Duty cycle determination for radio frequency exposure assessment

Abstract

Certain aspects of the present disclosure provide techniques and apparatus for duty cycle determination for radio frequency (RF) exposure assessment. A method of wireless communication by a wireless device includes determining a duty cycle associated with a transmission scenario based at least in part on a past duty cycle associated with the transmission scenario; and transmitting the signal at a transmit power determined based at least in part on the duty cycle and the RF exposure limit.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application serial number 18 / 348,034, filed on July 6, 2023, which claims the benefit and priority of U.S. provisional application serial number 63 / 367,981, filed on July 8, 2022, both of which are hereby expressly incorporated herein by reference in their entirety.

[0003] introduction Technical Field

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

[0005] Related technologies

[0006] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, broadcasting, etc. Modern wireless devices, such as cellular phones, are often 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 may undergo an extensive certification process before being shipped to the market. To ensure that wireless devices comply with RF exposure limits, technologies have been developed that enable wireless devices to assess RF exposure from the wireless device and adjust the transmit power of the wireless device accordingly to comply with the RF exposure limits. Summary of the invention

[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 characteristics. Without limiting the scope of the present disclosure as expressed in the appended claims, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description," one will understand how the features of the present disclosure provide advantages, including improved wireless communication performance.

[0008] Certain aspects of the subject matter described in this disclosure may be implemented in a method for wireless communication by a wireless device. The method generally includes determining a duty cycle associated with a transmission scenario based at least in part on past duty cycles associated with the transmission scenario; and transmitting a signal at a transmission power determined at least in part on the duty cycle and a radio frequency (RF) exposure limit.

[0009] Certain aspects of the subject matter described in this disclosure may be implemented in an apparatus for wireless communication. The apparatus generally includes a memory and one or more processors coupled to the memory. The one or more processors are configured to determine a duty cycle associated with a transmission scenario based at least in part on past duty cycles associated with the transmission scenario, and control the transmission of a signal at a transmission power determined at least in part on the duty cycle and a radio frequency (RF) exposure limit.

[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 determining a duty cycle associated with a transmit scenario based at least in part on past duty cycles associated with the transmit scenario; and means for transmitting a signal at a transmit power determined at least in part on the duty cycle and a radio frequency (RF) exposure limit.

[0011] Certain aspects of the subject matter described in the present disclosure may be implemented in a non-transitory computer-readable medium having instructions stored thereon that, when executed by an apparatus, cause the apparatus to perform operations including: determining a duty cycle associated with a transmit scenario based at least in part on past duty cycles associated with the transmit scenario; and transmitting a signal at a transmit power determined at least in part on the duty cycle and a radio frequency (RF) exposure limit.

[0012] 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.

[0013] To achieve the aforementioned and related purposes, one or more aspects include the features described in full 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 are only indicative of only some of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order that the above-mentioned features of the present disclosure can be understood in detail, a more specific description briefly summarized above can be obtained by referring 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 specification may admit to other equally effective aspects.

[0015] Figure 1 is a block diagram conceptually illustrating an example wireless communication network.

[0016] Figure 2 is a block diagram conceptually illustrating a design of an example base station (BS) and user equipment (UE).

[0017] Figure 3 is a block diagram of an example radio frequency (RF) transceiver.

[0018] Figure 4A , Figure 4B and Figure 4C is a graph illustrating an example of transmit power over time complying with time-averaged RF exposure limits.

[0019] Figure 5 is a diagram of an example processing architecture for assessing RF exposure across multiple radios.

[0020] Figure 6 is a diagram illustrating example operations for determining a maximum average power for a radio in communication with an RF exposure manager.

[0021] Figure 7 is a diagram illustrating example operations for determining a maximum allowed transmit power based on a duty cycle.

[0022] Figure 8 is a diagram illustrating example operations for determining a maximum allowed transmit power based on a duty cycle and a threshold for determining a duty cycle power.

[0023] Fig. 9 is a flow diagram illustrating example operations for wireless communications by a wireless device in accordance with certain aspects of the present disclosure.

[0024] Fig.10 Illustrated are communications devices that may include various components configured to perform operations for the techniques disclosed herein in accordance with certain aspects of the present disclosure.

[0025] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation. DETAILED DESCRIPTION

[0026] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for determining a duty cycle associated with a transmission for radio frequency (RF) exposure assessment.

[0027] The wireless communication device may use a time averaging operation to assess RF exposure compliance. The wireless device may perform an RF exposure assessment of past RF exposures within a given time window to determine a maximum allowed transmit power for a future time interval within the time window. In some cases, the wireless device may determine the maximum allowed transmit power by taking into account a duty cycle associated with certain transmissions, where the duty cycle indicates the proportion of time that the wireless device transmits during a given time period. For example, if the wireless device is transmitting at a low duty cycle (e.g., less than 10%), the wireless device may use a higher value for the maximum allowed transmit power. If the wireless device is transmitting at a high duty cycle (greater than 80%), the wireless device may use a lower value for the maximum allowed transmit power.

[0028] In some cases, the wireless device may be configured with a duty cycle via a radio access network, for example, according to a time division duplex (TDD) uplink-downlink time slot mode in a 5G New Radio (NR) system. The wireless device may determine the duty cycle based on a TDD mode configured for uplink and downlink communications of the wireless access network. For example, the wireless device may obtain a TDD time slot mode indicating that there are eight downlink time slots and two uplink time slots in a time slot sequence, so that the wireless device is configured with a 20% duty cycle. In some cases, the wireless device may communicate, for example, via frequency division duplex (FDD) or via a random channel access method such as carrier sense multiple access for IEEE 802.11 communications, without a pre-configured duty cycle.

[0029] Various aspects of the present disclosure provide apparatus and methods for determining a duty cycle associated with a transmission for RF exposure compliance assessment. The wireless device may determine the duty cycle based at least in part on a history of transmissions over a particular time period. In certain aspects, the wireless device may apply smoothing to the duty cycle determination to reduce the impact of rapid changes in the duty cycle. For example, the wireless device may apply an exponential filter with a smoothing factor to determine a weighted average of the duty cycle. The wireless device may determine a maximum allowed transmit power for a future time interval based at least in part on the determined duty cycle compliance with a time-averaged RF exposure limit.

[0030] The apparatus and methods for determining duty cycle described herein may be beneficial for improving wireless communication performance (e.g., improved signal quality at the receiver, lower latency, higher throughput, etc.). For example, when the duty cycle is low, the duty cycle may allow the wireless device to allocate a higher maximum allowed transmit power for future time intervals.

[0031] As used herein, a radio may refer to a physical or logical transmission path associated with one or more active frequency bands (carriers, channels, bandwidths, subdivisions thereof, etc.), transceivers, and / or radio access technologies (RATs) (e.g., code division multiple access (CDMA), long term evolution (LTE), NR, IEEE 802.11, Bluetooth, etc.) for wireless communications. For example, for uplink carrier aggregation in LTE and / or NR, each of the active component carriers for wireless communications may be considered a separate radio. Similarly, multi-band transmissions for IEEE 802.11 communications may be considered a separate radio for each frequency band (e.g., 2.4 GHz, 5 GHz, or 6 GHz).

[0032] The following description provides an example of RF exposure compliance in a communication system, without limiting the scope, applicability or examples set forth in the claims. Without departing from the scope of the present disclosure, the functions and arrangements of the elements discussed may be changed. Each example may ignore, replace or add each procedure or component as appropriate. For example, the method described may be performed in a different order than described, and various steps may be added, omitted or combined. In addition, the features described for some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functionality, or structures and functionality that are supplementary or alternative to the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of the present invention. The word "exemplary" is used herein to mean "used as an example, instance, or illustration". Any aspect described herein as "exemplary" is not necessarily to be interpreted as being preferred or having an advantage over other aspects.

[0033] Generally, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a specific radio access technology (RAT) and may operate on one or more frequencies. RAT may also be referred to as a radio technology, an air interface, etc. Frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs, or may support multiple RATs.

[0034] The techniques described herein can be used for various wireless networks and radio technologies. Although various aspects may be described herein using terms commonly associated with 3G, 4G, and / or new radio (e.g., 5G NR) wireless technologies, various 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, etc.

[0035] NR access can support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or greater), millimeter wave (mmWave) targeting high carrier frequency (e.g., 24 GHz to 53 GHz or greater), massive machine type communication MTC (mMTC) targeting non-backward compatible MTC technology, and / or mission critical services targeting ultra-reliable low latency communication (URLLC). These services may include latency and reliability specifications. These services may also have different transmission time intervals (TTIs) to meet corresponding quality of service (QoS) specifications. In addition, these services can coexist in the same subframe. NR supports beamforming and can dynamically configure beam directions. Multiple input multiple output (MIMO) transmission using precoding can also be supported as multi-layer transmission. Aggregation of multiple cells can be supported.

[0036] Example Wireless Communications Networks and Devices

[0037] Figure 1 An example wireless communication network 100 is illustrated in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a NR system (e.g., a 5G NR network), an Evolved Universal Terrestrial Radio Access (E-UTRA) system (e.g., a 4G network), a Universal Mobile Telecommunications System (UMTS) (e.g., a 2G / 3G network), or a Code Division Multiple Access (CDMA) system (e.g., a 2G / 3G network), or may be configured for communication in accordance with IEEE standards such as one or more of the 802.11 standards. Figure 1 As shown, according to aspects of the present disclosure, UE 120a includes an RF exposure manager 122 that uses a duty cycle determined from past transmissions to ensure RF exposure compliance. UE 120a may be configured to communicate with multiple radio access networks (RANs), such as a 5G network and a WiFi network, or configured to communicate with a single RAN, such as only a WiFi network or only a Bluetooth network.

[0038] like Figure 1As illustrated in , the wireless communication network 100 may include multiple BSs 110a to 110z (each also individually referred to herein as BS 110, or collectively referred to as BS 110) and other network entities. BS 110 may provide communication coverage for a specific geographic area (sometimes referred to as a "cell"), which may be stationary or movable depending on the location of a mobile BS. In some examples, BS 110 may 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.) using any suitable transport network. Figure 1 In the example shown, BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more cells.

[0039] BS 110 communicates with UEs 120a-y (each also individually referred to herein as UE 120 or collectively referred to as UE 120) in the wireless communication network 100. UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. The wireless communication network 100 may also include a relay station (e.g., relay station 110r) (also referred to as a relay, etc.) that receives transmissions of data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and transmits the transmissions of the data and / or other information to a downstream station (e.g., UE 120 or BS 110), or relays transmissions between UEs 120 to facilitate communication between devices.

[0040] In certain aspects, UE 120a can act as an access point (AP) (such as a soft AP) and communicate with other WiFi clients (e.g., augmented reality (AR) glasses or headsets, tablet computers, etc.) and use the wireless link to BS 110 as a backhaul to a network (e.g., the Internet). As an example, UE 120a can stream video from an AP (e.g., another UE or a base station) and have a Bluetooth link to a pair of headphones.

[0041] The network controller 130 may communicate with a collection of BSs 110 and provide coordination and control (e.g., via backhaul) for these BSs 110. In some cases, such as in a 5G NR system, the network controller 130 may include a centralized unit (CU) and / or a distributed unit (DU). In various aspects, the network controller 130 may 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 functions, policy control functions, authentication server functions, unified data management, application functions, network open functions, network repository functions, network slice selection functions, etc.

[0042] In the present disclosure, the term "beam" may be used in various contexts. A beam may be used to refer to a set of gains and / or phases (e.g., precoding weights or co-phasing weights) applied to antenna elements in a UE and / or BS for transmission or reception. The term "beam" may also refer to an antenna or radiation pattern of a signal transmitted when the gain and / or phase are applied to an antenna element. Other references to a beam may include one or more characteristics or parameters associated with an antenna (radiation) pattern, such as angle of arrival (AoA), angle of departure (AoD), gain, phase, directivity, beamwidth, beam direction in azimuth and elevation (relative to a reference plane), peak-to-sidelobe ratio, or antenna ports associated with an antenna (radiation) pattern. The term "beam" may also refer to an associated number and / or configuration of antenna elements (e.g., a uniform linear array, a uniform rectangular array, or other uniform array).

[0043] Figure 2 1 and 120a (eg, Figure 1 Example components of a wireless communication network 100).

[0044] At BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller / processor 240. The control information may be for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH), a physical downlink control channel (PDCCH), a group common PDCCH (GC PDCCH), etc. The data may be for a physical downlink shared channel (PDSCH), etc. A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel such as a PDSCH, a physical uplink shared channel (PUSCH), or a physical sidelink shared channel (PSSCH).

[0045] The processor 220 may process (e.g., encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols such as for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a PBCH demodulation reference signal (DMRS), and a channel state information reference signal (CSI-RS). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., pre-decoding) on ​​data symbols, control symbols, and / or reference symbols (where applicable), and may provide an output symbol stream to a modulator (MOD) in a transceiver 232a-232t. Each modulator 232a-232t in the transceiver may process a respective output symbol stream (e.g., for orthogonal frequency division multiplexing (OFDM), etc.) to obtain an output sample stream. Each transceiver in the transceiver 232a-232t may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. Downlink signals from transceivers 232a-232t may be transmitted via antennas 234a-234t, respectively.

[0046] At UE 120a, antennas 252a-252r may receive downlink signals from BS110a and may provide received signals to transceivers 254a-254r, respectively. Transceivers 254a-254r may condition (e.g., filter, amplify, downconvert, and digitize) the corresponding received signals to obtain input samples. Each demodulator (DEMOD) in transceivers 232a-232t may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 may obtain received symbols from all demodulators in transceivers 254a-254r, perform MIMO detection on the received symbols (where applicable), and provide detected symbols. Receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to data sink 260, and provide decoded control information to controller / processor 280.

[0047] On the uplink, at the UE 120a, a transmit processor 264 may receive and process data from a data source 262 (e.g., for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 280 (e.g., for a physical uplink control channel (PUCCH)). The transmit processor 264 may also generate reference symbols for reference signals (e.g., for a sounding reference signal (SRS)). The symbols from the transmit processor 264 may be pre-decoded by a TX MIMO processor 266, if applicable, further processed by a modulator (MOD) 254a-254r in the transceiver (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At BS 110a, the uplink signal from UE 120a may be received by antenna 234, processed by demodulators in transceivers 232a-232t, detected by MIMO detector 236 (if applicable), and further processed by receive processor 238 to obtain decoded data and control information transmitted by UE 120a. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller / processor 240.

[0048] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively.A scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0049] 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. Figure 2 As shown, the controller / processor 280 of the UE 120a has an RF exposure manager 281 that represents the RF exposure manager 122, in accordance with aspects described herein. Although shown at the controller / processor, other components of the UE 120a and BS 110a may be used to perform the operations described herein.

[0050] NR can use orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. NR can use time division duplex (TDD) to support half-duplex operation. OFDM and single carrier frequency division multiplexing (SC-FDM) divide the system bandwidth into multiple orthogonal subcarriers, which are also commonly referred to as tones, frequency bands, etc. Each subcarrier can be modulated with data. Modulation symbols can be transmitted in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers can depend on the system bandwidth. The system bandwidth can also be divided into subbands. For example, one subband can cover multiple resource blocks (RBs).

[0051] Although the reference Figure 1 and Figure 2 UE 120a is described as communicating with a BS and / or within a network, but UE 120a may be configured to communicate / transmit directly to another UE 120 or directly to another wireless device without relaying the communication through a network. Figure 2 The BS 110 a illustrated in FIG. 4 and described above is an example of another UE 120 .

[0052] Example RF Transceiver

[0053] 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 antenna 306. When TX path 302 and RX path 304 share antenna 306, these paths can be connected to the antenna via interface 308, which can include any of a variety of suitable RF devices, such as switches, duplexers, diplexers, multiplexers, etc.

[0054] Receiving an in-phase (I) or quadrature (Q) baseband analog signal from a digital-to-analog converter (DAC) 310, the TX path 302 may include a baseband filter (BBF) 312, a mixer 314, a driver amplifier (DA) 316, and a power amplifier (PA) 318. The BBF 312, the mixer 314, and the DA 316 may be included in one or more radio frequency integrated circuits (RFICs). For some implementations, the PA 318 may be external to the RFIC.

[0055] The BBF 312 filters the baseband signal received from the DAC 310, and the mixer 314 mixes the filtered baseband signal with a transmit local oscillator (LO) signal to convert the baseband signal of interest to a different frequency (e.g., upconvert from baseband to radio frequency). This frequency conversion process produces sum and difference frequencies between the LO frequency and the frequency of the baseband signal of interest. The sum and difference frequencies are referred to as beat frequencies. The beat frequencies are typically in the RF range, so that the signal output by the mixer 314 is typically an RF signal, which may be amplified by the DA 316 and / or by the PA 318 before being transmitted through the antenna 306. Although one mixer 314 is illustrated, several mixers may be used to upconvert the filtered baseband signal to one or more intermediate frequencies and thereafter upconvert the intermediate frequency signal to a frequency for transmission.

[0056] The RX path 304 may include a low noise amplifier (LNA) 324, a mixer 326, and a baseband filter (BBF) 328. The LNA 324, the mixer 326, and the BBF 328 may be included in one or more RFICs, which may be the same RFIC as the RFIC that includes the TX path components, or may be a different RFIC. The RF signal received via the antenna 306 may be amplified by the LNA 324, and the mixer 326 mixes the amplified RF signal with a receive local oscillator (LO) signal to convert the RF signal of interest to a different baseband frequency (e.g., down-convert). The baseband signal output by the mixer 326 may be filtered by the BBF 328 before being converted to a digital I or Q signal by an analog-to-digital converter (ADC) 330 for digital signal processing.

[0057] Some transceivers may use 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 a TX frequency synthesizer 320, which may be buffered or amplified by an amplifier 322 before being mixed with the baseband signal in a mixer 314. Similarly, the receive LO may be generated by an RX frequency synthesizer 332, which may be buffered or amplified by an amplifier 334 before being mixed with the RF signal in a mixer 326.

[0058] Controller 336 may direct the operation of RF transceiver circuit 300, such as transmitting signals via TX path 302 and / or receiving signals via RX path 304. 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. Memory 338 may store data and program code for operating RF transceiver circuit 300. Controller 336 and / or memory 338 may include control logic. In some cases, controller 336 may determine the transmit power applied to TX path 302 (e.g., certain gain levels applied at BBF 312, DA 316, and / or PA 318) in compliance with RF exposure limits set by country-specific regulations and / or international standards, as further described herein.

[0059] Example RF Exposure Compliance

[0060] RF exposure can be expressed in terms of the specific absorption rate (SAR), which measures the energy absorbed per unit mass of human tissue and may have units of watts per kilogram (W / kg). RF exposure can also be expressed in terms of power density (PD), which measures the energy absorbed per unit area and may have units of milliwatts per square centimeter (mW / cm 2 ) units. In some cases, a maximum permissible exposure (MPE) limit (in the form of PD) may be imposed on wireless devices using transmit frequencies above 6 GHz. MPE limits are area-based exposure regulatory metrics, such as energy density limits, which are defined as the number X (watts per square meter (W / m2) averaged over a defined area and time-averaged over a frequency-dependent time window. 2 )) to prevent hazardous human exposure represented by changes in tissue temperature.

[0061] SAR may be used to assess RF exposure for transmission frequencies less than 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, etc. PD may be used to assess RF exposure for transmission frequencies above 6 GHz, which covers wireless communication technologies such as IEEE 802.11ad, 802.11ay, 5G in the millimeter wave band, etc. Therefore, different metrics may be used to assess RF exposure for different wireless communication technologies.

[0062] A wireless device (e.g., UE 120) may use multiple wireless communication technologies to send signals simultaneously. For example, a wireless device may use a first wireless communication technology (e.g., 3G, 4G, 5G, etc.) operating at or below 6 GHz and a second wireless communication technology (e.g., millimeter wave 5G in the 24 GHz to 60 GHz band, IEEE 802.11ad or 802.11ay) operating above 6 GHz to send signals simultaneously. In some aspects, a wireless device may 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 in 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 in PD) to send signals simultaneously. As used herein, sub-6 GHz frequency bands may include frequency bands from 300 MHz to 6,000 MHz in some examples, and may include frequency bands within the range of 6,000 MHz and / or 7,000 MHz in some examples.

[0063] In some cases, compliance with RF exposure limits may be performed as a time-averaged RF exposure assessment over a specified time window (T) associated with the RF exposure limit (e.g., 2 seconds for mmWave or 60 GHz bands, 100 seconds or 360 seconds for ≤6 GHz bands, etc.).

[0064] Figure 4A 400A is a graph of transmit power (P(t)) over time as it varies within a time window (T) associated with RF exposure limits in accordance with certain aspects of the present disclosure. As an example, during certain transmission opportunities within the time window (T), the instantaneous transmit power may exceed the maximum time-averaged transmit power level P(t). limit That is, the transmission power can be greater than the maximum time average transmission power level P limit In some cases, the UE can P max In some cases, at some transmission opportunities, the UE can transmit at a power level less than or equal to the maximum time-averaged transmit power level P. limit The maximum time average transmit power level P limit represents the time-averaged threshold value in terms of transmit power for RF exposure limit within a time window (T), and in some cases, P limit This may be referred to as a maximum time average power level or limit, or in terms of exposure, a maximum time average RF exposure level or limit. Graph 400A also illustrates gaps between transmit bursts, where these gaps represent periods during which no transmission is being output from the device.

[0065] In some cases, the transmit power may be maintained at a maximum time-averaged transmit power level (e.g., P) allowed for RF exposure compliance that enables continuous transmission during the time window. limit ).For example, Figure 4B is a graph 400B of transmit power (P(t)) over time, illustrating a case where the transmit power is limited to P in accordance with certain aspects of the present disclosure. limit As shown in the figure, the UE can follow the RF exposure limit to P limit Send continuously.

[0066] Figure 4C 400C is a graph of transmit power (P(t)) over time illustrating a time-averaged mode that provides reserved power to enable continuous transmission within a time window (T) in accordance with certain aspects of the present disclosure. As shown, the transmit power may be increased from a maximum instantaneous power (P max ) falls back to the reserved power (P reserve ), so that the UE can continue to operate at a lower power (P reserve ) to maintain continuous transmission (e.g., maintain a radio connection with the receiving entity) during the time window. Figure 4C In P max The duration between P max and P reserve The area between can be equal to the area between P and limit and P reserve The area between Figure 4C The area of ​​the transmission power (P(t)) in the time window T is equal to P limit This area can be considered to use 100% of the energy (transmitted power or exposure) to maintain compliance with the time-averaged RF exposure limit. reserve In the case of max The transmission is performed during the time window, and the transmitter is turned off during the remainder of the time window to ensure compliance with the time-averaged RF exposure limit. reserve A fixed power set to serve a certain purpose (e.g., reserving power for certain communications). max The transmission duration under P may 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., at P max in short bursts).

[0067] In some respects, Figure 4CIn the time average mode illustrated in FIG, the UE can operate at a power level higher than the average power level but less than P max Although Figure 4C A single transmit burst is illustrated in FIG. 1 , but it should be understood that the UE may alternatively utilize multiple transmit bursts within the time window (T), such as described herein with respect to Figure 4A The transmit bursts may be maintained at a transmit power equal to or lower than P reserve In addition, it should be understood that the transmit power of each transmit burst may vary (within a burst and / or compared to other bursts), and at least a portion of the burst may be above a maximum average power level (e.g., P limit ) power to send.

[0068] Although FIG. 4A to FIG. 4C Continuous transmission within a window, opportunity, burst, etc. is illustrated, but it should be understood that a transmission duty cycle can be implemented. In such a specific implementation, the transmission power may be periodically zero and maintained at a higher level during other parts of the duty cycle (e.g., as FIG. 4A to FIG. 4C The duty cycle transmitted may indicate a portion (e.g., 5 ms) of a specific time period (e.g., 500 ms) in which one or more signals are transmitted. The duty cycle may be a ratio of the portion to the specific time period. In some cases, the duty cycle may be standardized (e.g., predetermined) with a specific RAT and / or may change over time, for example, due to changes in radio conditions, mobility, user behavior, channel availability, etc.

[0069] Example Duty Cycle Determination for RF Exposure Assessment

[0070] A multi-mode / multi-band UE has multiple transmit antennas that can transmit simultaneously in the sub-6 GHz band and the frequency band greater than 6 GHz band (such as the mmWave band). As described herein, RF exposure in the sub-6 GHz band can be evaluated in terms of SAR, and RF exposure in the frequency band greater than 6 GHz can be evaluated in terms of PD. Due to regulations regarding simultaneous exposure, wireless devices can limit the maximum transmit power for both the sub-6 GHz band and the frequency band greater than 6 GHz.

[0071] Various aspects of the present disclosure provide apparatus and methods for determining a duty cycle associated with a transmission for RF exposure assessment. The wireless device may determine the duty cycle based at least in part on a history of transmissions over a particular time period. In certain aspects, the wireless device may apply smoothing to the duty cycle determination to reduce the impact of rapid changes in the duty cycle. For example, the wireless device may apply an exponential filter with a smoothing factor to determine a weighted average of the duty cycle. The wireless device may determine a maximum allowed transmit power for a future time interval based at least in part on the determined duty cycle complying with a time-averaged RF exposure limit.

[0072] In some cases, when the wireless device is not configured with a duty cycle, for example, according to a TDD mode, the duty cycle can be determined as described herein. For example, in a wireless local area network (WLAN) system, a wireless device uses carrier sense multiple access to access a channel, where the wireless device can communicate when the channel is detected as idle. In an FDD system, a wireless device can communicate in full-duplex mode in different subcarriers without a predefined time slot pattern.

[0073] The apparatus and methods described herein for determining duty cycle may be advantageous for improving wireless communication performance (e.g., improved signal quality at the receiver, lower latency, higher throughput, etc.). For example, in the case where the duty cycle is low (or was low), the duty cycle may allow the wireless device to allocate a higher maximum allowed transmit power for future time intervals.

[0074] For certain aspects, a centralized processing architecture may be used to perform RF exposure assessments. Figure 5 is a diagram of an example logical processing architecture for evaluating RF exposure across multiple radios 502a-d of a wireless device. The radios 502a-d (e.g., radio 1, radio 2, etc.) may receive RF information from a central algorithm or controller such as an RF exposure manager 504 (e.g., Figure 2 The RF exposure manager 281 of the embodiment of the present invention may request certain values ​​for reservations and / or margins. Each radio 502a-d may provide the requested values ​​for reservations and / or margins on a periodic basis (e.g., every 500 milliseconds) and / or in response to a specific event. Each radio 502a-d may also report a transmit power report indicating the RF exposure history for a specific time period (e.g., 500 milliseconds) associated with the time averaging time window. In certain aspects, the transmit power report may include the total normalized RF exposure exhibited by each antenna and / or antenna group associated with the radio.

[0075] The RF exposure manager 504 may determine the reservation and / or margin for each of the radios 502a-d, for example, based on the requested values ​​and transmit power reports from the individual radios. As an example, the RF exposure manager 504 may use the requested values ​​as initial values ​​for determining the reservation and margin for the respective radios 502a-d, and adjust these values, for example, based on the RF exposure history of some or all of the radios. The RF exposure manager 504 may provide the total allowed energy allocation for the corresponding time interval and / or the values ​​determined for the reservation and margin to each of the radios 502a-d. The RF exposure manager 504 may provide energy allocations on a periodic basis (e.g., every 500 milliseconds) and / or in response to specific events.

[0076] For example, each of the radios 502a-d may operate using a separate RF exposure compliance algorithm, such as according to a time-averaged RF exposure limit, a fixed RF exposure limit, etc. For example, the first radio 502a (radio 1) may operate using a time-averaged RF exposure limit when determining transmit power in compliance with the RF exposure limit, wherein the first radio 502a (radio 1) may operate using a time-averaged RF exposure limit according to the present disclosure. FIG. 4A to FIG. 4C The second radio 502b (Radio 2) may operate using fixed RF exposure limits, where the second radio 502b (Radio 2) is only allowed to transmit at or below a fixed transmit power limit such as P limit of transmission power.

[0077] In certain aspects, a controller or modem (e.g., one or more processors and / or one or more modems) may perform the functions of the RF exposure manager 504. A modem associated with wireless wide area network (WWAN) communications may perform the functions of the RF exposure manager 504. As an example, a first radio 502a (radio 1) may perform RF exposure operations for sub-6 GHz bands in 5G NR; a second radio 502b (radio 2) may perform RF exposure operations for millimeter wave bands in 5G NR; a third radio 502c (radio 3) may perform RF exposure operations for wireless local area network (WLAN) communications; and a fourth radio 502d (radio 4) may perform RF exposure operations for Bluetooth communications. In some cases, a modem associated with WWAN communications may be in a sleep mode, where the RF exposure manager 504 may temporarily refrain from evaluating RF exposure of some or all of the radios 502a-d. The sleep mode may be due to the modem operating in a discontinuous reception (DRX) mode or an airplane mode, for example, where WWAN communications are temporarily disabled. For example, when the centralized RF exposure manager is in sleep mode, some of the radios (e.g., Bluetooth and / or WLAN radios) may operate RF exposure compliance algorithms independently of the RF exposure manager to maintain RF exposure compliance. When the RF exposure manager 504 is operational or in sleep or low power mode, aspects described herein may be performed, such as with respect to Figure 6The aspects described herein provide certain benefits when the RF exposure manager 504 is in a sleep or low power mode, such as being able to adjust transmit power to regulate time-averaged exposure (when transmissions are random, opportunistic, or otherwise unpredictable or unscheduled) despite not receiving updated power allocations from the RF exposure manager. In some cases, the control operations of the RF exposure manager may be referred to as outer loop (OL) operations, and the RF exposure compliance operations that communicate with the RF exposure manager and are performed at a particular radio may be referred to as inner loop (IL) operations.

[0078] It should be understood that the RF exposure manager and / or radio depicted in the processing architecture may be implemented in hardware, software, or a combination of both. For example, the RF exposure manager and / or radio included in the processing architecture may be implemented in one or more modems, RF circuits (e.g., transceivers), memory blocks, registers, processing blocks, and / or instructions (e.g., software code or executable instructions). The executable instructions may be stored in a memory and executed on a processor (e.g., an application processor and / or a modem processor).

[0079] In some examples, the RF exposure manager is coupled to and configured to manage exposure to radios configured for different RANs, such as described above. In other examples, the RF exposure manager may be coupled to and configured to manage exposure to one or more radios configured to operate using a single RAN, such as WiFi, Bluetooth, or other technologies (e.g., cellular technologies). In any of these configurations, the radios that the RF exposure manager is configured to manage may be limited to radios configured to communicate on unlicensed bands. In still other examples, such as in a configuration with a single radio, the RF exposure manager is not separate from the radio, but is integrated into the radio. In such an example, allocations and / or reports may not be communicated back and forth, but rather exposure and determination of transmit power may all be evaluated within the radio. Other configurations that may also be used with the aspects described herein may be possible.

[0080] Figure 6 is a diagram illustrating example operations for determining a maximum average power for a radio (eg, a WLAN radio) in communication with an RF exposure manager, such as a Figure 5602. In this example, at activity 602, the radio may determine exposure information for one or more antennas associated with the radio. If the RF exposure manager is in an active mode (e.g., evaluating RF exposure to one or more radios), the radio may periodically (e.g., every 500 milliseconds) obtain exposure information 604 from the RF exposure manager. The exposure information 604 may include a normalized total exposure limit and / or reservation level for each antenna and / or antenna group associated with the radio. If the RF exposure manager is in a sleep mode (e.g., temporarily refraining from evaluating RF exposure to one or more radios), the radio may determine the exposure information 604, for example, from an exposure history or default value. For example, if the RF exposure manager is in a DRX mode or an airplane mode (APM), the radio may determine a reservation level (e.g., P reserve ), which may be based on whether other radios (e.g., Bluetooth) are active. If the RF exposure manager is in sleep mode, the radio may determine a normalized exposure limit based on exposure history or default values. The radio may obtain an APM indicator 606 indicating whether the WWAN modem is in airplane mode, for example, via an application processor. If the APM indicator 606 indicates that the RF exposure manager is in airplane mode, the radio may trigger determination of exposure information 604 without the assistance of the RF exposure manager. If the radio does not receive exposure information 604 from the RF exposure manager after a certain time (e.g., 500 milliseconds), the radio may detect that the RF exposure manager is in sleep mode and determine the exposure information 604 without the assistance of the RF exposure manager.

[0081] At activity 608, the radio may determine a maximum allowed average power (AMAP) 610 for each antenna and / or frequency band associated with the radio. The radio may determine the maximum allowed average power (AMAP) 610 based at least in part on a normalized total exposure limit (which may be obtained from the RF exposure manager or determined at the radio) and a time average power limit 612 (e.g., P limit ) to determine the AMAP 610. The time average power limit may be stored in memory as a table of values ​​for different antennas, frequency bands, RF exposure scenarios (e.g., head exposure, hand or limb exposure, body exposure, hot spot exposure, etc.), RF exposure categories, surfaces of the wireless device, etc.

[0082] Figure 7 is a diagram illustrating example operations for determining a maximum allowed transmit power based on a duty cycle. These operations may be performed by a radio implemented in hardware, software, or a combination of both, for example, as described herein with respect to Figure 5 as described.

[0083] In this example, the radio may determine the maximum allowed transmit power per transmit scenario. The radio may obtain transmit information 702 associated with a particular time interval (e.g., 500 milliseconds), wherein the transmit information 702 may include the duration of the transmission within the time interval. In some aspects, the transmit information may be associated with a particular transmit scenario such as, one or more antennas and / or one or more frequency bands. The time interval may be a portion of a time window (e.g., 100 seconds, 360 seconds, etc.) associated with a time-averaged RF exposure limit, such that the time window includes multiple time intervals, including a future time interval and one or more past time intervals. The time interval for the transmit information 702 may be associated with a past time interval, and the corresponding transmit information 702 may be used to determine the transmit power for the future time interval, as further described herein.

[0084] At activity 704, the radio may determine (e.g., estimate) a past duty cycle based on the transmission information 702. For example, the duty cycle may be equal to the duration of the transmission within the time interval divided by the time interval (e.g., where t TX The radio may determine the past duty cycle of each transmission scenario (e.g., one or more antennas and / or one or more frequency bands) in a plurality of transmission scenarios.

[0085] At activity 706, to determine the expected duty cycle, the radio may apply smoothing to the past duty cycles. For example, the radio may use an exponential filter applied to the past duty cycles to determine the expected duty cycle. The expected duty cycle may be determined using an exponential filter according to the following expression:

[0086] DCF ant(i)_band(i) (n) = α·DC ant(i)_band(i) (n)+(1-α)DCF ant(i)_band(i) (n-1) (1)

[0087] DCF ant(i)_band(i) (n) is the filter duty cycle for a specific antenna and frequency band; DCF ant(i)_band(i) (n-1) is the duty cycle determined for the previous iteration (eg, the previous smoothed duty cycle); DC ant(i)_band(i) (n) is the past duty cycle determined for the antenna and frequency band at action 704; and α is a smoothing factor having a value ranging from 0 to 1. For the initial iteration or when the WLAN radio wakes up from sleep mode, the DFC ant(i)_band(i) (0) is set to a default value, such as 1 (1.0).

[0088] At activity 708, the radio may determine a transmit power associated with the duty cycle (e.g., duty cycle power). The duty cycle power may indicate the remaining power available after taking the duty cycle into account. The duty cycle power may be determined, for example, as the product of the power limit and the difference between 1 and the duty cycle according to the following expression:

[0089] P DC_ant(i)_band(i) =P DC_limit_ant(i)_band(i) (1-DCF ant(i)_band(i) (n)) (2)

[0090] Where P DC_ant(i)_band(i) is the duty cycle power, and P DC_limit_ant(i)_band(i) is the power limit associated with the duty cycle. Figure 8 As further described, the power limit may be selected based on the value of the duty cycle. For example, the value of the power limit may be inversely proportional to the duty cycle.

[0091] At activity 710, the radio may determine a maximum allowed transmit power (eg, P) based at least in part on a maximum allowed average power (AMAP), power reservation, and / or duty cycle power. SAR ). In some cases, the Figure 6 The maximum allowed transmit power may be determined based on the following expression:

[0092]

[0093] in AMAP is the maximum allowed transmit power for a given time interval; ant(i)_band(i) is the maximum average power determined based on the exposure history or obtained from the RF Exposure Manager; P reserve It is the reserved power that can provide the basic power level for some communications (in some cases, P reserve can be normalized and converted to 10 (P reserve ) converted to decibels); and P DC_ant(i)_band(i) is, for example, the duty cycle power determined in action 708 .

[0094] At activity 712, the radio may determine the maximum allowable transmit power (eg, P SAR) determines a transmit power for transmitting a signal. The transmit power may be selected as a minimum of a plurality of transmit powers, such as a target power, a host limited power, or a control power, wherein the plurality of transmit powers may be determined locally or obtained from a network entity, such as an access point. The selected transmit power may also satisfy a threshold value such that the transmit power is less than or equal to a maximum allowed transmit power. The radio may output the determined transmit power to a transceiver circuit 714 (e.g., the RF transceiver circuit 300). The transceiver circuit 714 may output a signal at the transmit power using at least one of the corresponding antennas coupled to the transceiver circuit 714.

[0095] Figure 8 is a diagram illustrating example operations for determining a maximum allowed transmit power based on a duty cycle and a threshold for determining a duty cycle power. In this example, the radio may perform the Figure 7 The operations described above are performed except that the radio may apply an activity 808 for determining a threshold for duty cycle power. For example, if the duty cycle determined at activity 706 is less than a threshold (e.g., DCF_thres=0.6), the radio may apply a first value for the power limit in expression (2) (e.g., 6 decibels (dB)); otherwise, if the duty cycle is greater than or equal to the threshold, the radio may apply a second value for the power limit in expression (2) (e.g., 5 dB). In some cases, the radio may apply a multi-level threshold to select a value for the power limit from two or more values. In some cases, the radio may select a value for the power limit in response to a difference between two consecutive duty cycles (e.g., DCF(n)-DCF(n-1)) satisfying a threshold. For example, if the difference exceeds a threshold, the value of the power limit may be reduced. Adjusting the power limit used to determine the duty cycle power may allow the radio to respond to changes in the duty cycle and ensure RF exposure compliance (e.g., when the wireless device transitions from transmitting at a low duty cycle to a high duty cycle or vice versa).

[0096] Fig. 9 900 for wireless communications in accordance with certain aspects of the present disclosure. Operations 900 may be performed, for example, by a wireless device (e.g., UE 120a in wireless communication network 100). Operations 900 may be implemented as a processor (e.g., Figure 2 In addition, the signal transmission and / or reception performed by the wireless device in operation 900 may be performed by one or more antennas (e.g., Figure 2 In some aspects, the transmission and / or reception of signals by the wireless device may be achieved by obtaining and / or outputting signals via a bus interface of one or more processors (eg, controller / processor 280).

[0097] Operations 900 may optionally begin at block 902, where the wireless device may determine a duty cycle associated with a transmission scenario based at least in part on past duty cycles (e.g., DC ant(i)_band(i) (n)) to determine the duty cycle associated with the transmission scenario (e.g., DCF ant(i)_band(i) (n)). The past duty cycle can be for the time average RF exposure compliance assessment for the previous tracking period or as described herein with respect to Figure 6 For example, a wireless device may determine a duty cycle for a previously reported period in a centralized RF exposure architecture as described herein. Figure 7 or Figure 8 The duty cycle may be determined as described above. The duty cycle may be associated with a transmission scenario so that the transmission duration used to determine the duty cycle is performed under the transmission scenario. In some aspects, the transmission scenario may include one or more antennas and / or one or more frequency bands. In some cases, the transmission scenario may include a MIMO scenario using multiple antennas for transmission. For example, the duty cycle may be determined using the transmission duration for a specific antenna and / or frequency band of the transmission scenario in a given time interval.

[0098] At block 904, the wireless device may transmit a signal at a transmit power determined at least in part based on a duty cycle and a radio frequency (RF) exposure limit. In some cases, the wireless device may transmit simultaneously via a single antenna or multiple antennas (and / or antenna modules), where the simultaneous transmissions may include transmissions in the same transmission opportunity or time interval associated with the RF exposure limit. In some cases, the wireless device may transmit simultaneously via multiple radios. For example, the wireless device may transmit simultaneously via any combination of a WWAN radio (e.g., CDMA, E-UTRA, NR, etc.), a WLAN radio (e.g., IEEE 802.11), and / or a Bluetooth radio.

[0099] In certain aspects, the duty cycle may be determined using smoothing or filtering applied to past duty cycles (such as an exponential filter, double exponential smoothing, triple exponential smoothing, and / or a moving average). To determine the duty cycle, the wireless device may determine the duty cycle using an exponential filter applied to past duty cycles, for example, as described herein with respect to expression (1). The wireless device may determine the duty cycle as a weighted average of the past duty cycle and a previously determined duty cycle (e.g., a previously filtered or smoothed duty cycle). The previously determined duty cycle may be smoothed using an exponential filter, and the previously determined duty cycle may be a value of a previous iteration of the exponential filter. The past duty cycle and the previously determined duty cycle may be weighted using a smoothing factor (e.g., α). To determine the duty cycle, the wireless device may determine the past duty cycle as a ratio of the time used for one or more past transmissions associated with the transmission scenario in a time interval to the time interval (e.g., ).

[0100] For certain aspects, the wireless device may determine a duty cycle for each of a plurality of transmission scenarios. The plurality of transmission scenarios may include different combinations of antennas and frequency bands in at least one of a plurality of antennas or a plurality of frequency bands. For example, the wireless device may determine a first duty cycle associated with a first antenna and a first frequency band, and determine a second duty cycle associated with a second antenna and a second frequency band.

[0101] In some aspects, the wireless device may provide a duty cycle based on the power (eg, P DC ) to determine the transmission power, for example, as described herein Figure 7 or Figure 8 The duty cycle power may indicate the amount of energy remaining for future time intervals, taking into account the amount of energy used for past duty cycles. The wireless device may determine the duty cycle power as the product of the power limit and the difference between 1 and the duty cycle (e.g., P DC_limit_ant(i)_band(i) ), for example, as described herein with respect to expression (2). In some cases, the wireless device may select a value for power limiting based on the duty cycle, for example, as described herein with respect to expression (2). Figure 8 In the case where the duty cycle satisfies the threshold (e.g., if the duty cycle is less than (or equal to) the threshold), the wireless device may select a first value (e.g., 6 dB) for power limiting, and in the case where the duty cycle does not satisfy the threshold (e.g., if the duty cycle is greater than (or equal to) the threshold), the wireless device may select a second value (e.g., 5 dB) for power limiting.

[0102] The wireless device may determine a maximum allowed transmit power for a future time interval based at least in part on the duty cycle complying with the time-averaged RF exposure limit. The wireless device may determine a transmit power that is less than or equal to the maximum allowed transmit power. The wireless device may set the maximum allowed transmit power (e.g., PSAR ) is determined as the maximum average power (e.g., AMAP), the power reservation (e.g., P reserve ) and duty cycle power (e.g., P DC ) and, for example, as in this article on Figure 7 and described by expression (3).

[0103] In certain aspects, the Figure 6 The maximum average power may be determined as described. The maximum average power may be derived from exposure information obtained from a centralized RF exposure manager, such as a modem associated with a WWAN radio. The maximum average power may be derived from a normalized exposure limit selected by a WLAN radio or other radio when the RF exposure manager temporarily refrains from providing exposure information. The wireless device may select the maximum average power in response to detecting that a modem associated with the WWAN is in a sleep mode. The sleep mode may include an airplane mode or a discontinuous reception (DRX) mode.

[0104] For certain aspects, the maximum average power may be determined with assistance from a centralized RF exposure manager, as described herein with respect to Figure 6 The wireless device may determine a maximum average power based at least in part on one or more past transmit powers within a time window associated with a time average RF exposure limit.

[0105] In some aspects, a wireless device may select the transmit power from among multiple transmit power values, for example, as described herein with respect to Figure 7 The wireless device may select the transmit power as a minimum of a plurality of transmit power values, such as a target power, a host-limited power, or a control power. The selected transmit power may also satisfy a threshold such that the transmit power is less than or equal to a maximum allowed transmit power.

[0106] The RF exposure limit may be a time-averaged RF exposure limit, for example, as described herein with respect to FIG. 4A to FIG. 4C RF exposure limits may include time-averaged SAR limits, time-averaged PD limits, or a combination thereof.

[0107] For certain aspects, the duty cycle may be determined as described herein for certain types of wireless communications (e.g., WLAN communications, Bluetooth communications, and / or WWAN communications with a predetermined duty cycle). The duty cycle may also be associated with one or more transmissions via a shared spectrum (such as a WiFi band and / or a Bluetooth band). The signal may include a WiFi signal and / or a Bluetooth signal.

[0108] although Figures 1 to 9The examples depicted in are described herein with respect to a UE that performs various methods for providing RF exposure compliance to facilitate understanding, but aspects of the present disclosure may also be applied to other wireless devices that perform the RF exposure compliance described herein, such as wireless stations, access points, base stations, and / or customer premises equipment (CPE). In addition, although these examples are described with respect to communications between a UE (or other wireless device) and a network entity, a 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.

[0109] It will be appreciated that determining the duty cycle as described herein can achieve desired wireless communication performance, such as reduced latency, increased (uplink) data rate, and / or increased transmission range (e.g., uplink connections at a cell edge), for example, due to increased transmit power that can be assigned to transmissions in low duty cycle scenarios.

[0110] Example Communication Device

[0111] Fig.10 Examples include operations that may be configured to perform the techniques disclosed herein (such as Fig. 9 1000 (e.g., UE 120) includes various components (e.g., corresponding to means plus function components) of the operations illustrated in the figure. The communication device 1000 includes a processing system 1002 that can be coupled to a transceiver 1008 (e.g., a transmitter and / or a receiver). The transceiver 1008 is configured to send and receive signals for the communication device 1000 via an antenna 1010, such as various signals described herein. The processing system 1002 can be configured to perform processing functions of the communication device 1000, including processing signals received and / or to be transmitted by the communication device 1000.

[0112] The processing system 1002 includes a processor 1004 (e.g., one or more processors) coupled to a computer-readable medium / memory 1012 via a bus 1006. In some aspects, the computer-readable medium / memory 1012 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1004, cause the communication device 1000 to perform Fig. 9 Operations 900 illustrated in or other operations for performing various techniques discussed herein for providing RF exposure compliance. In some aspects, computer readable medium / memory 1012 stores code 1014 for determining (selecting), code 1016 for sending (or outputting), or any combination thereof.

[0113] In some aspects, the processing system 1002 has circuitry 1020 configured to implement code stored in the computer-readable medium / memory 1012. In some aspects, the circuitry 1020 is coupled to the processor 1004 and / or the computer-readable medium / memory 1012 via a bus 1006. For example, the circuitry 1020 includes circuitry 1022 for determining (selecting), circuitry 1024 for sending (or outputting), or any combination thereof.

[0114] In some examples, means for sending or transmitting (or means for outputting for sending) may include Figure 2 The transceiver 254 and / or antenna 252 and / or Fig.10 The transceiver 1008 and antenna 1010 of the communication device 1000 in FIG.

[0115] In some cases, a device may not actually send, for example, signals and / or data, but may have an interface (components for outputting) signals and / or data for transmission. For example, a processor may output signals and / or data to a radio frequency (RF) front end via a bus interface for transmission. Similarly, a device may not actually receive signals and / or data, but may have an interface (components for obtaining) for obtaining signals and / or data received from another device. For example, a processor may obtain (or receive) signals and / or data from an RF front end via a bus interface for reception. 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.

[0116] In some examples, the means for determining and / or the means for selecting may include various processing system components, such as: Fig.10 The processor 1004 in, or Figure 2 Aspects of the UE 120 are depicted, including a receive processor 258 , a transmit processor 264 , a TX MIMO processor 266 , and / or a controller / processor 280 .

[0117] Example aspects

[0118] Specific implementation examples are described in the following numbered clauses:

[0119] Aspect 1: A method for wireless communication by a wireless device, the method comprising: determining a duty cycle associated with a transmission scenario based at least in part on past duty cycles associated with the transmission scenario; and transmitting a signal at a transmission power determined at least in part on the duty cycle and a radio frequency (RF) exposure limit.

[0120] Aspect 2: The method according to aspect 1, wherein the transmission scenario includes an antenna and a frequency band.

[0121] Aspect 3: The method according to aspect 1 or aspect 2, wherein determining the duty cycle comprises determining the duty cycle using an exponential filter applied to the past duty cycles.

[0122] Aspect 4: The method according to any one of aspects 1 to 3, wherein determining the duty cycle comprises determining the duty cycle as a weighted average of the past duty cycle and a previously determined duty cycle.

[0123] Aspect 5: The method according to Aspect 4, wherein: the previously determined duty cycle is smoothed using an exponential filter; and the past duty cycle and the previously determined duty cycle are weighted using a smoothing factor.

[0124] Aspect 6: The method according to any one of aspects 1 to 5, wherein determining the duty cycle comprises determining the past duty cycle as a ratio of time for one or more past transmissions to a time interval.

[0125] Aspect 7: The method according to any one of aspects 1 to 6, wherein determining the duty cycle comprises determining the duty cycle of each of the transmission scenarios in a plurality of transmission scenarios.

[0126] Aspect 8: The method according to aspect 7, wherein the multiple transmission scenarios include different combinations of antennas and frequency bands in at least one of multiple antennas or multiple frequency bands.

[0127] Aspect 9: The method according to any one of aspects 1 to 8, further comprising determining the transmit power based at least in part on a power limit multiplied by a difference between 1 and the duty cycle.

[0128] Aspect 10: According to the method described in Aspect 9, the method also includes: when the duty cycle meets a threshold, selecting a first value for the power limit; and when the duty cycle does not meet the threshold, selecting a second value for the power limit.

[0129] Aspect 11: According to the method described in any one of Aspects 1 to 10, the method further includes: determining a maximum allowable transmit power for a time interval based at least in part on the duty cycle complying with the RF exposure limit; and determining the transmit power that is less than or equal to the maximum allowable transmit power.

[0130] Aspect 12: A method according to Aspect 11, wherein: determining the maximum allowed transmit power includes determining the maximum allowed transmit power as the sum of the maximum average power, the power reservation and the duty cycle power; and the duty cycle power is the product of the power limit and the difference between 1 and the duty cycle.

[0131] Aspect 13: The method according to aspect 11 or aspect 12, wherein determining the transmit power comprises selecting the transmit power as a minimum value among a plurality of transmit power values.

[0132] Aspect 14: The method of aspect 12 or aspect 13, further comprising selecting the maximum average power in response to detecting that a modem associated with a wireless wide area network is in a sleep mode.

[0133] Aspect 15: The method according to aspect 14, wherein the sleep mode comprises an airplane mode or a discontinuous reception mode.

[0134] Aspect 16: The method of aspect 12 or aspect 13, further comprising determining the maximum average power based at least in part on one or more past transmit powers within a time window associated with the RF exposure limit.

[0135] Aspect 17: The method according to any one of aspects 1 to 16, wherein the RF exposure limit comprises a time-averaged specific absorption rate limit, a time-averaged power density limit, or a combination thereof.

[0136] Aspect 18: The method according to any one of aspects 1 to 17, wherein the duty cycle is further associated with one or more transmissions via a shared spectrum.

[0137] Aspect 19: A method according to any one of Aspects 1 to 18, wherein the signal comprises a WiFi signal.

[0138] Aspect 20: The method according to any one of aspects 1 to 18, wherein the signal comprises a Bluetooth signal.

[0139] Aspect 21: A device for wireless communication, the device comprising: a memory; and one or more processors coupled to the memory, the one or more processors being configured to: determine a duty cycle associated with a transmission scenario based at least in part on past duty cycles associated with the transmission scenario, and control the transmission of a signal with a transmission power determined at least in part based on the duty cycle and a radio frequency (RF) exposure limit.

[0140] Aspect 22: The apparatus according to Aspect 21, further comprising a transmitter, the transmitter being configured to transmit the signal at the transmission power, wherein the transmission scenario comprises an antenna and a frequency band.

[0141] Aspect 23: The apparatus according to aspect 21 or 22, wherein to determine the duty cycle, the one or more processors are further configured to determine the duty cycle using an exponential filter applied to the past duty cycles.

[0142] Aspect 24: The apparatus according to aspect 21 or 22, wherein to determine the duty cycle, the one or more processors are further configured to determine the duty cycle as a weighted average of the past duty cycle and a previously determined duty cycle.

[0143] Aspect 25: An apparatus according to Aspect 24, wherein: the previously determined duty cycle is smoothed using an exponential filter; and the past duty cycle and the previously determined duty cycle are weighted using a smoothing factor.

[0144] Aspect 26: The apparatus according to aspect 21 or 22, wherein to determine the duty cycle, the one or more processors are further configured to determine the past duty cycle as a ratio of time for one or more past transmissions to a time interval.

[0145] Aspect 27: The apparatus according to aspect 21 or 22, wherein, in order to determine the duty cycle, the one or more processors are further configured to determine the duty cycle of each of the transmission scenarios in a plurality of transmission scenarios.

[0146] Aspect 28: The apparatus according to aspect 27, wherein the plurality of transmission scenarios include different combinations of antennas and frequency bands in at least one of a plurality of antennas or a plurality of frequency bands.

[0147] Aspect 29: An apparatus according to any one of aspects 21 to 28, wherein the one or more processors are further configured to determine the transmit power based at least in part on a power limit multiplied by a difference between 1 and the duty cycle.

[0148] Aspect 30: An apparatus according to Aspect 29, wherein the one or more processors are further configured to: select a first value for the power limit when the duty cycle satisfies a threshold; and select a second value for the power limit when the duty cycle does not satisfy the threshold.

[0149] Aspect 31: An apparatus according to any one of Aspects 21 to 28, wherein the one or more processors are further configured to: determine a maximum allowable transmit power for a time interval based at least in part on the duty cycle complying with the RF exposure limit; and determine the transmit power that is less than or equal to the maximum allowable transmit power.

[0150] Aspect 32: An apparatus according to Aspect 31, wherein: in order to determine the maximum allowed transmit power, the one or more processors are further configured to determine the maximum allowed transmit power as the sum of the maximum average power, the power reservation and the duty cycle power; and the duty cycle power is the product of the power limit and the difference between 1 and the duty cycle.

[0151] Aspect 33: The apparatus of aspect 32, wherein the one or more processors are further configured to select the maximum average power in response to detecting that a modem associated with a wireless wide area network is in a sleep mode.

[0152] Aspect 34: The apparatus of aspect 32, wherein the one or more processors are further configured to determine the maximum average power based at least in part on one or more past transmit powers within a time window associated with the RF exposure limit.

[0153] Aspect 35: An apparatus according to any one of aspects 21 to 34, wherein the signal comprises a wireless local area network (WLAN) signal or a Bluetooth signal.

[0154] Aspect 36: A device comprising: a memory comprising computer-executable instructions; and one or more processors configured to execute the computer-executable instructions and cause the device to perform a method according to any one of Aspects 1 to 20.

[0155] Aspect 37: An apparatus comprising means for performing the method according to any one of aspects 1 to 20.

[0156] Aspect 38: A non-transitory computer-readable medium comprising computer-executable instructions which, when executed by one or more processors of a processing system, cause the processing system to perform the method of any one of aspects 1 to 20.

[0157] Aspect 39: A computer program product embodied on a computer-readable storage medium, the computer program product comprising code for executing the method according to any one of aspects 1 to 20.

[0158] The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), Advanced LTE (LTE-A), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network 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, and the like. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is an emerging wireless communication technology under development.

[0159] In 3GPP, the term "cell" can refer to the coverage area of ​​a Node B (NB) and / or a NB subsystem serving the coverage area, depending on the context in which the term is used. In NR systems, the terms "cell" and BS, next-generation NodeB (gNB or gNodeB), access point (AP), distributed unit (DU), carrier, or transmit receive point (TRP) can be used interchangeably. The 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 geographic area (e.g., a radius of several kilometers) and can allow unrestricted access by UEs with service subscriptions. A pico cell can cover a relatively small geographic area and can allow unrestricted access by UEs with service subscriptions. A femto cell can cover a relatively small geographic area (e.g., a home) and can allow restricted access by UEs associated with a femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in a home, etc.). A BS for a macro cell can be referred to as a macro BS. A BS for a pico cell can be referred to as a pico BS. A BS for a femto cell may be called a femto BS or a home BS.

[0160] UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a customer premises equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor / device, a wearable device (such as a smart watch, smart clothing, smart glasses, a smart wristband, smart jewelry (e.g., a smart ring, a smart bracelet, etc.)), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs may be considered as 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 may provide, for example, connectivity to or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

[0161] In some examples, access to the air interface can be scheduled. A scheduling entity (e.g., BS) allocates resources for communications between some or all devices and equipment within the service area or cell of the entity. A scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, subordinate entities use resources allocated by the scheduling entity. The base station is not the only entity that acts as a scheduling entity. In some examples, a UE may be used as a scheduling entity, and resources for one or more subordinate entities (e.g., one or more other UEs) may be scheduled, and other UEs may utilize resources scheduled by the UE for wireless communications. In some examples, a UE may be used as a scheduling entity in a peer-to-peer (P2P) network or in a mesh network. In a mesh network example, in addition to communicating with a scheduling entity, UEs may also communicate directly with each other.

[0162] The method disclosed herein includes one or more steps or actions for implementing the method. The steps and / or actions of the method can be interchangeable with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of the claims.

[0163] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items (including single members). As an example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0164] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, generating, investigating, searching (e.g., searching in a table, a database, or another data structure), ascertaining, and the like. Furthermore, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Furthermore, "determining" may include resolving, selecting, choosing, establishing, and the like.

[0165] The preceding 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 apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the various aspects shown herein, but should be given the full scope consistent with the language of the claims, wherein unless otherwise specified, references to elements in the singular form are not intended to mean "one and only one", but "one or more". Unless otherwise specified, the term "some" refers to one or more. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure that are known or will be known later to a person of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. Any claim element should not be interpreted according to the provisions of 35 U.S.C. § 112 (f), unless the element is explicitly stated using the phrase "member for...", or in the case of a method claim, the element is stated using the phrase "step for...".

[0166] The various operations of the above method can be performed by any suitable member capable of performing the corresponding function. The member may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs) or processors. Typically, where there are operations illustrated in the accompanying drawings, those operations may have corresponding corresponding members plus functional components with similar numbers.

[0167] The various illustrative logical blocks, modules, and circuits described in conjunction with the present disclosure may be implemented or executed with a general purpose processor, a neural 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 an 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, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0168] 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 specific application of the processing system and the overall design constraints, the bus may include any number of interconnecting buses and bridges. The bus may link various circuits together, including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter, etc., to the processing system via the bus. The network adapter may be used to implement signal processing functions at the physical (PHY) layer. In the UE (see Figure 1 ), a user interface (e.g., a keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art and therefore will not be described further. The processor may be implemented using one or more general purpose processors and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits that can execute 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 the overall design constraints imposed on the entire system.

[0169] If implemented in software, each function may be stored on or transmitted through a computer-readable medium as one or more instructions or codes. Software should be broadly interpreted as meaning instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or other. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of computer programs 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. A computer-readable storage medium may be coupled to a processor so that the processor may read information from the storage medium and write information to the storage medium. In an alternative solution, the storage medium may be integral with the processor. For example, a machine-readable medium may include a transmission line, a carrier modulated by data, and / or a computer-readable storage medium having instructions stored thereon that is separated from a wireless node, all of which may be accessed by a processor through a bus interface. Alternatively or in addition thereto, a machine-readable medium or any part thereof may be integrated into a processor, such as in the case of having a cache and / or a general register stack. By way of example, examples of machine-readable storage 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 drives, or any other suitable storage media, or any combination thereof. Machine-readable media may be implemented in a computer program product.

[0170] A software module may include a single instruction, perhaps multiple instructions, and may be distributed over several different code segments, between different programs, and across multiple storage media. A computer-readable medium may include multiple software modules. A software module includes instructions that, when executed by a device such as a processor, cause a processing system to perform various functions. A software module may include a sending module and a receiving module. Each software module may reside in a single storage device or may be distributed across multiple storage devices. By way of example, when a triggering event occurs, a software module may be loaded from a hard drive into a RAM. During the execution of a software module, a processor may load some of the instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register stack for execution by the processor. When the functionality of a software module is mentioned below, it will be understood that such functionality is implemented by a processor when executing instructions from the software module.

[0171] Moreover, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared (IR), radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology such as infrared, radio, and microwave are included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Optical disks, where magnetic disks typically reproduce data magnetically, and optical disks use lasers to reproduce data optically. Thus, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). Additionally, for other aspects, computer-readable media may include transient computer-readable media (e.g., signals). Combinations of the above should also be included within the scope of computer-readable media.

[0172] Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and / or encoded) thereon, such instructions (e.g., for performing the operations described herein and in Fig. 9 The instructions (including the operations illustrated in the figure) can be executed by one or more processors to perform the operations described herein.

[0173] In addition, it should be understood that the modules and / or other appropriate components for executing the methods and techniques described herein can be downloaded and / or otherwise obtained by the user terminal and / or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of components for executing the methods described herein. Alternatively, the various methods described herein can be provided via a storage component (e.g., RAM, ROM, or a physical storage medium such as a compact disc (CD) or a floppy disk) so that the user terminal and / or base station can obtain the various methods when the storage component is coupled to or provided to the device. In addition, any other appropriate technology for providing the methods and techniques described herein to the device can be used.

[0174] It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method for wireless communication by a wireless device, the method comprising: determining a duty cycle associated with the transmission scenario based at least in part on past duty cycles associated with the transmission scenario; as well as A signal is transmitted at a transmit power determined based at least in part on the duty cycle and a radio frequency (RF) exposure limit. The method according to claim 1 , wherein the transmission scenario includes an antenna and a frequency band. 3 . The method of claim 1 , wherein determining the duty cycle comprises determining the duty cycle using an exponential filter applied to the past duty cycles. 4 . The method of claim 1 , wherein determining the duty cycle comprises determining the duty cycle as a weighted average of the past duty cycle and a previously determined duty cycle.

5. The method according to claim 4, wherein: smoothing the previously determined duty cycle using an exponential filter; and The past duty cycle and the previously determined duty cycle are weighted using a smoothing factor.

6. The method of claim 1, wherein determining the duty cycle comprises determining the past duty cycle as a ratio of time for one or more past transmissions to a time interval. The method of claim 1 , wherein determining the duty cycle comprises determining the duty cycle for each of a plurality of transmission scenarios. 8 . The method of claim 7 , wherein the plurality of transmission scenarios include different combinations of antennas and frequency bands in at least one of a plurality of antennas or a plurality of frequency bands.

9. The method of claim 1, further comprising determining the transmit power based at least in part on a power limit multiplied by a difference between 1 and the duty cycle.

10. The method according to claim 9, further comprising: In case the duty cycle satisfies a threshold, selecting a first value for the power limit; as well as In the event that the duty cycle does not satisfy the threshold, a second value for the power limit is selected.

11. The method according to claim 1, further comprising: determining a maximum allowed transmit power for a time interval based at least in part on the duty cycle complying with the RF exposure limit; as well as The transmit power is determined to be less than or equal to the maximum allowed transmit power.

12. The method according to claim 11, wherein: Determining the maximum allowed transmit power includes determining the maximum allowed transmit power as a sum of a maximum average power, a power reservation, and a duty cycle power; and The duty cycle power is the product of the power limit and the difference between 1 and the duty cycle.

13. The method of claim 12, further comprising selecting the maximum average power in response to detecting that a modem associated with a wireless wide area network is in a sleep mode. The method of claim 13 , wherein the sleep mode comprises an airplane mode or a discontinuous reception mode.

15. The method of claim 12, further comprising determining the maximum average power based at least in part on one or more past transmit powers within a time window associated with the RF exposure limit.

16. An apparatus for wireless communication, the apparatus comprising: Memory; and one or more processors coupled to the memory, the one or more processors configured to: determining a duty cycle associated with the transmission scenario based at least in part on past duty cycles associated with the transmission scenario, and Transmission of the signal is controlled at a transmit power determined based at least in part on the duty cycle and a radio frequency (RF) exposure limit. 17 . The apparatus according to claim 16 , further comprising a transmitter configured to transmit the signal at the transmission power, wherein the transmission scenario comprises an antenna and a frequency band.

18. The apparatus of claim 16, wherein to determine the duty cycle, the one or more processors are further configured to determine the duty cycle using an exponential filter applied to the past duty cycles.

19. The apparatus of claim 16, wherein to determine the duty cycle, the one or more processors are further configured to determine the duty cycle as a weighted average of the past duty cycle and a previously determined duty cycle.

20. The apparatus of claim 19, wherein: smoothing the previously determined duty cycle using an exponential filter; and The past duty cycle and the previously determined duty cycle are weighted using a smoothing factor.

21. The apparatus of claim 16, wherein to determine the duty cycle, the one or more processors are further configured to determine the past duty cycle as a ratio of time for one or more past transmissions to a time interval.

22. The apparatus of claim 16, wherein to determine the duty cycle, the one or more processors are further configured to determine the duty cycle for each of a plurality of transmission scenarios.

23. The apparatus of claim 22, wherein the plurality of transmission scenarios comprise different combinations of antennas and frequency bands in at least one of a plurality of antennas or a plurality of frequency bands.

24. The apparatus of claim 16, wherein the one or more processors are further configured to determine the transmit power based at least in part on a power limit multiplied by a difference between 1 and the duty cycle.

25. The apparatus of claim 24, wherein the one or more processors are further configured to: In case the duty cycle satisfies a threshold, selecting a first value for the power limit; and In the event that the duty cycle does not satisfy the threshold, a second value for the power limit is selected.

26. The apparatus of claim 16, wherein the one or more processors are further configured to: determining a maximum allowed transmit power for a time interval based at least in part on the duty cycle complying with the RF exposure limit; and The transmit power is determined to be less than or equal to the maximum allowed transmit power.

27. The apparatus of claim 26, wherein: To determine the maximum allowed transmit power, the one or more processors are further configured to determine the maximum allowed transmit power as a sum of a maximum average power, a power reservation, and a duty cycle power; and The duty cycle power is the product of the power limit and the difference between 1 and the duty cycle.

28. The apparatus of claim 27, wherein the one or more processors are further configured to select the maximum average power in response to detecting that a modem associated with a wireless wide area network is in a sleep mode.

29. The apparatus of claim 27, wherein the one or more processors are further configured to determine the maximum average power based at least in part on one or more past transmit powers within a time window associated with the RF exposure limit.

30. The apparatus of claim 16, wherein the signal comprises a wireless local area network (WLAN) signal or a Bluetooth signal.

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