exposure compliance must be ideally ensured. For example, when switching from M1 grouping to M2 grouping (or to one of M3 and M4 groupings), if each millimeter wave module was previously operating with a 100% RF exposure margin, when switching to M2 grouping (e.g., from an LTE+FR2 call to an LTE+FR1 call) or to one of M3 and M4 groupings, the time history for all antenna groups in M1 grouping may exceed the RF exposure compliance limit at this point. Thus, aspects of the present disclosure provide one or more criteria (referred to herein as "switching criteria") for switching between different groupings to maximize or at least increase the benefits of switching while simultaneously ensuring RF exposure compliance.

[0145] For example, assume that there are "B" millimeter-wave groups in M1 grouping (with all sub-6 GHz groups added to each of the millimeter-wave groups), and "A" sub-6 GHz groups in M2 grouping (with all millimeter-wave groups added to each of the sub-6 groups). In this case, the total RF exposure margin available in M1 grouping is equal to 100% - (sub6_1 + sub6_2 +... + sub6_A) - max{mmW_1, mmW_2,..., mmW_B}, and the total RF exposure margin available in M2 grouping is equal to 100% - (mmW_1 + mmW_2 +... + mmW_B) - max{sub6_1, sub6_2,..., sub6_A}. The switching criterion for the change from M1 grouping to M2 grouping (e.g., handover from an LTE+FR2 call to an LTE+FR1 call) may include that the total available margin (TAM) in M2 grouping is greater than the total available margin in M1 grouping (TAM,M2>TAM,M1). Similarly, the switching criterion for the change from M2 grouping to M1 grouping (e.g., handover from an LTE+FR1 call to an LTE+FR2 call) may include that the total available margin in M1 grouping is greater than the total available margin in M2 grouping (TAM,M1>TAM,M2).

[0146] The above example has only two different sets of antenna groups (M1 and M2 groupings). However, this concept and the criteria for switching between antenna groups can be extended to three or more different groupings (e.g., also to M3 and M4, or by using M3 and M4 instead of M2 in the above example). Generally, the switching criterion for changing from one radio configuration to another may include that the total available margin in the new grouping is greater than the total available margin in the current (old) grouping.

[0147] Furthermore, the determination to switch between sets of antenna groups may be based on one or more criteria in addition to the available total margin. For example, in a combined transmission scenario of multiple sub-6 GHz radios and multiple mmW radios, a wireless communication device may use the priority of the radios to select an operation of using a particular set of antenna groups that gives the highest priority radio the largest available total margin. In other words, the wireless communication device may select a grouping that divides the antennas related to the highest priority radio into the largest number of antenna groups.

[0148] Returning to FIG. 10, operation 1000 may further involve the UE selecting a first grouping among a plurality of antenna groups based on one or more criteria. In a particular aspect, the antenna groups in block 1002 are included in the first grouping, the backoff factor in block 1002 is included among the plurality of stored backoff factors for the first grouping, and is associated with the antenna groups in the first grouping. In this case, the one or more criteria may include the total RF exposure margin available for different groupings among the plurality of antenna groups including those for the first grouping. In a particular aspect, the one or more criteria may also include the priority of the radio type.

[0149] According to a particular aspect, operation 1000 may further involve the UE selecting a second grouping among a plurality of antenna groups based on one or more criteria, accessing another stored back-off coefficient associated with the antenna group in the second grouping, and transmitting another signal from at least one transmit antenna within the antenna group in the second grouping at another transmit power level based on another back-off coefficient that complies with the RF exposure limit. In this case, the one or more criteria may include the total RF exposure margin available for different groupings among the plurality of antenna groups, for the first grouping and for the second grouping. Further, the total RF exposure margin available for the second grouping may be greater than the total RF exposure margin available for the first grouping when selecting the second grouping.

[0150] According to a particular aspect, accessing in block 1002 may include accessing a first stored back-off coefficient associated with a first antenna group in a first grouping among a plurality of antenna groups. In this case, operation 1000 may further involve the UE accessing a second stored back-off coefficient associated with a second antenna group in a second grouping among the plurality of antenna groups based on one or more switching criteria.

[0151] In certain aspects, a wireless communication device (e.g., a UE) may select a particular antenna grouping, such as M1, M2, etc., or all FR2 antennas may be assigned to every antenna group, and the FR1 antennas may be distributed among antenna groups such that at least one of the FR1 antennas is assigned to multiple antenna groups, and select (e.g., select between M3 and M4) one of several antenna groupings. The wireless communication device may select an antenna grouping for a particular transmission scenario, as described herein with respect to operation 600 for grouping antennas for RF exposure compliance. As an example, the wireless communication device may select an antenna grouping for a particular region when the wireless communication device is located in that region. In some cases, the wireless communication device may select an antenna grouping for a particular exposure scenario, such as when the wireless communication device is in close proximity to the user's head, arm, or abdomen. In some cases, the wireless communication device may select an antenna grouping for when several antennas are used for simultaneous transmission. Further, the wireless device may select an antenna grouping based on a combination of these factors, e.g., based on a particular region and the total margin available within the grouping corresponding to or available for use within that particular region.

[0152] RF Exposure per Exposure Scenario or Category As described herein, a wireless communication device may adjust certain RF exposure settings (e.g., back-off factor, antenna grouping, RF exposure limit, etc.) in response to changes in RF exposure scenarios (e.g., head exposure, torso exposure, limb exposure, or hotspot exposure). A device state index (DSI) may represent or be associated with a particular RF exposure scenario such that a particular DSI may refer to a particular RF exposure scenario. During regulatory certification, RF exposure may be characterized for different usage conditions or exposure scenarios (e.g., DSI), including, for example, a head exposure scenario, a torso exposure scenario (e.g., a body-worn torso or trunk region), a hotspot exposure scenario (e.g., displaced from the trunk region and placed on a tabletop or desk), and a limb exposure scenario (hand / foot region triggered by a grip sensor). Limbs may include, for example, any of the hand, wrist, foot, ankle, or earlobe.

[0153] Depending on the use case, over time, a wireless communication device may expose different human tissues or different parts of the human body to RF energy at different times. FIG. 11 shows an illustration of exemplary wireless device locations 1104a-i (collectively "location 1104") relative to a profile of a user's body 1102. For example, during a first period, the wireless device may be held next to the user's head (e.g., locations 1104a, 1104b) for a voice call, and the RF exposure may be to the head. During a second period, the user may switch to using Bluetooth for a voice call and place the wireless device in a pocket (e.g., locations 1104d, 1104g, 1104h), and the RF exposure during the second period may be to both the head (from the Bluetooth radio) and the torso (from the wireless device). At other times, the user may place the wireless device in other locations, such as any of locations 1104c-i.

[0154] FIG. 11 shows nine different locations 1104a - i, but the reader will understand that there may be more or fewer different locations than nine that are being evaluated for exposure. The number of different locations used for RF exposure tracking may depend, for example, on the sensing and / or memory capabilities of the wireless device, the desired tissue exposure tracking resolution, etc.

[0155] The RF exposure history can be tracked as a function of time across different locations on the user's body (thus, the RF exposure history may also be referred to as an "tissue exposure history"). The time - varying RF exposure may be recorded as a function f(exposure(i),t) of the exposure, where exposure(i) is the exposure recorded at time t for a particular tissue location (e.g., tissue i )). tissue i can represent a unique location (or region) across multiple locations or regions on the user's body. For example, a unique location can represent a particular tissue and / or part of the human body, such as the right or left side of the user's head, a particular hand, wrist / , or arm (e.g., when the wireless device is applied to the user's hand, wrist, or arm during exercise), a finger (e.g., when the wireless device is being used for a game), the torso (e.g., when the wireless device is placed in a pocket), etc. In some cases, (as described herein), for tracking and recording the time - varying exposure history, the exposed tissue may be grouped and classified into a certain number of exposure categories, and the transmitting antennas may be grouped into different antenna groups. Each exposure category (described in more detail below) can be mutually exclusive with respect to the RF exposure over time, and each antenna group can transmit independently during a given time. For example, during a given time, the RF exposure from any antenna within one antenna group may not contribute to the RF exposure of antennas within other antenna groups.

[0156] In some embodiments, the tissue may be classified for each location on the user's body. The wireless device can, for example, use sensor information to track its location relative to the human body over time. The RF exposure can be tracked as a function of time and the tissue location (tissue i ) over the user's body. This approach may be generalized to any tissue location on the user's body, and tissue i may represent a specific tissue location in multiple dimensions, e.g., x i , y i , z i . The RF exposure time averaging may be performed for each tissue location (e.g., tissue i ). To demonstrate compliance, the time-averaged RF exposure can be calculated and audited according to the following formula. [Equation] where T is the time window associated with the time-averaged RF exposure limit (e.g., 360 seconds, 100 seconds, 60 seconds, 3 seconds, etc.), f(exposure(i),t) is the RF exposure encountered in tissue i at time t, and [Equation] is for all tissue locations (tissue i) exposure. In some cases, the wireless communication device may evaluate the time-averaged RF exposure over a time window during which the wireless communication device encounters different exposure scenarios. For example, during the first part of the time window, the wireless communication device may be in a head exposure scenario (e.g., exp1), and during the second part of the time window, the wireless communication device may be in a body-worn exposure scenario (e.g., exp2). In these cases, different exposures may be correlated over the time window of the time-averaged RF exposure limit such that different exposures are evaluated in the same time-averaging function (e.g., f(exp1, exp2, t)) for determining the available transmit power margin. Such a technique for determining the available transmit power margin may cause a degradation in wireless communication performance, for example, due to applying the same RF exposure settings to the time-averaging function despite different RF exposure scenarios.

[0157] Aspects of the present disclosure provide techniques and apparatus for evaluating time-averaged RF exposure for each RF exposure scenario and / or RF exposure category. When the exposure DSI changes from head to body-worn or vice versa, the same tissue may not be exposed to RF energy by exposure from the active radio, and thus, the wireless communication device may or may consider taking into account the change in DSI when evaluating RF exposure compliance. As an example, the time-averaged RF exposure encountered in a head exposure scenario may be evaluated separately from the time-averaged RF exposure encountered in a body-worn exposure scenario such that the RF exposure history for each RF exposure scenario is tracked and evaluated separately, as further described herein. The RF exposure time averaging may be performed for each exposure scenario or exposure category that may include one or more exposure scenarios, as further described herein.

[0158] Techniques and apparatus for evaluating time-averaged RF exposure for each RF exposure scenario or category can enable desirable wireless communication performance (e.g., reduced latency, increased throughput, increased transmission range, and / or increased signal quality or signal strength), for example, due to an increase in the transmit power margin available for transmission. Tracking RF exposure for each tissue location and / or region can enable a wireless device to transmit at a higher power level in scenarios where different locations of a user's body are exposed to RF radiation for different periods of time. For example, assume that a wireless device is located at location 1104a during a first period and at location 1104g during a second period. As the wireless device is located at different locations over time, the wireless device can effectively resume compliance with time-averaged RF exposure for each new location associated with the user's body. In other words, each tissue location can have a separate RF exposure history for tracking past transmissions.

[0159] Certain configurations for ensuring compliance with RF exposure limit(s) across different tissues and / or locations on a user's body are described herein. As described above, some examples of tracking and recording a time-varying exposure history include calculating or determining RF exposure based on tissues grouped and / or classified into a certain number of exposure categories and / or based on transmit antennas grouped into different antenna groups. Other examples and configurations are possible and are encompassed by the present disclosure.

[0160] In some examples, the SAR or PD value or distribution is determined for a particular tissue for each transmission. For example, SAR or PD measurements can be performed in a laboratory for each potential tissue and / or location on a user's body (e.g., using a modeled or simulated tissue) during transmission from each antenna, and for each potential setting (e.g., RAT, modulation, frequency, etc.) that can be used at that antenna for transmission. In some aspects, a subset of these measurements is obtained and the remainder is determined using one or more of the techniques described above. The tissue and / or location may correspond to discrete points or locations (e.g., such that a grid of points covers the body) or may be defined to be substantially continuous. Each such tissue and / or location may be tracked separately for the purposes of RF exposure. When a transmission is sent from an antenna, the exposure at the associated tissue or location can be determined. In some examples, the exposure for each such transmission is determined individually without reference to an exposure category or antenna group. Rather, for each transmission, the exposure to all affected tissue(s) / locations can be tracked (individually). However, in some examples, discrete points (as referred to above) can correspond to or be equivalent to DSI or other such location classifications. In some embodiments, each transmission is associated with a distribution of exposure values, and tissue over an area or region of the body (or multiple areas or regions, e.g., the head and hand) can be RF exposed due to the transmission. As the transmitting device moves around, the distribution also moves and can vary due to the body's contours or tissue types (the distributions can partially or fully overlap), and thus the device (e.g., exposure managers 122, 281) can track all locations or tissues corresponding to values within the distribution (and add or accumulate the exposure at a particular tissue or location for time averaging purposes). Similarly, simultaneous or serial transmissions can expose the same or additional tissue, and the exposure from each of these can be tracked for each tissue and / or location.Thus, the settings and operations of a device (e.g., UE120) may be relevant to the determination of RF exposure, but the exposure can, in some examples, be tracked (e.g., by the device) from a tissue-centric perspective.

[0161] As described above, aspects for ensuring RF exposure compliance across different tissues and / or locations on a user's body may include tracking and recording a time-varying exposure history for the tissues and / or locations. In some cases, the tissues being exposed may be grouped and classified into a number of exposure categories, and the transmit antennas may be grouped into different antenna groups. Some examples including exposure categories and / or antenna groups are described below.

[0162] FIG. 12 shows an exemplary RF exposure time window in accordance with certain aspects of the present disclosure, in which RF exposure is evaluated separately for each RF exposure scenario and / or category. In this example, the exposure categories may be divided into a head exposure category that may include only head exposure scenarios (or multiple head exposure scenarios, e.g., left cheek scenario, right cheek scenario, left tilt scenario, etc.), and a non-head exposure category that may include body part exposure, limb exposure, and / or hot spot exposure scenarios. In a first time series 1200A, the wireless communication device may encounter a head exposure scenario 1202 (exp1) and then switch to a non-head exposure scenario 1204 (exp2), such as a body part exposure scenario. One example includes being in a voice call next to the head (head exposure scenario) and switching from a microphone to a Bluetooth ON call with the device placed on a belt buckle (non-head exposure scenario). Here, the head exposure scenario is evaluated in a first time window T0, and the non-head exposure scenario is evaluated in a second time window T1 (which may overlap the first time window T0). Here, T0 and T1 respectively correspond to the regulatory time-average windows for RF transmission in exp1 and exp2. T0 and T1 may have the same or different time window lengths depending on whether the transmit frequencies between exp1 and exp2 are the same or different.

[0163] When determining the time-averaged RF exposure for the first time window T0, a wireless communication device can consider only the RF exposure due to the head exposure scenario (exp1). The time-averaged RF exposure in the first time window T0 can be calculated using the head exposure scenario (exp1) without using the non-head exposure scenario (exp2). When determining the time-averaged RF exposure for the second time window T1, a wireless communication device can consider only the RF exposure due to the non-head exposure scenario (exp2). The time-averaged RF exposure in the second time window T1 can be calculated using the non-head exposure scenario (exp2) without using the head exposure scenario (exp1). The exposures in the head scenario and the non-head scenario may not be correlated to determine the time-averaged RF exposure in each scenario. Thus, the exposure categories can be mutually exclusive with respect to RF exposure.

[0164] In the second time series 1200B, the wireless communication device may encounter the first head exposure scenario 1206 (exp1), switch to the non-head exposure scenario 1208 (exp2), and then switch back to the second head exposure scenario 1210 (exp3). For example, a voice call next to the user's head can be switched to a Bluetooth ON call with the device placed on the belt buckle, and then back next to the user's head with Bluetooth turned off. Here, the head exposure scenario is evaluated in the first time window T0, and the non-head exposure scenario is evaluated in the second time window T1 (which may overlap with the first time window T0). When determining the time-averaged RF exposure for the first time window T0, the wireless communication device may consider only the RF exposure due to head exposure (exp1). The wireless communication device considers the RF exposure due to non-head exposure (exp2) in the first evaluation of the time-averaged RF exposure for the second time window T1, and may consider separately / independently the RF exposure due to head exposure (exp1 and exp3) in the second evaluation of the time-averaged RF exposure for the second time window T1. Wireless communication may consider head and non-head exposure in separate time-averaged evaluations for RF exposure compliance. As an example, the time-averaged exposure for head DSI can be determined as a function of exp1 and / or exp3 over a moving time window (e.g., f(exp1,exp3,t)). The time-averaged exposure for non-head DSI(s) can be determined as a function of exp2 over a moving time window (e.g., f(exp2,t)).

[0165] FIG. 13 shows exemplary RF exposure settings for certain exposure scenarios and / or exposure categories according to certain aspects of the present disclosure, where P limit represents the time-averaged transmit power level corresponding to the RF exposure limit for a given exposure scenario / RAT / frequency band / antenna (e.g., after considering device uncertainties). In this example, P limitSome values (e.g., p0, p1, p2, p3, etc.) can be assigned to various exposure scenarios and / or exposure categories for each frequency band (e.g., B0, B1, B2, etc.) of the RAT (e.g., CDMA, LTE, NR, etc.) of an antenna (e.g., a radio or an antenna module) and / or an antenna group. As an example, for antenna 1 (or antenna group 1), the P of p0 limit may be assigned to the head exposure scenarios and / or head exposure categories of different RAT / bands, and the P of p1 limit may be assigned to the non-head exposure categories and / or non-head exposure scenarios. In the case of an antenna group (e.g., antenna group 1), the value of P limit may represent the minimum value of P among the antennas within the antenna group. FIG. 13 shows that different P limit (e.g., p0 to p limit ) can be assigned to each combination of exposure scenario, exposure category, RAT, band, antenna, and / or antenna group. However, in some examples, the P for two or more combinations may be the same. 23 Those skilled in the art will understand that the parameters shown in FIG. 13 are merely examples. Other parameters (e.g., a back-off coefficient, or the power limit corresponding to P multiplied by the corresponding back-off coefficient for each combination of RAT, band, exposure scenario, exposure category, antenna, antenna group, etc.) or categories of parameters (e.g., antenna group, antenna grouping, or exposure categorization) can be used in addition to or instead of those shown. limit

[0166] limit

[0167] ​​​In some embodiments, the wireless communication device may use a specific antenna grouping for each exposure scenario and / or exposure category to evaluate the time-averaged RF exposure, as described herein with respect to FIGS. 6 and 7, such as antenna grouping deployed for separate transmission scenarios. For example, the various exposure scenarios may be grouped into several categories such that each exposure category is mutually exclusive with all other categories with respect to RF exposure. Since RF exposure for different DSIs exposes different parts of the human body, the DSIs may be classified into different exposure categories for the purpose of compliance with RF exposure, under the assumption that, for example, different DSIs may be scenarios where different human tissues are exposed.

[0168] In some cases, exposure continuity is handled in two categories including head exposure and non-head exposure. For example, the first exposure category may include the head region (head DSI), and the second exposure category may include the non-head region (body-worn DSI, hot spot DSI, or limb DSI). The head exposure category may include exposure to the left cheek, left tilt, right cheek, and right tilt. The non-head exposure category may include other exposure scenarios (e.g., body-worn, hot spot, limb, etc.). For a given antenna and / or antenna group, it may be assumed that all exposures within the head exposure category or non-head exposure category are collocated or assigned to that specific antenna group, as described herein.

[0169] In some cases, exposure continuity may be handled in three (or more) categories. As an example, a first exposure category may include the head region (head DSI), a second exposure category may include the trunk region (body-worn DSI, hot spot DSI), and a third exposure category may include the hand / foot region (limb DSI). All of the transmit antennas (e.g., radios or antenna modules) may be combined into one antenna group (e.g., it is assumed that all antennas are collocated), or may be assigned to different antenna groups for each exposure category. In some aspects, the exposure categories may provide a basis for grouping antennas into different antenna groups for some DSIs, as further described herein.

[0170] The wireless communication device may perform time averaging for each exposure category for each antenna group. When DSI is classified into different exposure categories, the time-averaged RF exposure can be evaluated for each exposure category by further classifying the transmit antennas into different antenna groups and performing time averaging for each antenna group, as described herein. In some aspects, for example, each exposure category may be mutually exclusive with respect to RF exposure, and each antenna group within each exposure category may be mutually exclusive with respect to RF exposure with other antenna groups within that exposure category. Thus, for example, as described herein with respect to FIG. 12, the RF exposure history may be tracked and stored separately for each exposure category for each antenna group. For example, the RF exposure for all exposure scenarios and / or categories may be tracked over time to evaluate the available transmit power margin for future time intervals within the time window of the time-averaged RF exposure limit. The time-averaged RF exposure may be calculated only for active exposure scenarios (or categories) (e.g., the head / limb DSI representing the head exposure category and the hand exposure category may be active when the UE is held in the user's hand and applied to the user's head). Among the time-averaged RF exposures for active exposure categories, the minimum allowable transmit power value determined for each transmit antenna may be selected to limit the transmit power of the corresponding antenna and maintain compliance in the active exposure category. For example, in the above situation where the UE is held in the user's hand and applied to the user's head, the power limit for transmission may be determined according to the head DSI, or the power limit for transmission may be determined according to the limb DSI, and the lower of the two determined power limits may be selected. An active exposure category may include one or more DSI that occur within the time window of the time-averaged RF exposure limit.

[0171] FIG. 14 shows various antenna groupings for exposure categories according to certain aspects of the present disclosure. In a first exemplary exposure categorization (or classification) 1400A, there are four exposure categories (e.g., exposure category 1, exposure category 2, exposure category 3, and / or exposure category 4). Each exposure category may be associated with an antenna grouping having one or more antenna groups, and all of the antennas for a wireless communication device may be assigned across the antenna groups for each exposure category. For example, in exposure category 1, all of the antennas may be assigned across antenna group 1 and antenna group 2. In exposure category 2, all of the antennas may be assigned across antenna groups 5 - 8, and so on for the other exposure categories.

[0172] In a second exemplary exposure categorization 1400B as well, there are four exposure categories, with a single antenna group assigned to each of the categories. In this example, all of the antennas are assigned to the same antenna group. For example, it may be assumed that all of the antennas within the device overlap, and that exposure to any one antenna contributes (partially or fully) to exposure to any other antenna. In another example, transmissions from individual antennas may be spatially averaged, or the exposure from one antenna may be evaluated in terms of how much it overlaps with the exposure from another antenna (e.g., it is not assumed that the antennas are mutually exclusive, but the amount of contribution between multiple antennas is calculated based on where they are located relative to each other and / or how their energy patterns overlap).

[0173] When a wireless communication device encounters a specific exposure scenario, the wireless communication device may evaluate the time-averaged RF exposure using at least one of the antenna groups within the antenna group associated with the corresponding RF exposure scenario of the exposure category. For example, assume that the first exposure category corresponds to head exposure. When the wireless communication device encounters head exposure, the wireless communication device may select one (or multiple in the case of a multi-transmission scenario) of the antenna groups within the first exposure category to evaluate the time-averaged RF exposure. When multiple exposure categories are active, for example, when the device is held in the hand (limb exposure category) and at the same time is placed next to the head (head exposure category), depending on the transmitting antenna(s), the wireless communication device may select one or multiple active antenna groups for each of the active exposure categories to evaluate the time-averaged RF exposure and determine the allowable power limit for future time intervals to maintain compliance with the time-averaged RF exposure. In this regard, the final allowable power limit for each transmitting antenna may be determined to limit the transmitting power of the wireless communication device, for example, by taking the minimum value from all the calculated allowable power limits obtained from evaluating all the active antenna groups in all the active exposure categories.

[0174] In some aspects, the wireless device may evaluate compliance with the time-averaged RF exposure for each combination of RF exposure scenarios and / or combinations of RF exposure categories. For example, the wireless device may consider the RF exposure related to hand exposure and head exposure in a particular scenario. For example, when the wireless device is held in the user's hand and applied to the user's head, the wireless device may consider the RF exposure history for the hand.

[0175] DSIs can be grouped into exposure categories such that each exposure category is mutually exclusive from all other categories with respect to RF exposure. RF exposure during regulatory certification can be characterized for different usage conditions (DSIs), namely, head, body-worn (trunk region), hot spot (trunk region), and limbs (hand / foot region triggered by grip sensors). Since RF exposure for a DSI can expose different parts of the human body, RF exposure scenarios can be classified into different categories.

[0176] Figure 15 shows exemplary classifications 1500A, 1500B, 1500C of RF exposure categories. As shown, the first classification 1500A (classification 0) can have a single category representing all exposure regions or scenarios (e.g., head DSI, body-worn DSI, hot spot DSI, and / or limb DSI). The second classification 1500B (classification 1) can have three sub-categories including a first category representing head exposure (e.g., head DSI), a second category representing trunk exposure (e.g., body-worn DSI and / or hot spot DSI), and a third category representing the hand / foot region (e.g., limb DSI). The third classification 1500C (classification 2) can have two exposure categories including a first category representing head exposure (e.g., head DSI) and a second category representing non-head exposure (e.g., body-worn DSI, hot spot DSI, and / or limb DSI).

[0177] In the above classifications, it is assumed that each exposure category is independent from other exposure categories. The exposure history of each exposure category may be independently tracked by an RF exposure control solution (e.g., a time-averaged RF exposure control solution) to demonstrate compliance with time-averaged RF exposure. This assumption may ignore hand tissue exposure when the hand is also exposed with a handheld device in a head exposure scenario (e.g., head DSI).

[0178] In some embodiments, the wireless device may consider hand exposure at any time when head exposure is active (e.g., when head DSI is detected because the user may hold the phone with a hand next to the head). The RF exposure history may be tracked for each exposure category for each antenna group (assuming these histories are independent of each other). In the case of head DSI (where the hand may also be exposed), the wireless device may populate the exposure histories for both the hand and the head, as shown in FIG. 15.

[0179] In the first classification 1500A, the past time-averaged histories of all regions (e.g., head DSI, body-worn DSI, hot-spot DSI, and / or limb DSI) may be combined to determine the available exposure margin for future transmission(s) (e.g., with respect to future transmit power) so as to maintain compliance with the time-averaged RF exposure limit.

[0180] In the second and third classifications 1500B and 1500C, the exposure history of hand exposure may be populated in the category with head exposure in addition to the exposure history of hand exposure (e.g., head exposure is populated with both head and hand exposure). In the case of active head exposure (e.g., head DSI), the past time-averaged histories of both the head region and the hand region (non-head in the case of the third classification 1500C) may be evaluated to determine the remaining available exposure margin for future transmission, and the minimum value among the exposure margins may be used to calculate the future transmit power so as to maintain compliance in the hand region and the head region. Such an operation may be implemented using two calculations, i.e., corresponding to the evaluations in both the hand and the head regions. Note that when either torso DSI or hand / limb DSI is active, the wireless device may evaluate the exposure history only for the torso region or the hand region, respectively.

[0181] In some aspects, the wireless device may apply hand exposure to antenna groups and / or antenna grouping as described herein. For a given exposure category (e.g., head, torso, or hand), the transmit antennas may be split into antenna groups that are mutually exclusive from the perspective of RF exposure. The antenna groups may be formed based on specific exposure categories such as head exposure, torso exposure, or hand exposure. In some cases, the antenna groups may differ between head exposure and hand exposure. Assuming that the wireless device does not recognize the active antennas (e.g., via a RF Exposure Control Solution (RFECS)), but recognizes the active antenna groups, the wireless device may enforce the antenna grouping to be the same between head and hand exposure, for example, as shown in FIG. 15. As shown in FIG. 15, the head exposure and hand exposure categories of the second classification 1500B can share the same antenna group, and the same applies to the third classification 1500C.

[0182] (e.g., with respect to FIGS. 16A - 19B) As further described herein, various techniques for considering hand exposure when the head exposure is active can be implemented for each antenna group. For example, under active head DSI conditions, the wireless device may populate the head exposure history with the maximum between the head exposure history and the hand exposure history for the active antenna group (e.g., max{Head exp., Hand exp.}) and populate the same value (or the hand exposure value) in the hand exposure history for the same antenna.

[0183] In some cases, the wireless device may perform a hand exposure assessment for each antenna at any given time, assuming that the wireless device recognizes not only the active antenna group (e.g., via RFECS) but also the active antennas. As further described herein, various techniques for considering hand exposure when the head exposure is active can be performed for each active antenna. The exposure history can be populated according to which antenna group is associated with the active antennas. For example, under active head DSI conditions, the wireless device may populate the maximum value (e.g., max{Head exp., Hand exp.}) between the head exposure history and the hand exposure history for a first antenna group (e.g., AG.x) corresponding to the active antenna(s) into the head exposure history, and the wireless device may populate the same value (or hand exposure value) within the hand exposure history for a second antenna group (e.g., AG.y) corresponding to the active antenna(s), assuming that hand exposure is applicable, as further described herein. If hand exposure is not applicable, the wireless device may perform other operations described herein, such as the operations described herein with respect to FIGS. 18A-19B, for each antenna group or for each active antenna.

[0184] In some cases, the wireless device may perform RF exposure compliance using a look-up table of maximum time-averaged transmit power levels (P limit ) associated with different scenarios. Look-up table-based operations can account for hand exposure with respect to active head exposure (e.g., head DSI). The wireless device may use the look-up table of P limit for head exposure at the lowest (or minimum) P limit_head in the maximum time-averaged power levels associated with head and hand exposure (e.g., min{P limit_hand}) limitBy replacing, when the head exposure (e.g., head DSI) is active, the past history of hand exposure can be considered. Such an operation can be equivalent to using the maximum exposure (e.g., exposure = max{Head exposure, Hand exposure}) in the exposure history of head exposure and hand exposure for all antennas when hand exposure is applicable in a head exposure scenario (e.g., head DSI).

[0185] In some aspects, the wireless device can separately track past exposures for each of the RF exposure scenarios (e.g., head exposure, hand exposure, and torso exposure). The wireless device can evaluate the past exposures for head exposure and hand exposure when the head exposure is active (e.g., when the wireless device is held by the user's hand next to the user's head).

[0186] Figures 16A - 19B illustrate exemplary RF exposure tracking timing diagrams for different exposure scenarios. Figure 16A is a timing diagram 1600A showing the tracking of past RF exposure over time for head exposure, hand exposure, and torso exposure, where hand exposure can be tracked when the head exposure is active. In this example, when the head exposure is active (e.g., exp1 and exp4), the wireless device can evaluate the head and hand exposure histories to determine the allowable transmit power for each exposure scenario. For example, assume the wireless device is located at location 1104a or 1104b by the user's hand. Such an operation can involve two calculations, e.g., calculating a first transmit power based on the head exposure history and a second transmit power based on the hand exposure history. The wireless device can use the minimum transmit power among the determined values of the allowable transition power and apply that transmit power in the RF circuit configuration (e.g., RF transceiver circuit 300). In a torso or hand exposure scenario (e.g., exp2 and exp3), the wireless device can evaluate only the exposure history for the torso exposure or hand exposure, respectively. For example, assume the wireless device is located at any of locations 1104c - i.

[0187] In certain embodiments, to reduce the calculations performed by a wireless device when head exposure is active, for each antenna (or radio), whenever hand exposure is applicable under head exposure conditions, the head exposure history may be (or may be considered to be) populated as the maximum exposure among head exposure and hand exposure for an active head DSI (e.g., exposure = max{Head exp., Hand exp.}). The hand exposure history may be considered to be the past history of the hand for an active hand DSI (e.g., exposure=Hand exp.). The head history may represent the worst case among the head and hand exposure histories. The hand exposure history may also be populated into the head exposure history when only hand exposure is active. By tracking the hand exposure history within the head exposure history, it may be possible for the wireless device to consider hand exposure when the head DSI is active.

[0188] FIG. 16B is a timing diagram 1600B showing the tracking over time of past RF exposure for head exposure, hand exposure, and torso exposure, and the hand exposure may be tracked using an alternative method when head exposure is active. In this example, exp1 for head exposure is equal to the maximum exposure among head exposure and hand exposure (e.g., max{Head exp., Hand exp.}), and exp1 for hand exposure is equal to the hand exposure. Exp4 for the head and hand may be evaluated similarly. As shown, when hand exposure is active, exp2 of the hand is populated in the head exposure history.

[0189] In certain embodiments, when the head exposure is active, the wireless device may use the same exposure history for head and hand tracking. For example, as shown in the timing diagram 1700A of FIG. 17A, the wireless device may determine the maximum value in the head and hand exposure histories for head and hand tracking over time. The head exposure may be equal to max{Head exp., Hand exp.} to populate the head exposure history, and since this value represents a conservative exposure assessment for hand exposure (e.g., a value higher than the actual exposure level), the same value can also be copied (or applied) to the hand exposure history.

[0190] In some embodiments, since hand exposure may exist relative to the head exposure condition, the wireless device may determine the maximum time-average power level for head exposure (e.g., P limit_head) can be replaced with the lowest (or smallest) value of the power level for head-hand exposure for all antennas (or radios) to which hand exposure is applicable (e.g., min{Plimit_head, Plimit_hand}). For antennas to which hand exposure is not applicable (such as an antenna near an ear / audio speaker), the wireless device may continue to use the maximum time-average power level for head exposure. Such an operation may rarely perform a minimum evaluation if the maximum time-average power levels are all static values. In this way, instead of determining the maximum exposure history, as described herein with respect to FIGS. 16B and 17A, the wireless device may determine a normalized head exposure, for example, as a power report (e.g., power.report / min{Plimit_head, Plimit_hand}) divided by the minimum maximum time-average power level for head and hand exposure, as shown in timing diagram 1700B of FIG. 17B. Head exposure tracking using max{Head exp., Hand exp.} may be considered equivalent to max{power.report / Plimit_head, power.report / Plimit_hand} or power.report / min{Plimit_head, Plimit_hand}. The power report may correspond to the transmit power history over a period, such as a time window associated with the time-average RF exposure limit.

[0191] In certain embodiments, a wireless device may consider hand exposure only in certain scenario(s), e.g., when the wireless device is held next to the head by the user's hand and / or when RF exposure compliance takes into account hand exposure along with head exposure. The wireless device may apply hand exposure to head exposure assessment using any of the techniques described herein, e.g., as described herein with respect to FIGS. 16A - 17B. As an example, the wireless device may monitor two categories of exposure history, namely, one category for head exposure and another category for non - head exposure (e.g., hand and torso exposure). When the head DSI is active (e.g., the wireless device is held next to the hand), hand exposure is also guaranteed to be maintained under steady - state conditions by replacing the head exposure with the maximum exposure among head exposure and hand exposure (e.g., head exposure = max{Head exp., Hand exp.}). The maximum time - averaged power level (P limit_head ) for head exposure can be replaced with the minimum value of the power levels for head and hand exposure (e.g., min{Plimit_head, Plimit_hand}) for all antennas to which hand exposure is applicable. As described herein, for antennas where hand exposure is not applicable (e.g., an antenna near the ear / audio speaker and it is assumed that the user's hand is under such an antenna on the device to hold the device), the wireless device continues to use the maximum time - averaged power level for head exposure without changing the power level.

[0192] FIG. 18A is a timing diagram 1800A showing that hand exposure is evaluated along with head exposure when hand exposure is applicable, e.g., when the user's hand is in proximity to the transmitting antenna and / or when the wireless device is held next to the user's head and when RF exposure compliance takes into account hand exposure.

[0193] FIG. 18B is a timing diagram 1800B showing head exposure evaluated without hand exposure when hand exposure is not applicable, e.g., when the user's hand is far from the transmitting antenna, or when the wireless device is located next to the user's head, or when the RF exposure compliance procedure does not consider hand exposure (e.g., in an augmented reality (AR) and / or virtual reality (VR) application where the wireless device may be strapped to the user's head or located next to the user's head).

[0194] In some cases, hand exposure may not be applicable to some antennas when head exposure is active. For example, when the wireless device is held next to the user's hand and the typical hand position of the user is directed towards the bottom of the handheld wireless device, hand exposure may be considered when transmitting using an antenna (s) and / or antenna group near the hand. If the hand is far from a particular antenna (e.g., an antenna at the top of the device, near the user's ear or audio speaker), hand exposure may not be applicable or reduced hand exposure may be applicable. Assuming that the RF exposure compliance procedure considers hand exposure using head exposure, in this case, hand exposure may be replaced by a specific exposure value (e.g., low.value) or an upper limit may be defined. As an example, the FCC has defined the use of 1g average SAR exposure = 0.4 W / kg when the antenna is more than 25 millimeters away from human tissue, and thus the wireless device may use 0.4 W / kg as a specific exposure value.

[0195] FIG. 19A is a timing diagram 1900A showing that hand exposure is being evaluated together with head exposure when hand exposure is applicable. It will be understood that the wireless device may consider hand exposure using, for example, any of the techniques described herein with respect to FIGS. 16A - 17A.

[0196] FIG. 19B is a timing diagram 1900B showing hand exposure evaluated using head exposure when encountering hand exposure from an antenna far from the user's hand. In this example, the wireless device may use the hand exposure (power report / P limit_hand ) and the minimum value among specific exposure values as the hand exposure (e.g., hand exposure = min{exp.hand, low.value}).

[0197] In some embodiments, considering hand exposure in a head exposure scenario may depend on the standards or regulatory assessment procedures of a particular region. For example, one country may have an RF exposure assessment procedure that considers hand exposure in a head exposure scenario, while another country may not have a procedure for considering hand exposure in a head exposure scenario. The wireless device may implement any of the techniques described herein to consider hand exposure in a head exposure scenario depending on the region where the wireless device is located. For example, the wireless device may determine whether to consider hand exposure in a head exposure scenario based on various location information such as the identifier of the wireless network (e.g., Mobile Country Code (MCC)), the address associated with the access point, or the global positioning information. The wireless device may be composed of several MCCs (or other location information) indicating whether the hand exposure history should be evaluated when the head exposure is active (e.g., when the wireless device is held next to the user's head by the user's hand).

[0198] FIG. 20 is a flowchart showing exemplary operation 2000 for wireless communication according to a particular aspect of the present disclosure. Operation 2000 may be performed, for example, by a wireless communication device (e.g., UE 120a within wireless communication network 100). Operation 2000 may be implemented as a software component that runs when executed on one or more processors (e.g., controller / processor 280 of FIG. 2). Further, the transmission of signals by the wireless device in operation 2000 may be enabled, for example, by one or more antennas (e.g., antenna 252 of FIG. 2). In some aspects, the transmission and / or reception of signals by the wireless device may be implemented via a bus interface of one or more processors (e.g., controller / processor 280) that acquire and / or output the signals.

[0199] Operation 2000 may begin at block 2002, and the wireless device may track multiple RF exposures over a plurality of locations (e.g., location 1104) associated with the human body over time. The RF exposure may be tracked as the transmit power used at the location over time, where a particular transmit power may correspond to an RF exposure level. To track the RF exposure, the wireless device may track the RF exposure over multiple exposure categories, as described herein with respect to FIGS. 12-15, for example. Each of the exposure categories may represent a different location (e.g., a particular location of human tissue such as the left cheek) or a set of different locations (e.g., a plurality of locations such as a non-head category) among the plurality of locations. As an example, the exposure categories may include a head exposure category and a non-head exposure category. The head exposure category may correspond to RF exposure encountered at the user's head, and the non-head exposure category may correspond to RF exposure encountered at non-head locations such as torso exposure and / or limb exposure. In some cases, the exposure categories may include separate categories for the left and right sides of the human body. For example, the head exposure category may be further divided into a left head exposure category (e.g., left cheek) and a right head exposure category (e.g., right cheek). The limb exposure category may be further divided into a left limb exposure category (e.g., left hand) and a right hand exposure category (e.g., right hand). In some cases, the limb exposure category may be further divided into exposure categories for each (or some) of the limbs such as individual hands, wrists, feet, ankles, or ears, for example.

[0200] At block 2004, the wireless device determines a time-averaged RF exposure limit (e.g., P limitTransmit the signal with a transmit power determined at least in part based on the time-averaged exposure limit for a time window (e.g., any of the time windows shown in FIG. 12) and the tracked RF exposure for the same time window. For example, a wireless device may transmit a signal to another wireless communication device (e.g., BS110 shown in FIG. 1 or any other wireless communication device). The signal may indicate (or carry) any of a variety of information, such as data and / or control information. In some cases, the signal may indicate (or carry) one or more packets or data blocks.

[0201] In some embodiments, the transmit power may be determined based on the time-averaged exposure limit for a time window (e.g., any of the time windows shown in FIG. 12) and the tracked RF exposure for the same time window. In some cases, the transmitted signal may be associated with an RF exposure profile. The wireless device may determine a subset of the plurality of locations where RF exposure occurs based on the profile and the output of one or more sensors of the wireless device (e.g., sensors that detect exposure scenarios or categories).

[0202] In some embodiments, the wireless device may handle RF exposures tracked for different exposure categories independently of each other, as described herein with respect to FIG. 12. Such processing of RF exposures associated with a particular exposure category may, for example, enable the wireless device to improve its wireless communication performance as the wireless device exposes different locations of the human body to RF energy over time. The wireless device may identify an RF exposure history (e.g., a corresponding transmit power history) associated with a set of exposure categories (e.g., all or a subset of exposure categories including one or more of the exposure categories) from among the tracked RF exposures. The RF exposure history may be within a moving time window associated with a time-averaged RF exposure limit (e.g., the time window described herein with respect to FIG. 12). In response to detecting that the set of locations is being exposed to RF energy by signal transmission, the wireless device may determine the transmit power based at least in part on the RF exposure history and the time-averaged RF exposure limit. The set of locations may correspond to the set of exposure categories. To determine the transmit power, the wireless device may process the RF exposure history associated with the set of exposure categories independently of any RF exposure history associated with other exposure categories from among the exposure categories. For example, the wireless device may process the RF exposure history associated with head exposure independently of the RF exposure history associated with non-head exposure, as described herein with respect to FIG. 12.

[0203] In some embodiments, when determining the transmit power to comply with the RF exposure limits, as described herein with respect to FIGS. 16A-19B, for example, a wireless device may consider (or take into account) the RF exposure associated with multiple exposure categories (e.g., head-hand exposure). When evaluating multiple exposure categories, the wireless device may consider (or take into account) the RF exposure associated with all of the exposure categories (e.g., when tracking RF exposure for a head category and a non-head category and detecting that the user's hand and the user's head are exposed to RF energy). By way of example, in some cases, the set of exposure categories may include two or more categories. The set of exposure categories may include a first exposure category and a second exposure category different from the first exposure category. The first exposure category may correspond to the RF exposure encountered in a first region of the body (e.g., one or more first locations corresponding to the head), and the second exposure category may correspond to the RF exposure encountered in a second region of the body different from the first region of the body (e.g., one or more second locations corresponding to the limbs or hands). As an example, the first exposure category may correspond to head exposure as a head exposure category, for example, and the second exposure category may correspond to limb exposure as a limb exposure category, for example. In some cases, the second exposure category may correspond to specific limbs such as the hand and / or wrist. In some embodiments, the first exposure category may correspond to the exposure associated with a specific side of the head (e.g., the left side of the head), and the second exposure category may correspond to the exposure associated with a specific hand (e.g., the left hand).

[0204] In some embodiments, the wireless device may determine the transmit power for each of the exposure categories in the set, and the wireless device may select a minimum (lowest) transmit power for use in transmitting a signal, as described herein with respect to, for example, FIG. 16A. To determine the transmit power, the wireless device may determine a first transmit power based at least in part on a first portion of the RF exposure history corresponding to a first exposure category and may determine a second transmit power based at least in part on a second portion of the RF exposure history corresponding to a second exposure category. The wireless device may select the transmit power as the minimum value of the first transmit power and the second transmit power.

[0205] In some embodiments, the wireless device may select the maximum or greatest level of RF exposure associated with a particular category from among a plurality of categories being evaluated, as described herein with respect to, for example, FIG. 16B. To identify the RF exposure history, the wireless device may select the maximum (greatest) exposure from among the tracked RF exposures that temporally overlap for a first exposure category and a second exposure category with respect to the RF exposure history.

[0206] In certain embodiments, a wireless device may populate a first exposure category with a particular RF exposure history associated with a second exposure category from among a plurality of categories, as described herein with respect to FIG. 16B. For example, the RF exposure history populated in the first exposure category may correspond when the second exposure category is active and the first exposure category is not active. To track RF exposure, the wireless device may track a first RF exposure history for the first exposure category, the first RF exposure history including one or more of the RF exposures associated with the first exposure category and the second exposure category, and the wireless device may track a second RF exposure history for the second exposure category, the second RF exposure history including one or more of the RF exposures associated with the second exposure category. To track the first RF exposure history, the wireless device may populate the first RF exposure history with the corresponding second RF exposure history when the first exposure category is not active (and the second exposure category is active), e.g., when the RF exposure history associated with the first exposure category does not temporally overlap with the RF exposure history associated with the second exposure category.

[0207] In some embodiments, a wireless device may select the minimum (lowest) maximum time-average power level (P limit ) from among a plurality of categories being evaluated, as described herein with respect to FIG. 17B. To determine transmit power, the wireless device may determine the transmit power based at least in part on the RF exposure history and the minimum level of a first maximum time-average power level for the first exposure category and a second maximum time-average power level for the second exposure category. For example, the wireless device may use the minimum P limit among the exposure categories being evaluated to determine a normalized RF exposure history. The minimum P limitBy using this, a wireless device may be enabled to transmit at a transmit power that complies with RF exposure limits corresponding to the exposure category (e.g., RF exposure limits for head and hand exposure).

[0208] In certain embodiments, the wireless device may perform such an evaluation in response to detecting that the wireless device is located in an area that designates a multi-category evaluation. For example, in order to determine the transmit power, the wireless device may further respond to detecting that the area in which the wireless device is located designates evaluating the time-averaged RF exposure limit based on an RF exposure history associated with a first exposure category and a second exposure category (e.g., a head and hand scenario), and determine the transmit power.

[0209] The examples shown in FIGS. 1 - 20 are described herein with respect to a UE implementing various methods for providing RF exposure compliance for ease of understanding, but aspects of the present disclosure may also apply to other wireless devices such as wireless stations, access points, base stations, and / or customer premises equipment (CPE) that perform the RF exposure compliance described herein. Further, the examples are described with respect to communication between a UE (or other wireless device) and a network entity, but the UE or other wireless device may communicate with devices other than network entities, e.g., another UE, or another device within a user's home that is not, for example, a network entity. Additionally, certain examples are described with respect to a first exposure category and a second exposure category, but the methods and configurations described herein may apply to more (e.g., three or more) exposure scenarios and / or categories (e.g., a set of three or more locations and / or exposure categories).

[0210] RF exposure evaluated for each exposure scenario or category can enable improvements in wireless communication performance, including, for example, increased throughput at the cell edge, decreased latency, increased transmission range, desirable uplink performance, desirable uplink data rate, uplink carrier aggregation, and / or uplink connection.

[0211] Exemplary communication device FIG. 21 shows a communication device 2100 (e.g., a wireless device including UE120) that may include various components configured to perform operations for the techniques disclosed herein, such as operations shown in FIGS. 6 and / or 10 (e.g., corresponding to means-plus-function components). The communication device 2100 includes a processing system 2102 that may be coupled to a transceiver 2108 (e.g., a transmitter and / or a receiver). The transceiver 2108 is configured to transmit and receive signals for the communication device 2100 via an antenna 2110, such as various signals as described herein. The processing system 2102 may be configured to perform processing functions for the communication device 2100, including processing signals received by and / or to be transmitted by the communication device 2100.

[0212] The processing system 2102 includes a processor 2104 coupled to a computer-readable recording medium / memory 2112 via a bus 2106. In some aspects, the computer-readable recording medium / memory 2112, when executed by the processor 2104, causes the processor 2104 to perform the operations shown in FIGS. 6 and / or 10, or other operations for implementing various techniques described herein for providing RF exposure compliance (e.g., computer-executable code). In some aspects, the computer-readable recording medium / memory 2112 stores code 2114 for generating, code 2116 for allocating, code 2118 for accessing, code 2120 for transmitting, code 2122 for receiving (or obtaining), and / or code (e.g., code for generating and / or code for receiving) 2124 for determining. In some aspects, the processing system 2102 has a circuitry 2126 configured to implement the code stored within the computer-readable recording medium / memory 2112. In some aspects, the circuitry 2126 is coupled to the processor 2104 and / or the computer-readable recording medium / memory 2112 via the bus 2106. For example, the circuitry 2126 includes circuitry 2128 for generating, circuitry 2130 for allocating, circuitry 2132 for accessing, circuitry 2134 for transmitting, circuitry 2136 for receiving (or obtaining), and / or circuitry (e.g., circuitry for generating and / or circuitry for receiving) 2138 for determining.

[0213] FIG. 22 shows a communication device 2200 (e.g., a wireless device including UE120) that may include various components configured to perform operations for techniques disclosed herein, such as the operations shown in FIG. 20 (e.g., corresponding to means-plus-function components). The communication device 2200 includes a processing system 2202 that may be coupled to a transceiver 2208 (e.g., a transmitter and / or a receiver). The transceiver 2208 is configured to transmit and receive signals for the communication device 2200 via an antenna 2210, such as various signals as described herein. The processing system 2202 may be configured to perform processing functions for the communication device 2200, including processing signals received by and / or to be transmitted by the communication device 2200.

[0214] The processing system 2202 includes a processor 2204 (e.g., one or more processors) coupled to a computer-readable recording medium / memory 2212 via a bus 2206. In some aspects, the computer-readable recording medium / memory 2212 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 2204, cause the processor 2204 to perform the operations shown in FIG. 20 or other operations for implementing various techniques described herein for providing RF exposure compliance. In some aspects, the computer-readable recording medium / memory 2212 stores code 2214 for tracking, code 2216 for transmitting, code 2218 for determining, code 2220 for selecting, or any combination thereof. In some aspects, the processing system 2202 has a circuit configuration 2222 configured to execute code stored within the computer-readable recording medium / memory 2212. In some aspects, the circuit configuration 2222 is coupled to the processor 2204 and / or the computer-readable recording medium / memory 2212 via the bus 2206. For example, the circuit configuration 2222 includes a circuit configuration 2224 for tracking, a circuit configuration 2226 for transmitting, a circuit configuration 2228 for determining, a circuit configuration 2230 for selecting, or any combination thereof.

[0215] Exemplary embodiments In the following numbered clauses, implementation examples are described.

[0216] Aspect 1: A method of wireless communication by a wireless device, the method comprising tracking a plurality of radio frequency (RF) exposures over a plurality of locations associated with a human body over time, and transmitting a signal with a transmission power determined at least in part based on a time-averaged RF exposure limit and the tracked RF exposure.

[0217] Aspect 2: The method of Aspect 1, wherein tracking the RF exposure comprises tracking the RF exposure over a plurality of exposure categories, each of the exposure categories representing a different location or a set of different locations among the plurality of locations associated with the human body.

[0218] Aspect 3: The method of Aspect 2, further comprising identifying an RF exposure history associated with a set of exposure categories among the tracked RF exposures, the RF exposure history being within a moving time window associated with the time-averaged RF exposure limit, and determining the transmission power based at least in part on the RF exposure history and the time-averaged RF exposure limit in response to detecting that a set of locations corresponding to the set of exposure categories is being exposed to RF energy by signal transmission.

[0219] Aspect 4: The method of Aspect 3, wherein determining the transmission power comprises processing an RF exposure history associated with a set of exposure categories independently from any RF exposure history associated with other exposure categories among the exposure categories.

[0220] Aspect 5: The method of Aspect 3 or 4, wherein the set of exposure categories comprises a first exposure category and a second exposure category different from the first exposure category.

[0221] Aspect 6: The method according to aspect 5, wherein the first exposure category corresponds to head exposure and the second exposure category corresponds to limb exposure.

[0222] Aspect 7: The method according to aspect 5, wherein the first exposure category corresponds to exposure associated with a particular side of the head and the second exposure category corresponds to exposure associated with a particular hand.

[0223] Aspect 8: Determining the transmission power includes determining a first transmission power based at least in part on a first portion of the RF exposure history corresponding to the first exposure category, determining a second transmission power based at least in part on a second portion of the RF exposure history corresponding to the second exposure category, and selecting the transmission power as the minimum value of the first transmission power and the second transmission power. The method according to any one of aspects 5 to 7.

[0224] Aspect 9: Identifying the RF exposure history includes selecting the maximum exposure from the tracked RF exposures that temporally overlap for the first exposure category and the second exposure category for the RF exposure history. The method according to any one of aspects 5 to 7.

[0225] Aspect 10: Tracking the RF exposure includes tracking a first RF exposure history for the first exposure category, the first RF exposure history including one or more of the RF exposures associated with the first exposure category and the second exposure category, and tracking a second RF exposure history for the second exposure category, the second RF exposure history including one or more of the RF exposures associated with the second exposure category. The method according to any one of aspects 5 to 9.

[0226] Aspect 11: Tracking the first RF exposure history includes populating the first RF exposure history with a second RF exposure history corresponding when the first exposure category is not active. The method according to aspect 10.

[0227] Aspect 12: The method according to any one of Aspects 5 to 7, wherein determining the transmission power includes determining the transmission power based at least in part on the RF exposure history and the minimum level among the first maximum time-average power level for the first exposure category and the second maximum time-average power level for the second exposure category.

[0228] Aspect 13: The method according to any one of Aspects 5 to 12, further including determining the transmission power in response to detecting that the area where the wireless device is located designates evaluating a time-average RF exposure limit based on an RF exposure history associated with the first exposure category and the second exposure category.

[0229] Aspect 14: The method according to any one of Aspects 1 to 13, wherein the transmission power is determined based on the time-average RF exposure limit for the time window and the tracked RF exposure for the same time window.

[0230] Aspect 15: The method according to any one of Aspects 1 to 14, wherein the transmitted signal is associated with an RF exposure distribution, and the method further includes determining a subset of locations exposed to RF based on the distribution and the output of one or more sensors of the wireless device.

[0231] An apparatus for wireless communication, comprising a memory and one or more processors coupled to the memory, wherein the one or more processors are configured to track over time a plurality of radio frequency (RF) exposures over a plurality of locations associated with a human body and control the transmission of a signal at a transmission power determined based at least in part on the time-average RF exposure limit and the tracked RF exposure.

[0232] Aspect 17: The apparatus according to aspect 16, further comprising a transmitter coupled to one or more processors, wherein the transmitter is configured to transmit a signal with a transmission power, and in order to track RF exposure, one or more processors are further configured to track RF exposure across a plurality of exposure categories, each of the exposure categories representing a different location or a set of different locations among a plurality of locations associated with the human body, the apparatus according to aspect 16.

[0233] Aspect 18: One or more processors are further configured to identify an RF exposure history associated with a set of exposure categories among the tracked RF exposures, the RF exposure history being within a moving time window associated with a time-averaged RF exposure limit, and to determine the transmission power based at least in part on the RF exposure history and the time-averaged RF exposure limit in response to detecting that a set of locations corresponding to the set of exposure categories is to be exposed to RF energy by signal transmission, the apparatus according to aspect 17.

[0234] Aspect 19: In order to determine the transmission power, one or more processors are further configured to process an RF exposure history associated with a set of exposure categories independently of any RF exposure history associated with other exposure categories within the exposure categories, the apparatus according to aspect 18.

[0235] Aspect 20: The apparatus according to aspect 18 or 19, wherein the set of exposure categories includes a first exposure category and a second exposure category different from the first exposure category.

[0236] Aspect 21: The apparatus according to aspect 20, wherein the first exposure category corresponds to head exposure and the second exposure category corresponds to limb exposure.

[0237] Aspect 22: The apparatus according to aspect 20, wherein the first exposure category corresponds to exposure associated with a particular side of the head and the second exposure category corresponds to exposure associated with a particular hand.

[0238] Aspect 23: To determine the transmission power, one or more processors determine a first transmission power based at least in part on a first portion of the RF exposure history corresponding to a first exposure category, determine a second transmission power based at least in part on a second portion of the RF exposure history corresponding to a second exposure category, and select the transmission power as the minimum value of the first transmission power and the second transmission power. The apparatus according to any one of Aspects 20 to 22, further configured as such.

[0239] Aspect 24: To identify the RF exposure history, one or more processors are further configured to select, for the RF exposure history, the maximum exposure from among the tracked RF exposures that temporally overlap for the first exposure category and the second exposure category. The apparatus according to any one of Aspects 20 to 22, further configured as such.

[0240] Aspect 25: To track RF exposure, one or more processors track a first RF exposure history for a first exposure category, the first RF exposure history including one or more of the RF exposures associated with the first exposure category and the second exposure category, and track a second RF exposure history for a second exposure category, the second RF exposure history including one or more of the RF exposures associated with the second exposure category. The apparatus according to any one of Aspects 20 to 24, further configured as such.

[0241] Aspect 26: To track the first RF exposure history, one or more processors are further configured to populate the first RF exposure history with a second RF exposure history corresponding when the first exposure category is not active. The apparatus according to Aspect 25.

[0242] Aspect 27: The apparatus according to any one of Aspects 20 - 22, wherein, to determine the transmission power, one or more processors are further configured to determine the transmission power based at least in part on the RF exposure history and the minimum level among a first maximum time-average power level for a first exposure category and a second maximum time-average power level for a second exposure category.

[0243] Aspect 28: The apparatus according to any one of Aspects 20 - 27, wherein, to determine the transmission power, one or more processors are further configured to determine the transmission power in response to detecting that the area where the apparatus is located is designated to evaluate a time-average RF exposure limit based on an RF exposure history associated with a first exposure category and a second exposure category.

[0244] Aspect 29: The apparatus according to any one of Aspects 16 - 28, wherein the transmission power is determined based on a time-average RF exposure limit for a time window and a tracked RF exposure for the same time window.

[0245] Aspect 30: The apparatus according to any one of Aspects 16 - 29, wherein the transmitted signal is associated with an RF exposure profile, and one or more processors are further configured to determine a subset of locations exposed to RF exposure based on the profile and the output of one or more sensors of the apparatus.

[0246] Clause 31: An apparatus comprising a memory including computer-executable instructions and one or more processors configured to execute the computer-executable instructions to cause the apparatus to perform the method according to any one of Clauses 1 - 15.

[0247] Aspect 32: An apparatus comprising means for performing the method according to any one of Aspects 1 - 15.

[0248] Aspect 33: A non-transitory computer-readable recording medium including computer-executable instructions that, when executed by one or more processors of a processing system, cause the processing system to perform the method according to any one of Aspects 1 to 15.

[0249] Aspect 34: A computer program product embodied on a computer-readable storage medium including code for performing the method according to any one of Aspects 1 to 15.

[0250] The techniques described herein may be used in various wireless communication technologies such as NR (e.g., 5G NR), 3GPP (registered trademark) 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 wireless technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA (registered trademark)) and other variants of CDMA. Cdma2000 covers the IS-2000 standard, IS-95 standard, and IS-856 standard. A TDMA network may implement wireless technologies such as Global System for Mobile Communications (GSM) for mobile communications. An OFDMA network may implement wireless technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part 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 a group called the "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from a group called the "3rd Generation Partnership Project 2" (3GPP2). NR is a new wireless communication technology under development.

[0251] In 3GPP, the term "cell" can refer to the coverage area of a Node B (NB) and / or the NB subsystem serving this coverage area, depending on the context in which the term is used. In the NR system, the term "cell" can be used interchangeably with BS, next-generation Node B (gNB or g-node B), access point (AP), distributed unit (DU), carrier, or transmission reception point (TRP). A BS can provide communication coverage for macrocells, picocells, femtocells, and / or other types of cells. A macrocell can cover a relatively large geographical area (e.g., several kilometers in radius) and can enable unrestricted access by UEs subscribed to the service. A picocell can cover a relatively small geographical area and can enable unrestricted access by UEs subscribed to the service. A femtocell can cover a relatively small geographical area (e.g., a home) and can enable restricted access by UEs associated with the femtocell (e.g., UEs in a closed subscriber group (CSG), UEs of users within the home, etc.). The BS for a macrocell may be called a macro BS. The BS for a picocell may be called a pico BS. The BS for a femtocell may be called a femto BS, home BS, or home NodeB.

[0252] The UEs described in this specification may be configured as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a customer premise equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a game device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or instrument, a biosensor / device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart list band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing device, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs may be regarded as machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs may communicate with, for example, a BS, another device (e.g., a remote device), or some other entity, including robots, drones, remote devices, sensors, meters, monitors, location tags, etc. A wireless node may provide connectivity to a network (e.g., a wide area network such as the Internet or a cellular network) via, for example, a wired or wireless communication link. Some UEs may be regarded as Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

[0253] In some examples, access to the air interface can be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication between some or all of the devices and apparatuses 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, in the case of scheduled communication, the subordinate entity uses the resources allocated by the scheduling entity. The base station is not the only entity that can 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 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 an example of a mesh network, a UE may communicate directly with each other in addition to communicating with a scheduling entity.

[0254] The methods disclosed herein include one or more steps or actions for achieving the method. The steps and / or actions of those methods can be interchanged with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order of specific steps and / or actions, and / or the use of those steps and / or actions, can be modified without departing from the scope of the claims.

[0255] As used herein, the phrase "at least one of" in a list of items refers to any combination of those items, including a single member. By way of example, "at least one of a, b, or c" includes a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination having multiple of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c, or any other arrangement of a, b, and c).

[0256] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" can include calculating, computing, processing, deriving, generating, investigating, searching (e.g., searching a table, database, or another data structure), ascertaining, etc. Further, "determining" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. Still further, "determining" can include resolving, selecting, choosing, establishing, etc.

[0257] The foregoing description has been provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein but are to be accorded the full scope consistent with the language of the claims, and the reference to an element in the singular is not intended to mean “sole and exclusive” unless expressly so stated but rather “one or more.” Unless otherwise expressly stated, the term “some” refers to one or more. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are known or later come to be known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Further, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No element of a claim is to be construed under the provisions of 35 U.S.C. § 112, paragraph (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is expressly recited using the phrase “step for.”

[0258] The various operations of the above-described method can be performed by any suitable means capable of performing the corresponding functions. The means can include various hardware and / or software components and / or modules (singular or plural) including, but not limited to, a circuit, an application specific integrated circuit (ASIC), or a processor. In general, where an operation is shown in the figures, those operations can have corresponding equivalent means-plus-function components with like reference numerals.

[0259] The various illustrative logical blocks, modules, and circuits described in connection with the present 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 gates 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 in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0260] When implemented in hardware, an exemplary hardware configuration may include a processing system within a wireless node. The processing system may be implemented using a bus architecture. The bus may include any number of interconnecting buses and bridges, depending on the specific application of the processing system and overall design constraints. The bus may link together various circuits including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter, in particular, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the physical (PHY) layer. In the case of a UE (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 a timing source, peripherals, a voltage regulator, a power management circuit, etc. These are well known in the art and thus will not be described further. The processor may be implemented using one or more general-purpose processors and / or dedicated processors. Examples include a microprocessor, a microcontroller, a DSP processor, and other circuit configurations capable of executing software. Those skilled in the art will recognize how best to implement the described functions of the processing system according to the specific application and overall design constraints imposed on the overall system.

[0261] When implemented in software, the functions may be stored on a computer-readable recording medium or transmitted via a computer-readable recording medium as one or more instructions or codes. Software is broadly interpreted to mean instructions, data, or any combination thereof, whether called software, firmware, middleware, microcode, hardware description language, or by any other name. The computer-readable recording medium includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. The processor may perform the role of general processing, including managing the bus and executing software modules stored on a machine-readable storage medium. The computer-readable storage medium may be coupled to the processor so that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integrated with 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 with stored instructions separate from the wireless node, all of which may be accessed by the processor through a bus interface. Alternatively, or in addition, the machine-readable medium or any portion thereof may be integrated with the processor, as is the case with a cache and / or a general-purpose register file. Examples of machine-readable storage media can 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.

[0262] A software module may include a single instruction or multiple instructions and may be distributed across different programs, across multiple storage media, and across several different code segments. A computer-readable recording medium may include several software modules. A software module includes instructions that, when executed by an apparatus such as a processor, cause a processing system to implement various functions. A software module may include a transmission module and a reception module. Each software module may reside within a single storage device or may be distributed across multiple storage devices. By way of example, a software module may be loaded from a hard drive to RAM when a trigger event occurs. During execution of a software module, the processor may load some of the instructions into a cache to increase access speed. Then, one or more cache lines may be loaded into a general-purpose register file for execution by the processor. When referring hereinafter to the functions of a software module, it will be understood that such functions are implemented by the processor when executing instructions from that software module.

[0263] Also, any connection is properly referred to as a computer-readable recording medium. For example, when 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), wireless, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, wireless, and microwave are included in the definition of the medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray (registered trademark) disc, and a disk typically magnetically reproduces data, while a disc optically reproduces data using a laser. Thus, in some embodiments, the computer-readable recording medium may comprise a non-transitory computer-readable recording medium (e.g., a tangible medium). Additionally, in other embodiments, the computer-readable recording medium may include a transitory computer-readable recording medium (e.g., a signal). The above combinations should also be included within the scope of the computer-readable recording medium.

[0264] Accordingly, certain embodiments may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable recording medium having (and / or encoded with) instructions executable by one or more processors to perform the operations described herein, such as the operations described and shown in FIGS. 6, 10, and / or 20.

[0265] Furthermore, it should be understood that modules and / or other suitable means for implementing the methods and techniques described herein may be downloaded and / or otherwise obtained by a user terminal and / or a base station, where applicable. For example, such devices may be coupled to a server to facilitate transfer of means for implementing the methods described herein. Alternatively, the various methods described herein may be provided via a storage means (e.g., a physical storage medium such as RAM, ROM, or a compact disk (CD) or floppy disk) such that a user terminal and / or a base station can obtain the various methods when the storage means is coupled to or provided to the device. Additionally, any other suitable technique for providing the methods and techniques described herein to a device may be utilized.

[0266] It should be understood that the claims are not limited to the exact configurations and components shown above. Various modifications, changes, and variations can be made to the arrangement, operation, and details of the methods and apparatuses described above without departing from the claims.

Claims

1. A method of wireless communication using wireless devices, Tracking multiple radio frequency (RF) exposures across multiple locations associated with the human body over time, Transmitting a signal with a transmit power determined at least partially based on a time-averaged RF exposure limit and the tracked RF exposure, Includes, Tracking the RF exposure includes tracking the RF exposure across multiple exposure categories, where each of the exposure categories represents a different location or set of different locations among the multiple locations associated with the human body, and the method further includes Identifying RF exposure history associated with the set of exposure categories among the tracked RF exposures, wherein the RF exposure history falls within a moving time window associated with the time-averaged RF exposure limit. In response to detecting that the signal transmission would expose the set of locations to RF energy, the transmit power is determined, at least in part, based on the RF exposure history and the time-averaged RF exposure limit, wherein the set of locations corresponds to the set of exposure categories. Methods that include...

2. The method according to claim 1, wherein determining the transmit power includes processing the RF exposure history associated with the set of exposure categories independently of any RF exposure history associated with other exposure categories among the exposure categories.

3. The method according to claim 1, wherein the set of exposure categories includes a first exposure category and a second exposure category different from the first exposure category.

4. The method according to claim 3, wherein the first exposure category corresponds to head exposure and the second exposure category corresponds to limb exposure.

5. The method according to claim 3, wherein the first exposure category corresponds to exposure associated with a particular side of the head, and the second exposure category corresponds to exposure associated with a particular hand.

6. Determining the aforementioned transmission power is Determining a first transmit power based at least partially on a first portion of the RF exposure history corresponding to the first exposure category, Determining a second transmit power based at least partially on a second portion of the RF exposure history corresponding to the second exposure category, Selecting the transmission power as the minimum value among the first transmission power and the second transmission power, The method according to claim 3, including the method described in claim 3.

7. The method according to claim 3, wherein identifying the RF exposure history includes selecting the largest exposure among the tracked RF exposures that overlaps in time with respect to the first exposure category and the second exposure category with respect to the RF exposure history.

8. Tracking the aforementioned RF exposure Tracking a first RF exposure history for the first exposure category, wherein the first RF exposure history includes one or more of the RF exposures associated with the first exposure category and the second exposure category. Tracking a second RF exposure history for the second exposure category, wherein the second RF exposure history includes one or more of the RF exposures associated with the second exposure category. The method according to claim 3, including the method described in claim 3.

9. The method according to claim 8, wherein tracking the first RF exposure history includes populating the second RF exposure history corresponding to the first RF exposure history when the first exposure category is not active.

10. The method according to claim 3, wherein determining the transmit power includes determining the transmit power at least in part on the RF exposure history and the minimum level of a first maximum time-averaged power level for the first exposure category and a second maximum time-averaged power level for the second exposure category.

11. The method according to claim 3, further comprising determining the transmit power in response to detecting that the region in which the wireless device is located specifies that the time-averaged RF exposure limit should be evaluated based on the RF exposure history associated with the first exposure category and the second exposure category.

12. The method according to claim 1, wherein the transmission power is determined based on the time-averaged RF exposure limit for a given time window and the tracked RF exposure for the same time window.

13. The method according to claim 1, wherein the transmitted signal is associated with an RF exposure distribution, and the method further comprises determining a subset of the plurality of locations that are subjected to RF exposure based on the distribution and the outputs of one or more sensors of the wireless device.

14. A device for wireless communication, Memory and One or more processors coupled to the memory, The system includes, and the one or more processors, Tracking multiple radio frequency (RF) exposures across multiple locations associated with the human body over time, Controlling the transmission of a signal at a transmit power determined at least partially based on a time-averaged RF exposure limit and the tracked RF exposure, The device is configured to perform the following: The system comprises a transmitter coupled to one or more of the processors, the transmitter being configured to transmit the signal with the transmit power, and the one or more processors being further configured to track the RF exposure across a plurality of exposure categories, each of which represents a different location or set of different locations among the plurality of locations associated with the human body. The aforementioned one or more processors Identifying RF exposure history associated with the set of exposure categories among the tracked RF exposures, wherein the RF exposure history falls within a moving time window associated with the time-averaged RF exposure limit. In response to detecting that the signal transmission would expose the set of locations to RF energy, the transmit power is determined, at least in part, based on the RF exposure history and the time-averaged RF exposure limit, wherein the set of locations corresponds to the set of exposure categories. A device further configured to perform the following actions.

15. The apparatus according to claim 14, wherein, in order to determine the transmit power, one or more processors are further configured to process the RF exposure history associated with the set of exposure categories independently of any RF exposure history associated with other exposure categories among the exposure categories.

16. The apparatus according to claim 14, wherein the set of exposure categories includes a first exposure category and a second exposure category different from the first exposure category.

17. The apparatus according to claim 16, wherein the first exposure category corresponds to head exposure and the second exposure category corresponds to limb exposure.

18. The apparatus according to claim 16, wherein the first exposure category corresponds to exposure associated with a particular side of the head, and the second exposure category corresponds to exposure associated with a particular hand.

19. In order to determine the transmission power, one or more processors, The first transmit power is determined based at least partially on the first portion of the RF exposure history corresponding to the first exposure category, The second transmit power is determined based at least partially on the second portion of the RF exposure history corresponding to the second exposure category, The transmission power is selected as the minimum value among the first transmission power and the second transmission power. The apparatus according to claim 16, further configured as follows.

20. The apparatus according to claim 16, wherein, in order to identify the RF exposure history, one or more processors are further configured to select the largest exposure among the tracked RF exposures that temporally overlap with respect to the first exposure category and the second exposure category with respect to the RF exposure history.

21. To track the RF exposure, one or more processors Tracking a first RF exposure history for the first exposure category, wherein the first RF exposure history includes one or more of the RF exposures associated with the first exposure category and the second exposure category. Tracking a second RF exposure history for the second exposure category, wherein the second RF exposure history includes one or more of the RF exposures associated with the second exposure category. The apparatus according to claim 16, further configured to perform the following:

22. The apparatus according to claim 21, wherein, in order to track the first RF exposure history, one or more processors are further configured to populate the second RF exposure history corresponding to the first RF exposure history when the first exposure category is not active.

23. The apparatus according to claim 16, wherein, in order to determine the transmit power, one or more processors are further configured to determine the transmit power at least in part on the RF exposure history and the minimum level of a first maximum time-averaged power level for the first exposure category and a second maximum time-averaged power level for the second exposure category.

24. The apparatus according to claim 16, wherein, in order to determine the transmit power, the one or more processors are further configured to determine the transmit power in response to detection that the region in which the apparatus is located specifies that the time-averaged RF exposure limits are evaluated based on the RF exposure history associated with the first exposure category and the second exposure category.

25. The apparatus according to claim 14, wherein the transmission power is determined based on the time-averaged RF exposure limit for a given time window and the tracked RF exposure for the same time window.

26. The apparatus according to claim 14, wherein the transmitted signal is associated with an RF exposure distribution, and the one or more processors are further configured to determine a subset of the multiple locations that are subjected to RF exposure based on the distribution and the outputs of one or more sensors of the apparatus.

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