TRANSMIT POWER CONTROL WITH RADIO FREQUENCY EXPOSURE COMPLIANCE

Certain aspects of the present disclosure provide techniques and apparatus for operating a wireless device pursuant to radio frequency (RF) exposure compliance. A method that may be performed by a wireless device includes determining a transmit power associated with a transmission occasion and determining an energy usage associated with the transmission occasion based on the transmit power. The method also includes determining a total energy usage for a time window or a time interval associated with a RF exposure limit based on the energy usage associated with the transmission occasion. The method further includes transmitting a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget.

INTRODUCTION

Field of the Disclosure

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

Description of Related Art

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. Modern wireless devices (such as cellular telephones) are generally mandated to meet radio frequency (RF) exposure limits set by certain governments and international standards and regulations. To ensure compliance with the standards, such devices may undergo an extensive certification process prior to being shipped to market. To ensure that a wireless device complies with an RF exposure limit, techniques have been developed to enable the wireless device to assess RF exposure from the wireless device and adjust the transmission power of the wireless device accordingly to comply with the RF exposure limit.

SUMMARY

Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communication by a wireless device. The method generally includes determining a transmit power associated with a transmission occasion and determining an energy usage associated with the transmission occasion based on the transmit power. The method also includes determining a total energy usage for a time window or a time interval associated with a radio frequency (RF) exposure limit based on the energy usage associated with the transmission occasion. The method further includes transmitting a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget.

Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus generally includes one or more memories collectively storing executable instructions and one or more processors coupled to the one or more memories. The one or more processors are collectively configured to execute the executable instructions to cause the apparatus to determine a transmit power associated with a transmission occasion, determine an energy usage associated with the transmission occasion based on the transmit power, determine a total energy usage for a time window or a time interval associated with a RF exposure limit based on the energy usage associated with the transmission occasion, and transmit a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget.

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 transmit power associated with a transmission occasion. The apparatus also includes means for determining an energy usage associated with the transmission occasion based on the transmit power. The apparatus also includes means for determining a total energy usage for a time window or a time interval associated with an RF exposure limit based on the energy usage associated with the transmission occasion. The apparatus further includes means for transmitting a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget.

Certain aspects of the subject matter described in this disclosure can be implemented in a computer-readable medium. The computer-readable medium has instructions stored thereon, that when executed by an apparatus, cause the apparatus to perform an operation. The operation includes determining a transmit power associated with a transmission occasion. The operation also includes determining an energy usage associated with the transmission occasion based on the transmit power. The operation also includes determining a total energy usage for a time window or a time interval associated with an RF exposure limit based on the energy usage associated with the transmission occasion. The operation further includes transmitting a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable mediums for transmit power control with radio frequency (RF) exposure compliance.

In certain cases, time-averaged RF exposure compliance may track the RF exposure from wireless communication devices (e.g., a Long Term Evolution (LTE) wireless device, a New Radio (NR) wireless device, a Bluetooth wireless device, etc.) over time. For example, during NR wireless communication, a wireless device (e.g., a user equipment (UE)) may determine a transmission power limit to guarantee RF exposure compliance for an uplink active duration. However, the actual uplink traffic may only be scheduled for a small part of the uplink duration. A transmission power limit that is compliant for a longer duration than actually used may result in a transmission power limit that is too weak for the communication link between the UE and network, and in certain cases, transmission energy may be wasted.

Aspects of the present disclosure provide apparatus and methods for performing transmit power control with RF exposure compliance. For example, for every transmission occasion, a wireless device (e.g., a UE) may determine an energy budget associated with an RF exposure limit for a time window. The wireless device may determine the energy usage for the time window by summing the energy usage associated with the transmission occasion and the past energy usage within the time window. The wireless device may transmit in the time window until the projected energy usage is greater than or equal to the energy budget, after which the wireless device may refrain from transmitting for the remainder of the time window.

The apparatus and methods for managing transmission power described herein may facilitate improved wireless communication performance (e.g., lower latencies and/or higher throughput) and/or increased energy efficiency. The improved wireless communication performance may be especially apparent when a wireless device is at or near the edge of a cell, where the wireless device may benefit from transmitting with a higher power level in order for the transmission to reach the network.

The techniques described herein may be used for various wireless networks and radio technologies. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or new radio (e.g., 5G NR) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems and/or to wireless technologies such as 802.11, 802.15, non-terrestrial networks (NTN), and radio frequency identification (RFID) use cases (e.g., which may involve maintaining high transmission powers to meet link budget targets), as illustrative, non-limiting examples. NR access may support various wireless communication services, such as enhanced mobile broadband (cMBB) targeting wide bandwidth (e.g., 80 megahertz (MHz) or beyond), millimeter wave (mmWave) targeting high carrier frequency (e.g., 24 gigahertz (GHz) to 53 GHz or beyond), massive machine type communications (MTC) (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs), for example to meet respective quality of service (QOS) requirements. In addition, these services may co-exist in the same subframe. NR supports beamforming, and beam direction may be dynamically configured. Multiple-input, multiple-output (MIMO) transmissions with precoding may also be supported, as may multi-layer transmissions. Aggregation of multiple cells may be supported.

Example Wireless Communication Network and Devices

FIG.1illustrates an example wireless communication network100in which aspects of the present disclosure may be performed. For example, the wireless communication network100may be an NR system (e.g., a 5G NR network), an Evolved Universal Terrestrial Radio Access (E-UTRA) system (e.g., a 4G network), a Universal Mobile Telecommunications System (UMTS) (e.g., a 2G/3G network), or a code division multiple access (CDMA) system (e.g., a 2G/3G network), a NTN, a communication system that uses RFID for communication, or may be configured for communications according to an IEEE standard such as one or more of the 802.11 standards, etc., or may be representative of several such networks or systems which overlap in coverage and/or which communicate concurrently with one or more devices (e.g., with a UE such as the UE120a). As shown inFIG.1, the UE120aincludes an RF exposure manager122that ensures RF exposure compliance based on an energy usage derived from transmit power controls, in accordance with aspects of the present disclosure.

The BSs110communicate with UEs120a-y(each also individually referred to herein as UE120or collectively as UEs120) in the wireless communication network100. The UEs120(e.g.,120x,120y,etc.) may be dispersed throughout the wireless communication network100, and each UE120may be stationary or mobile. Wireless communication network100may also include relay stations (e.g., relay station110r), also referred to as relays or the like, that receive a transmission of data and/or other information from an upstream station (e.g., a BS110aor a UE120r) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE120or a BS110), or that relays transmissions between UEs120, to facilitate communication between devices.

A network controller130may be in communication with a set of BSs110and provide coordination and control for these BSs110(e.g., via a backhaul). In certain cases, the network controller130may include a centralized unit (CU) and/or a distributed unit (DU), for example, in a 5G NR system. In some aspects, the network controller130may be in communication with a core network132(e.g., a 5G Core Network (5GC)), which provides various network functions such as Access and Mobility Management, Session Management, User Plane Function, Policy Control Function, Authentication Server Function, Unified Data Management, Application Function, Network Exposure Function, Network Repository Function, Network Slice Selection Function, etc.

FIG.2illustrates example components of BS110aand UE120a(e.g., the wireless communication network100ofFIG.1), which may be used to implement aspects of the present disclosure.

At the BS110a,a transmit processor220may receive data from a data source212and control information from a controller/processor240. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid automatic repeat request (HARQ) indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the 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).

The memories242and282may store data and program codes for BS110aand UE120a,respectively. A scheduler244may schedule UEs for data transmission on the downlink and/or uplink.

Antennas252, processors266,258,264, and/or controller/processor280of the UE120aand/or antennas234, processors220,230,238, and/or controller/processor240of the BS110amay be used to perform the various techniques and methods described herein. As shown inFIG.2, the controller/processor280of the UE120ahas an RF exposure manager281that is representative of the RF exposure manager122, according to aspects described herein. Although shown at the controller/processor, other components of the UE120aand BS110amay be used to perform the operations described herein.

While the UE120ais described with respect toFIGS.1and2as communicating with a BS and/or within a network, the UE120amay be configured to communicate directly with/transmit directly to another UE120, or with/to another wireless device without relaying communications through a network. In some aspects, the BS110aillustrated inFIG.2and described above is an example of another UE120. In some examples, the UE120ainFIG.2is representative of another device having similar components and/or functionality. For example, instead of the UE120acommunicating with the BS110a,a customer premises equipment (CPE) may be configured to communicate with the BS110aas described above and/or using components described above.

Example RF Transceiver

FIG.3is a block diagram of an example RF transceiver circuit300, in accordance with certain aspects of the present disclosure. The RF transceiver circuit300includes at least one transmit (TX) path302(also known as a transmit chain) for transmitting signals via one or more antennas306and at least one receive (RX) path304(also known as a receive chain) for receiving signals via the antennas306. When the TX path302and the RX path304share an antenna306, the paths may be connected with the antenna via an interface308, which may include any of various suitable RF devices, such as a switch, a duplexer, a diplexer, a multiplexer, and the like.

Receiving in-phase (I) or quadrature (Q) baseband analog signals from a digital-to-analog converter (DAC)310, the TX path302may include a baseband filter (BBF)312, a mixer314, a driver amplifier (DA)316, and a power amplifier (PA)318. The BBF312, the mixer314, and the DA316may be included in one or more radio frequency integrated circuits (RFICs). The PA318may be external to the RFIC(s) for some implementations.

The BBF312filters the baseband signals received from the DAC310, and the mixer314mixes the filtered baseband signals with a transmit local oscillator (LO) signal to convert the baseband signal of interest to a different frequency (e.g., upconvert from baseband to a radio frequency). This frequency conversion process produces the sum and difference frequencies between the LO frequency and the frequencies of the baseband signal of interest. The sum and difference frequencies are referred to as the beat frequencies. The beat frequencies are typically in the RF range, such that the signals output by the mixer314are typically RF signals, which may be amplified by the DA316and/or by the PA318before transmission by the antenna306. While one mixer314is illustrated, several mixers may be used to upconvert the filtered baseband signals to one or more intermediate frequencies and to thereafter upconvert the intermediate frequency signals to a frequency for transmission.

The RX path304may include a low noise amplifier (LNA)324, a mixer326, and a baseband filter (BBF)328. The LNA324, the mixer326, and the BBF328may be included in one or more RFICs, which may or may not be the same RFIC that includes the TX path components. RF signals received via the antenna306may be amplified by the LNA324, and the mixer326mixes the amplified RF signals with a receive local oscillator (LO) signal to convert the RF signal of interest to a different baseband frequency (e.g., downconvert). The baseband signals output by the mixer326may be filtered by the BBF328before being converted by an analog-to-digital converter (ADC)330to digital I or Q signals for digital signal processing.

Certain transceivers may employ frequency synthesizers with a voltage-controlled oscillator (VCO) to generate a stable, tunable LO with a particular tuning range. Thus, the transmit LO may be produced by a TX frequency synthesizer320, which may be buffered or amplified by amplifier322before being mixed with the baseband signals in the mixer314. Similarly, the receive LO may be produced by an RX frequency synthesizer332, which may be buffered or amplified by amplifier334before being mixed with the RF signals in the mixer326.

A controller336may direct the operation of the RF transceiver circuit300, such as transmitting signals via the TX path302and/or receiving signals via the RX path304. The controller336may be a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof. The memory338may store data and program codes for operating the RF transceiver circuit300. The controller336and/or memory338may include control logic. In certain cases, the controller336may determine a transmit power applied to the TX path302(e.g., certain levels of gain at the PA318) that complies with an RF exposure limit set by country-specific regulations and/or international standards as further described herein.

Example RF Exposure Compliance

RF exposure may be expressed in terms of a specific absorption rate (SAR), which measures energy absorption by human tissue per unit mass and may have units of watts per kilogram (W/kg). RF exposure may also be expressed in terms of power density (PD), which measures energy absorption per unit area and may have units of milliwatts per square centimeter (mW/cm2). In certain cases, a maximum permissible exposure (MPE) limit in terms of PD may be imposed for wireless devices using transmission frequencies above 6 GHz. The MPE limit is a regulatory metric for exposure based on area, e.g., an energy density limit defined as a number, X, watts per square meter (W/m2) averaged over a defined area and time-averaged over a frequency-dependent time window in order to prevent a human exposure hazard represented by a tissue temperature change.

SAR may be used to assess RF exposure for transmission frequencies less than 6 GHz, which cover wireless communication technologies such as 2G/3G (e.g., CDMA), 4G (e.g., LTE), 5G (e.g., NR in 6 GHz bands), IEEE 802.11ac, etc. PD may be used to assess RF exposure for transmission frequencies higher than 6 GHz, which cover wireless communication technologies such as IEEE 802.11ad, 802.11ay, 5G in mmWave bands, etc. Thus, different metrics may be used to assess RF exposure for different wireless communication technologies.

A wireless device (e.g., UE120) may simultaneously transmit signals using multiple wireless communication technologies. For example, the wireless device may simultaneously transmit signals using a first wireless communication technology operating at or below 6 GHz (e.g., 3G, 4G, 5G, etc.) and a second wireless communication technology operating above 6 GHZ (e.g., mmWave 5G in 24 to 70 GHz bands, IEEE 802.11ad or 802.11ay). In certain aspects, the wireless device may simultaneously transmit signals using the first wireless communication technology (e.g., 3G, 4G, 5G in sub-6 GHz bands, IEEE 802.11ac, etc.) in which RF exposure is measured in terms of SAR, and the second wireless communication technology (e.g., 5G in 24 to 60 GHz bands, IEEE 802.11ad, 802.11ay, etc.) in which RF exposure is measured in terms of PD. As used herein, sub-6 GHz bands may include frequency bands of 300 MHz to 6,000 MHz in some examples, and may include bands in the 6,000 MHz and/or 7,000 MHZ range in some examples.

In certain cases, compliance with an RF exposure limit may be performed as a time-averaged RF exposure evaluation within a specified time window (T) (e.g., 2 seconds for 60 GHz bands, 100 or 360 seconds for bands ≤ 6 GHZ, etc.) associated with the RF exposure limit. For example,FIG.4is a graph400of a transmit power over time (P(t)) that varies over the running time window (T) associated with the RF exposure limit, in accordance with certain aspects of the present disclosure. As an example, the instantaneous transmit power may exceed a maximum time-averaged transmit power level Plimit in certain transmission occasions in the time window (T). That is, the transmit power may be greater than Plimit. In certain cases, the UE may transmit at Pmax, which may be the maximum transmit power supported by the UE or the maximum transmit power that the UE is capable of outputting. In some cases, the UE may transmit at a transmit power less than or equal to Plimitin certain transmission occasions. Plimitrepresents the time-averaged threshold in terms of transmit power for the RF exposure limit over the time window (T), and in certain cases, Plimitmay be referred to as the maximum time-averaged power level or limit. Plimitmay represent the maximum transmit power that can be used continuously over the time window in compliance with the time-averaged RF exposure limit. The graph400also illustrates gaps between transmission bursts, where the gaps represent periods during which no transmission was sent from the device. In certain cases, the transmit power may be maintained at the maximum average transmit power level (e.g., Plimit) allowed for RF exposure compliance to enable continuous transmission during the time window. In some examples, the time-averaged RF exposure evaluation is calculated with respect to one or more rolling time windows.

RF exposure compliance may apply an RF exposure limit over a time window. For example, for certain mmWave bands, RF exposure compliance may apply a maximum power density exposure to human tissue limited to a 1 mW/cm2PD over a four-second window. If a wireless device transmits for the entirety of the four-second window (100% of the uplink transmission), the wireless device may only be allowed to transmit at a transmission power level corresponding to 1 mW/cm2. In some instances, the communication link between the UE and network may require a transmit power that correlates to a power density of more than 1 mW/cm2in order to be received at the network. In such cases, the maximum transmission power limit may restrict the transmit power in order to ensure RF exposure compliance, for example, based on an assumption that transmissions will occur throughout the time window or relatively continuously for the entirety of the time window. As a result, some transmissions from the UE may not reach the network.

Example Transmit Power Control with Radio Frequency Exposure Compliance

Multi-mode/multi-band UEs have multiple transmit antennas, which may be able to simultaneously transmit in sub-6 GHz bands and bands greater than 6 GHz bands, such as mm Wave bands. As described herein, the RF exposure of bands 6 GHz and below may be evaluated in terms of SAR, and the RF exposure of bands greater than 6 GHz may be evaluated in terms of PD. Due to the regulations on simultaneous exposure, the wireless device may limit maximum transmit power for bands lower than 6 GHz and/or bands greater than 6 GHz.

Aspects of the present disclosure provide apparatus and methods for transmit power control with RF exposure compliance. For example, for every transmission occasion, a wireless device (e.g., UE) may determine an energy budget associated with an RF exposure limit for a time window. As used herein, a transmission occasion may refer to a transmission time interval (TTI) or to another determined time within the time window during which the wireless device is able to transmit. The wireless device may determine the energy usage for the time window by summing the energy usage associated with the transmission occasion and the past energy usage within the time window. The wireless device may transmit in the time window until the projected energy usage is greater than or equal to the energy budget, after which the wireless device will refrain from transmitting.

The apparatus and methods for transmit power control described herein may facilitate improved wireless communication performance (e.g., lower latencies and/or higher throughput) and/or increased energy efficiency. The improved wireless communication performance may be especially apparent when a wireless device is at or near the edge of a cell, where the wireless device may benefit from transmitting with a higher power level in order for the transmission to reach the network. Energy efficiency may be improved by ensuring that the entirety of the energy budget is used without wasting energy due to a predetermined maximum transmission power limit.

Transmit power control described herein may allow for the entire RF exposure limit to be used. The available energy may allow the UE to transmit part of the uplink bursts within the time window when the energy is very low. If the available energy for UL transmission under RF exposure limit is not enough to close the link of any single burst within the time window, no further UL transmission may happen within the time window. For certain aspects, the unused energy from a previous time interval can be saved for the transmission in the next time interval, for example, depending on how the time windows are defined for RF exposure compliance.

FIG.5is a flow diagram illustrating example operations500for transmit power control by a wireless communications device, in accordance with certain aspects of the present disclosure. The operations500may be performed, for example, by a UE (e.g., the UE120ain the wireless communication network100).

The operations500may begin, at block502, where the wireless device may start a timer, which may have a duration of a time window associated with a time-averaged RF exposure limit. For example, the time window may be set to ensure compliance with a time-averaged RF exposure limit, for example, as described herein with respect toFIG.4. The wireless device may also determine an energy budget (E_budget) corresponding to the time-averaged RF exposure limit and used within the time window. For example, the wireless device may convert the time-averaged RF exposure limit (e.g., as defined by a regulatory body or by a device manufacturer based on the specifics of a device and information from a regulatory body) over the time window to the energy budget. In other examples, a regulatory body may define a total amount of energy allowed over a certain time, and this amount may be determined by the UE based on a location of the device, a frequency of operation, a disposition with respect to a user, etc. In certain cases, each type of channel (e.g., a random access channel (RACH), a PUCCH, a PUSCH, etc.) may have a separate associated energy budget (ExCH_budget, where xCH refers to the channel type). The energy budget (E_budget) may include the sum of all of the energy budgets associated with different channel types, an energy budget associated with a specific channel type, an energy budget associated with multiple channel types, or any combination thereof. The wireless device may determine available energy budgets of different uplink channels for transmission.

At block504, the wireless device may determine a transmit power associated with a transmission occasion (e.g., TTI). For example, in response to scheduling information received from the network for an uplink transmission, the wireless device may determine the transmit power. In some cases, the wireless device may determine the transmit power in response to obtaining or generating a data payload to transmit, for example, via the RACH. The transmit power associated with the transmission occasion may represent the transmit power the UE will use in the transmission occasion. In accordance with one or more examples, when an uplink channel is scheduled for transmission, a wireless device may determine a transmit power associated with the channel or signal based on certain uplink transmit power controls. The transmit power may be determined according to one or more transmit power control procedures provided in wireless communication standards, such as 3rd Generation Partnership Project (3GPP) standards for LTE and/or NR. As an example, 3GPP Technical Specification 38.213 for 5G NR may provide a transmit power control procedure for each of the PUSCH, PUCCH, RACH, and SRS. In some cases, the transmit power may be determined based on a link budget equation as a function of pathloss. In certain wireless communication systems (e.g., LTE and/or 5G NR), the wireless device may determine the transmit power of a channel (Preq_xCH) used to communicate with a base station according to the following expression:

where MTPL_RF is a maximum transmit power limit (e.g., a maximum output power) configured for a wireless communication network; Po_xCHis the received power at the base station as configured by the network; μ is the subcarrier spacing numerology; MRBxCHis indicative of the bandwidth of the transmission (e.g., the number of resource blocks (RBs)); PL is indicative of the pathloss measured at the UE between the UE and base station; and K is an adjustment factor (e.g., configured by the network and/or a base station configured power control factor). The transmit power of the channel (Preq_xCH) may be determined in terms of decibel-milliwatts (dBm). In some aspects, to determine the transmit power of a channel, the wireless device may select the transmit power (e.g., Preq_xCH) as a smallest value among a transmit power limit (e.g., MTPL_RF) and a computed transmit power (e.g., Po_xCH+10log10(2μ*MRBxCH)+PL+K) based at least in part on a pathloss (e.g., PL) between the wireless device and a receiving entity. For certain aspects, the wireless device may determine the transmit powers for a number of different channel types (e.g., RACH, PUCCH, PUSCH, etc.) that will be transmitted during the same transmission occasion. The wireless device may perform these determinations simultaneously, or one at a time.

It will be appreciated that Expression (1) is merely an example of a transmit power control expression for determining the transmit power at the UE. Other expression(s) and/or other parameters may be used in addition to or instead of Expression (1) to determine the transmit power associated with certain channels, signals, and/or RATs (e.g., LTE or 5G NR). For example, the MTPL_RF may be indicated as PCMAX,f,c(i) for a certain carrier f of a serving cell c in a PUSCH transmission occasion i. Further, other maximum transmit power limits may be used in addition to or instead of MTPL_RF, for example, based on a device configuration or type of power amplifier used in a transmit chain, etc. In some examples, the maximum transmit power limit includes the Pmaxdescribed above. Different channels may have different parameters and/or values configured by the network, such as K. In some cases, the adjustment factor may be representative of a function that depends on previous transmit power commands from the network.

At block506, the wireless device may determine a projected energy usage associated with the transmission occasion. For example, the wireless device may determine the energy associated with the transmission occasion as a product of the transmit power determined at block504(e.g., Preg_xCH) and the duration of the transmission occasion. At block506, the wireless device may also determine the energy usage for the time window. The energy usage may include the sum of the energy usage associated with the transmission occasion and the past energy usage within the time window. In certain aspects, the energy usage (Exch_used(j)) for a particular channel (xch) may be determined according to the following expression:

where Preg_xCH, iis the transmit power associated with the transmission occasion i determined at block504; xchDur(i) is the duration of the transmission occasion i in seconds; and j is a counter associated with the total number of transmissions in the time window. When i is equal to j, the transmission occasion i is representative of the current transmission being inspected for transmit power throttling, and when i is less than j, the transmission occasion i is in the past. The energy usage associated with the transmission occasion may include the sum of the energy usage for all channel types (e.g., RACH, PUCCH, PUSCH, etc.), the energy usage for a specific channel type, or the energy usage for any combination of channel types. The past energy usage within the time window may also include the past energy usage for all channel types (e.g., RACH, PUCCH, PUSCH, etc.), the energy usage for one channel type, or the energy usage for some combination of channel types within the time window.

At block508, the wireless device may determine if the total energy usage (E_used) satisfies the energy budget. For example, the wireless device may determine whether the energy usage (E_used) is greater than or equal to the energy budget (E_budget). In some aspects, the wireless device may perform the activities described herein with respect to blocks504-508before the wireless device is scheduled to transmit in the transmission occasion. As described above, the energy usage (E_used) may be the sum of the energy usage for each channel type in the transmission occasion, the energy usage for a specific channel type, or the energy usage for some combination of channel types. Further, the energy budget (E_budget) may be the sum of all various energy budgets associated with different channel types, an energy budget associated with a specific channel type, an energy budget associated with multiple channel types, or any combination thereof. The channel types may be associated with a single RAT, multiple RATs, one antenna or antenna array, a group of antennas and/or antenna arrays, or a non-grouped plurality (e.g., all) of antennas and/or antenna arrays.

If the wireless device determines there is not enough energy budget for the transmission, then the wireless device may refrain from transmitting (including the transmission associated with the transmit power determined for the current transmission occasion) until the timer expires. For example, if the energy usage (E_used) is greater than or equal to the energy budget (E_budget), then the operations500may proceed to block510, where the wireless device may refrain from transmitting until the time remaining in the time window expires, for example, based on the timer set at block502. When the timer expires, the operations500may then proceed to block502, where the wireless device restarts the timer beginning a new time window and resets the past energy usage, for example, to zero. In certain cases, the wireless device may reset the energy budget (E_budget).

If the wireless device determines there is enough energy budget for the transmission, then the wireless device may transmit during the transmission occasion. For example, if the energy usage (E_used) is less than the energy budget (E_budget), then the operations500may proceed to block512, where the wireless device may transmit signal(s) at the transmit power determined at block504in the transmission occasion (j).

At block514, the wireless device may determine whether the timer has expired. The wireless device may also increment the counter (j) associated with the total number of transmissions in the time window by one. If the timer has expired, then the operations500may proceed to block502, where the wireless device may restart the timer and reset the past energy usage, for example, to zero. If the timer has not expired, then the operations500may proceed to block504, where the wireless device may determine the transmit power for the next transmission occasion, for example, in response to scheduling or obtaining a transmission payload. It will be appreciated that due to the energy budget being set to a value in compliance with an RF exposure limit, such as a time-averaged SAR and/or MPE limit, the operations500may ensure that RF emissions from the wireless device are in compliance with the respective RF exposure limit.

It will be appreciated that the use of a timer in the operations500is merely an example. Other techniques for determining the expiration of the time window associated with the time-averaged RF exposure limit may be used. For example, the wireless device may count the number of transmission occasions occurring over time and check if the number of transmission occasions is less than or equal to a threshold, where the threshold corresponds to the duration of the time-averaging time window.

FIG.6is a diagram of an example interaction between an RF exposure manager and a radio, in accordance with certain aspects of the present disclosure. A wireless device (e.g., UE120) may include an RF exposure manager602and a radio604. The RF exposure manager602may be representative of the RF exposure manager122,281. The RF exposure manager602may determine the energy budget (E_budget) in compliance with an RF exposure limit, for example, as described herein with respect to the operations500. The RF exposure manager602may also determine the energy budget for some combination of channel types (e.g., RACH, PUCCH, PUSCH, etc.). For certain aspects, the RF exposure manager602may provide the energy budget (E_budget) to the radio604, which may be representative of the RF transceiver circuit300.

The radio604may perform medium access control (MAC) functions, such as determining the scheduling for uplink transmissions. The radio604may accumulate the actual energy used at the wireless device and may compare the energy used to the energy budget. The radio604may throttle transmissions when the projected energy usage is greater than the energy budget, for example, as described herein with respect to blocks508,510of the operations500. The radio604may determine whether to transmit a transmission, for example, according to the operations500, in response to uplink scheduling or obtaining a transmission payload, for example, for a RACH transmission.

In certain aspects, the RF exposure manager602may prioritize an energy budget associated with each of one or more specific channels (e.g., RACH, PUCCH, and/or PUSCH). For example, the RF exposure manager602may allocate more of the energy budget to PUSCH transmissions than to PUCCH transmission, or vice versa. The wireless device may allocate parts of the energy budget (E_budget) to certain channel(s) in accordance with the channel prioritization, and the wireless device may allocate the remaining energy budget (E_budget) to other channels. The energy budget prioritization may be based on channel conditions, traffic history, service type, quality of service settings, etc. The radio604may provide the energy usage—for example, as determined according to Expression (2)—to the RF exposure manager602. The RF exposure manager602may adjust the energy budget assigned to certain channels based on the energy usage obtained from the radio604.

FIG.7includes graphs700a,700billustrating an example of transmit power control over multiple transmission occasions in compliance with an energy budget, in accordance with certain aspects of the present disclosure. In this example, a wireless device may transmit multiple signal bursts in respective transmission occasions704ato704gacross a time window (T), such as the time window described herein with respect toFIG.4. In graph700a,multiple transmit powers702ato702g(collectively referred to as “transmit powers702”) associated with the signal bursts are depicted over time within the time window (T). The wireless device may determine the transmit power for each of the signal bursts in the respective transmission occasions704, for example, as described herein with respect toFIG.5. As an example, before transmission occasion704g,the wireless device may determine the transmit power702gfor the respective signal burst according to transmit power control procedure(s) for the respective channel(s) of the signal burst, such as Expression (1). The wireless device may convert the transmit power702gto an energy usage, for example, as described herein with respect to the operations500, e.g., according to Expression (2). The wireless device may determine whether there is enough energy budget for the transmission in transmission occasion704gbased on the past energy usage associated with transmission occasions704ato704fand the projected energy usage associated with the transmission occasion704g.In this example, the energy usage associated with the transmission occasion704gmay satisfy the energy budget. After the transmission occasion704g,the wireless device may apply transmit power throttling (e.g., refrain from transmitting during the remainder of the transmission occasion).

In graph700b,the curve706is representative of the cumulative energy usage of the signal bursts over time. As shown, the energy usage (E_used) reaches the energy budget (E_budget) at a particular time708, which, in this example, is before the end of the time window (T). The energy usage may reach the energy budget at the time708, for example, due to a future transmission (e.g., scheduled or triggered at will) adding to the energy usage, for example, as described herein with respect to the operations500. In response to the energy usage reaching the energy budget at the time708, the wireless device may refrain from transmitting for the remainder of the time window. After the energy budget (E_budget) is reached, there may be no transmission for the remainder of the time window, in order to guarantee RF exposure compliance.

It will be appreciated that the operations described herein facilitate RF exposure compliance with an energy budget instead of Plimit. The operations described herein allow for RF exposure compliance without time-averaging past RF exposure.FIG.7demonstrates that the wireless device is able to transmit at various transmit powers in the transmission occasions throughout the time window. The wireless device may allow the energy budget to be reached before the end of the time window.

FIG.8includes graphs800a,800billustrating an example of transmit power control over multiple transmission occasions in compliance with an energy budget, in accordance with certain aspects of the present disclosure. In this example, a wireless device may transmit multiple signal bursts in respective transmission occasions804as described herein with respect toFIG.7. In graph800a,multiple transmit powers802associated with the signal bursts are depicted over time within the time window (T). The wireless device may determine the transmit power for each of the signal bursts in the respective transmission occasions804, for example, as described herein with respect toFIG.5. In graph800b,the curve806is representative of the cumulative energy usage of the signal bursts over time. As shown, the energy usage (E_used) reaches the energy budget (E_budget) at a particular time808, which, in this example, is before the end of the time window (T). The energy usage may reach the energy budget at the time808, for example, due to a future transmission (e.g., scheduled or triggered at will) adding to the energy usage, for example, as described herein with respect to the operations500. In this example, the signal bursts may be transmitted contiguously without any time gaps between the signal bursts. As a result, the energy usage may reach the energy budget at a faster rate compared to the energy usage depicted inFIG.7, for example.

FIG.9includes graphs900a,900billustrating an example of transmit power control over multiple transmission occasions in compliance with an energy budget, in accordance with certain aspects of the present disclosure. In this example, a wireless device may transmit multiple signal bursts in respective transmission occasions904as described herein with respect toFIG.7. In graph900a,multiple transmit powers902associated with the signal bursts are depicted over time within the time window (T). The wireless device may determine the transmit power for each of the signal bursts in the respective transmission occasions904, for example, as described herein with respect toFIG.5. In graph900b,the curve906is representative of the cumulative energy usage of the signal bursts over time. As shown, the energy usage (E_used) does not reach the energy budget (E_budget) before the end of the time window (T). As a result, the wireless device may be allowed to transmit throughout the time window without the transmit power throttling described herein.

FIG.10includes graphs1000a,1000billustrating an example of transmit power control over multiple transmission occasions in compliance with an energy budget, in accordance with certain aspects of the present disclosure. In this example, a wireless device may transmit multiple signal bursts in respective transmission occasions1004as described herein with respect toFIG.7. In graph1000a,multiple transmit powers1002associated with the signal bursts are depicted over time within the time window (T). The wireless device may determine the transmit power for each of the signal bursts in the respective transmission occasions1004, for example, as described herein with respect toFIG.5. In graph1000b,the curve1006is representative of the cumulative energy usage of the signal bursts over time. As shown, the energy usage (E_used) does not reach the energy budget (E_budget) before the end of the time window (T). As a result, the wireless device may be allowed to transmit throughout the time window without the transmit power throttling described herein. Note that the transmit powers1002appear higher than the transmit powers802(FIG.8), but the transmit power scale may not be similar between the two figures and/or the energy budget (E_budget) inFIG.10may be greater than inFIG.8.

It will be appreciated that each of the examples depicted inFIGS.8-10may be representative of an energy budget allocated to a particular channel (e.g., RACH, PUCCH, PUSCH, etc.) and/or an energy budget associated with a combination of channels. For example, the transmit power behavior depicted inFIG.8may be representative of the energy budget allocated to the PUSCH, whereas the transmit power behavior depicted inFIG.10may be representative of the energy budget allocated to the RACH. In certain cases, the wireless device may adjust the energy budget allocation associated with one or more channels in response to certain events and/or periodically. For example, the wireless device may detect that the energy usage for RACH transmissions is not reaching the allocated energy budget for a certain number of time window(s). In response to such a detection, the wireless device may reduce the energy budget allocated for RACH transmissions and correspondingly increase the energy budget allocated for PUSCH transmissions.

It will be appreciated that the time-averaged RF exposure compliance operations described herein with respect toFIGS.5-10are merely examples. In certain aspects, the wireless device may apply an energy budget per one or more transmission time intervals (e.g., one or more slots, radio frames, or transmission occasions), where the energy budget may correspond to Plimitacross the one or more transmission time intervals. In some examples, the energy budget may vary between time intervals, and/or may be allocated by a RF exposure manager (e.g., the RF exposure manager602) at each time interval or at periodic time intervals. The wireless device may transmit at specified transmit power(s) in transmission occasion(s) until the energy budget for the one or more transmission time intervals is reached as described herein with respect toFIGS.5-10. The specified transmit power(s) may be determined according to a transmit power control procedure, for example, as described herein with respect toFIG.5. The time windows (T) depicted inFIGS.7-10may be representative of a duration corresponding to one or more transmission time intervals (e.g., one or more slots or radio frames). The wireless device may perform the time-averaged RF exposure evaluation per transmission occasion in the one or more transmission time intervals. In some cases, the wireless device may evaluate if a portion of a transmission occasion (e.g., each symbol) satisfies the energy budget. For example, the wireless device may transmit at the specified transmit power per symbol of a transmission occasion until the energy budget is reached for the one or more transmission time intervals.

FIG.11is a flow diagram illustrating example operations1100for wireless communication, in accordance with certain aspects of the present disclosure. The operations1100may be performed, for example, by a wireless device (e.g., the UE120ain the wireless communication network100). The operations1100may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor280ofFIG.2). Further, the transmission and/or reception of signals by the wireless device in the operations1100may be enabled, for example, by one or more antennas (e.g., antennas252ofFIG.2). In certain aspects, the transmission and/or reception of signals by the wireless device may be implemented via a bus interface of one or more processors (e.g., controller/processor280) obtaining and/or outputting signals.

The operations1100may optionally begin, at block1102, where the wireless device may determine a transmit power (e.g., the transmit power702g) associated with a transmission occasion (e.g., the transmission occasion704g). For example, the wireless device may determine the transmit power associated with a transmission occasion as described herein with respect toFIGS.5and6. The transmit power may be the transmit power of a number of different channel types (e.g., RACH, PUCCH, PUSCH, etc.) and the determining of the transmit power may include summing the power of multiple channel types in a transmission occasion.

At block1104, the wireless device may determine an energy usage (e.g., a portion of the energy usage in the curve706) associated with the transmission occasion based on the transmit power. For example, the wireless device may determine the energy usage associated with a transmission occasion as described herein with respect toFIGS.5and6. The energy usage may be sum of the energy usage for a number of different channel types (e.g., RACH, PUCCH, PUSCH, etc.) and determining the energy usage may include summing the energy usage for transmission occasion j for each channel type, for a specific channel type, or for some combination of channel types.

At block1106, the wireless device may determine a total energy usage for a time window (e.g., the time window (T) depicted inFIG.7) associated with a RF exposure limit based on the energy usage associated with the transmission occasion. For example, the wireless device may determine the total energy usage for a time window as described herein with respect toFIGS.5and6. In certain aspects, the total energy usage may comprise the energy usage associated with the transmission occasion and past energy usage within the time window, as described herein with respect toFIG.5. Referring to Expression (2), the total energy usage may be determined by summing the energy usage associated the transmission occasion j and the past energy usage (e.g., the energy usage associated with transmission occasion (i=0) through transmission occasion (i=j−1)) within the time window. For certain aspects, the past energy usage within the time window may also include the past energy usage for all channel types (e.g., RACH, PUCCH, PUSCH, etc.), the energy usage for a specific channel type, or the energy usage for some combination of channel types within the time window.

At block1108, the wireless device may transmit a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget (e.g., E_budget as depicted inFIG.7), for example, as described herein with respect toFIGS.5-10. The energy budget may be the sum of all of the energy budgets that are associated with different channels or any combination thereof. The energy budget may also be an energy budget associated with a specific channel type. For certain aspects, the wireless device may continue to transmit signals until the total energy usage is greater than or equal to the energy budget, for example, as depicted inFIGS.9and10.

At block1110, the wireless device may refrain from (e.g., pause from or temporarily stop) transmitting if the total energy usage does not satisfy the energy budget. The wireless device may refrain from transmitting if the total energy usage is greater than or equal to the energy budget, for example, as described herein with respect toFIGS.5and6. For certain aspects, in response to detecting that the total energy usage does not satisfy the energy budget, the wireless device may refrain from transmitting until a timer associated with the time window expires, such as the timer described herein with respect toFIG.5.

For certain aspects, the wireless device may set the total energy usage to a value when a timer associated with the time window expires, and the wireless device may restart the timer in response to the timer expiring, as described herein with respect toFIG.5. For example, the total energy usage may be set to zero when the timer expires.

In certain aspects, the wireless device may transmit a signal in the transmission occasion at the transmit power via a channel (e.g., RACH, PUCCH, PUSCH, etc.) if the energy usage satisfies the energy budget. For certain aspects, the energy budget may be associated with the channel. The channel may include a RACH, a PUCCH, a PUSCH, or any combination thereof. The energy budget may be allocated for the channel. For example, the energy budget may be allocated for the RACH or PUCCH.

In certain aspects, the wireless device may allocate an energy budget to multiple channels. The wireless device may determine, for each of multiple channels, a channel-specific energy budget. The multiple channels may include any combination of channel types (e.g., RACH, PUCCH, PUSCH, etc.). For certain aspects, the energy budget may include at least one of the channel-specific energy budgets, as described herein with respect toFIG.5.

For certain aspects, to determine the transmit power, the wireless device may determine the transmit power for at least one of the channels associated with the energy budget. For example, the wireless device may determine the transmit power for cach channel type (e.g., RACH, PUCCH, PUSCH, etc.). The wireless device may perform these determinations simultaneously, or one at a time. As described above, each channel type may have its own energy budget.

In certain aspects, to determine the channel-specific energy budget, the wireless device may allocate a portion of a total energy budget as the respective channel-specific energy budget for each of the channels. As an example, the energy budget inFIG.7may be representative of the total energy budget, and each of the energy budgets inFIGS.8-10may be representative of a portion of the total energy budget as the respective channel-specific energy budget for each of the channels. The wireless device may prioritize some channels (e.g., RACH, PUCCH) over others as determined by a per-signal type channel prioritization. The wireless device may allocate parts of the energy budget to certain channels in accordance with the prioritization. For example, the wireless device may allocate a first portion of the total energy budget to PUSCH transmissions, a second portion of the total energy budget to PUCCH transmissions, and a third portion of the total energy budget to RACH transmissions. In certain aspects, the wireless device may allocate portions of the total energy budget to different radios, such as LTE, 5G NR, Bluetooth, WiFi, etc. The wireless device may allocate portions of the total energy budget to different subscriptions, for example, for a multi-subscription device (e.g., via multiple subscriber identity modules (SIMs) or universal SIMs (USIMs)). Some multi-SIM configurations enable multiple subscriptions to be active at a time, allowing communications at any given time with multiple transceivers, such as Dual SIM Dual Active (DSDA). As an example, the wireless device may allocate first portion of the total energy budget to a first subscription and a second portion of the total energy budget to a second subscription.

For certain aspects, the wireless device may determine the transmit power based on a power control procedure, such as the power control procedures for LTE and/or 5G NR. In certain aspects, the power control procedure may be for uplink communication, sidelink communication, or both.

For certain aspects, to determine the transmit power, the wireless device may select the transmit power as a smallest value among a transmit power limit and a computed transmit power based at least in part on a pathloss between the wireless device and a receiving entity, for example, as described herein with respect to Expression (1). For example, the wireless device may select the transmit power limit if the computed transmit power is larger. In some cases, the wireless device may select the computed transmit power if the transmit power limit is larger. In certain aspects, to determine the transmit power, the wireless device may determine the computed transmit power further based at least in part on an estimated received power at the receiving entity (e.g., the BS110), a subcarrier spacing numerology associated with the signal, a bandwidth associated with the signal, and the pathloss, for example, as described herein with respect toFIG.5.

For certain aspects, to determine the transmit power, the wireless device may determine the transmit power based on a pathloss between the wireless device and a receiving entity (e.g., the BS110). In some cases, instead of relying on the transmit power control procedure(s) described herein, the wireless device may determine the transmit power to facilitate reception at the receiving entity based on the measured pathloss between the wireless device and the receiving entity.

While the examples depicted inFIGS.1-11are described herein with respect to a UE performing the various methods for providing RF exposure compliance to facilitate understanding, aspects of the present disclosure may also be applied to other wireless devices, such as a wireless station, an access point, a base station and/or a CPE, performing the RF exposure compliance described herein. Further, while the examples are described with respect to communication between the UE (or other wireless device) and a network entity, the UE or other wireless device may be communicating with a device other than a network entity, for example another UE or with another device in a user's home that is not a network entity, for example.

It will be appreciated that the transmit power control described herein may enable desirable wireless communication performance, such as reduced latencies, increased uplink data rates, and/or an uplink connection at the edge of a cell.

Example Communications Device

FIG.12illustrates a communications device1200(e.g., the UE120) that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIG.11. The communications device1200includes a processing system1202, which may be coupled to a transceiver1208(e.g., a transmitter and/or a receiver). The transceiver1208is configured to transmit and receive signals for the communications device1200via an antenna1210, such as the various signals as described herein. The processing system1202may be configured to perform processing functions for the communications device1200, including processing signals received and/or to be transmitted by the communications device1200.

The processing system1202includes a processor1204coupled to a computer-readable medium/memory1212via a bus1206. In certain aspects, the computer-readable medium/memory1212is configured to store instructions (e.g., computer-executable code) that when executed by the processor1204, cause the communications device1200to perform the operations1100illustrated inFIG.11, or other operations for performing the various techniques discussed herein for providing RF exposure compliance. In certain aspects, computer-readable medium/memory1212stores code for determining1214, code for refraining1216, code for setting1218, code for restarting1220, code for transmitting (or providing)1222, or any combination thereof.

In certain aspects, the processing system1202has circuitry1226configured to implement the code stored in the computer-readable medium/memory1212. In certain aspects, the circuitry1226is coupled to the processor1204and/or the computer-readable medium/memory1212via the bus1206.

For example, the circuitry1226includes circuitry for determining1228, circuitry for refraining1230, circuitry for setting1232, circuitry for restarting1234, circuitry for transmitting (or providing)1236, or any combination thereof.

In some examples, means for transmitting or sending (or means for outputting for transmission) may include the transceivers232and/or antenna(s)234of the BS102illustrated inFIG.2and/or transceiver1008and antenna1210of the communication device1200inFIG.12.

In some cases, rather than actually transmitting, for example, signals and/or data, a device may have an interface to output signals and/or data for transmission (a means for outputting). For example, a processor may output signals and/or data, via a bus interface, to a radio frequency (RF) front end for transmission. Similarly, rather than actually receiving signals and/or data, a device may have an interface to obtain the signals and/or data received from another device (a means for obtaining). For example, a processor may obtain (or receive) the signals and/or data, via a bus interface, from an RF front end for reception. In various aspects, an RF front end may include various components, including transmit and receive processors, transmit and receive MIMO processors, modulators, demodulators, and the like, such as depicted in the examples inFIG.2.

In some examples, means for determining, means for refraining, means for setting, and/or means for restarting may include various processing system components, such as: the one or more processors1204inFIG.12, or aspects of the BS102depicted inFIG.2, including receive processor238, transmit processor220, TX MIMO processor230, and/or controller/processor240.

EXAMPLE ASPECTS

Aspect 1: A method of wireless communication by a wireless device, comprising: determining a transmit power associated with a transmission occasion; determining an energy usage associated with the transmission occasion based on the transmit power; determining a total energy usage for a time window or a time interval associated with a radio frequency (RF) exposure limit based on the energy usage associated with the transmission occasion; and transmitting a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget.

Aspect 2: The method of Aspect 1, wherein determining the total energy usage comprises determining a sum of the energy usage associated with the transmission occasion and past energy usage within the time window or the time interval.

Aspect 3: The method of Aspect 1 or 2, further comprising refraining from transmitting in the time window or the time interval if the total energy usage is greater than or equal to the energy budget.

Aspect 4: The method according to any of Aspects 1-3, further comprising: setting the total energy usage to a value when a timer associated with the time window or the time interval expires; and restarting the timer in response to the timer expiring.

Aspect 5: The method of Aspect 4, wherein the value is equal to zero.

Aspect 6: The method according to any of Aspects 1-5, wherein transmitting the signal comprises transmitting the signal in the transmission occasion at the transmit power via a channel if the total energy usage satisfies the energy budget, wherein the energy budget is associated with the channel.

Aspect 7: The method of Aspect 6, wherein the channel includes a random access channel, a physical uplink control channel, a physical uplink shared channel, or any combination thereof.

Aspect 8: The method of Aspect 6 or 7, further comprising: determining, for each of a plurality of channels, a channel-specific energy budget, wherein the energy budget includes at least one of the channel-specific energy budgets and wherein determining the transmit power comprises determining the transmit power for at least one of the channels associated with the energy budget.

Aspect 9: The method of Aspect 8, wherein determining the channel-specific energy budget comprises allocating a portion of a total energy budget as the respective channel-specific energy budget for each of the channels.

Aspect 10: The method according to any of Aspects 1-9, wherein determining the transmit power comprises determining the transmit power based on a power control procedure.

Aspect 11: The method of Aspect 10, wherein the power control procedure is for uplink communication or sidelink communication.

Aspect 12: The method according to any of Aspects 1-11, wherein determining the transmit power comprises selecting the transmit power as a smallest value among a transmit power limit and a computed transmit power based at least in part on a pathloss between the wireless device and a receiving entity.

Aspect 13: The method of Aspect 12, wherein determining the transmit power comprises determining the computed transmit power further based at least in part on an estimated received power at the receiving entity, a subcarrier spacing numerology associated with the signal, a bandwidth associated with the signal, and the pathloss.

Aspect 14: The method according to any of Aspects 1-13, wherein determining the transmit power comprises determining the transmit power based on a pathloss between the wireless device and a receiving entity.

Aspect 15: An apparatus for wireless communication, comprising: one or more memories collectively storing executable instructions; and one or more processors coupled to the one or more memories, the one or more processors being collectively configured to execute the executable instructions to cause the apparatus to: determine a transmit power associated with a transmission occasion, determine an energy usage associated with the transmission occasion based on the transmit power, determine a total energy usage for a time window or a time interval associated with a radio frequency (RF) exposure limit based on the energy usage associated with the transmission occasion, and transmit a signal in the transmission occasion at the transmit power if the total energy usage satisfies an energy budget.

Aspect 16: The apparatus of Aspect 15, wherein to determine the total energy usage, one or more processors are collectively configured to execute the executable instructions to cause the apparatus to determine a sum of the energy usage associated with the transmission occasion and past energy usage within the time window or the time interval.

Aspect 17: The apparatus of Aspect 15 or 16, wherein the one or more processors are further collectively configured to execute the executable instructions to cause the apparatus to refrain from transmitting in the time window or the time interval if the total energy usage is greater than or equal to the energy budget.

Aspect 18: The apparatus according to any of Aspects 15-17, wherein the one or more processors are further collectively configured to execute the executable instructions to cause the apparatus to: set the total energy usage to a value when a timer associated with the time window expires or the time interval; and restart the timer in response to the timer expiring.

Aspect 19: The apparatus of Aspect 18, wherein the value is equal to zero.

Aspect 20: The apparatus according to any of Aspects 15-19, wherein to transmit the signal, the one or more processors are collectively configured to execute the executable instructions to cause the apparatus to transmit the signal in the transmission occasion at the transmit power via a channel if the total energy usage satisfies the energy budget, and wherein the energy budget is associated with the channel.

Aspect 21: The apparatus of Aspect 20, wherein the channel includes a random access channel, a physical uplink control channel, a physical uplink shared channel, or any combination thereof.

Aspect 22: The apparatus of Aspect 20 or 21, wherein the one or more processors are further collectively configured to execute the executable instructions to cause the apparatus to: determine, for each of a plurality of channels, a channel-specific energy budget, wherein the energy budget includes at least one of the channel-specific energy budgets, and determine the transmit power for at least one of the channels associated with the energy budget.

Aspect 23: The apparatus of Aspect 22, wherein to determine the channel-specific energy budget, the one or more processors are collectively configured to execute the executable instructions to cause the apparatus to allocate a portion of a total energy budget as the respective channel-specific energy budget for each of the channels.

Aspect 24: The apparatus according to any of Aspects 15-23, wherein to determine the transmit power, the one or more processors are collectively configured to execute the executable instructions to cause the apparatus to determine the transmit power based on a power control procedure.

Aspect 25: The apparatus of Aspect 24, wherein the power control procedure is for uplink communication or sidelink communication.

Aspect 26: The apparatus according to any of Aspects 15-25, wherein to determine the transmit power, the one or more processors are collectively configured to execute the executable instructions to cause the apparatus to select the transmit power as a smallest value among a transmit power limit and a computed transmit power based at least in part on a pathloss between the apparatus and a receiving entity.

Aspect 27: The apparatus of Aspect 26, wherein to determine the transmit power, the one or more processors are collectively configured to execute the executable instructions to cause the apparatus to determine the computed transmit power further based at least in part on an estimated received power at the receiving entity, a subcarrier spacing numerology associated with the signal, a bandwidth associated with the signal, and the pathloss.

Aspect 28: The apparatus according to any of Aspects 15-27, wherein to determine the transmit power, the one or more processors are collectively configured to execute the executable instructions to cause the apparatus to determine the transmit power based on a pathloss between the apparatus and a receiving entity.

Aspect 29: An apparatus, comprising: at least one memory comprising executable instructions; and one or more processors coupled to the at least one memory and collectively configured to execute the executable instructions and cause the apparatus to perform a method in accordance with any of Aspects 1-14.

Aspect 30: An apparatus, comprising means for performing a method in accordance with any of Aspects 1-14.

Aspect 32: A computer program product embodied on a computer-readable storage medium comprising code for performing a method in accordance with any of Aspects 1-14.

The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), LTE-Advanced (LTE-A), code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA), time division synchronous code division multiple access (TD-SCDMA), non-terrestrial networks (NTNs), radio frequency identification (RFID) systems, and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. 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 a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). NR is an emerging wireless communications technology under development. A NTN is a wireless communication system that generally operates above the Earth's surface, involving satellites at low Earth orbit (LEO), medium Earth orbit (MEO), and geostationary orbit (GEO), high-altitude platforms (HAPS), and drones. RFID systems may implement a communication technology such as RFID, which relies on electromagnetic fields to transmit data between a reader (or scanner) and a tag (or label). RFID tags can generally be categorized into three types: active, semi-passive, and passive.

As used herein, “a processor,” “at least one processor,” or “one or more processors” generally refer to a single processor configured to perform one or multiple operations or multiple processors configured to collectively perform one or more operations. In the case of multiple processors, performance of the one or more operations could be divided amongst different processors, though one processor may perform multiple operations, and multiple processors could collectively perform a single operation. Similarly, “a memory,” “at least one memory,” or “one or more memories” generally refer to a single memory configured to store data and/or instructions or multiple memories configured to collectively store data and/or instructions.