PATENT DOCUMENT

Publication Number: US-11265100-B2
Application Number: US-201916662582-A
Country: US
Kind Code: B2

Title: Error vector magnitude requirement negotiation for ranging operation

Abstract:
Some embodiments of this disclosure include apparatuses and methods for implementing a requirement negotiation for an error vector magnitude (EVM) (or other metrics for measuring transmission signal quality) for ranging and/or positioning operation(s). Some embodiments relate to an electronic device including a transceiver and one or more processors communicatively coupled to the transceiver. The one or more processors transmit, during a negotiation phase of a ranging operation, an initial request frame to a second electronic device, wherein the initial request frame comprises a first indication of an error vector magnitude (EVM) requirement. The one or more processors receive an initial response frame from the second electronic device and determine a second indication of the EVM requirement based at least in part on the received initial response frame. The one or more processors implement a measurement phase of the ranging operation in accordance with the second indication of the EVM requirement.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a transceiver configured to communicate over a wireless network; and 
 one or more processors communicatively coupled to the transceiver and configured to:
 transmit, during a negotiation phase of a ranging operation, an initial request frame to a second electronic device, wherein the initial request frame comprises a first indication of an error vector magnitude (EVM) requirement for a first measurement frame to be transmitted from the second electronic device to the electronic device; 
 receive an initial response frame from the second electronic device; 
 determine a second indication of the EVM requirement for the first measurement frame based at least in part on the received initial response frame; and 
 implement a measurement phase of the ranging operation in accordance with the second indication of the EVM requirement. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein:
 the first indication of the EVM requirement comprises a first EVM level requested by the electronic device, and 
 the second indication of the EVM requirement comprises a value set in an indication field of the initial response frame representing an acceptance of the first EVM level by the second electronic device. 
 
     
     
       3. The electronic device of  claim 1 , wherein:
 the first indication of the EVM requirement comprises a first EVM level requested by the electronic device, and 
 the second indication of the EVM requirement comprises a second EVM level different than the first EVM level. 
 
     
     
       4. The electronic device of  claim 1 , wherein the first indication of the EVM requirement comprises:
 a first EVM level used by the electronic device in transmitting a second measurement frame to the second electronic device, and 
 a second EVM level requested by the electronic device from the second electronic device to use in transmitting the first measurement frame to the electronic device. 
 
     
     
       5. The electronic device of  claim 1 , wherein to implement the measurement phase of the ranging operation, the one or more processors are configured to:
 transmit, to the second electronic device, a second measurement frame in accordance with the first indication of the EVM requirement; and 
 receive, from the second electronic device, the first measurement frame, wherein the first measurement frame is transmitted in accordance with the second indication of the EVM requirement. 
 
     
     
       6. The electronic device of  claim 5 , wherein to implement the measurement phase of the ranging operation, the one or more processors are configured to:
 transmit, to the second electronic device, a time of departure of the second measurement frame and a time of arrival of the first measurement frame; 
 receive, from the second electronic device, a time of arrival of the second measurement frame and a time of departure of the first measurement frame; and 
 determine a distance from the electronic device to the second electronic device using at least the time of arrival and the time of departure of the first measurement frame and the time of arrival and the time of departure of the second measurement frame. 
 
     
     
       7. The electronic device of  claim 1 , wherein the one or more processors are further configured to transmit, during the measurement phase of the ranging operation, a second request frame to the second electronic device for re-negotiation, the second request frame comprising an updated EVM requirement. 
     
     
       8. A method, comprising:
 transmitting, from a first electronic device and during a negotiation phase of a ranging operation, an initial request frame to a second electronic device, wherein the initial request frame comprises a first indication of an error vector magnitude (EVM) requirement for a first measurement frame to be transmitted from the second electronic device to the first electronic device; 
 receiving, by the first electronic device and from the second electronic device, an initial response frame; 
 determining, by the first electronic device, a second indication of the EVM requirement for the first measurement frame based at least in part on the received initial response frame; and 
 implementing, by the first electronic device, a measurement phase of the ranging operation in accordance with at least one of the first indication of the EVM requirement or the second indication of the EVM requirement. 
 
     
     
       9. The method of  claim 8 , wherein:
 the first indication of the EVM requirement comprises a first EVM level requested by the first electronic device, and 
 the second indication of the EVM requirement comprises a value set in an indication field of the initial response frame representing an acceptance of the first EVM level by the second electronic device. 
 
     
     
       10. The method of  claim 8 , wherein:
 the first indication of the EVM requirement comprises a first EVM level requested by the first electronic device, and 
 the second indication of the EVM requirement comprises a second EVM level different than the first EVM level. 
 
     
     
       11. The method of  claim 8 , wherein the first indication of the EVM requirement comprises:
 a first EVM level used by the first electronic device in transmitting a second measurement frame to the second electronic device, and 
 a second EVM level requested by the first electronic device from the second electronic device to use in transmitting the first measurement frame to the first electronic device. 
 
     
     
       12. The method of  claim 8 , wherein implementing the measurement phase of the ranging operation comprises:
 transmitting, from the first electronic device to the second electronic device, a second measurement frame in accordance with the first indication of the EVM requirement; and 
 receiving, by the first electronic device from the second electronic device, the first measurement frame, wherein the first measurement frame is transmitted in accordance with the second indication of the EVM requirement. 
 
     
     
       13. The method of  claim 12 , wherein implementing the measurement phase of the ranging operation further comprises:
 transmitting a time of departure of the second measurement frame and a time of arrival of the first measurement frame; 
 receiving a time of arrival of the second measurement frame and a time of departure of the first measurement frame; and 
 determining a distance from the first electronic device to the second electronic device using at least the time of arrival and the time of departure of the first measurement frame and the time of arrival and the time of departure of the second measurement frame. 
 
     
     
       14. A non-transitory computer-readable medium storing instructions that, when executed by a processor of an electronic device, cause the processor to perform operations, the operations comprising:
 determining a first indication of an error vector magnitude (EVM) requirement for a first measurement frame to be transmitted from a second electronic device to the electronic device for a ranging operation; 
 transmitting, during a negotiation phase of the ranging operation, an initial request frame to the second electronic device, wherein the initial request frame comprises the first indication of the EVM requirement; 
 receiving, from the second electronic device, an initial response frame, wherein the initial response frame comprises a second indication of the EVM requirement for the first measurement frame; 
 determining the second indication of the EVM requirement for the first measurement frame based at least in part on the received initial response frame; 
 transmitting, to the second electronic device, a second measurement frame in accordance with the first indication of the EVM requirement; and 
 receiving, from the second electronic device, the first measurement frame, wherein the first measurement frame is generated in accordance with the second indication of the EVM requirement. 
 
     
     
       15. The non-transitory computer-readable medium of  claim 14 , wherein:
 the first indication of the EVM requirement comprises a first EVM level requested by the electronic device, and 
 the second indication of the EVM requirement comprises a value set in an indication field of the initial response frame representing an acceptance of the first EVM level by the second electronic device. 
 
     
     
       16. The non-transitory computer-readable medium of  claim 14 , wherein:
 the first indication of the EVM requirement comprises a first EVM level requested by the electronic device, and 
 the second indication of the EVM requirement comprises a second EVM level different than the first EVM level. 
 
     
     
       17. The non-transitory computer-readable medium of  claim 14 , wherein the first indication of the EVM requirement comprises:
 a first EVM level used by the electronic device in transmitting the second measurement frame to the second electronic device, 
 a second EVM level requested by the electronic device from the second electronic device to use in transmitting the second measurement frame to the electronic device, and 
 the second indication of the EVM requirement comprises a third EVM level different than the second EVM level. 
 
     
     
       18. The non-transitory computer-readable medium of  claim 14 , the operation further comprising:
 transmitting, to the second electronic device, a time of departure of the second measurement frame and a time of arrival of the first measurement frame; 
 receiving, from the second electronic device, a time of arrival of the second measurement frame and a time of departure of the first measurement frame; and 
 determining a distance from the second electronic device using at least the time of arrival and the time of departure of the first measurement frame and the time of arrival and the time of departure of the second measurement frame. 
 
     
     
       19. The non-transitory computer-readable medium of  claim 14 , wherein the first and second measurement frames comprise null data packets including no data payload.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application No. 62/751,046, filed on Oct. 26, 2018, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Field 
     The described embodiments generally relate to ranging and positioning operations in wireless communications. 
     Related Art 
     An electronic device can use different methods for determining its location. For example, the electronic device may use satellite based systems (e.g., global positioning system (GPS)), cellular networks (e.g., 3G, 4G, 5G networks), wireless local area networks (WLANs) (also called Wi-Fi networks), or a combination thereof to determine its location. In some examples, the electronic device may use location determination using WLAN when the electronic device is inside a closed location (e.g., access to GPS is limited) or when the electronic device desires more accurate positioning determination. When determining the location, a trade off exits between the power consumed by the electronic device for position determination, the accuracy of the determined position, and the range of position determination. 
     SUMMARY 
     Some embodiments of this disclosure include apparatuses and methods for implementing improved ranging and/or positioning operation(s). The improved ranging and/or positioning operation(s) can include a negotiation phase for the requirement on error vector magnitude (EVM) (or other equivalent metrics for measuring transmission signal quality) of transmitted measurement frames. 
     Some embodiments relate to an electronic device. The electronic device includes a transceiver configured to communicate over a wireless network and one or more processors communicatively coupled to the transceiver. The one or more processors transmit, during a negotiation phase of a ranging operation, an initial request frame to a second electronic device, wherein the initial request frame comprises a first indication of an error vector magnitude (EVM) requirement for a first measurement frame (e.g., null data packet(s) (NDPs)) to be transmitted from the second electronic device to the electronic device. The one or more processors receive an initial response frame from the second electronic device and determine a second indication of the EVM requirement for the first measurement frame based at least in part on the received initial response frame. The one or more processors implement a measurement phase of the ranging operation in accordance with the second indication of the EVM requirement. 
     Some embodiments relate to a method including transmitting, from a first electronic device and during a negotiation phase of a ranging operation, an initial request frame to a second electronic device, where the initial request frame comprises a first indication of an error vector magnitude (EVM) requirement for a first measurement frame to be transmitted from the second electronic device to the first electronic device. The method further includes receiving, from the second electronic device, an initial response frame and determining a second indication of the EVM requirement for the first measurement frame based at least in part on the received initial response frame. The method also includes implementing a measurement phase of the ranging operation in accordance with at least one of the first indication of the EVM requirement or the second indication of the EVM requirement. 
     Some embodiments relate to a non-transitory computer-readable medium storing instructions. When the instructions are executed by a processor of an electronic device, the instructions cause the processor to perform operations including determining a first indication of an error vector magnitude (EVM) requirement for a first measurement frame to be transmitted from the second electronic device to the electronic device for a ranging operation. The operations further include transmitting, during a negotiation phase of the ranging operation, an initial request frame to a second electronic device, where the initial request frame comprises the first indication of the EVM requirement. The operations also include receiving, from the second electronic device, an initial response frame, where the initial response frame comprises a second indication of the EVM requirement for the first measurement frame. The operations further include transmitting, to the second electronic device, a first measurement frame in accordance with the first indication of the EVM requirement and receiving, from the second electronic device, a second measurement frame. The second measurement frame is generated in accordance with the second indication of the EVM requirement. 
     Some embodiments relate to an electronic device. The electronic device includes a transceiver configured to communicate over a wireless network and one or more processors communicatively coupled to the transceiver. The one or more processors receive a first measurement frame transmitted by a first electronic device in accordance with a first indication of an error vector magnitude (EVM) requirement associated with the first electronic device and determine a time of arrival of the first measurement frame at the electronic device. The one or more processors receive a second measurement frame transmitted by a second electronic device in accordance with a second indication of the EVM requirement associated with the second electronic device and determine a time of arrival of the second measurement frame at the electronic device. The one or more processor receive timing information transmitted by the first and second electronic devices. The one or more processors determine a relative distance from the first and second electronic devices based at least in part on the received timing information, the determined time of arrival of the first measurement frame, and the determined time of arrival of the second measurement frame. 
     This Summary is provided merely for purposes of illustrating some embodiments to provide an understanding of the subject matter described herein. Accordingly, the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter in this disclosure. Other features, aspects, and advantages of this disclosure will become apparent from the following Detailed Description, Figures, and Claims. Without loss of generality, the methods described in this document not only apply to the negotiation of EVM but also apply to the negotiation of other equivalent metrics that measure transmission signal quality. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the presented disclosure and, together with the description, further serve to explain the principles of the disclosure and enable a person of skill in the relevant art(s) to make and use the disclosure. 
         FIG. 1  illustrates an example system implementing an error vector magnitude (EVM) requirement negotiation for ranging and/or positioning operation(s), according to some embodiments of the disclosure. 
         FIG. 2  illustrates a block diagram of an example wireless system of an electronic device implementing an error vector magnitude (EVM) requirement negotiation for ranging and/or positioning operation(s), according to some embodiments of the disclosure. 
         FIG. 3  illustrates example operations of communication between two electronic devices for an error vector magnitude (EVM) requirement negotiation, according to some embodiments of the disclosure. 
         FIG. 4A  illustrates example operations of communication between two electronic devices for measurement phase of a ranging operation, according to some embodiments of the disclosure. 
         FIG. 4B  illustrates an example positioning determination using triangulation, according to some embodiments of the disclosure. 
         FIG. 5A  illustrates an example method for a wireless system implementing an error vector magnitude (EVM) requirement negotiation, according to some embodiments of the disclosure. 
         FIG. 5B  illustrates an example method for a wireless system implementing a measurement phase of the ranging operation, according to some embodiments of the disclosure. 
         FIG. 6  illustrates example operations of communication between three electronic devices for a passive ranging operation, according to some embodiments of the disclosure. 
         FIG. 7  illustrates an example method for a wireless system implementing a measurement phase of the passive ranging operation, according to some embodiments of the disclosure. 
         FIG. 8  illustrates an example computer system for implementing some embodiments or portion(s) thereof. 
     
    
    
     The present disclosure is described with reference to the accompanying drawings. In the drawings, generally, like reference numbers indicate identical or functionally similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. 
     DETAILED DESCRIPTION 
     Some embodiments of this disclosure include apparatuses and methods for implementing improved ranging and/or positioning operation(s). The improved ranging and/or positioning operation(s) can include an error vector magnitude (EVM) requirement negotiation. 
     A ranging operation is an operation that enables, for example, a first electronic device to determine its distance from a second electronic device. The first electronic device can use three or more of the determined distances from three or more electronic devices to determine its position using a position operation. As discussed in more detail in the embodiments of this disclosure, to determine its distance from the second electronic device, the first electronic device communicates one or more packets or frames with the second electronic device. Using time(s) of departure and time(s) of arrival of the packets, the first electronic device is configured to determine its distance from the second electronic device. 
     The determination of the range (e.g., the distance from the second electronic device) is coupled with the transmission signal quality for transmitting the one or more frames between the first and the second electronic devices. One metric for the transmission signal quality can include the error vector magnitude (EVM). In one example, if the first electronic device desires to transmit a signal with a high Modulation and Coding Scheme (MCS) index value (as a non-limiting example, MCS7), the first electronic device may use an EVM associated with high quality transmission signal (as a non-limiting example, at least −27 dB). If the first electronic device desires to transmit a signal with a low MCS index value (as a non-limiting example, MCS0), the first electronic device may use an EVM associated with a lower quality transmission signal (as a non-limiting example, −9 dB). According to some embodiments, if the one or more packets are transmitted with higher transmission signal quality (e.g., higher EVM—higher absolute value of the EVM level), the transmission range of the one or more packets are less than the transmission range of the one or more packets if the one or more packets are transmitted with lower transmission signal quality (e.g., lower EVM—lower absolute value of the EVM level). However, when the one or more packets are transmitted with higher transmission signal quality, the distance(s) can be determined with more accuracy. Therefore, a tradeoff exists between the transmission signal quality and the transmission range. According to some embodiments, the ranging operation of the first electronic device can include a negotiation phase with the second electronic device to negotiate the EVM requirement to manage this tradeoff. 
     By negotiating EVM requirements and dynamically controlling the EVM levels, the embodiments of this disclosure are configured to manage between the required and/or desired accuracy for determining distances and the required and/or desired range for determining distances. 
     As a non-limiting example, when the first electronic device is within a stadium, the first electronic device can determine that it does not need to know its position (and therefore its distance from a second electronic device) with high accuracy. Also, the first electronic device can determine that the second electronic device may be located far from the first electronic device. Therefore, the first electronic device can use lower transmission signal quality (e.g., lower EVM) with higher transmission range for its ranging operation. In contrast, in another non-limiting example, when the first electronic device is in a shopping mall, the first electronic device can determine that it needs to know its position (and therefore its distance from a second electronic device) with high accuracy. The high accuracy of the ranging operation (and/or positioning operation) can help the first electronic device determine the store(s) within the shopping mall to which it is close. Also, the first electronic device can determine that the second electronic device may be located close to the first electronic device. Therefore, the first electronic device can use higher transmission signal quality (e.g., higher EVM) with lower transmission range for its ranging operation. 
     According to some examples, the EVM is a measure of the quality of a signal transmitted and/or received within a wireless communication system. In an ideal system, the constellation points of a received signal are at their ideal locations, e.g., at the locations where they were generated at the transmitter. However, because of limitations and/or errors in the system, an error can exist between the constellation points of the received signal and their ideal locations. An error vector can be a vector (for example, in an I-Q plane) between the received constellation points and the ideal locations. The error vector, in other words, is the difference between an actual received symbol and an ideal symbol. In some examples, the difference between an actual received symbol and an ideal symbol is determined after the received signal is equalized (e.g., passed through an equalizer). According to some examples, an average amplitude of the error vector, normalized to peak signal amplitude, can be the EVM. It is noted that other calculations can be used for determining the EVM as the difference between an actual received symbol and an ideal symbol. 
       FIG. 1  illustrates an example system  100  implementing an error vector magnitude (EVM) requirement negotiation for ranging and/or positioning operation(s), according to some embodiments of the disclosure. Example system  100  is provided for the purpose of illustration only and is not limiting of the disclosed embodiments. System  100  may include, but is not limited to, stations  120 , access points  110 , and network  130 . Stations (STAs)  120   a - 120   c  may include, but are not limited to, Wireless Local Area Network (WLAN) stations such as wireless communication devices, smart phones, laptops, desktops, tablets, personal assistants, monitors, televisions, and the like. Access point (AP)  110  may include but are not limited to WLAN electronic devices such as a wireless router, a wearable device (e.g., a smart watch), a wireless communication device (e.g., a smart phone), or a combination thereof. Network  130  may be the Internet and/or a WLAN. Station  120 &#39;s communications are shown as wireless communications  140 . The wireless communications  140   a - 140   e  can be based on a wide variety of wireless communication techniques. These techniques can include, but are not limited to, techniques based on IEEE 802.11, IEEE 802.11v, IEEE 802.11ax, IEEE 802.11az, etc. standards. 
     It is noted that although some embodiments are discussed with respect to some examples of WLAN, the embodiments of this disclosure are not limited to these examples of WLAN and can be used for ranging and/or location operation(s) using other WLAN topologies such as, but not limited to, infrastructure network, peer-to-peer network, mesh network, and the like. 
     Also, the embodiments of this disclosure are not limited to WLAN and can be used for other communication systems. For example, the embodiments of this disclosure can be implemented for ranging and/or location operation(s) using cellular technologies in cellular networks such as, but not limited to, 3G/4G/5G networks such as Universal Mobile Telecommunications System (UMTS), Long-Term Evolution (LTE), and the like. The embodiments of this disclosure can also be implemented for ranging and/or location operation(s) using Bluetooth™ technologies such as, but not limited to, Bluetooth™ protocol, the Bluetooth™ Low Energy protocol, or the Bluetooth™ Low Energy Long Range protocol. 
     In addition to ranging and/or location operation(s), the embodiments of this disclosure can also be applied to other protocols and operations, e.g., in WLAN, cellular, and/or Bluetooth™. For example, the embodiments of this disclosure can be applied to beam forming procedures for data communication. 
     According to some embodiments, AP  110  and STAs  120  are configured to implement EVM requirement negotiation for ranging and/or positioning operation(s). During the ranging operation, STA  120   a  is configured to communicate with AP  110   a  to determine STA  120   a &#39;s distance from AP  110   a , according to some examples. It is noted that although some embodiments of this disclosure are discussed with respect to a ranging operation, the embodiments of this disclosure also apply to location operation(s). Also, although some embodiments of this disclosure are discussed with respect to the ranging operation between STA  120   a  and AP  110   a , the embodiments of this disclosure also apply to ranging operations between any two or more electronic devices. For example, the embodiments of this disclosure also apply to ranging operations between STAs  120 , between APs  110 , between any STA  120  and any AP  120 , and the like. 
     The ranging operation can include a ranging session such as, but not limited to, a fine timing measurement (FTM) ranging session. The ranging operation can include a negotiation phase, a measurement phase, and a termination phase, according to some embodiments. During the negotiation phase, STA  120   a  transmits an initial request frame to AP  110   a . According to some examples, the initial request frame can include an initial FTM request frame. The initial request frame can include a set of measurement parameters that can describe STA  120   a &#39;s availability and capability for the ranging operation. The set of measurement parameters can include, but is not limited to, a bandwidth to be used for the measurement phase, a number of repetitions to be used for the measurement phase, and the like. According to some examples, the initial request frame can include STA  120   a &#39;s EVM requirement. The EVM requirement can include STA  120   a &#39;s required and/or desired EVM level for AP  110   a  to meet when AP  110  transmits measurement frame(s) (e.g., null data packet(s) (NDP)) to STA  120   a . According to some embodiments, when STA  120   a  transmits its EVM requirement (e.g., its required and/or desired EVM level), STA  120   a  also indicates that STA  120   a  uses such EVM level in its own transmission to AP  110   a . Additionally or alternatively, when STA  120   a  transmits its EVM requirement, STA  120   a  also indicates its EVM level that it will use for its transmission to AP  110   a . In this example, the indicated STA  120   a &#39;s EVM level can be the same as or different than the EVM level requested for AP  110   a.    
     After receiving the initial request frame, AP  110   a  can transmit an initial response frame to STA  120   a . In an example, AP  110   a  transmits the initial response frame within a predetermined time (e.g., 10 ms.) The initial response frame can include an initial FTM frame. The initial response frame can include a set of measurement parameters that describe AP  110 &#39;s availability and capability for the ranging operation. The set of measurement parameters can include, but is not limited to, the bandwidth to be used for the measurement phase, the number of repetitions to be used for the measurement phase, and the like. According to some embodiments, the initial response frame from AP  110   a  to STA  120   a  can include information indicating whether AP  110   a  can meet the requested EVM requirement. For example, the initial response frame can include AP  110 &#39;s actual EVM level, which can be a level closest to the requested EVM level (requested by STA  120   a ) and is supported by the AP  110   a &#39;s capability. Additionally or alternatively, the initial response frame can include a status indication field value to indicate whether AP  110   a  can meet the requested EVM requirement. For example, AP  110   a  can set the status indication field value of the initial response frame to a first value (e.g., “2”) to indicate that AP  110   a  cannot meet the requested EVM requirement. AP  110   a  can set the status indication field value of the initial response frame to a second value (e.g., “1”) to indicate that AP  110   a  can meet the requested EVM requirement. 
     After receiving the initial response frame from AP  110   a , STA  120   a  can decide whether to continue or terminate the ranging operation, according to some embodiments. The exchange of the initial request frame and the initial response frame can ensure an agreement between STA  120   a  and AP  110   a  on the parameters (including, but not limited to, the EVM requirement) for the ranging operation. According to some embodiments, if no agreement is reached between STA  120   a  and AP  110   a , STA  120   a  can terminate the ranging operation. Alternatively, if no agreement is reached, STA  120   a  can continue with the ranging operation with available/possible parameters. If an agreement is reached between STA  120   a  and AP  110   a , STA  120   a  can continue with the ranging operation with the agreed-on parameters. 
     By negotiating EVM requirements and dynamically controlling the EVM levels, STA  120   a  and/or AP  110  are configured to manage between the required and/or desired accuracy for determining distances and the required and/or desired range for determining distances. 
     If STA  120   a  continues with the ranging operation, the next phase after the negotiation phase is the measurement phase. During the measurement phase, STA  120   a  transmits a first measurement frame to AP  110   a . STA  120   a  transmits the first measurement frame using the agreed-on parameters (e.g., the negotiated EVM requirement). After receiving the first measurement frame, AP  110   a  transmits a second measurement frame to STA  120   a . According to some embodiments, AP  110   a  transmits the second measurement frame using the agreed-on parameters (e.g., the negotiated EVM requirement). STA  120   a  can transmit the time of departure (ToD) of the first measurement frame and the time of arrival (ToA) of the second measurement frame to AP  110   a . Similarly, AP  110   a  can transmit the time of arrival (ToA) of the first measurement frame and the time of departure (ToD) of the second measurement frame to STA  120   a . Using the ToD and ToA of the first measurement frame and the ToD and ToA of the second measurement frame, STA  120   a  can determine its distance from AP  110   a , according to some embodiments. Similarly, using the ToD and ToA of the first measurement frame and the ToD and ToA of the second measurement frame, AP  110   a  can determine its distance from STA  120   a , according to some embodiments. In addition to ToD and ToA, STA  120   a  and AP  110   a  can use directional measurement (e.g., measurement of angle of arrival (AoA) and/or angle of departure (AoD)) to assist with the ranging and/or positioning operation(s), according to some embodiments. In some embodiments, an alternative order of the measurement frame transmissions is used, where AP  110  transmits the first measurement frame before STA  120   a  transmits the second measurement frame, each applying the negotiated respective EVM level for its transmission. 
     In some examples, STA  120   a  can use similar ranging operation with two or more other access points (e.g., AP  110   b  and another AP—in addition to AP  110   a ). Using the determined distances and known positions of the APs, STA  120   a  can determine its position. STA  120   a  can use triangulation to determine its position, according to some embodiments. 
     After the measurement phase is complete, STA  120   a  can terminate the ranging operation (e.g., termination phase). 
       FIG. 2  illustrates a block diagram of an example wireless system  200  of an electronic device implementing an error vector magnitude (EVM) requirement negotiation for ranging and/or positioning operation(s), according to some embodiments of the disclosure. System  200  may be any of the electronic devices (e.g., AP  110 , STA  120 ) of system  100 . System  200  includes central processing unit (CPU)  210 , transceiver  220 , communication interface  230 , communication infrastructure  240 , memory  250 , and antenna  260 . Illustrated systems are provided as exemplary parts of wireless system  200 , and system  200  can include other circuit(s) and subsystem(s). Also, although the systems of wireless system  200  are illustrated as separate components, the embodiments of this disclosure can include any combination of these, less, or more components. 
     Memory  250  may include random access memory (RAM) and/or cache, and may include control logic (e.g., computer software) and/or data. Memory  250  may include other storage devices or memory such as, but not limited to, a hard disk drive and/or a removable storage device/unit. According to some examples, an operating system (not shown) can be stored in memory  250  and can manage transfer of data from memory  250  and/or one or more applications (not shown) to CPU  210 , transceiver  220 , and/or communication interface  230 . In some examples, the operating system maintains one or more network protocol stacks (e.g., Internet protocol stack, cellular protocol stack, and the like) that can include a number of logical layers. At corresponding layers of the protocol stack, the operating system includes control mechanism and data structures to perform the functions associated with that layer. 
     In addition to or in alternate to the operating system, system  200  can include communication infrastructure  240 . Communication infrastructure  240  provides communication between, for example, CPU  210 , transceiver  220 , communication interface  230 , and memory  250 . Communication infrastructure  240  may be a bus. CPU  210  together with instructions stored in memory  250  perform operations enabling wireless system  200  to implement the EVM requirement negotiation and the ranging and/or positioning operation(s) as described herein. 
     Transceiver  220  transmits and receives communications signals that support the EVM requirement negotiation and the ranging and/or positioning operation(s), according to some embodiments, and may be coupled to antenna  260 . Antenna  260  may include one or more antennas that may be the same or different types. Communication interface  230  allows system  200  to communicate with other devices that may be wired and/or wireless. Transceiver  220  and/or communication interface  230  can include processors, controllers, radios, sockets, plugs, and like circuits/devices used for connecting to and communication on networks. According to some examples, transceiver  220  and/or communication interface  230  includes one or more circuits to connect to and communicate on wired and/or wireless networks. Transceiver  220  and/or communication interface  230  can include a cellular subsystem, a WLAN subsystem, and a Bluetooth™ subsystem, each including its own radio transceiver and protocol(s) as will be understood by those skilled arts based on the discussion provided herein. Transceiver  220  and/or communication interface  230  can include more or less systems for communicating with other devices. 
     Cellular subsystem (not shown) can include one or more circuits (including a cellular transceiver) for connecting to and communicating on cellular networks. The cellular networks can include, but are not limited to, 3G/4G/5G networks such as Universal Mobile Telecommunications System (UMTS), Long-Term Evolution (LTE), and the like. Bluetooth™ subsystem (not shown) can include one or more circuits (including a Bluetooth™ transceiver) to enable connection(s) and communication based on, for example, Bluetooth™ protocol, the Bluetooth™ Low Energy protocol, or the Bluetooth™ Low Energy Long Range protocol. WLAN subsystem (not shown) can include one or more circuits (including a WLAN transceiver) to enable connection(s) and communication over WLAN networks such as, but not limited to networks based on standards described in IEEE 802.11. 
     According to some embodiments, CPU  210 , alone or in combination with memory  250 , transceiver  220 , and/or communication interface  230 , implements the EVM requirement negotiation and the ranging and/or positioning operation(s). For example, CPU  210 , alone or in combination with memory  250 , transceiver  220 , and/or communication interface  230  implements the negotiation phase including the EVM negotiation, the measurement phase of the ranging and/or positioning operations, and/or the termination phase of the ranging and/or positioning operations, as discussed herein. 
       FIG. 3  illustrates example operations of communication between two electronic devices for an error vector magnitude (EVM) requirement negotiation, according to some embodiments of the disclosure.  FIG. 3  may be described with regard to elements of  FIG. 1 . Operation  300  of  FIG. 3  represents the communication between two electronic devices—initiating station (iSTA)  301  and responding station (rSTA)  303 . According to some examples, iSTA  301  or rSTA  303  can be any one of STAs  120  and/or APs  110 . Operation  300  of  FIG. 3  can include the EVM requirement negotiation. 
     According to some embodiments, iSTA  301  transmits an initial request frame  305  to rSTA  303 . In general, the data communicated between iSTA  301  and rSTA  303  in the disclosed embodiments may be conveyed in packets or frames that are transmitted and received by radios in iSTA  301  and rSTA  303  in accordance with a communication protocol, such as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, Bluetooth™ (from the Bluetooth Special Interest Group of Kirkland, Wash.), a cellular-telephone communication protocol, and/or another type of wireless interface (such as a peer-to-peer communication technique, a mesh-network technique, and the like). Some of the embodiments are discussed with respect to a wireless local area Network (WLAN), but the embodiments of this disclosure are not limited to use with a WLAN. 
     According to some embodiments, iSTA  301  transmits initial request frame  305  when iSTA  301  initiates the EVM requirement negotiation. Additionally or alternatively, iSTA  301  transmits initial request frame  305  when iSTA  301  updates one or more measurement parameters such as, but not limited to, the EVM requirement. According to some examples, initial request frame  305  can be an initial FTM request frame. Initial request frame  305  can include a set of measurement parameters that can describe iSTA  301 &#39;s availability and capability for the ranging operation. According to some examples, initial request frame  305  can include iSTA  301 &#39;s EVM requirement. Additionally or alternatively, initial request frame  305  can include updated measurement parameter(s) such as, but not limited to, updated EVM requirement, transmitted during the measurement phase operation. 
     The EVM requirement can include iSTA  301 &#39;s required and/or desired EVM level for rSTA  303  to meet when rSTA  303  transmits measurement frame(s) (e.g., null data packet(s) (NDP)) to iSTA  301 . According to some embodiments, when iSTA  301  transmits its EVM requirement (e.g., its required and/or desired EVM level), iSTA  301  also indicates that iSTA  301  uses such EVM level in its own transmission to rSTA  303 . Additionally or alternatively, when iSTA  301  transmits its EVM requirement, iSTA  301  also indicates iSTA  301 &#39;s EVM level that iSTA  301  will use for its transmission to rSTA  303 . In this example, the indicated iSTA  301 &#39;s EVM level can be the same as or different than the EVM level requested for rSTA  303 . 
     When determining the EVM requirement, iSTA  301  can consider the tradeoff between a high EVM level and a low EVM level. A high EVM level improves ranging accuracy but usually requires iSTA  301  and/or rSTA  303  to reduce its transmitter output power, and therefore limits the distance at which the ranging operation can be performed. On the other hand, a low EVM level may degrade accuracy but enable the ranging operation be performed at a further distance. 
     According to some embodiments, rSTA  303  can send an acknowledgment (ACK)  307  after receiving initial request frame  305 . In some embodiments, ACK  307  can be optional. 
     After receiving initial request frame  305 , or after transmitting the optional ACK  307 , rSTA  303  can transmit an initial response frame  309  to iSTA  301 . In an example, rSTA  303  transmits initial response frame  309  within a predetermined time  311  (e.g., 10 ms). Initial response frame  309  can include an initial FTM frame. As discussed above, initial response frame  309  can include a set of measurement parameters that describe rSTA  303 &#39;s availability and capability for the ranging operation. According to some embodiments, initial response frame  309  can include information indicating whether rSTA  303  can meet the requested EVM requirement. For example, initial response frame  309  can include rSTA  303 &#39;s actual EVM level, which can be a level closest to the requested EVM level (requested by iSTA  301 ) and is supported by the rSTA  303 &#39;s capability. In some examples, when rSTA  303  transmits its actual EVM level, such EVM level is included in initial response frame  309  (e.g., within a container in initial response frame  309 ). 
     Additionally or alternatively, initial response frame  309  can include a status indication field value to indicate whether rSTA  303  can meet the requested EVM requirement. As a non-limiting example, the status indication field of initial response frame  309  can have four values—e.g., “0”, “1”, “2”, and “3”. In this non-limiting example, value “0” can be a reserved value. rSTA  303  can set the status indication field value of initial response frame  309  to, for example, “1” to indicate that rSTA  303  can meet the requested EVM requirement. rSTA  303  can set the status indication field value of initial response frame  309  to, for example, “2” to indicate that rSTA  303  cannot meet the requested EVM requirement. In some examples, value “2” of the status indication field can also signal to iSTA  301  not to send the same request (e.g., with the same set of measurement parameters) and that the ranging operation is terminated. rSTA  303  can set the status indication field value of initial response frame  309  to, for example, “3” to indicate that the request from iSTA  301  has failed. In some examples, value “3” of the status indication field can also signal to iSTA  301  not to send any new request for a determined period of time, and that the ranging operation is terminated. 
     After receiving initial response frame  309  from rSTA  303 , iSTA  301  transmits an acknowledgment (ACK)  313 . According to some embodiments, ACK  313  is optional. TSTA  301  can also decide whether to continue or terminate the ranging operation, according to some embodiments. 
     According to some embodiments, the requested EVM requirement (requested by, for example, iSTA  301 ) can be located within a container in initial request frame  305 . The reported EVM requirement (reported by, for example rSTA  303 ) can be located within a container in initial response frame  309 . According to some embodiments, the container in initial request frame  305  and/or the container in initial response frame  309  can include a field or a subfield of a frame, an Information Element, an Information subelement, or the like. In some examples, the format of the container in initial request frame  305  can be the same as or similar to the format of the container in initial response frame  309 . As a non-limiting example, the container for the iSTA  301 &#39;s EVM requirement (in initial request frame  305 ) can include 6 bits in duration, where the value can be expressed in units of dB. For example, the allowed values can be [0:63], which corresponds to [0 dB EVM: −63 dB EVM]. In a non-limiting example, the granularity of the steps between the lowest and highest EVM may be 3 dB or less. However, the embodiments of this disclosure are not limited to these examples and other formats, containers, units, and/or field duration may be used for communicating the requested and/or responded EVM requirements. The EVM re-negotiation can occur during the measurement phase operation. In some embodiments, other types of frames, instead of the initial request frame and/or the initial response frame, can be used to contain the EVM requirement. 
       FIG. 4A  illustrates example operations of communication between two electronic devices for a measurement phase of a ranging operation, according to some embodiments of the disclosure.  FIG. 4A  may be described with regard to elements of  FIG. 1 . Operation  400  of  FIG. 4A  represents the communication between two electronic devices—initiating station (iSTA)  401  and responding station (rSTA)  403 . According to some examples, iSTA  401  or rSTA  403  can be any one of STAs  120  and/or APs  110 . Operation  400  of  FIG. 4A  can include the measurement phase of the ranging operation. The measurement phase may include a time of flight (ToF) measurement, according to some embodiments. 
     After the iSTA  401  and rSTA  403  have negotiated the set of measurement parameters including, but not limited to, the EVM requirement using, for example, the EVM requirement negotiation phase of operation  300  of  FIG. 3 , iSTA  401  and rSTA  403  can perform the measurement phase of the ranging operation. The exchange of initial request frame  305  and initial response frame  309  of  FIG. 3  can ensure an agreement between iSTA  401  and rSTA  403  on the parameters (including, but not limited to, EVM requirement) for the ranging operation. If an agreement is reached between iSTA  401  and rSTA  403 , iSTA  401  can perform the ranging operation using the agreed-on parameters. 
     During the measurement phase operation  400 , iSTA  401  transmits a first measurement frame  405  to rSTA  403 . iSTA  401  transmits first measurement frame  405  using the agreed-on parameters (e.g., the negotiated EVM requirement). The measurement phase operation  400  can be based on a number of ranging modes defined for fine timing measurement (FTM) protocol. In one example, first measurement frame  405  can include null data packets (NDPs) used in accordance with a trigger-based (e.g., formerly known as HEz-based) ranging measurement mode. In another example, first measurement frame  405  can include NDPs used in accordance with a non-trigger-based (e.g., formerly known as VHTz-based) ranging measurement mode. NDP is a frame that has only the physical layer (PHY) header, but does not contain the media access control (MAC) data payload. According to some embodiments NPDs are used for estimation of a channel between two stations. iSTA  401  transmits first measurement frame  405  based on the EVM level negotiated and agreed-on during, for example, operation  300 . 
     According to some examples, iSTA  401  transmits first measurement frame at ToD time instant t 1 . rSTA  403  receives first measurement frame  405  at ToA time instant t 2 . After receiving first measurement frame  405 , rSTA  403  transmits a second measurement frame  407  to iSTA  401  at ToD time instant t 3 . According to some embodiments, rSTA  403  transmits second measurement frame  407  using the agreed-on parameters (e.g., the negotiated EVM requirement). In other words, rSTA  403  transmits second measurement frame  407  based on the EVM level negotiated and agreed-on during, for example, operation  300 . iSTA  401  receives second measurement frame  407  at ToA time instant t 4 . 
     Although not shown, iSTA  401  can transmit the value of ToD time instant t 1  and the value of ToA time instant t 4  to rSTA  403 . In some embodiments, iSTA  401  can transmit the value of ToD time instant t 1  along with first measurement frame  405 . Similarly, rSTA  403  can transmit the value of ToD time instant t 3  and the value of ToA time instant t 2  to iSTA  403 . In some examples, rSTA  403  can transmit the value of ToD time instant t 3  and the value of ToA time instant t 2  along with the second measurement frame  407 . Using these time instants, iSTA  401  can determine its distance from rSTA  403 , according to some embodiments. For example, iSTA  401  can use the following equation to determine the distance from rSTA  403 : 
     
       
         
           
             
               distance 
               = 
               
                 
                   [ 
                   
                     
                       ( 
                       
                         
                           t 
                           4 
                         
                         - 
                         
                           t 
                           1 
                         
                       
                       ) 
                     
                     - 
                     
                       ( 
                       
                         
                           t 
                           3 
                         
                         - 
                         
                           t 
                           3 
                         
                       
                       ) 
                     
                   
                   ] 
                 
                 × 
                 
                   c 
                   2 
                 
               
             
             , 
           
         
       
     
     where c is the speed of light. 
     Similarly, rSTA  403  can use the same equation to determine the distance from iSTA  401 . According to some embodiments, iSTA  401  and/or rSTA  403  may transmit the values of the time instants in a unicast mode. Additionally or alternatively, iSTA  401  and/or rSTA  403  may transmit the values of the time instants in a broadcast mode. 
     In addition to the above ToD and ToA, iSTA  401  and rSTA  403  can use directional measurement (e.g., measurement of angle of arrival (AoA) and/or angle of departure (AoD)) to assist with the ranging and/or positioning operation(s), according to some embodiments. 
     In some embodiments (or some ranging modes), during the measurement phase after the negotiation phase, rSTA  403  may transmit the first measurement frame to iSTA  401 , followed by a second measurement frame transmitted from iSTA  401  to rSTA  403 . The principle and method of using the four timestamps to compute the distance between the two devices remains the same. According to some embodiments, the device that computes the distance is the one that initiates the EVM negotiation, regardless of the direction of the first and the second measurement frames. 
       FIG. 4B  illustrates an example positioning determination using triangulation, according to some embodiments of the disclosure.  FIG. 4B  may be described with regard to elements of  FIGS. 1 and 4A .  FIG. 4B  represents the communication between five electronic devices—initiating station (iSTA)  401  and access points  411 . According to some examples, iSTA  401  or AP  411  can be any one of STAs  120  and/or APs  110 . 
     In some examples, iSTA  401  can use similar ranging operation discussed with respect to  FIGS. 3 and 4A  with AP 1   411   a , AP 2   411   b , and AP 3   411   c . Accordingly, iSTA  401  can determine its respective distance from each of AP 1   411   a , AP 2   411   b , and AP 3   411   c . Using the determined respective distances and also known positions of AP 1   411   a , AP 2   411   b , and AP 3   411   c , iSTA  411  can determine its position. iSTA  411  can use triangulation to determine its position, according to some embodiments. 
       FIG. 5A  illustrates an example method  500  for a wireless system implementing an error vector magnitude (EVM) requirement negotiation, according to some embodiments of the disclosure. As a convenience and not a limitation,  FIG. 5A  may be described with regard to elements of  FIGS. 1-4 . Method  500  may represent the operation of an electronic device, e.g., iSTA  301  of  FIG. 3  implementing the EVM requirement negotiation. Method  500  may also be performed by system  200  of  FIG. 2  and/or computer system  800  of  FIG. 8 . But method  500  is not limited to the specific embodiments depicted in those figures and other systems may be used to perform the method as will be understood by those skilled in the arts. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown in  FIG. 5A . 
     At  502 , the electronic device (e.g., iSTA  301  of  FIG. 3 ) determines an EVM requirement. According to some embodiments, iSTA  301  takes into account different information in determining the EVM requirement. In one example, iSTA  301  can consider the use case for the ranging operation in determining the EVM requirement. Different use cases may have different requirements for ranging accuracy. For example, iSTA  301  can consider the requirements of a client application on, for example, iSTA  301  that will use the ranging operation (and the determined distance) in determining the EVM requirement. If a higher accuracy is desired, then a higher quality transmission signal (e.g., higher EVM) for transmitting the measurement frame(s) is used. But, if a lower accuracy is acceptable, then a lower quality transmission signal (e.g., lower EVM) for transmitting the measurement frame(s) is used. 
     As another example, iSTA  301  can use the signal to noise ratio (SNR) on the channel (channel between, for example, iSTA  301  and rSTA  303 ) and/or the SNR at iSTA  301  in determining the EVM requirement. Additionally or alternatively, iSTA  301  can consider an internal algorithm used by the iSTA  301  for estimating the ToA of the measurement frame (e.g., NDP), or the directional (e.g., the angular) measurement of NDP in determining the EVM requirement. For example, if iSTA  301  does not support an algorithm that uses a high EVM level, iSTA  301  will not request that rSTA  303  use a high EVM level. These factors in determining the EVM requirement are provided as examples. Alternatively or additionally, iSTA  301  can use other factor(s) to determine the EVM requirement. 
     According to some embodiments, the EVM requirement can include two EVM levels. A first EVM level is signaled from iSTA  301  to rSTA  303  such that the transmission of measurement frame(s) from rSTA  303  to iSTA  301  would be in accordance with this first EVM level. The second EVM level can indicate the EVM requirement for transmission of measurement frame(s) from iSTA  301  to rSTA  303 . iSTA  301  can also signal the second EVM level to rSTA  303 . According to some embodiments, the first and second EVM levels can be the same or similar in value. Alternatively, the first and second EVM levels can have different values. 
     At  504 , iSTA  301  transmits the EVM requirement to a second electronic device, e.g., rSTA  303 . For example, iSTA  301  transmits initial request frame  305  to rSTA  303 , where initial request frame  305  includes an indication of the EVM requirement. The indication of the EVM requirement can include the first EVM level and/or the second EVM level, according to some embodiments. For example, iSTA  301  transmits the first EVM level of the determined EVM requirement to rSTA  303 . Additionally or alternatively, iSTA  301  transmits the second EVM level of the determined EVM requirement to rSTA  303 . 
     At  506 , iSTA  301  receives a response frame from the second electronic device, e.g., rSTA  303 . For example, iSTA  301  receives an initial response frame  309  from the second electronic device. In some example, before receiving initial response frame  309 , iSTA  301  can receive an acknowledgment (e.g., ACK  307 ) from rSTA  303  indicating the receipt of initial request frame  305 . 
     At  508 , iSTA  301  can determine the second electronic device&#39;s response to the EVM requirement. As discussed below, the second electronic device&#39;s response to the EVM requirement can include the second electronic device&#39;s indication of the EVM requirement. iSTA  301  can determine the second electronic device&#39;s response to the EVM requirement based at least in part on the received initial response frame  309 . For example, initial response frame  309  can include information indicating whether the second electronic device can meet the requested EVM requirement. For example, initial response frame  309  can include a third EVM level. In some embodiments the third EMV level is the same as, or similar to, the requested EVM level (requested by iSTA  301 , e.g., first EMV level). Alternatively, the third EMV level is the second electronic device&#39;s actual EVM level, which can be a level closest to the requested EVM level (requested by iSTA  301 , e.g., first EMV level) and is supported by the rSTA  303 &#39;s capability. The third EVM level may be different than the first EVM level. In some examples, when iSTA  301  determines the third EVM level (e.g., the second electronic device&#39;s actual EVM level) based at least in part on the initial response frame  309 . 
     Additionally or alternatively, iSTA  301  can determine the second electronic device&#39;s response to the requested EVM requirement from a status indication field value within initial response frame  309 . The status indication field value indicates whether rSTA  303  can meet the requested EVM requirement. 
     In some examples, at  508 , iSTA  301  can also send an acknowledgment (e.g., ACK  313 ) to the second electronic device indicating the receipt of initial response frame  305 . 
     At  510 , iSTA  301  performs the measurement phase of the ranging operation based on the negotiated and agreed-on EVM requirement (e.g., the second EVM level and the third EVM level). 
       FIG. 5B  illustrates an example method  520  for a wireless system implementing a measurement phase of the ranging operation, according to some embodiments of the disclosure. As a convenience and not a limitation,  FIG. 5B  may be described with regard to elements of  FIGS. 1-5A . Method  520  may represent the operation of an electronic device, e.g., iSTA  401  of  FIG. 4A  implementing the measurement phase of the ranging operation. Method  520  may also be performed by system  200  of  FIG. 2  and/or computer system  800  of  FIG. 8 . But method  520  is not limited to the specific embodiments depicted in those figures and other systems may be used to perform the method as will be understood by those skilled in the arts. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown in  FIG. 5B . 
     At  522 , an electronic device (e.g., iSTA  401 ) transmits a first measurement frame (e.g., first measurement frame  405 ) to another electronic device (e.g., rSTA  403 ). According to some embodiments, iSTA  401  transmits first measurement frame  405  using the agreed-on parameters (e.g., the negotiated EVM requirement). For example, iSTA  401  transmits first measurement frame  405  using the second EVM level discussed above with respect to, for example,  FIG. 5A . 
     At  524 , iSTA  401  receives a second measurement frame (e.g., second measurement frame  407 ) from rSTA  403 . According to some examples, rSTA  403  transmits second measurement frame  407  using the agreed-on parameters (e.g., the negotiated EVM requirement). For example, rSTA  403  transmits (and iSTA  401  receives) second measurement frame  407  using the third EVM level discussed above with respect to, for example,  FIG. 5A . 
     At  526 , iSTA  401  transmits the ToD of first measurement frame  405  and the ToA of second measurement frame  407 . At  528 , iSTA  401  receives the ToA of first measurement frame  405  and the ToD of second measurement frame  407  from iSTA  403 . 
     At  530 , iSTA  401  uses these time instants (e.g., the ToD of first measurement frame  405 , the ToA of first measurement frame  405 , the ToD of second measurement frame  407 , and the ToA of second measurement frame  407 ) to determine its distance from rSTA  403 , according to some embodiments. For example, iSTA  401  may use the following equation (as discussed above with respect to  FIG. 4A ) to determine its distance from rSTA  403 : 
               distance   =       [       (       t   4     -     t   1       )     -     (       t   3     -     t   3       )       ]     ×     c   2         ,         
where
 
     c is the speed of light, 
     t 1  is ToD of first measurement frame  405  from iSTA  401 , 
     t 2  is ToA of first measurement frame  405  at rSTA  403 , 
     t 3  is ToD of second measurement frame  407  from rSTA  403 , 
     t 4  is ToA of second measurement frame  407  at iSTA  401 . 
       FIG. 6  illustrates example operations of communication between three electronic devices for a passive ranging operation, according to some embodiments of the disclosure.  FIG. 6  may be described with regard to elements of  FIGS. 1 and 4A . Operation  600  of  FIG. 6  represents the communication between three electronic devices—initiating station (iSTA)  601 , responding station (rSTA)  603 , and a client electronic device  621 . According to some examples, iSTA  601 , rSTA  603 , or client electronic device  621  can be any one of STAs  120  and/or APs  110 . Operation  600  of  FIG. 6  can include the measurement phase of a passive ranging operation. 
     According to some embodiments, iSTA  601  and rSTA  603  perform a measurement phase of a ranging operation based on the methods discussed with respect to, for example,  FIGS. 4A and 5B . Before performing the measurement phase, iSTA  601  and rSTA  603  also perform EVM requirement negotiation as discussed with respect to, for example,  FIGS. 3 and 5A , according to some embodiments. Client electronic device  621  may passively listen to one or both of the EVM requirement negotiation and the measurement phase between iSTA  601  and rSTA  603 . Client electronic device  621  can determine its relative distance to iSTA  601  and rSTA  603  using, at least, the information client electronic device  621  receives by passively listening to iSTA  601  and rSTA  603 . 
     After the iSTA  601  and rSTA  603  have negotiated the set of measurement parameters including, but not limited to, the EVM requirement using, for example, the EVM requirement negotiation phase of operation  300  of  FIG. 3 , iSTA  601  and rSTA  603  can perform the measurement phase of the ranging operation. According to some embodiments, rSTA  603  can send frame  604  to iSTA  601  to start the measurement phase of the ranging operation. According to some examples, the measurement phase operation  600  can be based on a number of ranging modes defined for fine timing measurement (FTM) protocol. In one example, frame  604  can include a TF (trigger frame) location sound frame used in accordance with a trigger-based (e.g., formerly known as HEz-based) ranging measurement mode. However, frame  604  can include one or more other frames used for asking iSTA  601  to initiate the measurement phase of the ranging operation. 
     iSTA  601  transmits a first measurement frame  605  to rSTA  603 . iSTA  601  transmits first measurement frame  605  using the agreed-on parameters (e.g., the negotiated EVM requirement). First measurement frame  605  can include the first measurement frame  405  of  FIG. 4A . iSTA  601  transmits first measurement frame  605  based on the EVM level negotiated and agreed-on during, for example, operation  300  of  FIG. 3  and/or method  500  of  FIG. 5A . 
     According to some examples, iSTA  601  transmits a first measurement frame at ToD time instant t 1 . rSTA  603  receives the first measurement frame  605  at ToA time instant t 2 . Additionally, client electronic device  621  also receives the first measurement frame  605  (illustrated as  608  on  FIG. 6 ) at ToA time instant t 5 . 
     After receiving the first measurement frame  605 , rSTA  603  transmits a second measurement frame  607  to iSTA  601  at ToD time instant t 3 . According to some embodiments, rSTA  603  transmits the second measurement frame  607  using the agreed-on parameters (e.g., the negotiated EVM requirement). In other words, rSTA  603  transmits the second measurement frame  607  based on the EVM level negotiated and agreed-on during, for example, operation  300  of  FIG. 3  and/or method  500  of  FIG. 5A . 
     According to some embodiments, iSTA  601  receives the second measurement frame  607  at ToA time instant t 4 . Additionally, client electronic device  621  also receives the second measurement frame  607  (illustrated as  609  on  FIG. 6 ) at ToA time instant t 6 . 
     According to some examples, before transmitting the second measurement frame  607 , rSTA  603  may transmit frame  606  to iSTA  601  announcing that second measurement frame  607  will be transmitted. Frame  606  can include an null data packet announcement (NDPA) frame, for example. 
     Although not shown, iSTA  601  can broadcast ToD time instant t 1  and ToA time instant t 4 . Therefore, rSTA  603  and client electronic device  621  can become aware of these time instants. Similarly, rSTA  603  can broadcast ToD time instant t 3  and ToA time instant t 2 . Therefore, iSTA  601  and client electronic device  621  can become aware of these time instants. Using these time instants and also time instants t 5  and t 6 , client electronic device  621  may determine its relative distance from iSTA  601  and rSTA  603 , according to some embodiments. For example, client electronic device  621  can use the following equation to determine its relative distance from iSTA  601  and rSTA  603 :
 
Diff_range=[ t   5   −t   6 −( t   4   −t   1   −T   12 )]× c , where
 
                 T   12     =       [       (       t   4     -     t   1       )     -     (       t   3     -     t   2       )       ]     2       ,         
and where
 
     c is the speed of light. 
     The relative distance “Diff_range” is client electronic device  621 &#39;s distance to rSTA  603  minus client electronic device  621 &#39;s distance to iSTA  601 . 
     Client electronic device  621  can use the similar passive ranging operation with three or more pairs of electronic devices to determine three or more relative distances. Using the three or more relative distances and the known locations of the three or more pairs of electronic devices, client electronic device  621  may determine its position. Client electronic device  621  may use triangulation to determine its position, according to some embodiments. 
     In the passive ranging operation  600 , iSTA  601  and rSTA  603  may make their EVM levels used in the passive ranging operation  600  known to the client electronic device  621 . According to one example, iSTA  601  and rSTA  603  announce their EVM levels periodically in either Beacon frames, or Probe Response frames or some other frames, so that the client electronic device  621  can hear and obtain the EVM levels used in the passive ranging operation  600 . Additionally or alternatively, iSTA  601  and rSTA  603  may include their EVM levels in the EVM requirement negotiation phase, so that client electronic device  621  can hear the negotiation between iSTA  601  and rSTA  603  and obtain the EVM levels used in the passive ranging operation  600 . 
     According to some embodiments, client electronic device  621  may use the received EVM levels of iSTA  601  and rSTA  603  in choosing an appropriate algorithm for determining the relative distance. For example, if client electronic device  621  determines that the EVM levels of iSTA  601  and rSTA  603  indicate that the measurement frames are transmitted using high quality signal transmission, client electronic device  621  can use an algorithm associated with high quality signal transmission for determining the relative distance. Therefore, client electronic device  621  determines the relative distance with higher accuracy. Additionally or alternatively, client electronic device  621  may use the received EVM levels of iSTA  601  and rSTA  603  to determine the quality and/or accuracy of the determined relative distance. For example, if client electronic device  621  determines that the EVM levels of iSTA  601  and rSTA  603  indicate that the measurement frames are transmitted using low quality signal transmission, client electronic device  621  may determine that the relative distance it determines has (or may have) a low degree of accuracy. 
       FIG. 7  illustrates an example method  700  for a wireless system implementing a measurement phase of the passive ranging operation, according to some embodiments of the disclosure. As a convenience and not a limitation,  FIG. 7  may be described with regard to elements of  FIGS. 1-6 . Method  700  may represent the operation of an electronic device, e.g., client electronic device  621  of  FIG. 6  implementing the passive ranging operation. Method  700  may also be performed by system  200  of  FIG. 2  and/or computer system  800  of  FIG. 8 . But method  700  is not limited to the specific embodiments depicted in those figures and other systems may be used to perform the method as will be understood by those skilled in the arts. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown in  FIG. 7 . 
     At  702 , an electronic device (e.g., client electronic device  621 ) receives a first frame (e.g., first measurement frame  605 ) from a first electronic device (e.g., iSTA  601 ). According to some embodiments, iSTA  601  transmits the first frame using the agreed-on parameters (e.g., the negotiated EVM requirement) that were determined during an EVM requirement negotiation with a second electronic device (e.g., rSTA  603 ). For example, the first frame is transmitted by the first electronic device in accordance with a first indication of EVM requirement (e.g., the second EVM level discussed above) associated with the first electronic device. Client electronic device  621  records the time instant the first frame was received (e.g., time instant t 5 .) 
     At  704 , client electronic device  621  receives a second frame (e.g., second measurement frame  607 ) from the second electronic device (e.g., rSTA  603 ). According to some embodiments, rSTA  603  transmits the second frame using the agreed-on parameters (e.g., the negotiated EVM requirement) that were determined during the EVM requirement negotiation with the first electronic device (e.g., iSTA  601 ). For example, the second frame is transmitted by the second electronic device in accordance with a second indication of EVM requirement (e.g., the third EVM level discussed above) associated with the second electronic device. Client electronic device  621  records the time instant the second frame was received (e.g., time instant t 6 ). 
     At  706 , client electronic device  621  listens and receives the time instants reported by the first electronic device and/or the second electronic device (e.g., time instants t 1 , t 2 , t 3 , and t 4 ). 
     At  708 , client electronic device  621  determines its relative distance to the first and second electronic devices using, at least, the recorded and received time instants. According to some embodiments, client device  621  also receives the EVM levels associated with the first and second frames transmitted by iSTA  601  and rSTA  603 . Client electronic device  621  may use the received EVM levels of iSTA  601  and rSTA  603  in determining its relative distance to the first and second electronic devices. For example, client electronic device  621  may use the received EVM levels in choosing an appropriate algorithm for determining the relative distance. Additionally or alternatively, client electronic device  621  may use the received EVM levels of iSTA  601  and rSTA  603  to determine the quality and/or accuracy of the determined relative distance. 
     Various embodiments can be implemented, for example, using one or more computer systems, such as computer system  800  shown in  FIG. 8 . Computer system  800  can be any well-known computer capable of performing the functions described herein such as devices  110 ,  120  of  FIG. 1, 200  of  FIG. 2, 301, 303  of  FIG. 3, 401, 403, 411  of  FIGS. 4A-B , or  601 ,  603 ,  621  of  FIG. 6 . Computer system  800  can be used, for example, to implement method discussed in this disclosure such as, but not limited to, method  500  of  FIG. 5A , method  520  of  FIG. 5B , and/or method  700  of  FIG. 7 . 
     Computer system  800  includes one or more processors (also called central processing units, or CPUs), such as a processor  804 . Processor  804  is connected to a communication infrastructure  806  (e.g., a bus.) Computer system  800  also includes user input/output device(s)  803 , such as monitors, keyboards, pointing devices, etc., that communicate with communication infrastructure  806  through user input/output interface(s)  802 . Computer system  800  also includes a main or primary memory  808 , such as random access memory (RAM). Main memory  808  may include one or more levels of cache. Main memory  808  has stored therein control logic (e.g., computer software) and/or data. 
     Computer system  800  may also include one or more secondary storage devices or memory  810 . Secondary memory  810  may include, for example, a hard disk drive  812  and/or a removable storage device or drive  814 . Removable storage drive  814  may be a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, tape backup device, and/or any other storage device/drive. 
     Removable storage drive  814  may interact with a removable storage unit  818 . Removable storage unit  818  includes a computer usable or readable storage device having stored thereon computer software (control logic) and/or data. Removable storage unit  818  may be a floppy disk, magnetic tape, compact disk, DVD, optical storage disk, and/any other computer data storage device. Removable storage drive  814  reads from and/or writes to removable storage unit  818  in a well-known manner. 
     According to some embodiments, secondary memory  810  may include other means, instrumentalities or other approaches for allowing computer programs and/or other instructions and/or data to be accessed by computer system  800 . Such means, instrumentalities or other approaches may include, for example, a removable storage unit  822  and an interface  820 . Examples of the removable storage unit  822  and the interface  820  may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM or PROM) and associated socket, a memory stick and USB port, a memory card and associated memory card slot, and/or any other removable storage unit and associated interface. 
     Computer system  800  may further include a communication or network interface  824 . Communication interface  824  enables computer system  800  to communicate and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referenced by reference number  828 ). For example, communication interface  824  may allow computer system  800  to communicate with remote devices  828  over communications path  826 , which may be wired and/or wireless, and which may include any combination of LANs, WANs, the Internet, etc. Control logic and/or data may be transmitted to and from computer system  800  via communication path  826 . 
     The operations in the preceding embodiments can be implemented in a wide variety of configurations and architectures. Therefore, some or all of the operations in the preceding embodiments may be performed in hardware, in software or both. In some embodiments, a tangible, non-transitory apparatus or article of manufacture includes a tangible, non-transitory computer useable or readable medium having control logic (software) stored thereon is also referred to herein as a computer program product or program storage device. This includes, but is not limited to, computer system  800 , main memory  808 , secondary memory  810  and removable storage units  818  and  822 , as well as tangible articles of manufacture embodying any combination of the foregoing. Such control logic, when executed by one or more data processing devices (such as computer system  800 ), causes such data processing devices to operate as described herein. 
     Based on the teachings contained in this disclosure, it will be apparent to persons skilled in the relevant art(s) how to make and use embodiments of the disclosure using data processing devices, computer systems and/or computer architectures other than that shown in  FIG. 8 . In particular, embodiments may operate with software, hardware, and/or operating system implementations other than those described herein. 
     It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more, but not all, exemplary embodiments of the disclosure as contemplated by the inventor(s), and thus, are not intended to limit the disclosure or the appended claims in any way. 
     While the disclosure has been described herein with reference to exemplary embodiments for exemplary fields and applications, it should be understood that the disclosure is not limited thereto. Other embodiments and modifications thereto are possible, and are within the scope and spirit of the disclosure. For example, and without limiting the generality of this paragraph, embodiments are not limited to the software, hardware, firmware, and/or entities illustrated in the figures and/or described herein. Further, embodiments (whether or not explicitly described herein) have significant utility to fields and applications beyond the examples described herein. 
     Embodiments have been described herein with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined as long as the specified functions and relationships (or equivalents thereof) are appropriately performed. In addition, alternative embodiments may perform functional blocks, steps, operations, methods, etc. using orderings different from those described herein. 
     References herein to “one embodiment,” “an embodiment,” “an example embodiment,” or similar phrases, indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of persons skilled in the relevant art(s) to incorporate such feature, structure, or characteristic into other embodiments whether or not explicitly mentioned or described herein. 
     The breadth and scope of the disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Metadata:
Filing Date: 20191024
Publication Date: 20220301
Grant Date: 20220301
Priority Date: 20181026
Inventors: BEERI, ROY
WANG, QI
SHANI, OREN
FEINMESSER, YOAV
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B17/309", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L1/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/0003", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B17/21", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S5/0244", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/0003", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W24/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S11/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B17/309", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L1/0003", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W24/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B17/21", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B17/309", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/20", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 70325856