PATENT DOCUMENT

Publication Number: US-11828833-B2
Application Number: US-202117543374-A
Country: US
Kind Code: B2

Title: Systems and methods for object detection by radio frequency systems

Abstract:
Systems, methods, and devices are provided for detecting the presence of an object near an electronic device. A radio frequency (RF) system of an electronic device may include a first circuit that includes one or more transmission paths for transmitting a reference signal external to the electronic device. The RF system may include a second circuit that includes one or more receiving paths for receiving a reflection signal based on the reference signal. The RF system may also include a processor that may instruct the RF system to perform a comparison between the reference signal and the reflection signal, determine whether the object is in proximity based at least in part on whether comparison results exceed a comparison threshold, and decrease power output by the RF system below the comparison threshold.

Claims:
What is claimed is: 
     
       1. A millimeter wave radio frequency system, comprising:
 a first circuit, configured to transmit data over a first one or more frequency bands, the first circuit further configured to transmit a reference signal over a second one or more frequency bands outside the first one or more frequency bands; 
 a second circuit configured to receive a reflection signal in the second one or more frequency bands based on the reference signal; and 
 a processor configured to instruct the millimeter wave radio frequency system to
 perform a comparison between the reference signal and the reflection signal, 
 determine that an object is in proximity to the millimeter wave radio frequency system based on the comparison exceeding a comparison threshold, and 
 in response to determining that the comparison exceeds the comparison threshold, decrease power output of communications of the first circuit over the first one or more frequency bands. 
 
 
     
     
       2. The millimeter wave radio frequency system of  claim 1 , wherein the second one or more frequency bands comprise industrial, scientific, and medical (ISM) bands. 
     
     
       3. The millimeter wave radio frequency system of  claim 1 , wherein the millimeter wave radio frequency system is configured to communicate the reference signal during a measurement gap from communicating over the first one or more frequency bands. 
     
     
       4. The millimeter wave radio frequency system of  claim 1 , wherein the reference signal comprises industrial radar waveforms. 
     
     
       5. The millimeter wave radio frequency system of  claim 1 , wherein the first circuit comprises one or more transmission paths configured to transmit and process signals generated by the millimeter wave radio frequency system, the second circuit comprises one or more reception paths configured to receive and process signals transmitted by an external electronic device. 
     
     
       6. The millimeter wave radio frequency system of  claim 5 , wherein the first circuit comprises one or more additional reception paths and the second circuit comprises one or more additional transmission paths, and wherein the millimeter wave radio frequency system comprises a switch configured to control whether the second circuit receives the signals or transmits the signals. 
     
     
       7. The millimeter wave radio frequency system of  claim 5 , wherein the one or more transmission paths are configured to transmit the reference signal via a first polarization, and wherein the one or more reception paths are configured to receive the reflection signal via a second polarization. 
     
     
       8. The millimeter wave radio frequency system of  claim 1 , wherein the first one or more frequency bands comprise fifth generation new radio frequency bands. 
     
     
       9. The millimeter wave radio frequency system of  claim 1 , comprising a modem coupled to the first circuit and the second circuit, wherein the modem is configured to perform the comparison between the reference signal and the reflection signal. 
     
     
       10. The millimeter wave radio frequency system of  claim 1 , wherein the comparison threshold is associated with a level of energy absorption, and wherein the comparison comprises a cross-correlation measurement of the reference signal and the reflection signal. 
     
     
       11. The millimeter wave radio frequency system of  claim 1 , wherein in response to determining that the comparison is below the comparison threshold, maintain or increase power output. 
     
     
       12. The millimeter wave radio frequency system of  claim 1 , wherein the comparison threshold is based at least in part on a maximum permissible exposure (MPE) specification for millimeter wave (mmWave) systems, specific absorption rate (SAR) specification for sub-6 GHz systems, or any combination thereof. 
     
     
       13. A circuit, comprising:
 an antenna element configured to transmit and receive wireless signals; 
 one or more transmission paths coupled to the antenna element, the one or more transmission paths are configured to
 process a reference signal of a selected polarization, and 
 transmit the reference signal from an electronic device comprising the circuit using the selected polarization, the reference signal transmitted during a measurement gap of communicating the wireless signals, and 
 
 one or more receiving paths coupled to the antenna element, the one or more receiving paths are configured to receive a reflection signal based on the reference signal using the selected polarization; 
 wherein the circuit is configured to
 determine whether an object is in proximity to the electronic device based at least in part on a comparison between the reference signal and the reflection signal, and 
 in response to the object being in proximity to the electronic device, decrease power output by the circuit. 
 
 
     
     
       14. The circuit of  claim 13 , wherein the one or more transmission paths are configured to transmit the reference signal over an industrial, scientific, and medical (ISM) band. 
     
     
       15. The circuit of  claim 13 , wherein at least a first portion of the one or more transmission paths are configurable to transmit the reference signal and at least a second portion of the one or more transmission paths are configurable to not transmit the reference signal, and wherein at least a first portion of the one or more receiving paths are configurable to receive the reflection signal and at least a second portion of the one or more receiving paths are configurable to not receive the reflected signal. 
     
     
       16. The circuit of  claim 13 , wherein the measurement gap is defined by a standard for communicating the wireless signals. 
     
     
       17. The circuit of  claim 13 , comprising:
 one or more bi-directional couplers coupled to the one or more transmission paths and the antenna element, the one or more bi-directional couplers configured to transmit the reference signal and the reflection signal to one or more envelope detectors. 
 
     
     
       18. The circuit of  claim 17 , wherein the one or more envelope detectors are configured to generate an envelope signal for each signal transmitted to the one or more envelope detectors from the one or more bi-directional couplers, the one or more envelope detectors configured to digitize the envelope signals, as digitized envelope signals. 
     
     
       19. The circuit of  claim 18 , wherein determining whether the object is in proximity to the electronic device comprises comparing the digitized envelope signals of the reflection signal and the digitized envelope signals of the reference signal via cross-correlation. 
     
     
       20. A method, comprising:
 transmitting, via a communication circuitry, data over a first one or more frequency bands and a reference signal over a second one or more frequency bands outside the first one or more frequency bands; 
 receiving, via the communication circuitry, a reflection signal based on a reflection of the reference signal off an object; 
 comparing, via the communication circuitry, the reflection signal and the reference signal; 
 determining, via the communication circuitry, whether the object is within a pre-defined proximity to an electronic device comprising the communication circuitry; 
 in response to the object being within the pre-defined proximity, decreasing power output by the electronic device; and 
 in response to the object not being within the pre-defined proximity, increasing power output by the electronic device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/362,124, filed Mar. 22, 2019, entitled “SYSTEMS AND METHODS FOR OBJECT DETECTION BY RADIO FREQUENCY SYSTEMS,” the disclosure of which is incorporated herein by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     The present disclosure relates generally to radio frequency systems and, more particularly, to using the radio frequency system to detect nearby objects and adjusting system operations to comply with energy absorption (e.g., specific absorption rate (SAR), maximum permissible exposure (MPE)) specifications when the object is detected by the radio frequency system. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Electronic devices, such as smartphones and laptops, often include a radio frequency system to facilitate wireless communication of data with other electronic devices and/or networks. To facilitate the wireless communication, the radio frequency system may emit energy in the form of radio waves. In some cases, the emitted energy may be absorbed by an object (e.g., a human body) that is within proximity to the radio frequency system. The allowable amount of energy that may be absorbed by such an object may be regulated, and to ensure that these absorption specifications are met, the radio frequency system may lower energy (e.g., power) output when the object is nearby. However, traditional radio frequency systems may be incapable of detecting the presence of an object and thus, must output lower than maximum energy during all times of operation. Operating at a lower than maximum energy output may result in performance inefficiency of the radio frequency system. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     The present disclosure generally relates to adjusting radio frequency system operations when an object (e.g., a human body) is within proximity by using existing radio frequency system hardware as a radar to detect the presence of an object and modifying energy (e.g., power) output by the radio frequency system accordingly. Radio frequency systems of electronic devices may employ 5G New Radio (NR) millimeter-wave (mmWave) technology and/or one of sub-6 GHz technologies (e.g., 4G LTE, 5G NR sub-6 GHz, non-mmWave technologies, and the like). Such radio frequency systems must comply with regulations (e.g., maximum permissible exposure (MPE) or specific absorption rate (SAR), respectively) on the rate at which energy carried by wireless signals are absorbed by the human body. To comply with the MPE or the SAR depending on the radio frequency technology implemented, the radio frequency system may output lower than maximum output power when the human body is near the radio frequency system. However, in many cases, the radio frequency system may be incapable of detecting the presence of the nearby human body and thus, must output lower than maximum output power at nearly all operation times. In such instances, the performance and operational efficiency of the radio frequency system may be reduced. 
     To ensure compliance with the MPE or SAR while avoiding compromises on the radio frequency system performance, in some embodiments, existing radio frequency hardware may be implemented to detect the presence of the nearby human body, and the output of the radio frequency system may be adjusted accordingly. In some embodiments, the hardware may be implemented as a bi-static radar with multiple transmitting/receiving circuits (e.g., quads). A first quad of the bi-static radar may transmit a 5G NR signal of a first polarization to an external environment. A second quad of the bi-static radar may receive a reflection of the transmitted 5G NR signal using a second polarization. The reflected 5G NR signal, for example, may be generated when the transmitted 5G NR signal is reflected off the human body. The radio frequency system may perform a comparison between the transmitted 5G NR signal and the reflected 5G NR signal to determine whether the human body is within proximity to the device. In this example, based on the comparison, the radio frequency system may adjust its output power to meet the MPE. In some embodiments, when the sub-6 GHz technology is used, the radio frequency system may adjust its output power to meet the SAR. 
     In some embodiments, the hardware may be implemented as a mono-static radar. For example, the mono-static radar may transmit the 5G NR signal and receive the reflected 5G NR signal using a single transmitting/receiving quad and polarization. The mono-static radar may use circuit components, such as bi-directional couplers and envelope detectors, to facilitate transmitting and receiving the 5G NR signal using the single quad. Further, the radio frequency system may perform a comparison between the transmitted 5G NR signal and the reflected 5G NR signal to determine whether the human body is within proximity to the device. Based on the comparison, the radio frequency system may adjust its output power to meet the MPE. In some embodiments, when the sub-6 GHz technology is used, the radio frequency system may adjust its output power to meet the SAR. 
     Further, in some embodiments, the hardware may be implemented as a Body Detection Sensor operating in the 24 giga-hertz (GHz) band. In particular, multiple transmitting/receiving quads or a single transmitting/receiving quad may be used to detect the presence of the human body, in a manner similar to that of the bi-static and mono-static radars, respectively. For example, the first quad may use the existing 24 GHz band to transmit a chirp (e.g., non-5G NR impulse response) signal of a first polarization, and the second quad may receive the reflected chirp signal using a second polarization. As another example, a single quad may transmit the chirp signal and may receive a reflection of the chirp signal using a single polarity. The radio frequency system may perform a comparison between the transmitted chirp signal and the reflected chirp signal to determine whether the human body is within proximity to the device. Based on the comparison, the radio frequency system may adjust its output power to meet the MPE. In some embodiments, when the sub-6 GHz technology is used, the radio frequency system may adjust its output power to meet the SAR. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG.  1    is a block diagram of an electronic device with a radio frequency system, in accordance with an embodiment; 
         FIG.  2    is a front view of a hand-held device representing an example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  3    is a front view of another hand-held device representing another example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  4    is a perspective view of a notebook computer representing another example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  5    is a front view of a wearable electronic device representing another example of the electronic device of  FIG.  1   , in accordance with an embodiment; 
         FIG.  6    is a schematic of hardware of the radio frequency system of  FIG.  1    implemented as a bi-static radar to detect the presence of a human body, in accordance with an embodiment; 
         FIG.  7    is a schematic of the hardware of the radio frequency system of  FIG.  1    implemented as a mono-static radar to detect presence of the human body, in accordance with an embodiment; 
         FIG.  8    is a schematic of the hardware of the radio frequency system of  FIG.  1    implemented as a Body Detection Sensor operating in the 24 giga-hertz (GHz) band to detect the presence of the human body, in accordance with an embodiment; and 
         FIG.  9    is a flow chart of a process for adjusting operations of the radio frequency system of  FIG.  1    based at least in part on the detection of the human body by the radio frequency system of  FIG.  1   , in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     The present disclosure generally relates to radio frequency systems used to facilitate wireless communication of data between electronic devices and/or with a network. For example, the radio frequency system may wirelessly communicate data by transmitting wireless signals (e.g., radio waves) modulated in a manner representative of the data, for example, via a personal area network (e.g., Bluetooth network), a local area network (e.g., an 802.11x Wi-Fi network), and/or a wide area network (e.g., a 4G, 5G, or LTE cellular network). 
     In particular, the radio frequency system may implement millimeter-wave (mmWave) wireless communication technologies due to large amounts of available bandwidth in millimeter frequency bands that are capable of supporting high rates of information transfer. As an example, the radio frequency system may use Fifth-Generation New Radio millimeter-wave (e.g., 5G NR mmWave) wireless technology or 5G NR Sub-6 GHz (e.g., hereinafter “sub-6 GHz”) technology to facilitate better connection and more efficient data transfer between electronic devices. 
     Such radio frequency systems may emit energy in the form of radio waves (e.g., wireless signals) to facilitate data transfer. In some instances, the emitted energy may be absorbed by an object (e.g., a human body) that is within proximity to the radio frequency system. The rate at which the emitted energy may be absorbed is regulated by a Maximum Permissible Exposure (MPE) limit for 5G NR mmWave systems and by a Specific Absorption Rate (SAR) set for sub-6 GHz systems. In particular, for mmWave technologies, the wavelength of the radio frequency waves is small enough for the human body to be considered as part of a far-field of the electronic device and thus, MPE (e.g., electromagnetic field incident on an object&#39;s surface, such as human skin, in Watts/meter 2 ) may be used as an appropriate limit for emitted energy absorbed by an object. On the other hand, for sub-6 GHz technology, the wavelength of the radio frequency waves used is larger compared to that of the mmWave radio frequency waves and thus, the human body may be considered as part of a near-field of the electronic device. In such embodiments, the SAR (e.g., electromagnetic field through a volume, such as human tissue, or power absorbed per mass of volume in Watts/kilogram) may provide a better comparison limit for emitted energy absorbed by an object. 
     To comply with the MPE or SAR, the radio frequency system may output lower than maximum output energy (e.g., output power) when the human body is near the electronic device, such as a hand-held device. It should be noted that while this disclosure contemplates compliance with the MPE or SAR for nearby human bodies, any object or number of objects that may absorb emitted radio wave energy may be considered. Further, it should be appreciated that the following techniques may be applicable to any mmWave system architecture. 
     In some cases, specialized circuitry (e.g., 60 GHz Body Proximity Sensor) may be implemented in the radio frequency system to detect the presence of the nearby human body. However, implementation of such specialized circuitry may be technically challenging and costly. For example, the specialized circuitry may not be compatible with the mmWave circuitry and the specialized circuitry may increase silicon area consumed per radio frequency system chip. 
     Thus, in many instances, the radio frequency system may not have the capability for detecting the presence of the nearby human body. This may result in the radio frequency system outputting lower than maximum output power during all operating (e.g., online) times to ensure compliance with the MPE or SAR at all times. However, outputting wireless signals with lower than maximum output power during online operation may reduce the performance of the radio frequency system. Accordingly, the present disclosure provides systems and techniques for detecting the presence of the nearby human body and modifying system operations to comply with the MPE for mmWave and the SAR for sub-6 GHz systems without compromising system performance. 
     In particular, the hardware of the radio frequency system may be implemented to detect the presence of the nearby human body. In some embodiments, the radio frequency system may employ hardware tailored to better suit wireless transmission via mmWave communication technology, such as the 5G NR mmWave technology. As an example, an electronic device using 5G wireless technology may employ multiple transmission (TX) paths (e.g., chains), multiple reception (RX) paths, and multiple antenna elements. The TX paths, RX paths, and antenna elements may be divided into groups (e.g., quads) that together form a phased array antenna to transmit and/or receive wireless signals via particular signal polarizations and via beams. The beams may communicate information in a particular direction while reducing data loss that may occur over the air at 5G frequencies. 
     With the foregoing in mind, in some embodiments, the hardware of the radio frequency system may be implemented as a bi-static radar. One or more TX paths within a first quad may transmit a 5G NR signal of a first polarization to an environment external to the electronic device. One or more RX paths within a second quad may detect a reflection of the transmitted 5G NR signal using a second polarization. The reflected 5G NR signal may be generated when the transmitted 5G NR signal is reflected off of the nearby human body. The radio frequency system may perform a cross-correlation measurement of the transmitted 5G NR signal and the reflected NR signal to determine whether the human body is within proximity to the electronic device. Based on the cross-correlation measurement, the radio frequency system may reduce emitted output power to comply with the MPE or the SAR when the human body is detected nearby. 
     Further, in some embodiments, the hardware of the radio frequency system may be implemented as a mono-static radar. For example, the mono-static radar may transmit the 5G NR signal and receive the reflected 5G NR signal using a single transmitting/receiving quad and polarization. The mono-static radar may include a bi-directional coupler in the TX path of the single quad as well as envelope detectors associated with each of the TX paths of the single quad. The bi-directional coupler and envelope detectors may facilitate detection of the reflected 5G NR signal. The radio frequency system may analyze the phase delay difference between the transmitted 5G NR signal and the reflected 5G NR signal. The radio frequency system may subsequently perform a cross-correlation on the transmitted 5G NR signal and the reflected 5G NR signal to determine the presence of the nearby human body. Based on the cross-correlation measurement, the radio frequency system may reduce emitted output power to comply with the MPE or the SAR when the human body is detected nearby. 
     Additionally or alternatively, in some embodiments, the hardware of the radio frequency system may be implemented as a Body Detection Sensor operating in the 24 giga-hertz (GHz) industrial, scientific, medical (ISM) band (e.g., 24-24.25 GHz). Using either multiple quads and polarizations or a single quad and polarization, the 24 GHz sensor may transmit a chirp (e.g., non-5G NR impulse response) signal via the 24 GHz ISM band and may detect a reflection of the transmitted chirp signal. Further, the radio frequency system may perform a cross-correlation of the transmitted chirp signal and the reflected chirp signal to determine the presence of the nearby human body. Based on the cross-correlation result, the radio frequency system may reduce emitted output power to comply with the MPE or the SAR when the human body is detected nearby. Further, the radio frequency system may using the 24 GHz sensor technique during measurement gaps (e.g., periods during which the electronic device does not have up-link or down-link transmissions scheduled) defined by 3 rd  Generation Partnership Project (3GPP) 5G NR standard. Additional details with regard to the detection of the nearby human body using the embodiments described herein are detailed below with reference to  FIGS.  1 - 9   . 
     As such, an embodiment of an electronic device  10  that includes a radio frequency system  12  is shown in  FIG.  1   . As will be described in more detail below, the electronic device  10  may be any suitable electronic device, such as a computer, a mobile phone, a portable media device, a tablet, a television, a virtual-reality headset, a vehicle dashboard, and the like. Thus, it should be noted that  FIG.  1    is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in an electronic device  10 . 
     In the depicted embodiment, the electronic device  10  includes the radio frequency system  12 , one or more input devices  14 , local memory  16 , a processor core complex  18 , one or more main memory storage devices  20 , a power source  22 , one or more input/output ports  24 , and an electronic display  26 . The various components described in  FIG.  1    may include hardware elements (e.g., circuitry), software elements (e.g., a tangible, non-transitory computer-readable medium storing instructions), or a combination of both hardware and software elements. It should be noted that the various depicted components may be combined into fewer components or separated into additional components. For example, the local memory  16  and a main memory storage device  20  may be included in a single component. 
     As depicted, the processor core complex  18  is operably coupled with local memory  16  and the main memory storage device  20 . Thus, the processor core complex  18  may execute instruction stored in local memory  16  and/or the main memory storage device  20  to perform operations, such as instructing the radio frequency system  12  to communicate with another electronic device and/or a network. As such, the processor core complex  18  may include one or more general purpose microprocessors, one or more application specific processors (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof. 
     In addition to the instructions, the local memory  16  and/or the main memory storage device  20  may store data to be processed by the processor core complex  18 . Thus, in some embodiments, the local memory and/or the main memory storage device  20  may include one or more tangible, non-transitory, computer-readable mediums. For example, the local memory  16  may include random access memory (RAM) and the main memory storage device  20  may include read only memory (ROM), rewritable non-volatile memory such as flash memory, hard drives, optical discs, and the like. 
     As depicted, the processor core complex  18  is also operably coupled with the I/O ports  24 . In some embodiments, the I/O ports  24  may enable the electronic device  10  to interface with other electronic devices. For example, a portable storage device may be connected to an I/O port  24 , thereby enabling the processor core complex  18  to communicate data with a portable storage device. 
     Additionally, as depicted, the processor core complex  18  is operably coupled to the power source  22 . In some embodiments, the power source  22  may provide power to one or more components in the electronic device  10 , such as the processor core complex  18  and/or the radio frequency system  12 . Thus, the power source  22  may include any suitable energy source, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. 
     Furthermore, as depicted, processor core complex  18  is operably coupled with the input devices  14 . In some embodiments, the input device  14  may facilitate user interaction with the electronic device  10 , for example, by receiving user inputs. Thus, the input devices  14  may include a button, a keyboard, a mouse, a trackpad, and/or the like. Additionally, in some embodiments, the input devices  14  may include touch-sensing components in the electronic display  26 . In such embodiments, the touch-sensing components may receive user inputs by detecting occurrence and/or position of an object touching the surface of the electronic display  26 . 
     In addition to enabling user inputs, the electronic display  26  may display image frames, such as a graphical user interface (GUI) for an operating system, an application interface, a still image, or video content. As depicted, the electronic display  26  is operably coupled to the processor core complex  18 . In this manner, the electronic display  26  may display image frames based at least in part on image data received from the processor core complex  18 . 
     As depicted, the processor core complex  18  is also operably coupled with the radio frequency system  12 . As described above, the radio frequency system  12  may facilitate wireless communication of data with another electronic device and/or a network. For example, the radio frequency system  12  may enable the electronic device  10  to communicatively couple to a personal area network (PAN), such as a Bluetooth network, a local area network (LAN), such as an 802.11x Wi-Fi network, and/or a wide area network (WAN), such as a fourth-generation wireless technology (4G), 5G, or LTE cellular network. In other words, the radio frequency system  12  may enable wirelessly communicating data using various communication protocols and/or at various output powers (e.g., strength of transmitted analog wireless signals). 
     As mentioned previously, the radio frequency system  12  may be tailored to better support wireless transmission via certain wireless technologies. In one embodiment, the radio frequency system  12  may include hardware and/or software that supports mmWave communications on high frequency bands (e.g., 10-400 GHz), such as 5G NR mmWave technology or sub-6 GHz technologies. Thus, in some embodiments, the radio frequency system  12  may include one or more antenna elements  28 , a mmWave module (e.g., radio frequency integrated circuit (RFIC))  30  that includes one or more quads  32  associated with the antenna elements  28 , and transceiver circuitry (e.g., filters, power dividers, and the like) plus modem  33 . The one or more antenna elements  28  may facilitate receiving and/or transmitting wireless signals using the 5G NR mmWave technology. 
     Further, the radio frequency system  12  may include the mmWave module  30 , which in turn includes one or more quads  32  that further facilitate wireless signal transmission and reception. For example, each of the quads  32  may be electrically coupled to one or more antenna elements  28  and may include one or more RX paths and TX paths to form a phased array antenna that transmits and/or receives wireless signals via beams. The beams may be formed by constructive/destructive interference of signals transmitted and/or received by each antenna  28 . Additionally, and as discussed in more detail below, the quads  32  may be used to detect the presence of a nearby object, for example, to adjust radio frequency system  12  operations to meet maximum permissible exposure (MPE) for mmWave systems or specific absorption rate (SAR) specifications for sub-6 GHz systems. In particular, the one or more quads  32  may transmit a reference signal to an external environment and may detect a reflection of the reference signal. The radio frequency system  12  may compare a strength of the reference signal and a strength of the reflected signal to determine whether the results of the comparison exceed a comparison threshold that correlates to the specific absorption rate. Based on the determination, the radio frequency system  12  may adjust energy output by the radio frequency system to below the comparison threshold. 
     Additionally, the radio frequency system  12  may include the transceiver circuitry and modem  33  that further processes the wireless signals to filter noise, amplify signals, and the like. By way of example, the transceiver circuitry and modem  33  may facilitate performing a cross-correlation measurement on a received signal and a transmitted signal. 
     As described above, the electronic device  10  may be any suitable electronic device. To help illustrate, one example of a suitable electronic device  10 , specifically a handheld electronic device  10 A, is shown in  FIG.  2   . In some embodiments, the handheld electronic device  10 A may be a portable phone, a media player, a personal data organizer, a handheld game platform, and/or the like. For example, the handheld electronic device  10 A may be a smart phone, such as any iPhone® model available from Apple Inc. 
     As depicted, the handheld electronic device  10 A includes an enclosure  34  (e.g., housing). In some embodiments, the enclosure  34  may protect interior components from physical damage and/or shield them from electromagnetic interference. Thus, a radio frequency system  12  (not shown) may also be enclosed within the enclosure  34  and internal to the handheld electronic device  10 A. In some examples, the enclosure  34  may operate as part of the one or more antenna elements  28  of the radio frequency system  12 . 
     Additionally, as depicted, the enclosure  34  may surround the electronic display  26 . In the depicted embodiment, the electronic display  26  is displaying a graphical user interface (GUI)  36  having an array of icons  38 . By way of example, when an icon is selected either by an input device  14  or a touch sensing component of the electronic display  26 , an application program may launch. 
     Furthermore, as depicted, input devices  14  open through the enclosure  34 . As described above, the input devices  14  may enable a user to interact with the handheld electronic device  10 A. For example, the input devices  14  may enable the user to activate or deactivate the handheld electronic device  10 A, navigate a user interface to a home screen, navigate a user interface to a user-configurable application screen, activate a voice-recognition feature, provide volume control, and/or toggle between vibrate and ring modes. As depicted, the I/O ports  24  also open through the enclosure  34 . In some embodiments, the I/O ports  24  may include, for example, a multi-function connector port (e.g., Lightning port) to connect to external devices. 
     To further illustrate, another example of a suitable electronic device  10 , specifically a tablet electronic device  10 B is shown in  FIG.  3   . For example, the tablet electronic device  10 B may be any iPad® model available from Apple Inc. A further example of a suitable electronic device  10 , specifically a computer  10 C, is shown in  FIG.  4   . For example, the computer  10 C may be any Macbook® or iMac® model available from Apple Inc. Another example of a suitable electronic device  10 , specifically a watch  10 D, is shown in  FIG.  5   . For example, the watch  10 D may be any Apple Watch® model available from Apple Inc. 
     As depicted, the tablet electronic device  10 B, the computer  10 C, and the watch  10 D each also include an electronic display  26 , input devices  14 , I/O ports  24 , and an enclosure  34 . Thus, in some embodiments, the enclosure  34  may enclose a radio frequency system  12  in the tablet electronic device  10 B, the computer  10 C, and/or the watch  10 D to facilitate wireless communication of data with other electronic devices and/or a network. 
     As previously mentioned, the hardware of the radio frequency system  12  may be tailored to support particular wireless technologies, such as mmWave communication technology. In some embodiments, the radio frequency system  12  may implement phased array antenna(s), which includes multiple antenna elements and multiple quads of TX paths and RX paths. Such hardware may facilitate transmission and/or reception of wireless signals according to mmWave communication technology. To ensure compliance with the MPE or the SAR without compromising on the performance of the radio frequency system  12 , this hardware may be implemented as a radar/sensor that may detect the presence of the nearby human body in a cost-effective and easily implementable manner. 
     To help illustrate, an example the radio frequency system hardware implemented as a bi-static radar  600  is shown in  FIG.  6   , in accordance with an embodiment. As depicted, the bi-static radar  600  may include multiple antennas  602 , multiple quads  604 A-B, one or more cables/traces  606 , transceiver circuitry  608 , and other radio frequency components used to transmit and/or receive wireless signals. It should be appreciated that the bi-static radar  600  may include a greater or fewer number of radio frequency components than shown. 
     Briefly, the bi-static radar  600  may include the mmWave module  30  with multiple quads  604 A-B that are each coupled to one or more antennas  602  (e.g., the antenna element  28 ). In particular, each antenna  602  may be coupled to a TX/RX chain pair  610  of the quads  604 A-B and may transmit wireless signals to or from the TX/RX chain pair  610 . For example, the quad  604 B may be coupled to the one or more antennas  602  to form a phased array antenna that transmits wireless signals via beams formed by constructive/destructive interference of signals transmitted by each antenna  602 . 
     Each of the TX/RX chain pair  610  may include a TX path  612  and a RX path  614  that together facilitate transmission and/or reception of wireless signals, such as those communicated between electronic devices  10  using mmWave communication technology or any other suitable communication protocol. The TX path  612  and the RX path  614  may be alternatively coupled to the respective antenna  602  via a switch  616 . For example, the switch  616  may couple to the TX path  612  to enable transmission of the wireless signals to the respective antenna  602 . Alternatively, in some embodiments, the respective antenna  602  may be coupled directly to a bi-directional coupler  618  in the TX path  612  to enable transmission and reception of the wireless signals. 
     In some embodiments, the RX path  614  may amplify a received wireless signal using an amplifier  620 , such as RX Low-Noise Amplifier (LNA) or a RX variable-gain Low-Noise Amplifier (LNA). The amplifier  620  may amplify an input RX signal received via the respective antenna  602  without degrading signal-to-noise ratio (SNR) of the input RX signal (e.g., amplifies power of both the wireless signal and input noise). The amplified signal may pass through a phase shifter  622  that may modify phase information programmed into the input RX signal during transmission from a different electronic device  10  that generated the input RX signal. The input RX signal may be further amplified by a RX variable-gain amplifier (VGA)  624 , for example, to compensate for signal strength loss between the respective antenna  602  and the RX VGA  624 . 
     Each of the RX paths  614  in the quad (e.g.,  604 A) may subsequently transmit the pre-processed input RX signals to a second VGA  626  coupled to each of the TX/RX chain pairs  610 . The second VGA  626  may provide additional amplification of the input RX signal in preparation for further processing by the transceiver  608  and/or the modem  644 . Although each of the quads  604 A-B are shown to include four TX/RX chain pairs  610  for each frequency band (e.g., 28 GHz, 39 GHz) used by the 5G NR mmWave architecture, a greater or fewer number of TX/RX chain pairs  610  may be included in each quad  604 A-B for each of the frequency bands used. 
     The input RX signal may then be passed to power dividers (e.g., radio frequency splitters 1:2, radio frequency splitters 1:4)  628 A and one or more frequency filters  630 A, such as a bandpass filter and/or low pass filter. The power dividers  628 A and frequency filters  630 A may combine filter the input RX signal to facilitate further processing by the radio frequency system  12 . Once processed by the mmWave module  30 , the input RX signal may be transmitted to the transceiver  608  via traces  606 A-B (collectively, “ 606 ”), which act as interfaces between the transceiver  608  and the quads  604 A-B. The traces  606  may be designated as horizontal polarization traces or vertical polarization traces, such that either horizontal or vertical polarised signals (e.g., electromagnetic waves with the electric field in the horizontal plane or vertical plane, respectively) are picked up and transmitted via the traces  606 . For example, the trace  606 A may be implemented to transmit signals of polarization 1, such as horizontal polarization, while the trace  606 B may be implemented to transmit signals of polarization 0, such as vertical polarization, or vice versa. In some embodiments, the polarization of each trace  606  may be configurable. 
     The transceiver  608  may include additional radio frequency processing blocks. For example, the traces  606  may transmit the input RX signal to additional power dividers (e.g.,  632 A) and to an additional set of frequency filters (e.g.,  634 A) dedicated to processing the input RX signal. Additional TX/RX paths  636 A may be coupled to the frequency filters  634 A and may transmit the input RX signal for further post-processing. The additional TX/RX paths  636 A may be implemented to transmit signals of a particular frequency band (e.g., 28 GHz, 39 GHz). It should be appreciated that the radio frequency processing blocks may include other varieties of processing circuitry, such as a down-converter. 
     In addition to receiving wireless signals, the radio frequency system  12  may also transmit wireless signals to other electronic devices. As an example, the modem  644  may generate a reference output TX signal that is pre-processed by processing blocks of the transceiver  608 , such as a digital pre-distortion processing block, filters  634 B, and power dividers  632 B. The output TX signal may be subsequently transmitted to the mmWave module  30  via the trace (e.g.,  608 B) coupled to the transmitting quad (e.g.,  604 B). 
     The mmWave module  30  may perform additional filtering and power splitting operations via the filters  630 B and the power dividers  628 B. Further, based on the frequency of the output TX signal, the output TX signal may be transmitted to an appropriate second VGA  638  of the mmWave module  30  for amplification before processing by the TX path  612 . Once amplified, the output TX signal may be further amplified by a TX VGA  640  of the TX path  612  to compensate for expected strength loss from the connections and components of the TX path  612 . 
     The output TX signal may then be modulated (e.g., phase shifted) using the phase shifter  622 . The phase shifter  622  may work with other phase shifters of the other TX/RX path pairs  610  to form beams of wireless signals that may be steered in a particular direction, such as towards another electronic device  10 . Although a single phase shifter  622  is shown for both the TX path  612  and the RX path  614 , it should be appreciated that each TX path  612  and RX path  614  may include their own dedicated phase shifter  622 . 
     Prior to transmission of the output TX signal to the external environment, a power amplifier  642  may amplify the output TX signal to ensure that the output TX signal has sufficient range, for example, to reach the target electronic device  10 . Once amplified, the output TX signal may be transmitted to the respective antenna  602 , either through the switch  616  or through the bi-directional coupler  618 . 
     As previously discussed, the hardware may be implemented as the bi-static radar  600  to detect the presence of objects (e.g., a human body) near the electronic device  10 . In particular, the bi-static radar  600  may use a first quad (e.g.,  604 B) to transmit the reference output TX signal as a beam to the external environment. In particular, one or more TX paths  612  of the first quad (e.g.,  604 B) may process and transmit a 5G NR signal (e.g., TX 5G NR signal) generated by the modem  644 . The TX 5G NR signal  646  may be generated with a frequency allocated to the 5G NR protocol. For example, the TX 5G NR signal  646  may be of a 28 GHz frequency band (e.g., 5G NR band n257, n258, n261) or of a 39 GHz (e.g., 5G NR band n260) frequency band, in accordance with the 3GPP protocol for Discrete Fourier Transform-spread-Orthogonal Frequency Division Multiplexing (DFT-s-OFDM) or Cyclic-Prefix OFDM (CP-OFDM). This may ensure that the bi-static radar  600  may function without affecting regular 5G NR cellular communications. Additionally, the TX 5G NR signal  646  may be of a first polarization, such as the horizontal polarization of trace  606 B. 
     When the object, such as a human body  648 , is within proximity to the radio frequency system  12 , the TX 5G NR signal  6464  may be reflected back by the human body  648 . Generally, the larger the object, the greater the strength of the reflected signal. Further, the closer the object to the radio frequency system  12 , the greater the strength of the reflected signal. 
     A second quad (e.g.,  604 A) may receive the reflected 5G NR signal (e.g., RX 5G NR signal)  650 . In particular, the one or more RX paths  614  of the second quad (e.g.,  604 A) may receive the RX 5G NR signal  650  via the first polarization. However, the one or more RX paths  614  may transmit the RX 5G NR signal  650  back to the transceiver  608  using a second polarization, such as the vertical polarization of trace  606 A. 
     Once the RX 5G NR signal  650  has been received by the transceiver  608 , the transceiver  608  may transmit the RX 5G NR signal  650  to the modem  644 . The modem  644  may perform a post-processing comparison between the TX 5G NR signal  646  it previously generated and the received RX 5G NR signal  650 . The comparison may involve performing a cross-correlation of the RX 5G NR signal  650  and the TX 5G NR signal  646 , which may generate a spectrum that reveals whether an object is present near the radio frequency system  12 . For example, close and narrow peak(s) may reveal that the object is within proximity. In other words, the object is within an unacceptable distance threshold for the amount of output power being emitted by the radio frequency system  12 . In some embodiments, the distance threshold for the amount of output power may be determined based on the MPE or the SAR. Once the radio frequency system  12  determines that an object is within proximity, the radio frequency system  12  may adjust output power to comply with the MPE or the SAR specifications (e.g., reduce output power to meet an energy absorption threshold). 
     By implementing the hardware as the bi-static radar  600 , this technique for detecting the presence of the object may have better dynamic range. In particular, the RX paths  614  used to detect the RX 5G NR signal  650  may have enhanced signal sensitivity without using additional amplifiers and thus, increased ability to detect the RX 5G NR signal  650 , even if the RX 5G NR signal  650  is relatively weak (e.g., due to reflection off of a relatively distant object). Further, the detection sensitivity may be increased when multiple RX paths  614  are used to detect the RX 5G NR signal  650 . Additionally, to increase signal-to-noise ratio (SNR) of the RX 5G NR signal  650  and the TX 5G NR signal  646 , all of the available TX paths  612  and the RX paths  614  may be used to transmit and receive the 5G NR signal. 
     The radio frequency hardware may be additionally or alternatively implemented as a mono-static radar  700  that may detect the presence of the nearby object, as shown in  FIG.  7    in accordance with an embodiment. The hardware of the mono-static radar  700  may have similar functionality as the hardware of the bi-static radar  600 . For example, the multiple RX paths  614  and multiple TX paths  612  of the mmWave module  30  may facilitate transmission and reception of wireless signals, the transceiver  608  may perform processing operations on the transmitted and received signals, and the modem  644  may compare the transmitted and received signals to detect nearby objects. 
     However, the mono-static radar  700  may operate in a different manner than the bi-static radar  600 . In particular, the mono-static radar  700  may use a single quad (e.g.,  604 B), rather than multiple quads  604 A-B, to determine the presence of the nearby human body. For example, one or more TX paths  612  of the single quad (e.g.,  604 B) may process and transmit a 5G NR signal (e.g., TX 5G NR signal)  702  generated by the modem  644  and of a frequency allocated to the 5G NR protocol. For example, the TX 5G NR signal  702  may be of a 28 GHz frequency band (e.g., 5G NR band n257, n258, n261) or of a 39 GHz (e.g., 5G NR band n260) frequency band, in accordance with the 3GPP protocol for DFT-s-OFDM or CP-OFDM. This may ensure that the mono-static radar  700  may function without affecting regular 5G NR cellular communications. Additionally, the TX 5G NR signal  702  may be polarized, such as the horizontal polarization of trace  606 B. 
     The TX 5G NR signal  702  may be transmitted to the respective antenna  602  via the bi-directional coupler  618  and eventually to the external environment by the respective antenna  602 . When the external environment includes an object, such as a human body  704 , near the radio frequency system  12 , the TX 5G NR signal  702  may be reflected by the human body  704 . 
     The reflected 5G NR signal (e.g., RX 5G NR signal)  706  may be detected by the antenna element  28  (e.g., one or more antennas  602 ) of the single quad (e.g.,  604 B). During detection of the RX 5G NR signal  706 , the one or more antennas  602  may be coupled to the TX path  612 . In some embodiments, to transmit the RX 5G NR signal  706  to the transceiver  608  and the modem  644  using the same transmitting polarization, the mono-static radar  700  may use the bi-directional coupler  618  in each of the TX path  612 , the envelope detector(s)  708 , and the ADC  710 . 
     In particular, the bi-directional coupler  618  may be coupled to a respective envelope detector  708  associated with a respective TX path  612 . The bi-directional coupler  618  of a receiving RX path  614  may transfer a portion of the RX 5G NR signal  706  to the envelope detector  708 . The bandwidth of the envelope detector  708  may allow the envelope detector  708  to recover an envelope signal of the RX 5G NR signal  706  as opposed to other signal recover detectors, such as root-mean-square (RMS) detectors. The envelope detector  708  may be coupled to the ADC  710 , which may generate a digital representation of the RX envelope signal. Once digitized, the digital representation may be transmitted to the transceiver  608  and to the modem  644  for post-processing. 
     As previously described, the modem  644  may perform a post-processing comparison between the TX 5G NR signal  702  and the RX 5G NR signal  706 . In particular, the modem  644  may have the TX 5G NR signal  702  stored from the generation of the TX 5G NR signal  702  and may also receive the digitized RX envelope signal. Additionally or alternatively, the modem  644  may also receive a digitized TX envelope signal that is generated in a similar manner at the digitized RX envelope signal. The modem  644  may subsequently determine a phase difference (e.g., delay between the TX envelope signal and the RX envelope signal) between the digitized envelope signals and may perform a cross-correlation on the digitized envelope signals. The cross-correlation may generate a spectrum that may reveal whether the object is present near the radio frequency system  12 . For example, close and narrow peak(s) may reveal that the object is within proximity. In other words, the object is within an unacceptable distance threshold for the amount of output power being emitted by the radio frequency system  12 . In some embodiments, the distance threshold for the amount of output power may be determined based on the MPE or the SAR. Once the radio frequency system  12  determines that an object is within proximity, the radio frequency system  12  may adjust output power to comply with the MPE or the SAR specifications (e.g., reduce output power). 
     By implementing the hardware as the mono-static radar  700 , this technique for detecting the presence of the object may be independent of polarization effects on the TX 5G NR signal  702  and the RX 5G NR signal  706  since only a single quad (e.g.,  604 B) and a single polarized trace (e.g.,  606 B) are used. Further, to increase signal-to-noise ratio (SNR) of the TX 5G NR signal  702  and the RX 5G NR signal  706 , multiple TX paths  612  and RX paths  610  may be used to transmit and receive the 5G NR signal. Furthermore, the bi-directional coupler  618 , envelope detector  708 , and ADC  710  may enable measurement of both the TX 5G NR signal  702  and the RX 5G NR signal  706  without relying on use of the RX paths  614 . 
     Additionally or alternatively, the hardware of the radio frequency system  12  may be implemented as a specialized Body Detection Sensor operating in the 24 giga-hertz (GHz) band (e.g., 24 GHz sensor)  800 , as shown in  FIG.  8    in accordance with an embodiment. The hardware of the 24 GHz sensor  800  may have similar functionality as the hardware of the bi-static radar  600 . For example, the multiple RX paths  614  and multiple TX paths  612  of two quads  604 A-B in the mmWave module  30  may facilitate transmission and reception of wireless signals. Further, the transceiver  608  may perform processing operations the transmitted and received signals, and the modem  644  may compare the transmitted and received signals to detect nearby objects. 
     However, the 24 GHz sensor  800  may operate using a chirp signal rather than a 5G NR signal. In particular, the mmWave module  30  and the antennas  602  may include circuitry that can transmit, receive, and process wireless signals between the frequencies 24 to 24.25 GHz. The modem  644  may generate a chirp signal (e.g., non-5G NR impulse response signal) that may be transmitted to a first quad (e.g.,  604 B) using a first polarization and subsequently to the external environment. The chirp signal may be transmitted during measurement gaps (e.g., 10-80 ms gap during which an electronic device  10  is not transmitting or receiving communication) defined by the 3GPP 5G NR standard. 
     The transmitted chirp signal  802  may be reflected off of a nearby object, such as a human body  804 . The reflected chirp signal  806  may be received by one or more TX paths  164  of the second quad (e.g.,  604 A), which may be subsequently relayed back to the transceiver  608  and to the modem  644  using a second polarization. As previously described, the modem  644  may perform a post-processing comparison between the TX chirp signal  802  and the RX chirp signal  806 . In particular, the modem  644  may perform a cross-correlation of the digitized TX envelope signal and the digitized RX envelope signal. The cross-correlation may yield a spectrum that reveals whether the object is present near the radio frequency system  12 . For example, close and narrow peak(s) may reveal that the object is within proximity. In other words, the object is within an unacceptable distance threshold for the amount of output power being emitted by the radio frequency system  12 . In some embodiments, the distance threshold for the amount of output power may be determined based on the MPE or the SAR. Once the radio frequency system  12  determines that an object is within proximity, the radio frequency system  12  may adjust output power to comply with the MPE or the SAR specifications (e.g., reduce output power). 
     By implementing the hardware as the 24 GHz sensor  800 , this technique may enable flexibility in detecting the presence of the object. For example, a chirp signal used in industrial radar applications may be used instead of a 5G NR signal due to the use of a 24 GHz band outside of the 5G radio bands. Thus, this technique may also be compatible with sub-6 GHz technologies. Additionally, because the chirp signal may be transmitted during measurement gaps defined by the 3GPP 5G NR standard, this technique may not affect the 5G NR cellular communications. 
     Further, it should be appreciated that the 24 GHz sensor  800  may operate in a manner similar to that of the mono-static radar  700 . For example, the 24 GHz sensor  800  may use a single quad (e.g.,  604 B) and single polarization to transmit and receive the chirp signal. The 24 GHz sensor  800  may also use the bi-directional coupler  618 , the envelope detectors  708 , and the ADC  710  to transmit digitized, envelope signals of the transmitted and reflected chirp signals to the modem  644 . By implementing the 24 GHz sensor  800  in a manner similar to that of the mono-static radar  700 , the technique may be independent of polarization effects on the transmitted and reflected chirp signals. 
     A process  900  for adjusting operations of the radio frequency system  12  based at least in part on the detection of the object is described in  FIG.  9   , in accordance with an embodiment. While process  900  is described according to a certain sequence, it should be understood that the present disclosure contemplates that the described steps may be performed in different sequences than the sequence illustrated, and certain described steps may be skipped or not performed altogether. In some embodiments, the process  900  may be implemented at least in part by executing instructions stored in a tangible, non-transitory, computer-readable medium, such as the memory  20 , using processing circuitry, such as the processor core complex  18  or a separate controller designated for the radio frequency system. Additionally or alternatively, the process  900  may be implemented at least in part by circuit connections and/or control logic implemented in an electronic device  10 . 
     Generally, the process  900  may be initiated by configuring the radio frequency hardware as a bi-static radar  600 , a mono-static radar  700 , or a 24 GHz sensor  800  (process block  902 ). In particular, the processor core complex  18  may instruct the mmWave RFIC hardware to use a single quad (e.g.,  604 A) or multiple quads  604 A-B implement either the radar configuration or the sensor configuration. The processor core complex  18  may instruct the mmWave module  30  hardware to use a single quad (e.g.,  604 A) or multiple quads  604 A-B. The processor core complex  18  may then instruct the radio frequency system  12  to transmit the selected signal to the external environment (process block  904 ). For example, one or more of the TX paths  612  may process and transmit the selected signal. The radio frequency system  12  may subsequently receive a reflection of the transmitted signal when the transmitted signal is reflected of the nearby object (process core complex  906 ). 
     Furthermore, the processor core complex  18  may instruct the modem  644  to perform a comparison between the transmitted signal and the reflected signal (process block  908 ). For example, the modem  644  may perform the cross-correlation measurement on the transmitted signal and the reflected signal. Once the comparison is complete, the electronic device  10  may determine whether the object is within proximity of the radio frequency system  12  (decision block  910 ). That is, the spectrum generated from the cross-correlation measurement may be used to determine whether the object is nearby. The cross-correlation measurements may be compared to a comparison threshold correlated to the MPE or the SAR specifications. When it is determined that the object is nearby (e.g., the comparison results exceed the comparison threshold), the power output by the radio frequency system  12  may be decreased to meet the MPE or the SAR (process block  912 ). If the object is not within proximity, then the radio frequency system  12  may increase or maintain the power output of the radio frequency system  12  (process block  914 ). 
     By employing the techniques described above, the radio frequency system  12  may detect the presence of the nearby object and adjust system  12  operations to meet the MPE for mmWave operations or the SAR for the sub-6 GHz operations. Further, the present techniques provide object detection using existing radio frequency circuitry rather via dedicated radar circuitry (e.g., 60 GHz body proximity sensor radar) which may increase silicon area if integrated in the radio frequency circuitry. Additionally, the present techniques provide flexibility in the dynamic range offered during detection by varying the number of TX paths  612  and/or RX paths  614  used to transmit and receive the signals, respectively. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20211206
Publication Date: 20231128
Grant Date: 20231128
Priority Date: 20190322
Inventors: CETINONERI, Berke
SARKAS, IOANNIS
YU, Qishan
Assignee: APPLE INC
CPC Classifications: [{"code": "G01S13/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S7/024", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/03", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S13/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S7/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/006", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/343", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/03", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/024", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/003", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 72514049