Compressing radio frequency exposure maps

Abstract

Techniques and apparatus are described for generating compressed radio frequency (RF) exposure maps and using such compressed RF exposure maps to determine transmit power to meet RF exposure compliance limits. One example method generally includes obtaining a first RF exposure map associated with at least one antenna of a wireless device, and converting the first RF exposure map to a second RF exposure map. The second RF exposure map is compressed compared to the first RF exposure map. Another example method includes accessing an RF exposure map associated with at least one antenna of the wireless device. The RF exposure map includes a representation of a maximum RF exposure of a region of the RF exposure map. The method also includes transmitting a signal from the antenna at a transmit power that follows an RF exposure limit determined based on the RF exposure map.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Patent Application No. 18 / 544,768, filed on Dec. 19, 2023, which claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 476,615, filed on Dec. 21, 2022, the entire contents of both of which are incorporated herein by reference for all applicable purposes. Background of the Disclosure

[0004] Aspects of the present disclosure relate to wireless communication and, more particularly, to radio frequency (RF) exposure compliance.

[0006] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasting, etc. Modern wireless devices such as cellular phones are typically required to meet radio frequency (RF) exposure limits set by certain government and international standards and regulations. To ensure compliance with the standards, such devices typically undergo extensive certification processes before being shipped to the market. To ensure that wireless devices comply with RF exposure limits, techniques have been developed that enable wireless devices to evaluate the RF exposure from the wireless device and accordingly adjust the transmit power of the wireless device to comply with the RF exposure limits. Summary of the Disclosure

[0007] The systems, methods, and devices of the present disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the appended claims, some features will now be briefly discussed. After considering these discussions and particularly after reading the section entitled "Detailed Description," one will understand how the features of the present disclosure provide advantages that include improved wireless communication performance.

[0008] Certain aspects of the subject matter described in the present disclosure may be implemented in a method for generating a radio frequency (RF) exposure map. The method generally includes obtaining a first RF exposure map associated with at least one antenna of a wireless device. The method further includes converting the first RF exposure map to a second RF exposure map. The second RF exposure map is compressed compared to the first RF exposure map.

[0009] Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus generally includes: one or more memories that jointly store executable instructions; and one or more processors coupled to the one or more memories. The one or more processors are jointly configured to execute the executable instructions to cause the apparatus to obtain a first RF exposure map associated with at least one antenna of a wireless device, and to convert the first RF exposure map into a second RF exposure map. The second RF exposure map is compressed compared to the first RF exposure map.

[0010] Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus generally includes means for obtaining a first RF exposure map associated with at least one antenna of a wireless device. The apparatus also includes means for converting the first RF exposure map into a second RF exposure map. The second RF exposure map is compressed compared to the first RF exposure map.

[0011] Certain aspects of the subject matter described in this disclosure can be implemented in a computer-readable medium. The computer-readable medium has instructions stored thereon that, when executed by an apparatus, cause the apparatus to perform operations. The operations generally include obtaining a first RF exposure map associated with at least one antenna of a wireless device. The operations also include converting the first RF exposure map into a second RF exposure map. The second RF exposure map is compressed compared to the first RF exposure map.

[0012] Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication by a wireless device. The method generally includes accessing a radio frequency (RF) exposure map associated with at least one antenna of the wireless device. The RF exposure map includes a representation of a maximum RF exposure of regions of the RF exposure map. The method also includes transmitting a signal from the at least one antenna at a transmit power that follows RF exposure limits determined at least in part based on the RF exposure map.

[0013] Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus generally includes: one or more memories that jointly store executable instructions; and one or more processors coupled to the one or more memories. The one or more processors are jointly configured to execute the executable instructions to cause the apparatus to access a radio frequency (RF) exposure map associated with at least one antenna of the apparatus. The RF exposure map includes a representation of a maximum RF exposure of regions of the RF exposure map. The one or more processors are also jointly configured to execute the executable instructions to cause the apparatus to transmit a signal from the at least one antenna at a transmit power that follows RF exposure limits determined at least in part based on the RF exposure map.

[0014] Certain aspects of the subject matter described in this disclosure may be implemented in an apparatus for wireless communication. The apparatus generally includes components for accessing a radio frequency (RF) exposure map associated with at least one antenna of the apparatus. The RF exposure map includes a representation of a maximum RF exposure for a zone of the RF exposure map. The apparatus also includes components for transmitting a signal from the at least one antenna at a transmit power that complies with an RF exposure limit determined at least in part based on the RF exposure map.

[0015] Certain aspects of the subject matter described in this disclosure may be implemented in a computer-readable medium. The computer-readable medium has instructions stored thereon that, when executed by a device, cause the device to perform operations. The operations generally include accessing a radio frequency (RF) exposure map associated with at least one antenna of the device. The RF exposure map includes a representation of a maximum RF exposure for a zone of the RF exposure map. The operations also include transmitting a signal from the at least one antenna at a transmit power that complies with an RF exposure limit determined at least in part based on the RF exposure map.

[0016] Other aspects provide: an apparatus operable to, configured to, or otherwise adapted to perform any one or more of the foregoing methods and / or those described elsewhere herein; a non-transitory computer-readable medium comprising instructions that, when executed by a processor of the apparatus, cause the apparatus to perform the foregoing methods and those described elsewhere herein; a computer program product embodied on a computer-readable storage medium comprising: code for performing the foregoing methods and those described elsewhere herein; and / or an apparatus comprising components for performing the foregoing methods and those described elsewhere herein. By way of example, an apparatus may include a processing system, a device having a processing system, or a processing system cooperating through one or more networks.

[0017] To achieve the aforementioned and related purposes, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain exemplary features of the one or more aspects. However, these features indicate only some of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order that the above-mentioned features of the present disclosure may be understood in detail, a more particular description briefly summarized above may be obtained by reference to some aspects illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only certain typical aspects of the present disclosure and are therefore not to be considered as limiting the scope thereof, as the description may admit to other equally effective aspects.

[0019] Figure 1 is a block diagram conceptually illustrating an example wireless communication network.

[0020] Figure 2 is a block diagram conceptually illustrating the design of an example base station (BS) and user equipment (UE).

[0021] Figure 3 is a block diagram of an example radio frequency (RF) transceiver.

[0022] Figure 4A , Figure 4B and Figure 4C are diagrams illustrating examples of transmit power over time that complies with time-averaged RF exposure limits.

[0023] Figure 5 is a diagram illustrating an example system for measuring RF exposure values or distributions.

[0024] Figure 6 is a flowchart illustrating example operations for generating an RF exposure map in accordance with certain aspects of the present disclosure.

[0025] Figure 7 is a diagram illustrating the progress of generating an RF exposure map from one or more RF distributions in accordance with certain aspects of the present disclosure.

[0026] Figure 8 is a diagram illustrating the addition together of eight normalized composite maps per antenna to obtain a total exposure map in accordance with certain aspects of the present disclosure.

[0027] Figure 9 illustrates an example total exposure map and an updated version of the total exposure map in accordance with certain aspects of the present disclosure, where the follow location is set to a specific value.

[0028] Figure 10 illustrates an example of identifying non-compliant regions until all non-compliant regions are covered by identified regions in accordance with certain aspects of the present disclosure.

[0029] Figure 11 illustrates an example subset of non-compliant regions selected for a compressed RF exposure map in accordance with certain aspects of the present disclosure.

[0030] Figure 12 illustrates an example of a composite map and a corresponding subset of non-compliant regions in accordance with certain aspects of the present disclosure.

[0031] Figure 13 illustrates an example table of maximum RF exposure values associated with specific maps for each region in accordance with certain aspects of the present disclosure.

[0032] Figure 14is a flowchart illustrating an example operation for generating an RF exposure map with additional details in accordance with certain aspects of the present disclosure.

[0033] Figure 15 is an example graph showing the average backoff difference in decibels for different on / off combinations of an antenna across different test scenarios in accordance with certain aspects of the present disclosure.

[0034] Figure 16 is a diagram illustrating that an RF exposure map is segmented into multiple zones in accordance with certain aspects of the present disclosure.

[0035] Figure 17 is a flowchart illustrating an example operation for generating an RF exposure map in accordance with certain aspects of the present disclosure.

[0036] Figure 18 is a flowchart illustrating an example operation for wireless communication by a wireless device in accordance with certain aspects of the present disclosure.

[0037] Figure 19 Illustrates a communication device (e.g., a UE) that may include various components configured to perform operations of the techniques disclosed herein in accordance with certain aspects of the present disclosure.

[0038] For ease of understanding, the same reference numerals have been used, where possible, to denote the same elements common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized in other aspects without detailed recitation. Detailed Description

[0039] Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable media for generating and / or using a compressed radio frequency (RF) exposure map associated with a wireless device.

[0040] In some cases, a wireless communication device may use a two-dimensional RF exposure distribution (e.g., a specific absorption rate (SAR) distribution and / or a power density (PD) distribution) to evaluate RF exposure compliance. The wireless device may perform SAR and PD evaluations within a given time window to determine a maximum allowable transmit power using the RF exposure distribution. The RF exposure distribution may represent the maximum RF exposure exhibited by one or more antennas of the wireless device. In some cases, the RF exposure distribution may be a look-up table of the maximum RF exposure exhibited by antennas transmitting at various frequency bands. Each of the maximum RF exposures may correspond to a peak RF exposure across all surfaces of the wireless device such that there is no distinction with respect to the location from which the RF exposure is transmitted from the wireless device. Although the aspects described herein relate to two-dimensional (2D) distributions, it will be understood that the described operations and configurations may also be applied to three-dimensional maps or distributions.

[0041] Aspects of the present disclosure provide apparatuses and methods for generating and / or using compressed RF exposure maps, where the compressed RF exposure maps may represent the maximum RF exposure exhibited in a particular region of a wireless device for certain radio combinations. The RF exposure maps may be reduced to the maximum RF exposure in certain regions across the wireless device such that the wireless device evaluates RF exposure compliance across the regions identified for the RF exposure maps. In some aspects, the compressed RF exposure maps may represent RF exposure in terms of SAR and / or PD.

[0042] The apparatuses and methods for generating and using compressed RF exposure maps described herein may facilitate improved wireless communication performance (e.g., improved signal quality at the receiver, lower latency, higher throughput, etc.). The apparatuses and methods for generating and using compressed RF exposure maps described herein may also enable improved processing performance, e.g., due to a reduced memory size used for the compressed RF exposure maps and / or a reduced number of calculations for performing RF exposure evaluations to meet time-average RF exposure compliance during simultaneous transmission scenarios.

[0043] As used herein, a radio may refer to one or more active frequency bands, transceivers, and / or radio access technologies (RATs) for wireless communication (e.g., 2G or 3G such as Code Division Multiple Access (CDMA), 4G such as Long Term Evolution (LTE), 5G New Radio (NR), IEEE 802.11, Bluetooth, Non-Terrestrial Network (NTN) communication, etc.). For example, for uplink carrier aggregation in LTE and / or NR, each active component carrier in the active component carriers for wireless communication may be considered a separate radio. Similarly, multi-band transmission in IEEE 802.11 communication may be considered separate radios for each frequency band (e.g., 2.4 gigahertz (GHz), 5 GHz, or 6 GHz).

[0044] 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 functionality and arrangement of the elements discussed without departing from the scope of the present disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For example, the methods described may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with respect to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement an apparatus or practice a method. Further, the scope of the present disclosure is intended to cover such apparatus or methods practiced using other structures, functionality, or a combination of structures and functionality that supplement or replace various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure herein may be embodied by one or more elements of the claims. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

[0045] In general, any number of wireless networks may be deployed in a given geographical area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, air interface, etc. A frequency may also be referred to as a carrier, subcarrier, frequency channel, tone, subband, etc. Each frequency may support a single RAT in a given geographical area to avoid interference between wireless networks of different RATs, or may support multiple RATs.

[0046] The techniques described herein may be used in various wireless networks and radio technologies. Although aspects herein may be described using terms typically associated with 3G, 4G, and / or new radio (e.g., 5G NR) wireless technologies, aspects of the present disclosure may be applied to communication systems based on other generations and / or to wireless technologies such as 802.11, 802.15, NTN communications, etc.

[0047] NR access can support various wireless communication services, such as enhanced mobile broadband (eMBB) targeted at wide bandwidth (e.g., 80 megahertz (MHz) or greater), millimeter wave (mmWave) targeted at high carrier frequencies (e.g., 24 GHz to 53 GHz or greater), massive machine type communication (MTC) (mMTC) targeted at non-backward compatible MTC technologies, and / or mission-critical targeted at ultra-reliable low-latency communication (URLLC). These services can include latency and reliability specifications. These services can also have different transmission time intervals (TTIs) to meet the corresponding quality of service (QoS) requirements. In addition, these services can coexist in the same subframe. NR supports beamforming and can dynamically configure the beam direction. Precoded multiple-input multiple-output (MIMO) transmission can also be supported as multi-layer transmission. Aggregation of multiple cells can be supported.

[0048] Example Wireless Communication Network and Device

[0049] Figure 1 An example wireless communication network 100 in which aspects of the present disclosure may be implemented is illustrated. For example, the wireless communication network 100 can 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 can be configured to communicate according to IEEE standards (such as one or more of the 802.11 standards). As Figure 1 shown, according to aspects of the present disclosure, the UE 120a includes an RF exposure manager 122 that uses a compressed RF exposure map to ensure RF exposure compliance.

[0050] As Figure 1 illustrated, the wireless communication network 100 can include multiple base stations (BSs) 110a through 110z (each also referred to herein individually as a BS 110, or collectively as BSs 110) and other network entities. The BS 110 can provide communication coverage for a specific geographical area (sometimes referred to as a "cell"), which can be stationary or can move according to the location of the mobile BS. In some examples, the BS 110 can use any suitable transport network and be interconnected with each other and / or connected to one or more other BSs or network nodes (not shown) in the wireless communication network 100 through various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.). In Figure 1In the example shown, BS 110a, 110b, and 110c can be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x can be a pico BS for pico cell 102x. BS 110y and 110z can be femto BSs for femto cells 102y and 102z, respectively. A BS can support one or more cells.

[0051] BS 110 communicates with UEs 120a - y in the wireless communication network 100 (each of which is also referred to herein individually as UE 120 or collectively as UEs 120). The UEs 120 (e.g., 120x, 120y, etc.) can be spread throughout the wireless communication network 100, and each UE 120 can be stationary or mobile. The wireless communication network 100 can also include relay stations (e.g., relay station 110r) (also referred to as relays, etc.), which receive a transmission of data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and transmit the data and / or other information to a downstream station (e.g., UE 120 or BS 110), or relay transmissions between UEs 120 to facilitate communication between devices.

[0052] 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, such as in a 5G NR system, the network controller 130 can include a centralized unit (CU) and / or a distributed unit (DU). In some aspects, the network controller 130 can communicate with a core network 132 (e.g., a 5G core network (5GC)), which provides various network functions such as access and mobility management, session management, user plane function, policy control function, authentication server function, unified data management, application function, network exposure function, network repository function, network slice selection function, etc.

[0053] Figure 2 Illustrative example components of BS 110a and UE 120a (e.g., Figure 1 of the wireless communication network 100) that can be used to implement aspects of the present disclosure.

[0054] At BS 110a, the transmit processor 220 may receive data from the data source 212 and control information from the controller / processor 240. The control information may be used for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid automatic repeat request (HARQ) indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be used for the physical downlink shared channel (PDSCH), etc. The medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for the exchange of control commands between wireless nodes. The MAC-CE may be carried in a shared channel such as the PDSCH, physical uplink shared channel (PUSCH), or physical sidelink shared channel (PSSCH).

[0055] The processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS). The transmit (TX) multiple input multiple output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, control symbols, and / or reference symbols (where applicable) and may provide the output symbol streams to the modulators (MOD) in the transceivers 232a - 232t. Each modulator 232a - 232t in the transceivers may process its respective output symbol stream (e.g., for orthogonal frequency division multiplexing (OFDM), etc.) to obtain an output sample stream. Each transceiver in the transceivers 232a - 232t may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signals from the transceivers 232a - 232t may be transmitted via the antennas 234a - 234t, respectively.

[0056] At the UE 120a, antennas 252a - 252r can receive downlink signals from the BS 110a and can provide the received signals to transceivers 254a - 254r, respectively. The transceivers 254a - 254r can condition (e.g., filter, amplify, down-convert, and digitize) the respective received signals to obtain input samples. Each demodulator (DEMOD) in transceivers 232a - 232t can further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. The MIMO detector 256 can obtain the received symbols from all the demodulators in transceivers 254a - 254r, perform MIMO detection (if applicable) on the received symbols, and provide detected symbols. The receive processor 258 can process (e.g., demodulate, de-interleave, and decode) the detected symbols, provide the decoded data for the UE 120a to the data sink 260, and provide the decoded control information to the controller / processor 280.

[0057] On the uplink, at the UE 120a, the transmit processor 264 can receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from the data source 262, and receive and process control information (e.g., for the physical uplink control channel (PUCCH)) from the controller / processor 280. The transmit processor 264 can also generate reference symbols for reference signals (e.g., for the sounding reference signal (SRS)). The symbols from the transmit processor 264 can be pre-coded by the TX MIMO processor 266 (if applicable), further processed by the modulators (MOD) in transceivers 254a - 254r (e.g., for single carrier frequency division multiplexing (SC-FDM), etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signal from the UE 120a can be received by the antenna 234, processed by the demodulators in transceivers 232a - 232t, detected by the MIMO detector 236 (if applicable), and further processed by the receive processor 238 to obtain the decoded data and control information transmitted by the UE 120a. The receive processor 238 can provide the decoded data to the data sink 239, and provide the decoded control information to the controller / processor 240.

[0058] Memories 242 and 282 can store data and program codes for the BS 110a and the UE 120a, respectively. The scheduler 244 can schedule the UE for data transmission on the downlink and / or uplink.

[0059] The antennas 252, processors 266, 258, 264, and / or controller / processor 280 of the UE 120a and / or the antennas 234, processors 220, 230, 238, and / or controller / processor 240 of the BS 110a may be used to perform the various techniques and methods described herein. As Figure 2 shown, in accordance with aspects described herein, the controller / processor 280 of the UE 120a has an RF exposure manager 281 that represents the RF exposure manager 122. Although shown at the controller / processor, other components of the UE 120a and the BS 110a may be used to perform the operations described herein.

[0060] NR may utilize OFDM with a cyclic prefix (CP) on both the uplink and downlink. NR may use time division duplex (TDD) to support half-duplex operation. OFDM and SC-FDM divide the system bandwidth into multiple orthogonal subcarriers, which are also often referred to as tones, frequency bins, etc. Each subcarrier may be modulated with data. Modulation symbols may be transmitted in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers may depend on the system bandwidth. The system bandwidth may also be divided into subbands. For example, one subband may cover multiple resource blocks (RBs).

[0061] Although the UE 120a is described with reference to Figure 1 and Figure 2 as communicating with the BS and / or within a network, the UE 120a may be configured to communicate directly with another UE 120 / directly transmit to the other UE, or communicate directly with another wireless device / transmit to the other wireless device without relaying the communication through a network. In some aspects, the Figure 2 BS 110a illustrated and described above is an example of another UE 120.

[0062] Example RF Transceiver

[0063] Figure 3 is a block diagram of an example 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 antenna 306. When the TX path 302 and the RX path 304 share the antenna 306, these paths may be connected to the antenna via an interface 308, which may include any of various suitable RF devices such as switches, duplexers, diplexers, multiplexers, etc.

[0064] Receiving an in-phase (I) or quadrature (Q) baseband analog signal from a digital-to-analog converter (DAC) 310, TX path 302 may include a baseband filter (BBF) 312, a mixer 314, a driver amplifier (DA) 316, and a power amplifier (PA) 318. BBF 312, mixer 314, and DA 316 may be included in one or more radio frequency integrated circuits (RFICs). For some embodiments, PA 318 may be external to the RFIC.

[0065] BBF 312 filters the baseband signal received from DAC 310, and mixer 314 mixes the filtered baseband signal with a transmit local oscillator (LO) signal to convert the baseband signal of interest to a different frequency (e.g., up-converting 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 baseband signal of interest. The sum frequency and the difference frequency are referred to as beat frequencies. The beat frequencies are typically in the RF range, such that the signal output by mixer 314 is typically an RF signal, which may be amplified by DA 316 and / or by PA 318 before being transmitted through antenna 306. Although one mixer 314 is illustrated, several mixers may 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.

[0066] 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 in one or more RFICs, which may be the same RFIC as the RFIC including the TX path components or may be a different RFIC. The RF signal received via antenna 306 may be amplified by LNA 324, and mixer 326 mixes the amplified RF signal with a receive local oscillator (LO) signal to convert the RF signal of interest to a different baseband frequency (e.g., down-converting). The baseband signal output by mixer 326 may be filtered by BBF 328 before being converted to a digital I or Q signal by an analog-to-digital converter (ADC) 330 for digital signal processing.

[0067] Certain transceivers may employ a frequency synthesizer with a voltage controlled oscillator (VCO) to generate a stable, tunable LO with a specific tuning range. Thus, the transmit LO may be generated by TX frequency synthesizer 320, which may be buffered or amplified by amplifier 322 before being mixed with the baseband signal in mixer 314. Similarly, the receive LO may be generated by RX frequency synthesizer 332, which may be buffered or amplified by amplifier 334 before being mixed with the RF signal in mixer 326.

[0068] The controller 336 may direct the operation of the RF transceiver circuitry 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 gate or transistor logic, discrete hardware components, or any combination thereof. The memory 338 may store data and program code for operating the RF transceiver circuitry 300. The controller 336 and / or the memory 338 may include control logic. In some cases, the controller 336 may determine the transmit power (e.g., certain gain levels applied to the BBF 312, DA 316, and / or PA 318) applied to the TX path 302 that complies with RF exposure limits set by country-specific regulations and / or international standards, as further described herein.

[0069] Example RF Exposure Compliance

[0070] RF exposure may be expressed in terms of the specific absorption rate (SAR), which measures the energy absorption of human tissue per unit mass and may have the unit of watts per kilogram (W / kg). RF exposure may also be expressed in terms of power density (PD), which measures the energy absorption per unit area and may have the unit of milliwatts per square centimeter (mW / cm 2 ). In some cases, maximum permissible exposure (MPE) limits (in the form of PD) may be imposed on wireless devices using transmit frequencies above 6 GHz. The MPE limit is an area-based exposure regulatory metric, such as an energy density limit, which is defined as the number X (watts per square meter (W / m 2 ) averaged over a defined area and time-averaged over a frequency-dependent time window) to prevent human exposure hazards represented by tissue temperature changes.

[0071] The SAR may be used to evaluate RF exposure for transmit frequencies below 6 GHz, which covers wireless communication technologies such as 2G / 3G (e.g., CDMA), 4G (e.g., LTE), 5G (e.g., NR in the 6 GHz band), IEEE 802.11ac, NTN, etc. The PD may be used to evaluate RF exposure for transmit frequencies above 6 GHz, which covers wireless communication technologies such as IEEE 802.11ad, 802.11ay, 5G in the mmWave band, etc. Thus, different metrics may be used to evaluate RF exposure for different wireless communication technologies.

[0072] A wireless device (e.g., UE 120) can use multiple wireless communication technologies to transmit signals simultaneously. For example, the wireless device can use 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., mmWave 5G in the 24 GHz to 60 GHz band, IEEE 802.11ad or 802.11ay) to transmit signals simultaneously. In some aspects, the wireless device can use a first wireless communication technology (e.g., 3G, 4G, 5G, IEEE 802.11ac, etc. in the sub-6 GHz band) (where RF exposure is measured by SAR) and a second wireless communication technology (e.g., 5G, IEEE 802.11ad, 802.11ay, etc. in the 24 GHz to 60 GHz band) (where RF exposure is measured by PD) to transmit signals simultaneously. As used herein, the sub-6 GHz band can include a band from 300 MHz to 6,000 MHz in some examples, and can include a band in the range of 6,000 MHz and / or 7,000 MHz in some examples.

[0073] To evaluate the RF exposure from transmissions using the first technology (e.g., 3G, 4G, 5G, IEEE 802.11ac, NTN, etc. in the sub-6 GHz band), the wireless communication device can include multiple SAR values and / or SAR distributions for the first technology stored in a memory (e.g., Figure 2 memory 282 of Figure 3 or Figure 2 memory 338 of Figure 3 ). Each of the SAR values and / or SAR distributions can correspond to a respective one of multiple transmission scenarios for the first technology supported by the wireless communication device. The transmission scenarios can correspond to various combinations of antennas (e.g.,

[0074] antennas 252a - 252r of Figure 2 or Figure 3The controller 336) is capable of evaluating RF exposure in real time, as further discussed below. Each SAR distribution may include a set of SAR values, where each SAR value may correspond to a different location (e.g., on a human model). Each SAR value may include the SAR value averaged over a 1g or 10g mass at the corresponding location.

[0075] The SAR values in each SAR distribution correspond to a specific transmit power level (e.g., the transmit power level when measuring the SAR values in a test laboratory). Since SAR scales with the transmit power level, the processor may scale the SAR values or SAR distributions for any transmit power level by multiplying each SAR value (e.g., in the SAR distribution) by the following transmit power scaler:

[0076] (1)

[0077] where Tx c is the current transmit power level of the corresponding transmit scenario, and Tx SAR is the transmit power level corresponding to the SAR value (e.g., the transmit power level when measuring the SAR value in a test laboratory).

[0078] As discussed above, the wireless communication device may support multiple transmit scenarios for a first technology. In some aspects, the transmit scenario may be specified by a set of parameters. The set of parameters may include one or more of the following: antenna parameters indicating one or more antennas (i.e., active antennas) used for transmission, band parameters indicating one or more frequency bands (i.e., active bands) used for transmission, channel parameters indicating one or more channels (i.e., active channels) used for transmission, body position parameters (e.g., device state index (DSI)) indicating the position of the wireless communication device relative to the user's body position (head, torso, away from the body, etc.), exposure class, and / or other parameters. In the case where the wireless communication device supports a large number of transmit scenarios, performing measurements for each transmit scenario in a test environment (e.g., a test laboratory) may be very time-consuming and expensive. To reduce the test time, measurements may be performed for a subset of the transmit scenarios to generate the SAR values and / or SAR distributions for the subset of the transmit scenarios. In this example, the SAR values and / or SAR distributions for each of the remaining transmit scenarios may be generated by combining two or more of the SAR values and / or SAR distributions for the subset of the transmit scenarios, as further discussed below.

[0079] For example, SAR measurements may be performed for each antenna to generate the SAR values or SAR distributions for each antenna. In this example, the SAR values or SAR distributions for the transmit scenarios in which two or more antennas are active may be generated by combining the SAR values or SAR distributions of two or more active antennas.

[0080] In another example, SAR measurements can be performed for each of multiple frequency bands to generate SAR values or SAR distributions for each of the multiple frequency bands. In this example, the SAR value or SAR distribution for a transmission scenario in which two or more frequency bands are active can be generated by combining the SAR values or SAR distributions of two or more active frequency bands.

[0081] In some aspects, the SAR distribution can be normalized relative to an SAR limit by dividing each SAR value in the SAR distribution by the SAR limit. In such a case, when the normalized SAR value is greater than 1, the normalized SAR value exceeds the SAR limit, and when the normalized SAR value is less than 1, the normalized SAR value is below the SAR limit. In these aspects, each PD distribution in the SAR distribution stored in the memory can be normalized relative to the SAR limit. Similarly, a single or individual SAR value can be normalized relative to the SAR limit. In some cases, the SAR limit can correspond to a regulatory or standardization limit or can correspond to a level below the regulatory or standardization limit to provide sufficient exposure margin to account for device uncertainties and / or other margins (e.g., for other radios).

[0082] In some aspects, the normalized SAR value or normalized SAR distribution for a transmission scenario can be generated by combining two or more normalized SAR values or normalized SAR distributions. For example, the normalized SAR value or normalized SAR distribution for a transmission scenario in which two or more antennas are active can be generated by combining the normalized SAR values or normalized SAR distributions of two or more active antennas. For the case where different transmission power levels are used for the active antennas, each normalized SAR value or normalized SAR distribution of the active antennas can be scaled by the corresponding transmission power level before combining the normalized SAR values or normalized SAR distributions of the active antennas. The normalized SAR value or normalized SAR distribution for simultaneous transmissions from multiple active antennas can be given by:

[0083] (2)

[0084] where SAR lim is the SAR limit, SAR norm_combined is the combined normalized SAR value or combined normalized SAR distribution for simultaneous transmissions from the active antennas, i is the index of the active antenna, SAR i is the SAR value or SAR distribution of the i-th active antenna, Tx i is the transmission power level of the i-th active antenna, Tx SARi is the transmission power level of the SAR distribution of the i-th active antenna, and K is the number of active antennas.

[0085] Formula (2) can be rewritten as follows:

[0086] (3a)

[0087] where SAR norm_i is the normalized SAR value or normalized SAR distribution of the i-th active antenna. In the case of simultaneous transmission using multiple active antennas at the same transmission frequency (e.g., multiple-input multiple-output (MIMO)), the combined normalized SAR value or combined normalized SAR distribution can be obtained by summing the square roots of the individual normalized SAR values or normalized SAR distributions and calculating the square of the sum, as given by the following formula:

[0088] (3b).

[0089] In another example, the normalized SAR values or normalized SAR distributions of different frequency bands can be stored in a memory. In this example, the normalized SAR distribution of a transmission scenario in which two or more frequency bands are active can be generated by combining the normalized SAR distributions of two or more active frequency bands. For the case where the transmission power levels are different for the active frequency bands, the normalized SAR value or normalized SAR distribution of each active frequency band in the active frequency bands can be scaled according to the corresponding transmission power level before combining the normalized SAR values or normalized SAR distributions of the active frequency bands. In this example, formula (3a) can also be used to calculate the combined SAR value or combined SAR distribution, where i is the index of the active frequency band, SAR norm_i is the normalized SAR value or normalized SAR distribution of the i-th active frequency band, Tx i is the transmission power level of the i-th active frequency band, and Tx SARi is the transmission power level of the normalized SAR value or normalized SAR distribution of the i-th active frequency band.

[0090] To evaluate the RF exposure from transmissions using a second technology (e.g., 5G, IEEE 802.11ad, 802.11ay, etc. in the 24 GHz to 60 GHz frequency band), a wireless communication device can include a plurality of PD values and / or PD distributions for the second technology stored in a memory (e.g., Figure 2 memory 282 of Figure 3 or Figure 2 antenna 252a - 252r of Figure 3for various combinations of antennas 306), frequency bands, channels, and / or body positions, as further discussed below. In some examples, the stored PD includes a single value (e.g., a peak determined based on the following description, or the sum of peaks).

[0091] PD values and / or PD distributions (also referred to as PD maps) for each transmission scenario can be generated based on measurements (e.g., electric field measurements) performed in a test laboratory using a human model. After generation, the PD distribution is stored in a memory such that a processor (e.g., Figure 2 processor 280 of Figure 3 or the controller 336 of

[0092] can evaluate RF exposure in real time, as further discussed below. Each PD distribution can include a set of PD values, where each PD value can correspond to a different location (e.g., on the human model).

[0093] (4)

[0094] where Tx c is the current transmission power level of the corresponding transmission scenario, and Tx PD is the transmission power level corresponding to the PD value (e.g., the transmission power level when the PD value was measured in the test laboratory).

[0095] As discussed above, a wireless communication device may support multiple transmission scenarios for a second technology. In some aspects, a transmission scenario may be specified by a parameter set. The parameter set may include one or more of the following: antenna parameters indicating one or more antennas (i.e., active antennas) for transmission, band parameters indicating one or more frequency bands (i.e., active bands) for transmission, channel parameters indicating one or more channels (i.e., active channels) for transmission, body position parameters (e.g., DSI) indicating the position of the wireless communication device relative to the user's body position (head, torso, away from the body, etc.), exposure class, and / or other parameters. In cases where the wireless communication device supports a large number of transmission scenarios, performing measurements for each transmission scenario in a test environment (e.g., a test laboratory) may be very time-consuming and expensive. To reduce the test time, measurements may be performed for a subset of the transmission scenarios to generate PD values and / or PD distributions for the subset of the transmission scenarios. In this example, the PD values and / or PD distributions for each of the remaining transmission scenarios may be generated by combining two or more of the PD values and / or PD distributions for the subset of the transmission scenarios, as further discussed below. In some cases, a subset of the PD distributions generated via measurements may be used to verify the PD distributions obtained from electromagnetic simulations of the wireless communication device, such that PD distributions may be obtained from simulations for all transmission scenarios supported by the wireless communication device.

[0096] For example, PD measurements may be performed for each antenna to generate PD values or PD distributions for each antenna. In this example, the PD values or PD distributions for a transmission scenario in which two or more antennas are active may be generated by combining the PD values or PD distributions of two or more active antennas.

[0097] In another example, PD measurements may be performed for each of a plurality of frequency bands to generate PD values or PD distributions for each of the plurality of frequency bands. In this example, the PD values or PD distributions for a transmission scenario in which two or more frequency bands are active may be generated by combining the PD values or PD distributions of two or more active frequency bands.

[0098] In some aspects, a PD distribution may be normalized relative to a PD limit by dividing each PD value in the PD distribution by the PD limit. In this case, when the normalized PD value is greater than 1, the normalized PD value exceeds the PD limit, and when the normalized PD value is less than 1, the normalized PD value is below the PD limit. In these aspects, each PD distribution stored in a memory may be normalized relative to the PD limit. Similarly, a single or individual PD value may be normalized relative to the PD limit.

[0099] In some aspects, a normalized PD value or a normalized PD distribution for a transmission scenario can be generated by combining two or more normalized PD values or normalized PD distributions. For example, a normalized PD value or a normalized PD distribution for a transmission scenario in which two or more antennas are active can be generated by combining the normalized PD values or normalized PD distributions of two or more active antennas. For cases where different transmission power levels are used for the active antennas, the normalized PD value or normalized PD distribution of each active antenna can be scaled by the corresponding transmission power level before combining the normalized PD values or normalized PD distributions of the active antennas. The normalized PD value or normalized PD distribution for simultaneous transmissions from multiple active antennas can be given by the following formula:

[0100] (5)

[0101] where PD lim is the PD limit, PD norm_combined is the combined normalized PD value or combined normalized PD distribution for simultaneous transmissions from the active antennas, i is the index of the active antenna, PD i is the PD value or PD distribution of the i-th active antenna, Tx i is the transmission power level of the i-th active antenna, Tx PDi is the transmission power level of the PD distribution of the i-th active antenna, and L is the number of active antennas.

[0102] Equation (5) can be rewritten as follows:

[0103] (6a)

[0104] where PD norm_i is the normalized PD value or normalized PD distribution of the i-th active antenna. In the case of simultaneous transmissions (e.g., MIMO) using multiple active antennas at the same transmission frequency, the combined normalized PD value or combined normalized PD distribution can be obtained by summing the square roots of the individual normalized PD values or individual normalized PD distributions and calculating the square of the sum, as given by the following formula:

[0105] (6b).

[0106] In some aspects, a composite normalized PD distribution for a given transmission band can be obtained by taking the maximum value at a given position (x, y, z) from all the normalized PD distributions of all the antenna configurations of the mmWave module. The composite normalized PD distribution can be used to represent the PD distribution of all the antenna configurations of the mmW antenna module:

[0107]

[0108] The PDnorm_composite Can be used to replace PD in formula (6a) norm_i , where a represents all N beams (or antenna configurations) supported by the i-th mmWave module for a given frequency band. In such cases, formula (6a) represents the combined PD distribution if multiple frequency bands or mmWave antenna modules are active.

[0109] In another example, the normalized PD values or normalized PD distributions of different frequency bands can be stored in a memory. In this example, the normalized PD values or normalized PD distributions for a transmission scenario where two or more frequency bands are active can be generated by combining the normalized PD distributions of two or more active frequency bands. For cases where the transmission power levels are different for the active frequency bands, the normalized PD values or normalized PD distributions of each active frequency band in the active frequency bands can be scaled by the corresponding transmission power levels before combining the normalized PD values or normalized PD distributions of the active frequency bands. In this example, formula (6a) can also be used to calculate the combined PD value or combined PD distribution, where i is the index of the active frequency band, PD norm _ i is the normalized PD value or normalized PD distribution of the i-th active frequency band, Tx i is the transmission power level of the i-th active frequency band, and Tx PDi is the transmission power level of the normalized PD value or normalized PD distribution of the i-th active frequency band.

[0110] In some cases, compliance with RF exposure limits can be performed as a time-averaged RF exposure assessment within a specified time window (T) associated with the RF exposure limits (e.g., 2 seconds for the 60 GHz frequency band, 100 seconds or 360 seconds for frequency bands ≤ 6 GHz, etc.).

[0111] Figure 4A is FIG. 400A of the transmit power (P(t)) varying over time within a time window (T) associated with the RF exposure limits according to certain aspects of the present disclosure. As an example, at certain transmission instances within the time window (T), the instantaneous transmit power may exceed the maximum time-averaged transmit power level P limit . That is, the transmit power can be greater than the maximum time-averaged transmit power level P limit . In some cases, the UE can transmit at P max , where this P max is the maximum transmit power supported by the UE. In some cases, at certain transmission instances, the UE can transmit at a transmit power less than or equal to the maximum time-averaged transmit power level P limit . The maximum time-averaged transmit power level P limitrepresents a time-average threshold with respect to the transmit power for RF exposure limits within a time window (T), and in some cases, P limit may be referred to as the maximum time-average power level or limit, or with respect to exposure, may be referred to as the maximum time-average RF exposure level or limit. Graph 400A also illustrates the gaps between transmission bursts, where these gaps represent periods during which no transmission is output from the device.

[0112] In some cases, the transmit power may be maintained at the maximum time-average transmit power level allowed for RF exposure compliance such that continuous transmission can occur during the time window (e.g., P limit ). For example, Figure 4B is a graph 400B of transmit power (P(t)) over time according to some aspects of the present disclosure, which graph illustrates an example where the transmit power is limited to P limit . As shown, the UE may comply with the RF exposure limit to transmit continuously at P limit .

[0113] Figure 4C is a graph 400C of transmit power (P(t)) over time illustrating a time-average pattern according to some aspects of the present disclosure, which time-average pattern provides reserved power such that continuous transmission can occur within the time window (T). As shown, the transmit power may back off from the maximum instantaneous power (P max ) to the reserved power (P reserve ) such that the UE can continue to transmit at a lower power (P reserve ) to maintain continuous transmission (e.g., maintain a radio connection with a receiving entity) during the time window. In Figure 4C , the area between P max and P max during the duration of P reserve may be equal to the area between P limit and P reserve within the time window T such that Figure 4C the area of the transmit power (P(t)) in limit is equal to the area of P reserve within the time window T. Such an area may be considered to use 100% of the energy (transmit power or exposure) to maintain compliance with the time-average RF exposure limit. In the absence of the reserved power P max , the transmitter may transmit at P reserve for a portion of the time window and the transmitter may be turned off for the remainder of the time window to ensure compliance with the time-average RF exposure limit. In some aspects, P maxThe transmission duration below can be referred to as the burst transmission time (or high power duration). When more margin is available in the future (after T seconds), the transmitter may be allowed to transmit again at a higher power (e.g., transmit in short bursts at P max below).

[0114] In some aspects, in the time averaging mode exemplified in Figure 4C , the UE can transmit at a power higher than the average power level but less than P max . Although a single transmission burst is exemplified in Figure 4C , it should be understood that the UE can alternatively utilize multiple transmission bursts within a time window (T), such as described herein with respect to Figure 4A , where these transmission bursts can be separated by periods during which the transmission power is maintained at or below P reserve . Additionally, it should be understood that the transmission power of each transmission burst can vary (within the burst and / or compared to other bursts), and at least a portion of the burst can be transmitted at a power higher than the maximum average power level (e.g., P limit ).

[0115] Although Figures 4A to 4C exemplifies continuous transmission within a window, timing, burst, etc., it should be understood that a transmission duty cycle can be implemented. In such embodiments, the transmission power can be periodically zero and maintained at a higher level during other portions of the duty cycle (e.g., at the level exemplified in Figures 4A to 4C ). As used herein, the duty cycle of a transmission can refer to the portion (e.g., 5 ms) of a specific period (e.g., 500 ms) during which one or more signals are transmitted. In some cases, the duty cycle can be normalized (e.g., pre - determined) with a specific RAT, and / or can change over time, e.g., due to changes in radio conditions, mobility, and / or user behavior.

[0116] Example RF Exposure Measurement

[0117] In some cases, the RF exposure of a wireless device may be certified by a regulatory body (e.g., the Federal Communications Commission (FCC)). Spatial measurements may be made relative to a model (phantom) representing the human body, where the model may be filled with a liquid simulating human tissue. As discussed above, the UE 120 may transmit signals using a first technology (e.g., 3G, 4G, IEEE 802.11ac, etc.) and a second technology (e.g., 5G, IEEE 802.11ad, etc.) simultaneously, where different metrics (e.g., SAR for the first technology and PD for the second technology) are used to measure the RF exposure for the first and second technologies. The RF exposure measurements may be performed differently for each transmission scenario and include, for example, electric field measurements using a human body model. Then, an RF exposure distribution (simulated and / or measured) may be generated for each transmit antenna / configuration (beam) (as described above) over all evaluation surfaces / locations at all positions.

[0118] Figure 5 FIG. is an illustration of an example system 500 for measuring RF exposure values or distributions in accordance with some 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 may perform RF measurements in various transmission scenarios and / or exposure scenarios associated with the UE 120. In some examples, these measurements may be used to generate an RF exposure map and evaluate a suitable backoff factor for the transmit power of the antenna 252 that complies with one or more RF exposure limits, as further described herein. The UE 120 may emit electromagnetic radiation at various transmit powers via the antenna 252, and the RF exposure measurement system 500 may perform RF measurements (e.g., to determine the RF exposure map and / or backoff factor of the antenna 252) via the robotic RF probe 504.

[0119] The processing system 502 may include a processor 508 coupled to a memory 510 via a bus 512. The processing system 502 may be a computing device, such as a computer. The processor 508 may 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 gate or transistor logic components, discrete hardware components, or any combination thereof designed to perform the functions described herein. For example, the processor 508 may communicate with the robotic RF probe 504 via an interface 514 (such as a computer bus interface) such that the processor 508 may obtain the RF measurements made by the robotic RF probe 504 and control the position of the robotic RF probe 504 relative to the human body model 506.

[0120] The memory 510 may be configured to store instructions (e.g., computer-executable code) that, when executed by the processor 508, cause the processor 508 to perform various operations. For example, the memory 510 may store instructions for obtaining RF exposure distributions associated with various RF exposure / transmission scenarios and / or adjusting the position of the robotic RF probe 504.

[0121] The robotic RF probe 504 may include an RF probe 516 coupled to a robotic arm 518. In some aspects, the RF probe 516 may be a dosimetry probe capable of measuring RF exposure at various frequencies such as below 6 GHz band and / or mmWave band. The RF probe 516 may be positioned by the robotic arm 518 at various locations (as indicated by the dashed arrows) to capture the electromagnetic radiation emitted by the antenna 252 of the UE 120. The robotic arm 518 may be a six-axis robot capable of performing precise movements to position the RF probe 516 at the location of the maximum electromagnetic field generated by the UE 120 (on the mannequin 506). In other words, the robotic arm 518 may provide six degrees of freedom when positioning the RF probe 516 relative to the antenna 252 of the UE 120 and / or the mannequin 506.

[0122] The mannequin 506 may be a specific anthropomorphic mannequin having simulated human tissues. For example, the mannequin 506 may include one or more liquids simulating human tissues of the head, body, and / or limbs. The mannequin 506 may simulate human tissues to determine the maximum allowable transmit power of the antenna 252 that complies with various RF exposure limits.

[0123] In certain aspects, the RF exposure values or distributions associated with the UE 120 may be measured without the mannequin 506. For example, the RF probe 516 may be an electric or magnetic field probe capable of estimating the SAR and / or PD in the free space around the UE 120.

[0124] Although Figure 5 the examples depicted herein are described with respect to obtaining RF exposure values or distributions with a robotic RF probe to facilitate understanding, aspects of the present disclosure may also be applied to other suitable RF probe architectures, such as using multiple fixed RF probes positioned at various locations along the mannequin 506 or in free space.

[0125] Example Compressed RF Exposure Map

[0126] A multi-mode / multi-band UE has multiple transmit antennas that can transmit simultaneously in a sub-6 GHz band and a band greater than 6 GHz, such as a millimeter wave band. As described herein, RF exposure in the sub-6 GHz band can be evaluated based on SAR, and RF exposure in a band greater than 6 GHz can be evaluated based on PD. Due to regulations regarding simultaneous exposure, a wireless device can limit the maximum transmit power for both the sub-6 GHz band and the band greater than 6 GHz.

[0127] In some cases, the complete SAR and PD distributions can be used to determine the maximum allowable transmit power for a future time interval based on the time-averaged RF exposure limits as described herein. Assuming n1 sub-6 GHz antennas for SAR exposure, n2 mmW antennas for mmW exposure, the sub-6 GHz radio is averaged over a T1 time window, the mmWave radio is averaged over a T2 time window, and these time windows are divided into p "Δt" time intervals and q "Δt" intervals respectively (e.g., p = T1 / Δt, q = T2 / Δt), the total RF exposure can be determined according to the following expression:

[0128]

[0129]

[0130] (7)

[0131] Where:

[0132]

[0133] And

[0134]

[0135] At the jth Δt time interval, it can be obtained by normalizing the corresponding P of the radio limitThe transmit power of each radio is summed and the sum of the transmit power is scaled by a normalized exposure map (e.g., a normalized SAR exposure map (x,y,z) and a normalized PD exposure map (x,y,z)) to calculate SAR and PD exposure. Note that the p-th and q-th time intervals represent future transmissions. The wireless device calculates the margins allocated for all sub-6GHz radios in the p-th time interval and for all mmWave radios in the q-th time interval. Such a process ensures compliance with the time-averaged RF exposure limits. If the entire SAR and PD exposure maps are used for all or any of the six surfaces of the wireless device, the calculation for predicting future transmit power for RF exposure compliance may be intensive and impractical for some wireless devices, such as portable wireless devices.

[0136] Aspects of the present disclosure provide apparatuses and methods for generating and / or using compressed RF exposure maps, where the RF exposure maps may represent the maximum RF exposure exhibited in a particular region associated with a wireless device for certain individual radios and / or radio combinations. The RF exposure maps may be reduced to the maximum RF exposure in certain regions such that the wireless device evaluates RF exposure compliance across the regions identified for the RF exposure maps. In some aspects, the RF exposure maps may represent RF exposure in terms of SAR and / or PD.

[0137] Note that, as used herein, the regions of the RF exposure maps may or may not represent actual points or regions of the wireless device. In some cases, for example, the regions of the RF exposure maps may represent one or more points on the wireless device. For example, a region may represent a single point on the wireless device or a set of points on the wireless device. In cases where the region represents a set of points on the wireless device, the set of points may be a continuous set of points or a non-continuous (or scattered) set of points. In some cases, the regions of the RF exposure maps may represent a collection of sets of points on the wireless device, where each corresponding set of points corresponds to a different region (within that region) of the wireless device. Each corresponding set of points within the collection may include continuous or non-continuous points. In some cases, the regions of the RF exposure maps may include one or more contribution values. The contribution values may not represent actual points on the wireless device or the RF exposure maps. For example, the contribution values may be based on the overlap of exposure distributions between different technologies / antennas being considered (e.g., radios, antennas (or antenna modules), beams, frequency bands, or combinations thereof). In some cases, the contribution values may be determined based on simulations of various exposure / transmission scenarios. For example, assuming that the user, manufacturer, and / or service provider decides to reduce the maps of multiple antennas, the interaction between the antennas may be evaluated during the simulation to determine a contribution matrix with contribution values that ensure RF exposure compliance.

[0138] The apparatuses and methods for generating and using RF exposure maps described herein may facilitate improved wireless communication performance (e.g., improved signal quality at a receiver, lower latency, higher throughput, etc.). The apparatuses and methods for generating and using RF exposure maps described herein may also enable improved processing performance, e.g., due to a reduced memory size used by the RF exposure map and / or a reduced number of calculations for performing RF exposure assessments to meet time-average RF exposure compliance during a simultaneous transmission scenario.

[0139] Exposure maps associated with a wireless device may be generated for various combinations of transmission and / or exposure scenarios, such as exposure maps for each antenna (and / or antenna module) of the wireless device. Assuming there are m1 zones identified for the RF exposure map, rather than performing calculations on the full exposure distribution for all exposure maps associated with the antenna, m1 zones may be considered for each exposure distribution, e.g., according to the following expression:

[0140]

[0141] And

[0142]

[0143] In the above formula, the initial SAR / PD matrix size is significantly reduced by the process described herein, while minimizing the impairment to the achievable transmit power levels (e.g., a reduction of approximately <0.5 decibels (dB) compared to using the full exposure distribution method for most cases). For example, a full exposure distribution associated with a device having eight antennas and a size of 21 cm × 16 cm with 1 mm resolution may have more than 200,000 points to perform calculations on a single surface. In some cases, the compressed RF exposure maps described herein may have fewer than one hundred (e.g., ≤88) zones to achieve results similar to the full exposure distribution method, e.g., with a small (e.g., approximately 0.5 dB) trade-off in transmit power.

[0144] Figure 6 is a flow chart illustrating an example operation 600 for generating a compressed RF exposure map. Operation 600 may be performed using a processing system (e.g., processing system 502) or another computing device. As described herein with respect to operation 600, Figure 7 is a diagram illustrating the progress of generating a compressed RF exposure map based on one or more RF distributions.

[0145] Operation 600 may optionally begin at block 602, where the processing system may obtain an exposure map (e.g., a total normalized exposure map 702), e.g., covering the exposure exhibited by all (or at least some) of the radios, antennas (or antenna modules), beams, and / or frequency bands supported by the wireless device. The processing system may obtain a plurality of composite normalized exposure maps associated with the plurality of exposure maps, e.g., by adding individual normalized maps. The obtained exposure map may be a total exposure map derived from a set of normalized composite exposure maps (e.g., a normalized RF exposure distribution). The composite exposure maps may be normalized with respect to corresponding RF exposure limits (e.g., SAR limits and / or PD limits). In some cases, the processing system may obtain an RF exposure distribution, e.g., using the RF exposure measurement system 500. In some aspects, the RF exposure distribution may be generated via simulation, such as a simulation of various exposure / transmission scenarios using a human model exposed to electromagnetic radiation from the wireless device. For example, the set of normalized exposure maps may represent the exposure exhibited by sub-6 GHz and / or mmWave antennas and supported by the wireless device.

[0146] At block 604, the processing system may partition (e.g., segment) the total exposure map into smaller regions, such as regions 704. For example, the processing system may identify regions for each radio, antenna (or antenna module), beam, and / or frequency band in the region for each maximum contribution, thereby allowing the RF distribution to be reduced to the number of regions that total the maximum contributions for each radio, antenna (or antenna module), beam, and / or frequency band in the region.

[0147] At block 606, the processing system may select a subset of regions (e.g., region subset 706). The processing system may perform an iterative process to determine whether the maximum RF exposure associated with the region subset provides RF exposure compliance. If RF exposure compliance is not met for the selected region subset, the processing system may re-select the regions included in the subset, e.g., by adding one or more regions to the subset. The regions selected for the subset may be based on certain constraints, such as wireless performance constraints (e.g., tolerance values) and / or memory constraints (e.g., the size of the RF exposure map).

[0148] At block 608, the processing system may identify the maximum RF exposure in each of the regions in the subset. In some cases, the processing system may store the maximum RF exposure associated with the region subset as a table (e.g., table 708). After identifying the region subset (e.g., m regions), the processing system may obtain a reduced normalized exposure map within the selected region subset (m regions) for the composite maps used to create the total exposure map (e.g., the n normalized exposure maps obtained at block 602). For example, the maximum RF exposure in the region subset for each of the composite maps (e.g., an m×n value) may be determined according to the following expression:

[0149] Normalized Exposure Map (Exposure Map i, Zone j) =

[0150] max(Exposure Map i (x, y, z), (x, y, z) ϵ Zone j)(8)

[0151] where i is a sequence from 1 to n, and j is a sequence from 1 to m.

[0152] In some aspects, the exposure distribution obtained at block 602 can be determined (e.g., measured or simulated) for all antennas in the low, medium, and high channels of all supported frequency bands. As previously described herein, the RF exposure distribution can include RF exposure associated with various transmission scenarios corresponding to a particular frequency band and / or the position of the human body relative to the antenna or antenna module. For example, the RF exposure distribution can be represented by the expression: RFexp(s,x,y,z,i), where s represents a particular surface or position, (x, y,z) represents a given position, and i represents a particular transmission configuration, such as a particular antenna or transmission beam. In some cases, a transmitting antenna can support multiple frequency bands, so multiple RF exposure distributions for each frequency band / channel (low / medium / high) can be used for a particular transmitting antenna. In such cases, the RF exposure distribution of a particular transmitting antenna can represent the maximum exposure in all technologies / frequency bands / channels supported by the transmitting antenna at each location / exposure surface. In some cases, a transmitting antenna module can support multiple antenna configurations (or beams), such that the RF exposure distribution of a particular transmitting antenna module can represent the maximum exposure in all beams supported by the transmitting antenna module at each location / exposure surface.

[0153] A composite map can be determined for each frequency band for each antenna (e.g., the maximum exposure of the low, medium, and high channels at each position (x,y,z) across the surface). A composite map can be determined for each antenna (e.g., the maximum exposure of all frequency bands for a given antenna). Assuming a given antenna can support 40 frequency bands, these frequency bands can be divided into frequency band subsets. For example, the first frequency band b1 can include frequency bands 1, 5, and 8 (e.g., b1 = {frequency bands 1, 5, and 8}), the second frequency band b2 can include frequency bands 3 and 9 (e.g., b2 = {frequency bands 3, 9}), and the third frequency band b3 can include frequency bands 2 and 32 (b3 = {frequency bands 2, 32}), etc., where the superset of b1 + b2 + b3 + … = 40 frequency bands. A composite map can be determined for each frequency band subset for each antenna. The set of composite maps covering all (or at least some) antennas and all (or at least some) frequency bands can include: (1) the composite map for each antenna (or antenna module), (2) the composite map for each frequency band for each antenna, or (3) the composite map for each frequency band subset for each antenna, or a combination thereof.

[0154] Figure 8FIG. 802 illustrates eight normalized composite maps for each antenna added together to obtain a total exposure map 804. In this example, each of the composite maps 802 may be normalized to 1.0 by a corresponding RF exposure limit (e.g., SAR limit or PD limit), and due to the limited overlap between the distributions of the composite maps, the total exposure map 804 may have points greater than 1.0.

[0155] To partition (e.g., segment) the total exposure map at block 604 into zones, the processing system may perform various activities. The processing system may remove follow locations from the total exposure map. For example, to remove follow locations, the processing system may set the values associated with locations having a normalized value less than or equal to a threshold (e.g., 1.0) to a default value (such as zero). Figure 9 FIG. 902 and FIG. 904 illustrate example updated versions of the total exposure map, where the follow locations are set to a specific value (e.g., zero). Note that in other respects, instead of partitioning the total exposure map into zones, at block 604, the processing system may consider certain zones of the individual exposure maps (e.g., the composite maps 802) as zones (such as zone 704). Additionally, the processing system may evaluate the contributions from different technologies / antennas under consideration when determining a zone (such as zone 704).

[0156] The processing system may identify one or more non - follow zones (e.g., zones having an exposure value greater than or equal to 1.0) in the updated total exposure map. Figure 10 FIG. 10 illustrates an example of identifying non - follow zones until all non - follow regions are covered by identified zones 1010. For example, the processing system may identify a non - follow zone (e.g., non - follow zone 1002) as the zone in the updated total exposure map having the peak exposure value among the exposure values. The processing system may temporarily remove the identified zone from the total exposure map for subsequent partitioning of the total exposure map. The processing system may repeat identifying the next non - follow zone(s) (e.g., non - follow zones 1006, 1008) having the peak exposure value until all non - follow zones are covered by at least one zone. For example, the processing system may remove the boundaries 1004 of the zone (e.g., zone 1002) selected in a previous iteration from the non - follow map. The processing system may repeat identifying and removing non - follow zones until all non - follow zones (e.g., non - follow zone 1010) are identified. When all non - follow zones are covered, the processing system may save the identified zones. The processing system may obtain the maximum contribution of the exposure map in each zone and save the corresponding contributions.

[0157] In some aspects, the processing system may apply a threshold profile to identify non-compliance regions (e.g., non-compliance region 1002), such as a 95% profile. The profile level can be any non-zero value less than 100%. The 95% profile can provide efficient processing time to run the algorithm. The profile represents a boundary within which all points have values higher (greater) than the profile threshold (e.g., the product of the profile and the maximum value of the total exposure map).

[0158] The processing system may approximate the boundary of the profile as a rectangle or any other suitable polygon. For example, the processing system may determine a rectangular boundary (e.g., boundary 1004) that encloses the profile boundary of the non-compliance region. Any polygon shape or the profile shape itself can be used for the boundary of the non-compliance region. Other shapes may use more memory to store the region boundary, while a rectangular boundary can use the values of two starting coordinates, length, and width. Strategically selecting or fine-tuning the region (e.g., the size and shape of the exposure profile) can provide improved performance in terms of the backoff factor, as further described herein.

[0159] The processing system may identify the maximum contribution of each antenna within the non-compliance region, the worst interaction between antennas within the non-compliance region (e.g., the maximum contribution among a set of antennas), or a combination thereof. The processing may determine whether the sum of the maximum contributions from all antennas is less than or equal to the maximum value of the total exposure map plus a tolerance, where the tolerance value may vary based on criteria for reducing the number of cells. The tolerance value can be used to adjust the power reduction obtained by compressing the RF exposure map. A higher tolerance value for generating the compressed RF exposure map will result in fewer identified regions in the subset, which will use fewer processing resources (e.g., instructions per second and / or memory) and provide a higher backoff, as further described herein. A lower tolerance value for generating the compressed RF exposure map will result in more identified regions in the subset, which will use more processing resources and provide a lower backoff. The number of regions in the subset can be controlled by specifying an acceptable tolerance, which can correspond to the expected performance compared to the full-resolution map.

[0160] If the condition is not met (e.g., maximum contribution > maximum value + tolerance), the profile level is increased (e.g., 96%) to a value greater than the starting profile, and the updated profile level is used to re - determine the boundaries of the non - compliance region. Note that while aspects herein describe increasing the profile level, in general, aspects can change the size of the region of the exposure map being considered until the condition is met. If the condition is met (e.g., maximum contribution < maximum value + tolerance), the identified non - compliance region, along with the maximum contribution of each exposure map within that region, is stored in memory, and the identified region is removed for subsequent partitioning of the total exposure map. If two or more non - compliance regions are identified in an iteration, it can be verified that all non - compliance regions meet the condition. In some cases, non - compliance regions that meet the condition can be considered valid and removed without discarding all identified rectangles.

[0161] To determine a subset of non - compliance regions at block 606, the processing system can perform an iterative process to select a subset of non - compliance regions sufficient to demonstrate RF exposure compliance for the full - resolution map. Multiple points in each normalized map are represented by points in the subset of regions. The number of selected subset regions can vary based on various criteria, such as constraints imposed on device performance (e.g., the tolerance value in the algorithm) and memory usage. The selection can be performed during the calibration process (e.g., at a factory or manufacturing facility) or during the testing or compliance process. Alternatively, the selection can be performed on the wireless device, for example, due to settings input by the manufacturer or software developer, or based on user input. During the iterative process, back - off information (e.g., back - off factor) can be calculated for m1 points of i exposure maps, for all p on / off scenarios associated with the antenna, where p can be equal to 2 i-1 . For a given q - th on / off scenario, where the map is on = 1 or off = 0, represented by on_off(q), the compressed total normalized exposure can be verified as follows:

[0162] , (9)

[0163]

[0164] where is the back - off factor associated with the antenna, antenna module, or antenna group; j is a sequence from 1 to m1; and is the exposure map reduced to the subset of regions. The back - off factor can be adjusted until the total normalized exposure meets a threshold (e.g., ).

[0165] As used herein, a backoff factor can be a specific number representing a fraction (or portion) of the maximum transmit power level supported by a UE, such as a number in the range from 0 to 1. For example, a processing system can generate a normalized distribution of the RF exposure profile, generate a normalized composite plot of the normalized distribution for each of the antennas (or antenna modules or antenna groups), and generate a sum of the normalized composite plots for all antennas based on the backoff factor associated with each of the antennas (or antenna modules or antenna groups). For example, for each antenna, the backoff factor bf can be between [0, 1], such that the maximum allowed transmit power for each antenna is equal to the corresponding backoff factor multiplied by the transmit power limit of the antenna group (e.g., bf * Tx_power_limit), where bf = 1 represents no backoff, where bf = 0.3 represents operating the antenna group at 30% of the transmit power limit, and where the transmit power limit can be the maximum transmit power supported by that particular antenna and / or antenna group.

[0166] For each of the on-scenarios among the p on / off scenarios (e.g., q = 1), the backoff factor bf(q,k) can be verified to be valid for the full-resolution map using the following expression:

[0167]

[0168] ,(10)

[0169] .

[0170] The processing system can determine that m points of the selected subset of regions satisfy the above criteria for all p on / off combinations to confirm that the selected regions represent the full-resolution map. The subset of regions can be selected such that the backoff determined using the subset of regions provides RF exposure compliance for the full-resolution map. The number of regions in the subset can be determined by performance limitations such as processing capabilities. Various methods can be used to reduce the full-resolution map to a subset of regions such that when applied on the full-resolution map, the backoff obtained using the subset demonstrates RF exposure compliance.

[0171] In some aspects, the non-compliance region subset may be adjusted based on the backoff information. For example, the processing system may start with an initial non-compliance region (e.g., the rectangle determined at block 604) and, when applying the backoff to the full-resolution map, check whether the backoff value obtained for the region is sufficient to handle all (or at least some) antenna on / off cases. If the backoff value fails for a particular test case, the processing system may adjust the region to include the maximum exposure point of the test case. For example, the processing system may find the region to which the maximum exposure point belongs and include that region in the backoff calculation. The processing system may repeat such adjustments until the calculated backoff value is valid for all (or at least some) antenna on / off cases. After this adjustment, all regions in the subset may satisfy the RF exposure compliance. The processing system may store the maximum contribution from each antenna in the identified regions in a matrix (or table) format.

[0172] Figure 11 An example of a subset of the non-compliance region 1102 selected for the compressed RF exposure map is illustrated (e.g., as selected at block 606). For example, the backoff verification described herein may be used to determine the subset of the non-compliance region 1102.

[0173] Figure 12 An example of the composite maps 1202a - 1202h and a subset of the non-compliance regions is illustrated, where each of the composite maps 1202a - 1202h is associated with the contribution from a different antenna (or antenna module). As described herein, the maximum value within the identified region 1102 may be stored for each of the different composite maps 1202a - 1202h to perform time-averaged RF exposure compliance, e.g., as described herein with respect to Figures 4A to 4C as described.

[0174] Figure 13 An example table 1300 of the maximum RF exposure values associated with a particular map for each region (e.g., region subset) is illustrated. In this example, the table may have the size of an M×N table, where the maximum contribution from each of the N composite maps within each of the M identified regions is stored.

[0175] Figure 14 is a flowchart illustrating an example operation 1400 for generating an RF exposure map. Operation 1400 may be performed using a processing system (e.g., processing system 502) or any other computing device. Operation 1400 may optionally start at block 1402, where the processing system may obtain the normalized composite exposure (e.g., SAR and / or PD) maps for each radio, antenna (or antenna module), beam, and / or frequency band supported by the wireless device.

[0176] At block 1404, the processing system may combine the composite exposure maps to generate a total exposure map (e.g., total exposure map 804). To combine the composite exposure maps, the processing system may add the composite exposure maps together to form the total exposure map (e.g., the sum of the composite exposure maps).

[0177] At block 1406, the processing system may divide the total exposure map into smaller regions. For example, the processing system may use the contouring and removal methods described herein with respect to Figure 9 and Figure 10 to identify non-compliant regions in the total exposure map.

[0178] At block 1408, the processing system may add the regions including the highest exposure values of each of the composite exposure maps to a reduced matrix (e.g., a compressed RF exposure map represented as a table or matrix), e.g., as described herein with respect to Figure 12 and Figure 13 described.

[0179] At block 1410, the processing system may use the reduced matrix to perform power backoff calculations for on / off situations associated with the antenna. The processing system may use the reduced matrix to determine backoff information (e.g., backoff factor values) associated with the antenna.

[0180] At block 1412, the processing system may apply the power backoff values to a full-resolution exposure map (e.g., total exposure map 902).

[0181] At block 1414, the processing system may determine whether there are non-compliant regions in the full-resolution exposure map to which the backoff values have been applied.

[0182] At block 1416, if non-compliant regions are identified in the full-resolution exposure map, the processing system may add those regions to the reduced matrix. If no non-compliant regions are identified in the full-resolution exposure map, the processing system may consider the reduced matrix to be complete.

[0183] The operations described herein for generating a compressed RF exposure map may be performed on any set of SAR and / or PD distributions. A compressed RF exposure map may be generated on any number of composite maps, the exposure distributions in those composite maps, and the overlaps in the distributions. The operations described herein may be used to reduce any combination of normalized SAR or normalized PD maps.

[0184] Figure 15 is an example graph 1500 illustrating the average backoff difference in decibels for different on / off combinations of an antenna across different test scenarios. The backoff difference is for using a reduced exposure map (e.g., Figure 13Between the backoff calculated from the table 1300 depicted and the backoff calculated using the full exposure map. In this example, the backoff is evaluated based on a compressed exposure map and a full-resolution exposure map derived from a composite exposure map associated with eight antennas, where the total on / off combination equals 255 (e.g., 2 8 -1), the tolerance equals 0.4 (y = 0.4), and the contour equals 0.95 (x = 0.95). The compressed exposure map can have m regions, and in this example, m equals 11. The increment between the above two methods for determining the backoff shows the minimum performance impact encountered by the compressed RF exposure map. The performance loss can be inversely proportional to the number m of regions included in the compressed RF exposure map. For example, if m equals one, all distributions are represented by the highest exposure value, which would be equivalent to all antennas being collocated. As m approaches the number of points in the full-resolution map, the performance loss will decrease and the processing resources will increase (e.g., the number of calculations and / or the memory size). As shown in the graph, in the case of a single transmission scenario (e.g., only one composite map is active), there is no performance loss because there is no overlap with other composite maps, and for other transmission scenarios, the performance loss is minimal. For a simultaneous scenario where five antennas or fewer are active, the average additional backoff is less than 1 dB. The compressed RF exposure map can significantly reduce the number of calculations (e.g., reduced by a factor of 3,000).

[0185] In some aspects, the RF exposure map can be divided into multiple regions, and the RF exposure map can be compressed by obtaining the maximum RF exposure in each region. For example, Figure 16 is a diagram illustrating that the RF exposure map 1602 is segmented into multiple regions 1604. In this example, the RF exposure map 1602 can be compressed by identifying the maximum RF exposure value for each of the regions 1604, where the maximum RF exposure value in the regions 1604 can represent the compressed RF exposure map. The regions 1604 can be arranged in a grid or matrix (e.g., an M×N grid) across the RF exposure map 1602. In some aspects, each of the regions 1604 can have the same size or dimension.

[0186] Figure 17 is a flowchart illustrating an example operation 1700 for generating an RF exposure map. The operation 1700 can be performed using a processing system (e.g., the processing system 502) or other computing devices.

[0187] The operation 1700 can optionally start at block 1702, where the processing system can obtain a first RF exposure map associated with at least one antenna of a wireless device (e.g., the total exposure map 804). In some aspects, the first RF exposure map can be obtained by measuring RF exposure using the measurement system 500. In some cases, the first RF exposure map can be simulated using a model of the radiation pattern transmitted from the wireless device.

[0188] At block 1704, the processing system may convert the first RF exposure map into a second RF exposure map, where the second RF exposure map is compressed compared to the first RF exposure map. For example, the second RF exposure map may represent the maximum normalized exposure levels of a subset of regions in the first RF exposure map. To convert the first RF exposure map into the second RF exposure map, the processing system may use the first RF exposure map to generate a lookup table of exposure contributions across different regions (e.g., table 1300 depicted in Figure 13 ). In some aspects, the compressed RF exposure map may correspond to the maximum RF exposure values associated with different regions, e.g., as described herein with respect to Figure 16 .

[0189] In some aspects, the first RF exposure map may be derived from a composite RF exposure map. For example, to obtain the first RF exposure map, the processing system may obtain a plurality of RF exposure maps (e.g., normalized composite map 802), where each RF exposure map represents the RF distribution of a different antenna of the wireless device. The processing system may combine the plurality of RF exposure maps to form the first RF exposure map, e.g., as described herein with respect to Figure 8 . The first RF exposure map may include the normalized RF exposure contributions from a plurality of antennas of the wireless device (e.g., normalized composite map). The first RF exposure map indicates the RF exposure contributions from a plurality of antennas of the wireless device across one or more surfaces of the wireless device (e.g., top, bottom, front, back, left, and / or right). The first RF exposure map may represent the RF exposure contributions across one surface or multiple surfaces of the wireless device, where the distribution of the multiple surfaces of the wireless device may be represented in a single RF exposure map. The first RF exposure map may include a representation of the RF exposure contributions arranged in at least two dimensions (e.g., x-axis and y-axis).

[0190] For aspects, the processing system may segment the first RF exposure map into a plurality of regions (e.g., a subset of non-compliant regions 1102), e.g., as described herein with respect to Figure 10 and Figure 11 . The processing system may select, for each of the regions, the maximum RF exposure value among the plurality of values in the corresponding region. For example, the processing system may select the maximum RF exposure value for each region from each of the composite exposure maps associated with the total exposure map. The processing system may generate the second RF exposure map as the selected maximum RF exposure values in the regions, e.g., as described herein with respect to Figure 13 and / or Figure 16 . In some cases, the compressed RF exposure may be the selected maximum RF exposure value in the regions.

[0191] For certain aspects, the processing system may perform an iterative process to convert the first RF exposure map, e.g., as described herein with respect to Figures 8 to 14As described. The processing system may determine the total normalized composite RF exposure map of the plurality of antennas based on the back-off factor and the first RF exposure map at a reduced resolution (e.g., a subset of usage area 1102), e.g., according to expression (9). For example, the processing system may adjust the back-off factor until the total normalized composite RF exposure meets a threshold (e.g., ). The processing system may re-segment the first RF exposure map into multiple zones until the back-off factor meets the threshold for calculating the total normalized composite RF exposure map at the full resolution of the first RF exposure map, e.g., according to expression (10).

[0192] As described herein with respect to Figure 18 As further described, the wireless device may use the compressed RF exposure map to determine the transmit power that complies with the time-averaged RF exposure limit. For example, the wireless device may access a second RF exposure map associated with at least one antenna of the wireless device, where the second RF exposure map includes a representation of the maximum RF exposure of the zones. The wireless device may transmit a signal from the at least one antenna at a transmit power that complies with the RF exposure limit (e.g., time-averaged SAR limit) determined at least in part based on the second RF exposure map.

[0193] Figure 18 is a flowchart of an example operation 1800 for wireless communication according to certain aspects of the present disclosure. Operation 1800 may be performed, for example, by a wireless device (e.g., UE 120a in wireless communication network 100). Operation 1800 may be implemented as a software component executed and run on one or more processors (e.g., Figure 2 the controller / processor 280). Additionally, the signal transmission and / or reception by the wireless device in operation 1800 may be implemented, for example, by one or more antennas (e.g., Figure 2 the antenna 252). In certain aspects, the transmission and / or reception of signals by the wireless device may be implemented by obtaining and / or outputting signals via the bus interface of one or more processors (e.g., controller / processor 280).

[0194] Operation 1800 may optionally begin at block 1802, where the wireless device may access an RF exposure map associated with at least one antenna of the wireless device (e.g., Figure 2 the antenna 252), where the RF exposure map (e.g., the compressed RF exposure map represented by table 1300 depicted in Figure 13 ), and the RF exposure map includes a representation of the maximum RF exposure of the zones of the RF exposure map, such as Figure 11at least one of the zones 1102 therein. The wireless device may access the RF exposure map as a table or other data structure via the memory. For example, the RF exposure may be stored in the memory (e.g., memory 282 and / or memory 338), and the wireless device may access the memory to obtain the RF exposure map. The antenna may include a plurality of antenna elements that may operate at a frequency band range (e.g., below 6 GHz and / or mmWave band).

[0195] At block 1804, the wireless device may transmit a signal from at least one antenna with a transmit power that follows the RF exposure limit determined at least in part based on the RF exposure map. In some cases, the wireless device may transmit via a single antenna or multiple antennas simultaneously, where the simultaneous transmission may include transmissions in the same transmission opportunity, time interval, or time window associated with the RF exposure limit. In some cases, the wireless device may transmit via a single radio or multiple radios simultaneously. For example, the wireless device may transmit simultaneously via any combination of an LTE / NR radio, a WiFi radio (e.g., IEEE 802.11 channel), and / or a Bluetooth radio. In some cases, the wireless device may have transmitted via multiple radios within the same time window defined by a regulatory body or standard for averaging RF exposure. For example, the wireless device may transmit via any (2G / 3G / 4G / 5G) wireless wide area network (WWAN) radio in a first time interval and then transmit via a WiFi radio in a second time interval, where both time intervals are within the time averaging window specified by the regulatory body or standard.

[0196] The RF exposure map may represent the RF exposure contributions from multiple antennas of the wireless device. For example, the RF exposure map may include the maximum RF exposure values associated with a plurality of composite exposure maps (e.g., composite maps 1202a - 1202h) in a subset of zones (e.g., zones 1102). The RF exposure map may represent the RF exposure contributions arranged in at least two dimensions (e.g., an x - axis and y - axis coordinate system or an x - axis, y - axis, and z - axis coordinate system). The RF exposure map may represent the RF exposure contributions across one or more surfaces of the wireless device. In some aspects, the RF exposure map may be represented as a look - up table of the maximum RF exposure associated with multiple zones for each of the plurality of antennas of the wireless device, e.g., as depicted in Figure 13 as depicted. In some aspects, the RF exposure map may represent the RF exposure contributions from at least one antenna of the wireless device with respect to one or more RF exposure scenarios (e.g., head exposure, hand or limb exposure, body or torso exposure, and / or hotspot exposure scenarios). The representation of the maximum RF exposure of the zones may allow determination of the transmit power of at least one antenna to ensure compliance with the RF exposure limit.

[0197] In some aspects, the RF exposure contribution from an antenna spans a frequency range. The frequency range may include a sub-6 GHz band, a mmWave band, or a combination thereof. The RF exposure contribution may be derived from multiple bands, such as a sub-6 GHz band and a mmWave band. The RF exposure contribution includes a first RF exposure contribution from the sub-6 GHz band and a second RF exposure contribution from the mmWave band.

[0198] The region in the RF exposure map corresponding to the maximum RF exposure may include an area of multiple points in the RF exposure map. The region may be a sub-region (or sub-area) of a larger exposure region associated with at least one antenna. The region may be a collection of one or more points belonging to a larger exposure region associated with at least one antenna. For example, in some cases, the region may be a single point or a collection of sparse points (which may not include an area or contiguous points). The RF exposure map may include a representation of the maximum RF exposure for each of a plurality of regions (e.g., region 1102) including the region.

[0199] In some aspects, a wireless device may use backoff information (e.g., one or more backoff factors) applied to an RF exposure map to determine transmit power. For example, the wireless device may adjust the RF exposure map by the backoff factor to determine RF exposure compliance.

[0200] For some aspects, a wireless device may use multiple RF exposure maps to determine RF exposure compliance, where each of the RF exposure maps is associated with a different exposure or transmit scenario of the wireless device. For example, to access an RF exposure map, the wireless device may access the RF exposure map among multiple RF exposure maps, where each of the RF exposure maps represents a different exposure or transmit scenario of the wireless device (e.g., across antenna on / off combinations of the wireless device) or a different set of exposure scenarios. The different exposure or transmit scenarios may include various combinations of radios, beams, bands, antennas, and / or antenna groups that are active or inactive. For example, each of the RF exposure maps may be associated with a different combination of one or more active antennas among a plurality of antennas of the wireless device. In some cases, the different exposure or transmit scenarios may correspond to different positions relative to and / or near a human body (e.g., head exposure, hand or limb exposure, body or torso exposure, and / or hotspot exposure scenarios). The set of exposure scenarios may correspond to any combination of head exposure, hand or limb exposure, body or torso exposure, and / or hotspot exposure scenarios.

[0201] In some aspects, a wireless device may determine a transmit power for a future time interval within a time window associated with a time-averaged RF exposure limit. For example, the wireless device may obtain a total transmit power for a past time interval within the time window associated with the RF exposure limit. The wireless device may have transmitted at any time interval within the past time intervals within the time window associated with the RF exposure limit in different exposure or transmit scenarios. The wireless device may determine a provisional transmit power for a future time interval within the time window. The wireless device may convert a sum of the provisional transmit power and the total transmit power into a time-averaged RF exposure value for the time window based on an RF exposure map. The wireless device may adjust the provisional transmit power such that the time-averaged RF exposure value meets the RF exposure limit. The wireless device may transmit a signal at a transmit power less than or equal to the adjusted provisional transmit power that meets the RF exposure limit. For some aspects, the RF exposure limit may include a time-averaged SAR limit, a time-averaged PD limit, or any combination thereof.

[0202] Although Figures 1 to 18 the examples depicted herein are described in the context of a UE performing various methods for providing RF exposure compliance to aid understanding, aspects of the present disclosure may also be applied to other wireless devices performing the RF exposure compliance described herein, such as wireless stations, access points, base stations, and / or customer premise equipment (CPE). Additionally, while these examples are described with respect to communication between a UE (or other wireless device) and a network entity, the UE or other wireless device may communicate with a device other than a network entity (e.g., another UE) or with another device in a user's home that is not a network entity.

[0203] It should be understood that the compressed RF exposure maps described herein may achieve desired wireless communication performance, such as reduced latency, increased uplink data rate, and / or uplink connection at the cell edge. The compressed RF exposure maps described herein may provide efficient RF exposure compliance with respect to zone-specific RF exposure values as compared to RF exposure maps.

[0204] Example Communication Device

[0205] Figure 19 illustrates operations that may include being configured to perform the techniques disclosed herein, such as Figure 17 the operations illustrated, Figure 18A communication device 1900 (e.g., UE 120) of various components (e.g., corresponding to component-plus-function components) for the illustrated operations or other operations for providing RF exposure compliance described herein). The communication device 1900 includes a processing system 1902 that can be coupled to a transceiver 1908 (e.g., a transmitter and / or a receiver). The transceiver 1908 is configured to transmit and receive signals for the communication device 1900 via an antenna 1910, such as the various signals described herein. The processing system 1902 can be configured to perform the processing functions of the communication device 1900, including processing signals received by the communication device 1900 and / or to be transmitted by the communication device.

[0206] The processing system 1902 includes a processor 1904 coupled to a computer-readable medium / memory 1912 via a bus 1906. In some aspects, the computer-readable medium / memory 1912 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1904, cause the communication device 1900 to perform Figure 17 the illustrated operation 1700, Figure 18 the illustrated operation 1800, or other operations for performing the various techniques for providing RF exposure compliance discussed herein. In some aspects, the computer-readable medium / memory 1912 stores code 1914 for accessing (or obtaining), code 1916 for transmitting (or outputting), code 1918 for converting, or any combination thereof.

[0207] In some aspects, the processing system 1902 has circuitry 1920 configured to implement the code stored in the computer-readable medium / memory 1912. In some aspects, the circuitry 1920 is coupled to the processor 1904 and / or the computer-readable medium / memory 1912 via the bus 1906. For example, the circuitry 1920 includes circuitry 1922 for accessing (or obtaining), circuitry 1924 for transmitting (or outputting), circuitry 1926 for converting, or any combination thereof.

[0208] In some examples, the component for transmitting or conveying (or the component for outputting for transmission) may include Figure 2 the transceiver 254 and / or the antenna 252 of the illustrated UE 120 and / or Figure 19 the transceiver 1908 and the antenna 1910 of the communication device 1900 in

[0209] In some cases, the device may not actually send, for example, signals and / or data, but may have an interface (a component for output) for outputting signals and / or data for transmission. For example, a processor may output signals and / or data for transmission to a radio frequency (RF) front end via a bus interface. Similarly, the device may not actually receive signals and / or data, but may have an interface (a component for acquisition) for acquiring signals and / or data received from another device. For example, a processor may acquire (or receive) signals and / or data for reception from the RF front end via a bus interface. In various aspects, the RF front end may include various components, including transmit and receive processors, transmit and receive MIMO processors, modulators, demodulators, etc., such as Figure 2 as depicted in the example of

[0210] In some examples, the component for access and / or the component for conversion may include various processing system components, such as: Figure 19 the processor 1904 in Figure 2 the aspects of the UE 120 depicted in, including a receive processor 258, a transmit processor 264, a TX MIMO processor 266, and / or a controller / processor 280.

[0211] Example Aspects

[0212] Specific implementation examples are described in the following numbered clauses:

[0213] Aspect 1: A method for wireless communication by a wireless device, the method comprising: accessing a radio frequency (RF) exposure map associated with at least one antenna of the wireless device, wherein the RF exposure map includes a representation of a maximum RF exposure of regions of the RF exposure map; and transmitting a signal from the at least one antenna at a transmit power that follows RF exposure limits determined at least in part based on the RF exposure map.

[0214] Aspect 2: The method according to aspect 1, wherein the RF exposure map represents RF exposure contributions from a plurality of antennas of the wireless device.

[0215] Aspect 3: The method according to aspect 2, wherein the RF exposure map represents the RF exposure contributions arranged in at least two dimensions.

[0216] Aspect 4: The method according to aspect 2 or 3, wherein the RF exposure contributions span a frequency range.

[0217] Aspect 5: The method according to aspect 4, wherein the frequency range includes a sub-6 GHz band, a mmWave band, or a combination thereof.

[0218] Aspect 6: The method according to aspect 4 or 5, wherein the RF exposure contribution includes a first RF exposure contribution from a sub-6 GHz band and a second RF exposure contribution from a mmWave band.

[0219] Aspect 7: The method according to any one of aspects 1 to 6, wherein the RF exposure map represents the RF exposure contributions across a plurality of surfaces of the wireless device.

[0220] Aspect 8: The method according to any one of aspects 1 to 7, wherein the RF exposure map represents the RF exposure contributions from at least one antenna of the wireless device with respect to one or more RF exposure scenarios.

[0221] Aspect 9: The method according to any one of aspects 1 to 8, wherein: the region is a sub-region of a larger exposure region associated with the at least one antenna; the region represents one or more points of a larger exposure region associated with the at least one antenna; or the region represents one or more values of the RF exposure contribution associated with the at least one antenna.

[0222] Aspect 10: The method according to any one of aspects 1 to 9, wherein the representation of the maximum RF exposure of the region allows determination of the transmit power of the at least one antenna to ensure compliance with the RF exposure limit.

[0223] Aspect 11: The method according to any one of aspects 1 to 10, wherein the RF exposure map includes the representation of the maximum RF exposure for each of a plurality of regions including the region.

[0224] Aspect 12: The method according to any one of aspects 1 to 11, the method further comprising determining the transmit power using backoff information applied to the RF exposure map.

[0225] Aspect 13: The method according to any one of aspects 1 to 12, wherein accessing the RF exposure map includes accessing the RF exposure map among a plurality of RF exposure maps, wherein each of the RF exposure maps represents a different exposure scenario or a different set of exposure scenarios of the wireless device.

[0226] Aspect 14: The method according to aspect 13, wherein each of the RF exposure maps has a different combination of one or more active antennas among the plurality of antennas of the wireless device.

[0227] Aspect 15: The method according to any one of aspects 1 to 15, the method further comprising: obtaining a total transmission power for a past time interval within a time window associated with the RF exposure limit; determining a provisional transmission power for a future time interval within the time window; converting a sum of the provisional transmission power and the total transmission power into a time-averaged RF exposure value for the time window based on the RF exposure map; and adjusting the provisional transmission power such that the time-averaged RF exposure value meets the RF exposure limit, wherein transmitting the signal comprises transmitting the signal at a transmission power less than or equal to the adjusted provisional transmission power that meets the RF exposure limit.

[0228] Aspect 16: The method according to any one of aspects 1 to 15, wherein the RF exposure limit comprises a time-averaged specific absorption rate (SAR) limit, a time-averaged power density (PD) limit, or any combination thereof.

[0229] Aspect 17: A method of generating a radio frequency (RF) exposure map, the method comprising: obtaining a first RF exposure map associated with at least one antenna of a wireless device; and converting the first RF exposure map into a second RF exposure map, wherein the second RF exposure map is compressed compared to the first RF exposure map.

[0230] Aspect 18: The method according to aspect 17, wherein converting the first RF exposure map comprises using the first RF exposure map to generate a look-up table of exposure contributions across different zones.

[0231] Aspect 19: The method according to aspect 17 or 18, the method further comprising: accessing the second RF exposure map associated with the at least one antenna of the wireless device, wherein the second RF exposure map comprises a representation of a maximum RF exposure of a zone; and transmitting a signal from the at least one antenna at a transmission power that follows the RF exposure limit determined at least in part based on the second RF exposure map.

[0232] Aspect 20: The method according to aspect 19, wherein the representation of the maximum RF exposure of the zone allows determination of the transmission power of the at least one antenna to ensure compliance with the RF exposure limit.

[0233] Aspect 21: The method according to any one of aspects 17 to 20, wherein obtaining the first RF exposure map comprises: obtaining a plurality of RF exposure maps, wherein each of the RF exposure maps represents an RF distribution of a different antenna; and combining the plurality of RF exposure maps to form the first RF exposure map.

[0234] Aspect 22: The method according to any one of aspects 17 to 21, wherein the first RF exposure map includes normalized RF exposure contributions from a plurality of antennas of the wireless device.

[0235] Aspect 23: The method according to any one of aspects 17 to 22, wherein the first RF exposure map indicates RF exposure contributions from a plurality of antennas of the wireless device across one or more surfaces of the wireless device.

[0236] Aspect 24: The method according to aspect 23, wherein the first RF exposure map includes a representation of the RF exposure contributions arranged in at least two dimensions.

[0237] Aspect 25: The method according to any one of aspects 17 to 24, wherein converting the first RF exposure map to the second RF exposure map includes: segmenting the first RF exposure map into a plurality of zones; for each of the zones, selecting a maximum RF exposure value among a plurality of values in the corresponding zone; and generating the second RF exposure map as the selected maximum RF exposure value in the zones.

[0238] Aspect 26: The method according to aspect 25, wherein converting the first RF exposure map to the second RF exposure map further includes: determining a total normalized composite RF exposure map of a plurality of antennas based on a backoff factor and the first RF exposure map at a reduced resolution; and re-segmenting the first RF exposure map into the plurality of zones until the backoff factor meets a threshold for calculating the total normalized composite RF exposure map at the full resolution of the first RF exposure map.

[0239] Aspect 27: The method according to any one of aspects 17 to 26, wherein: obtaining the first RF exposure map includes combining a plurality of RF exposure maps to form the first RF exposure map; and converting the first RF exposure map to the second RF exposure map includes: segmenting the first RF exposure map into a plurality of zones, for each of the zones, selecting a maximum RF exposure value among a plurality of values in the corresponding zone, determining a total normalized composite RF exposure map of a plurality of antennas based on a backoff factor and the selected maximum RF exposure value in the zones, and re-segmenting the first RF exposure map into the plurality of zones until the backoff factor meets a threshold for calculating the total normalized composite RF exposure map at the full resolution of the first RF exposure map.

[0240] Aspect 28: An apparatus, the apparatus comprising: one or more memories that collectively store executable instructions; and one or more processors coupled to the one or more memories, the one or more processors being collectively configured to execute the executable instructions to cause the apparatus to perform the method according to any one of Aspects 1 to 27.

[0241] Aspect 29: An apparatus, the apparatus comprising components for performing the method according to any one of Aspects 1 to 27.

[0242] Aspect 30: A non-transitory computer-readable medium, the non-transitory computer-readable medium comprising 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 27.

[0243] Aspect 31: A computer program product embodied on a computer-readable storage medium, the computer program product comprising code for performing the method according to any one of Aspects 1 to 27.

[0244] The techniques described herein can be used in a variety of wireless communication technologies such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), LTE-Advanced (LTE-A), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. CDMA networks may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks may implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks may implement radio technologies such as NR (e.g., 5G RA), evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are UMTS versions that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is an emerging wireless communication technology that is under development.

[0245] In 3GPP, the term "cell" can refer to the coverage area of a Node B (NB) and / or the NB subsystem serving that coverage area, depending on the context in which the term is used. In an NR system, the terms "cell" and BS, Next Generation Node B (gNB or gNodeB), Access Point (AP), Distributed Unit (DU), carrier, or Transmission and Reception Point (TRP) can be used interchangeably. A BS can provide communication coverage for macro cells, pico cells, femto cells, and / or other types of cells. A macro cell can cover a relatively large geographical area (e.g., with a radius of several kilometers) and can allow unrestricted access for UEs with service subscriptions. A pico cell can cover a relatively small geographical area and can allow unrestricted access for UEs with service subscriptions. A femto cell can cover a relatively small geographical area (e.g., a home) and can allow restricted access by UEs associated with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in a home, etc.). The BS for a macro cell can be referred to as a macro BS. The BS for a pico cell can be called a pico BS. The BS for a femto cell can be referred to as a femto BS or a home BS.

[0246] A UE can also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smart phone, personal digital assistant (PDA), wireless modem, wireless device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet computer, camera, gaming device, netbook, smartbook, ultrabook, appliance, medical device or equipment, biometric sensor / device, wearable device (such as a smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs can be considered Machine-Type Communication (MTC) devices or Evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc. that can communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node can provide a connection to or for a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices, which can be NarrowBand IoT (NB-IoT) devices.

[0247] In some examples, access to an air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication between some or all of the devices and equipment within the service area or cell of that entity. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, the subordinate entities use the resources allocated by the scheduling entity. A base station is not the only entity that can be used as a scheduling entity. In some examples, a UE may be used as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and the other UEs may utilize the resources scheduled by that UE for wireless communication. In some examples, a UE may be used as a scheduling entity in a peer-to-peer (P2P) network or a mesh network. In a mesh network example, in addition to communicating with the scheduling entity, UEs may also communicate directly with each other.

[0248] The methods disclosed herein include one or more steps or acts for implementing the method. The steps and / or acts of the method may be interchanged with each other without departing from the scope of the claims. In other words, unless a specific order of steps or acts is specified, the order and / or use of specific steps and / or acts may be modified without departing from the scope of the claims.

[0249] As used herein, the phrase "processor", "at least one processor", or "one or more processors" generally refers to a single processor configured to perform one or more operations or multiple processors configured to jointly perform one or more operations. In the case of multiple processors, the execution of one or more operations may be divided among different processors, but one processor may perform multiple operations and multiple processors may jointly perform a single operation. Similarly, the phrase "memory", "at least one memory", or "one or more memories" generally refers to a single memory configured to store data and / or instructions or multiple memories configured to jointly store data and / or instructions.

[0250] As used herein, the phrase referring to "at least one of" a list of items refers to any combination of those items (which includes a single member). For example, "at least one of a, b, or c" is intended to cover a, b, c, a - b, a - c, b - c, and a - b - c, as well as any combination with multiple identical elements (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 ordering of a, b, and c).

[0251] As used herein, the term "determine" encompasses a variety of actions. For example, "determine" can include calculating, computing, processing, deriving, generating, investigating, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, and the like. Additionally, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. Further, "determine" can include parsing, selecting, picking, establishing, and the like.

[0252] The foregoing description is 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 generic 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, where the reference to an element in the singular is not intended to mean "one and only one" but rather "one or more" unless specifically stated otherwise. The term "some," unless specifically stated otherwise, 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 become known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is expressly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the phrase "step for."

[0253] The various operations of the methods described above can be performed by any suitable component capable of performing the corresponding functions. The component can include various hardware and / or software components and / or modules, including but not limited to circuitry, application specific integrated circuits (ASICs), or processors. Generally speaking, where there are operations illustrated in the figures, those operations can have corresponding components plus function components with similar numbers.

[0254] The various illustrative logical blocks, modules, and circuits described in connection with the present disclosure may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but 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, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0255] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. Depending on the particular application and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus may link together various circuits, including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, etc. 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 Figure 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, voltage regulators, power management circuits, and similar circuits, which are well known in the art and will not be described further herein. The processor may be implemented using one or more general-purpose processors and / or dedicated processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits capable of executing software. Those skilled in the art will recognize how best to implement the described functionality of the processing system depending on the specific application and overall design constraints imposed on the overall system.

[0256] If implemented in software, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including executing software modules stored on a machine-readable storage medium. The computer-readable storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In an alternative, the storage medium may be integral with the processor. By way of example, the machine-readable media may include a transmission line, a carrier modulated with data, and / or a computer-readable storage medium with instructions stored thereon that is separate from a wireless node, all of which may be accessed by the processor via a bus interface. Alternatively or in addition, the machine-readable media, or any part thereof, may be integrated into the processor, such as in the case of a cache and / or a general register file. By way of example, examples of the machine-readable media may include 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 disk drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer program product.

[0257] Software modules may include a single instruction, or many instructions, and may be distributed across several different code segments, among different programs, and across multiple storage media. The computer-readable media may include multiple software modules. Software modules include instructions that, when executed by an apparatus such as a processor, cause a processing system to perform various functions. Software modules may include a sending module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, when a triggering event occurs, a software module may be loaded from a hard disk drive into RAM. During execution of the software module, the processor may load some of the instructions into a cache to increase access speed. One or more cache lines may then be loaded into the general register file for execution by the processor. When the functionality of a software module is referred to hereinafter, it will be understood that such functionality is implemented by the processor in executing instructions from the software module.

[0258] Additionally, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, 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 ® disc, where disks typically reproduce data magnetically, while discs reproduce data optically with a laser. Thus, in some aspects, a computer-readable medium may include a non-transitory computer-readable medium (e.g., a tangible medium). Additionally, for other aspects, a computer-readable medium may include a transitory computer-readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

[0259] Accordingly, certain aspects may include a computer program product for performing the operations given herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and / or encoded) thereon that are executable by one or more processors to perform the operations described herein, such as instructions for performing the operations described and illustrated in Figure 6 , Figure 14 , Figure 17 and / or Figure 18 .

[0260] Furthermore, it should be understood that modules and / or other suitable components for performing 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 the transfer of components for performing the methods described herein. Alternatively, the various methods described herein may be provided via a storage component (e.g., RAM, ROM, or a physical storage medium such as a compact disc (CD) or floppy disk) such that a user terminal and / or a base station may obtain the various methods when the storage component is coupled to or provided to the device. Additionally, any other suitable techniques for providing the methods and techniques described herein to a device may be used.

[0261] It should be understood that the claims are not limited to the exact configurations and components illustrated above. Various modifications, variations, and alterations to the arrangements, operations, and details of the methods and apparatuses described above may be made without departing from the scope of the claims.

Claims

1. A method of wireless communication by a wireless device, the method comprising: accessing a radio frequency (RF) exposure map associated with at least one antenna of the wireless device, wherein the RF exposure map includes a representation of a maximum RF exposure of regions of the RF exposure map; and transmitting a signal from the at least one antenna at a transmit power that follows an RF exposure limit determined at least in part based on the RF exposure map.

2. The method according to claim 1, wherein the RF exposure map represents RF exposure contributions from a plurality of antennas of the wireless device.

3. The method according to claim 2, wherein the RF exposure map represents the RF exposure contributions arranged in at least two dimensions.

4. The method according to claim 2, wherein the RF exposure contributions span a frequency range.

5. The method according to claim 4, wherein the frequency range includes a sub-6 gigahertz (GHz) band, a millimeter wave (mmWave) band, or a combination thereof.

6. The method according to claim 4, wherein the RF exposure contributions include a first RF exposure contribution from a sub-6 gigahertz (GHz) band and a second RF exposure contribution from a millimeter wave (mmWave) band.

7. The method according to claim 1, wherein the RF exposure map represents RF exposure contributions across a plurality of surfaces of the wireless device.

8. The method according to claim 1, wherein the RF exposure map represents RF exposure contributions from at least one antenna of the wireless device relative to one or more RF exposure scenarios.

9. The method according to claim 1, wherein the region represents (i) one or more points of a larger exposure region associated with the at least one antenna or (ii) one or more values of the RF exposure contributions associated with the at least one antenna.

10. The method according to claim 1, wherein the representation of the maximum RF exposure of the region allows determination of the transmit power of the at least one antenna to ensure compliance with the RF exposure limit.

11. The method according to claim 1, wherein the RF exposure map includes the representation of the maximum RF exposure for each of a plurality of regions including the region.

12. The method according to claim 1, the method further comprising determining the transmit power using backoff information applied to the RF exposure map.

13. The method according to claim 1, wherein accessing the RF exposure map includes accessing the RF exposure map among a plurality of RF exposure maps, wherein each of the RF exposure maps represents a different exposure scenario or a different set of exposure scenarios of the wireless device.

14. The method according to claim 13, wherein each of the RF exposure maps has a different combination of one or more active antennas among a plurality of antennas of the wireless device.

15. The method according to claim 1, the method further comprising: obtaining a total transmit power for a past time interval within a time window associated with the RF exposure limit; determining a provisional transmit power for a future time interval within the time window; Convert the sum of the temporary transmit power and the total transmit power into a time-averaged RF exposure value for the time window based on the RF exposure map; and Adjust the temporary transmit power such that the time-averaged RF exposure value meets the RF exposure limit, where transmitting the signal includes transmitting the signal at a transmit power less than or equal to the adjusted temporary transmit power that meets the RF exposure limit.

16. The method according to claim 1, wherein the RF exposure limit includes a time-averaged specific absorption rate (SAR) limit, a time-averaged power density (PD) limit, or any combination thereof.

17. A method for generating a radio frequency (RF) exposure map, the method comprising: Obtain a first RF exposure map associated with at least one antenna of a wireless device; and Convert the first RF exposure map into a second RF exposure map, where the second RF exposure map is compressed compared to the first RF exposure map.

18. The method according to claim 17, wherein converting the first RF exposure map includes using the first RF exposure map to generate a look-up table of exposure contributions across different zones.

19. The method according to claim 17, the method further comprising: Access the second RF exposure map associated with the at least one antenna of the wireless device, where the second RF exposure map includes a representation of the maximum RF exposure of the zones; and Transmit a signal from the at least one antenna at a transmit power that follows the RF exposure limit determined at least in part based on the second RF exposure map.

20. The method according to claim 19, wherein the representation of the maximum RF exposure of the zones allows determination of the transmit power of the at least one antenna to ensure compliance with the RF exposure limit.

21. The method according to claim 17, wherein obtaining the first RF exposure map includes: Obtain a plurality of RF exposure maps, where each of the RF exposure maps represents the RF distribution of a different antenna; and Combine the plurality of RF exposure maps to form the first RF exposure map.

22. The method according to claim 17, wherein the first RF exposure map includes normalized RF exposure contributions from a plurality of antennas of the wireless device.

23. The method according to claim 17, wherein the first RF exposure map indicates RF exposure contributions from a plurality of antennas of the wireless device across one or more surfaces of the wireless device.

24. The method according to claim 23, wherein the first RF exposure map includes a representation of the RF exposure contributions arranged in at least two dimensions.

25. The method according to claim 17, wherein converting the first RF exposure map into the second RF exposure map includes: Segment the first RF exposure map into a plurality of zones; For each of the zones, select a maximum RF exposure value among a plurality of values in the corresponding zone; and Generate the second RF exposure map as the selected maximum RF exposure value in the zones.

26. The method according to claim 25, wherein converting the first RF exposure map to the second RF exposure map further comprises: determining a total normalized composite RF exposure map of a plurality of antennas based on a backoff factor and the first RF exposure map at a reduced resolution; and re-segmenting the first RF exposure map into the plurality of zones until the backoff factor meets a threshold for calculating the total normalized composite RF exposure map at the full resolution of the first RF exposure map.

27. The method according to claim 17, wherein: obtaining the first RF exposure map comprises combining a plurality of RF exposure maps to form the first RF exposure map; and converting the first RF exposure map to the second RF exposure map comprises: segmenting the first RF exposure map into a plurality of zones, for each of the zones, selecting a maximum RF exposure value among a plurality of values in the corresponding zone, determining a total normalized composite RF exposure map of a plurality of antennas based on a backoff factor and the selected maximum RF exposure value in the zone, and re-segmenting the first RF exposure map into the plurality of zones until the backoff factor meets a threshold for calculating the total normalized composite RF exposure map at the full resolution of the first RF exposure map.

28. An apparatus for wireless communication, the apparatus comprising: one or more memories that collectively store executable instructions; and one or more processors coupled to the one or more memories, the one or more processors being collectively configured to execute the executable instructions to cause the apparatus to: access a radio frequency (RF) exposure map associated with at least one antenna of the apparatus, wherein the RF exposure map includes a representation of a maximum RF exposure of zones of the RF exposure map; and control transmission of a signal from the at least one antenna at a transmission power that follows an RF exposure limit determined at least in part based on the RF exposure map.

29. An apparatus for generating a radio frequency (RF) exposure map, the apparatus comprising: one or more memories that collectively store executable instructions; and one or more processors coupled to the one or more memories, the one or more processors being collectively configured to execute the executable instructions to cause the apparatus to: obtain a first RF exposure map associated with at least one antenna of a wireless device; and convert the first RF exposure map to a second RF exposure map, wherein the second RF exposure map is compressed compared to the first RF exposure map.

30. The apparatus according to claim 29, wherein the one or more processors are further collectively configured to execute the executable instructions to cause the apparatus to: access the second RF exposure map associated with the at least one antenna of the wireless device, wherein the second RF exposure map includes a representation of a maximum RF exposure of zones; and transmit a signal from the at least one antenna at a transmission power that follows an RF exposure limit determined at least in part based on the second RF exposure map.

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