WO2018080597A1 - Multi-antenna range estimation for wireless networking - Google Patents

Abstract

A client station (STA) performs a ranging protocol with an access point (AP). The distance between the STA and the AP is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the STA and the AP. According to some embodiments, in support of spatial multiplexing ranging operations, antenna configuration information is exchanged in advance of the ranging measurements.

Description

MULTI-ANTENNA RANGE ESTIMATION FOR WIRELESS NETWORKING

PRIORITY CLAIM

[0001] This Application claims the benefit of U.S. Provisional application No. 62/412,162, filed October 24, 2016, the disclosure of which is incorporated by reference herein.

TECHNICAL FIELD

[0002] Aspects of the disclosure relate generally to information processing and

communications and, more particularly, to wireless networking. Some embodiments relate to client stations (STAs) and access point stations (APs) that operate according to the Institute of Electrical and Electronic Engineers (IEEE) 802.11 family of wireless networking standards. Some embodiments in particular relate to the IEEE 802.1 lax and 802.1 laz standards currently under development, and to similar implementations. Some embodiments relate to high-efficiency (HE) wireless or high-efficiency WLAN or Wi-Fi (HEW) communications.

BACKGROUND

[0003] Wireless local -area networking (WLAN) has been continually growing in its ubiquity over the years. For example, access point stations (APs) that operate according to the media access control and physical layer specifications standardized in the Institute of Electrical and Electronic Engineers (IEEE) 802.11 family of wireless networking standards are presently found in homes, businesses, public facilities, transportation vehicles, and even wider areas such as being deployed to provide coverage throughout some cities. Client stations (STAs) are commonly integrated into a variety of electronic devices, such as personal computers, smartphones, tablets, and other portable computing devices, televisions, media players, and other appliances, cameras and other data-gathering devices, medical equipment, and countless other applications.

[0004] Recent developments in WLAN technology include the use of the WLAN

infrastructure and communications protocols to determine the absolute or relative location, or position, of STAs. This functionality is likely to find uses in environments that are not amenable to the use of more conventional location technology such as the global positioning system (GPS), or as an alternative to GPS that may offer superior accuracy and speed of location determination. For instance, indoor environments that lack line-of-sight signal reception of GPS signals may be well suited to use WLAN-based location service. The working group for IEEE 802.1 laz standardization, which is currently under development, has proposed the use of signal round-trip time (RTT) measurements and, optionally, angle measurements to ascertain the distance of a given STA from one or more APs. Multiple distance measurements of a STA from multiple APs, referred to as ranging, may be used to locate the STA. Presently, there is a need for improved accuracy and effectiveness for WLAN-based location determination techniques. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0006] FIG. 1 A is a high-level system diagram illustrating a wireless local area network (WLAN) in accordance with some embodiments.

[0007] FIG. IB illustrates a basic service set (BSS) and an overlapping basic service set (OBSS) in accordance with some embodiments.

[0008] FIG. 2 is a block diagram of a radio architecture in accordance with some embodiments.

[0009] FIG. 3 illustrates a front-end module circuitry for use in the radio architecture of FIG. 2 in accordance with some embodiments.

[0010] FIG. 4A illustrates a radio IC circuitry for use in the radio architecture of FIG. 2 in accordance with some embodiments.

[0011] FIG. 4B illustrates a baseband processing circuitry for use in the radio architecture of FIG.1 in accordance with some embodiments.

[0012] FIG. 5 is a diagram illustrating a MEVIO arrangement utilizing an access point (AP) and a client station (STA), each having multiple antennas according to some embodiments.

[0013] FIGs. 6A-6B are diagrams illustrating position-measurement scenarios according to various examples.

[0014] FIG. 7 is a process flow diagram illustrating a sequence of phases of a ranging protocol carried out by an AP and one or more STAs, according to some embodiments. [0015] FIG. 8 is a process flow diagram illustrating an example set of operations that an AP is constructed, programmed, or otherwise configured, to perform, according to some embodiments.

[0016] FIG. 9 is a process flow diagram illustrating an example set of operations that a STA is constructed, programmed, or otherwise configured, to perform, according to some embodiments.

DETAILED DESCRIPTION

[0017] Embodiments are directed generally to wireless communi cations between mobile or fixed stations in which a ranging service is supported based on wireless communications signaling between the stations. The IEEE 802.11 family of wireless local area networking (WLA ) standards provide for variable and selectable channel configurations, and for the sake of brevity the present disclosure describes various embodiments in the context of certain IEEE 802.11 WLAN implementations. However, it will be understood that the principles described herein may be suitably adapted to be applied in other types of wireless

communications regimes, whether presently known, or arising in the future. These other types of wireless communications regimes may be other types of WLANs, peer-to-peer arrangements, wireless ad-hoc networks, wide-area networks (WANs), universal terrestrial radio access networks (UTRAN), evolved universal mobile telecommunications system (E- UTRA), or any hybrid or various combination of these, or other, wireless communication technologies.

[0018] As noted above, wireless network-based location determination protocols have been proposed. For instance, the ongoing work in developing standardization of IEEE 802.1 laz protocols seeks to build upon the medium access control (MAC) and physical (PHY) layers of defined WLAN technologies, including high throughput (HT), very high throughput (VHT), directional multi-gigabit (DMG), high-efficiency WLAN (HEW), next- generation 60 GHz (NG60), or the like, which may be standardized under IEEE 802.1 In, 802.1 lac, 802.1 lax, 802.1 lay, and the like. The stated purpose of the 802.1 laz standard is to provide wireless connectivity for fixed, portable, and moving stations within a local area, and to support a large number of STAs (e.g., over 200) in performing positioning determination concurrently. Also, a protocol is to be provided for determining the absolute or relative position of a STA, regardless of whether that STA is, or is not, associated with an AP. [0019] It will be understood that the principles described herein in the context of the illustrative examples that are provided are applicable in systems, devices, and processes that may or may not be compliant with any of the 802.11 -family standards of WLANs, whether published or under development, or other radio-access network (RAN) technologies that are mentioned herein. However, for the sake of brevity, many of the embodiments described herein are presented in the context of WLAN technology as examples of suitable settings in which the embodiments may be implemented.

[0020] FIG. 1 A illustrates a WLAN 10 in accordance with some aspects. The WLAN may comprise a basic service set (BSS) 10 that may include a master station 12, which may be an AP, a plurality of high-efficiency (HE) wireless (e.g., IEEE 802.11ax/ay) STAs 14 and a plurality of legacy (e.g., IEEE 802.11n/ac/g a/b/sd/ah) devices 16.

[0021] The master station 12 may be an AP using the IEEE 802.11 to transmit and receive. The master station 12 may be a device using peer-to-peer communications with other devices and using 802.11 and/or 3GPP cellular standards. The master station 12 may use other communications protocols instead or in addition to aforementioned standards like Bluetooth Low Energy. The IEEE 802.11 protocol may be IEEE 802.1 lax, 802.1 lad, or the like. The IEEE 802.11 protocol may include using orthogonal frequency division multiple-access (OFDMA), time division multiple access (TDMA), and/or code division multiple access (CDMA). The IEEE 802.11 protocol may include a multiple access technique. For example, the IEEE 802.11 protocol may include space-divisionmultiple access (SDMA) and/or multiple-user multiple-input multiple-output (MU-MIMO). In some aspects, the 802.11 system may include an antenna structure operated as one or more arrays to generate Orbital Angular Momentum (OAM) beams of varying OAM modes.

[0022] The legacy devices 16 may operate in accordance with one or more of IEEE 802.1 1 a/b/g n/ac/ad/af/ah/aj, or another legacy wireless communication standard. The legacy devices 16 may be STAs or IEEE STAs. The HE STAs 14 may be wireless transmit and receive devices such as cellular telephone, smart telephone, handheld wireless device, wireless glasses, wireless watch, wireless personal device, tablet, or another device that may be transmitting and receiving using the IEEE 802.11 protocol such as IEEE 802.1 lax or another wireless protocol.

[0023] The master station 12 may communicate with legacy devices 16 in accordance with legacy IEEE 802.11 communication techniques. In some examples, the master station 12 may also be configured to communicate with HE STAs 14 in accordance with legacy IEEE 802.11 communication techniques.

[0024] In some aspects, a HE frame may be configurable to have the same bandwidth as a subchannel. The bandwidth of a subchannel may be 20MHz, 40MHz, or 80 MHz, 160MHz, 320MHz contiguous bandwidths or an 80+80MHz (160MHz) non-contiguous bandwidth. In some examples, the bandwidth of a subchannel may be 1 MHz, 1.25MHz, 2.03MHz, 2.5MHz, 5 MHz and lOMHz, or a combination thereof or another bandwidth that is less or equal to the available bandwidth may also be used. In some examples the bandwidth of the subchannels may be based on a number of active subcarriers. In some examples the bandwidth of the subchannels are multiples of 26 (e.g., 26, 52, 104, etc.) active subcarriers or tones that are spaced by 20 MHz. In some examples the bandwidth of the subchannels is 256 tones spaced by 20 MHz. In some examples the subchannels are multiple of 26 tones or a multiple of 20 MHz. In some examples a 20 MHz subchannel may comprise 256 tones for a 256 point Fast Fourier Transform (FFT).

[0025] A HE frame may be configured for transmitting a number of spatial streams, which may be in accordance with MU-MDVIO. In some examples a HE frame may be configured for transmitting streams in accordance with antenna structures described herein and operated as one or more arrays or antenna structure(s) to generate Orbital Angular Momentum (OAM) beams of various OAM modes. In accordance with some IEEE 802.11 -family examples, a master station 12 may operate as a master station which may be arranged to contend for a wireless medium (e.g., during a contention period) to receive exclusive control of the medium for an HE control period. In some examples, the HE control period may be termed a transmission opportunity (TXOP). The master station 12 may transmit a HE master-sync transmission, which may be a trigger frame or HE control and schedule transmission, at the beginning of the HE control period. The master station 12 may transmit a time duration of the TXOP and sub-channel information. During the HE control period, HE STAs 14 may communicate with the master stati on 12 in accordance with a non-contenti on based multiple access technique such as OFDMA or MU-MEVIO. This is unlike conventional WLAN communications in which devices communicate in accordance with a contention-based communication technique, rather than a multiple access technique. During the HE control period, the master station 12 may communicate with HE stations 14 using one or more HE frames. During the HE control period, the HE STAs 14 may operate on a sub-channel smaller than the operating range of the master station 12. During the HE control period, legacy stations refrain from communicating. In other examples the HE STAs 14 may communicate with the master station 12 in accordance with an antenna array or structure(s) of the types discussed below for generating Orbital Angular Momentum (OAM) beams of various OAM modes. This may be full multiplexing where n data streams are mapped to n OAM modes; or fewer than n data streams are mapped to n OAM modes for partial diversity and partial multiplexing; or one data stream may be mapped to n OAM modes for full diversity, depending on channel conditions and the objectives of the system as discussed more fully below.

[0026] The master station 12 may also communicate with legacy stations 16 and/or HE stations 14 in accordance with legacy IEEE 802.11 communication techniques. In some examples, the master station 12 may also be configurable to communicate with HE stations 14 outside the HE control period in accordance with legacy IEEE 802.11 communication techniques, although this is not a requirement.

[0027] FIG. IB illustrates a basic service set (BSS) 24 and an overlapping basic service set (OBSS) 22 in accordance with some examples. Illustrated in FIG. IB are an OBSS 22 and BSS 24. The OBSS 22 includes one or more master stations 12, one or more HE stations 14, and one or more legacy devices 18. The HE station 14.1 and legacy device 16.1 are associated with the master station 12.2. The master station 12.2 has an identification (not illustrated) for the OBSS 22, which may be termed a BSS identification (BSSID). In some examples, the identification is termed the color of the OBSS 22. The HE station 14.1 stores a MAC address of the master station 12.2. The OBSS 22 is a BSS 10. The OBSS 22 is termed an OBSS 22 to BSS 24 because some of the signals 26 overlap with the BSS 24.

[0028] The BSS 24 includes one or more master stations 12, one or more HE stations 14.2, 14.3, and one or more legacy devices 16.2. The HE stations 14.2 and 14.3 and legacy device 16.1 are associated with the master station 12.1. The master station 12.1 has an identification (not illustrated) for the BSS 24, which may be termed a BSSID. In some examples, the identification is termed the color of the BSS 24. The HE stations 14.2 and 14.3 store a MAC address (see FIGS. 3, 4, and 5) of the master station 12.1.

[0029] Signal 26.1 is transmitted from the master station 12.2 and received by HE station 14.2. Signal 26.2 is transmitted from HE station 14.1 and received by HE station 14.2. Signal 26.4 is transmitted from the HE station 14.3 and received by HE station 14.2. Signal 26.3 is transmitted by master station 12.1 and received by HE station 14.2. The signals 26 may be packets transmitted by a master station 12, HE station 14, legacy device 16, and/or another wireless device (not illustrated).

[0030] In some examples the HE station 14 and/or master station 12 are configured to determine whether or not to use spatial re-use based on whether a signal 26 is from an OBSS 22 or BSS 24. The HE station 14 determines whether the detected frame is an inter-BSS (OBSS 24, signals 26.1 and 26.2) or intra-BSS frame (BSS 24, signals 26.3 and 26.4) by using BSS color, which may be indicated in a physical header (e.g., SIG-A) or MAC address in the MAC header. If the detected frame is an inter BSS frame, under predetermined conditions, the HE station 14 uses a predetermined a power detect level of the OBSS 22 that is greater than the minimum receive sensitivity level to determine whether or not the HE station 14 may perform an action such as spatially reuse the resource the frame is using.

[0031] FIG. 2 is a block diagram of a radio architecture 100 in accordance with some embodiments. Radio architecture 100 may include radio front-end module (FEM) circuitry 104, radio IC circuitry 106 and baseband processing circuitry 108. Radio architecture 100 as shown includes both Wireless Local Area Network (WLAN) functionality and Bluetooth

(BT) functionality although embodiments are not so limited. In this disclosure, "WLAN" and "Wi-Fi" are used interchangeably.

[0032] FEM circuitry 104 may include a WLAN or Wi-Fi FEM circuitry 104A and a Bluetooth (BT) FEM circuitry 104B. The WLAN FEM circuitry 104 A may include a receive signal path comprising circuitry configured to operate on WLAN RF signals received from one or more antennas 101, to amplify the received signals and to provide the amplified versions of the received signals to the WLAN radio IC circuitry 106A for further processing. The BT FEM circuitry 104B may include a receive signal path which may include circuitry configured to operate on BT RF signals received from one or more antennas 101, to amplify the received signals and to provide the amplified versions of the received signals to the BT radio IC circuitry 106B for further processing. FEM circuitry 104A may also include a transmit signal path which may include circuitry configured to amplify WLAN signals provided by the radio IC circuitry 106A for wireless transmission by one or more of the antennas 101. In addition, FEM circuitry 104B may also include a transmit signal path which may include circuitry configured to amplify BT signals provided by the radio IC circuitry 106B for wireless transmission by the one or more antennas. In the embodiment of FIG. 2, although FEM 104 A and FEM 104B are shown as being distinct from one another, embodiments are not so limited, and include within their scope the use of an FEM (not shown) that includes a transmit path and/or a receive path for both WLAN and BT signals, or the use of one or more FEM circuitries where at least some of the FEM circuitries share transmit and/or receive signal paths for both WLAN and BT signals.

[0033] Radio IC circuitry 106 as shown may include WLAN radio IC circuitry 106 A and BT radio IC circuitry 106B. The WLAN radio IC circuitry 106A may include a receive signal path which may include circui try to down-convert WLAN RF signals received from the FEM circuitry 104A and provide baseband signals to WLAN baseband processing circuitry 108A. BT radio IC circuitry 106B may in turn include a receive signal path which may include circuitry to down-convert BT RF signals received from the FEM circuitry 104B and provide baseband signals to BT baseband processing circuitry 108B. WLAN radio IC circuitry 106A may also include a transmit signal path which may include circuitry to up- convert WLAN baseband signals provided by the WLAN baseband processing circuitry 108A and provide WLAN RF output signals to the FEM circuitry 104A for subsequent wireless transmission by the one or more antennas 101. BT radio IC circuitry 106B may also include a transmit signal path which may include circuitry to up-convert BT baseband signals provided by the BT baseband processing circuitry 108B and provide BT RF output signals to the FEM circuitry 104B for subsequent wireless transmission by the one or more antennas 101. In the embodiment of FIG. 2, although radio IC circuitries 106A and 106B are shown as being distinct from one another, embodiments are not so limited, and include within their scope the use of a radio IC circuitry (not shown) that includes a transmit signal path and/or a receive signal path for both WLAN and BT signals, or the use of one or more radio IC circuitries where at least some of the radio IC circuitries share transmit and/or receive signal paths for both WLAN and BT signals.

[0034] Baseband processing circuity 108 may include a WLAN baseband processing circuitry 108A and a BT baseband processing circuitry 108B. The WLAN baseband processing circuitry 108A may include a memory, such as, for example, a set of RAM arrays in a Fast Fourier Transform or Inverse Fast Fourier Transform block (not shown) of the WLAN baseband processing circuitry 108 A. Each of the WLAN baseband circuitry 108 A and the BT baseband circuitry 108B may further include one or more processors and control logic to process the signals received from the corresponding WLAN or BT receive signal path of the radio IC circuitry 106, and to also generate corresponding WLAN or BT baseband signals for the transmit signal path of the radio IC circuitry 106. Each of the baseband processing circuitries 108A and 108B may further include physical layer (PHY) and medium access control layer (MAC) circuitry, and may further interface with application processor 111 for generation and processing of the baseband signals and for controlling operations of the radio IC circuitry 106.

[0035] Referring still to FIG. 2, according to the shown embodiment, WLAN-BT coexistence circuitry 113 may include logic providing an interface between the WLAN baseband circuitry 108A and the BT baseband circuitry 108B to enable use cases requiring WLAN and BT coexistence. In addition, a switch 103 may be provided between the WLAN FEM circuitry 104A and the BT FEM circuitry 104B to allow switching between the WLAN and BT radios according to application needs. In addition, although the antennas 101 are depicted as being respectively connected to the WLAN FEM circuitry 104A and the BT FEM circuitry 104B, embodiments include within their scope the sharing of one or more antennas as between the WLAN and BT FEMs, or the provision of more than one antenna connected to each of FEM 104 A or 104B.

[0036] In some embodiments, the front-end module circuitry 104, the radio IC circuitry 106, and baseband processing circuitry 108 may be provided on a single radio card, such as wireless radio card 102. In some other embodiments, the one or more antennas 101, the FEM circuitry 104 and the radio IC circuitry 106 may be provided on a single radio card. In some other embodiments, the radio IC circuitry 106 and the baseband processing circuitry 108 may be provided on a single chip or integrated circuit (IC), such as IC 112.

[0037] In some embodiments, the wireless radio card 102 may include a WLAN radio card and may be configured for Wi-Fi communications, although the scope of the embodiments is not limited in this respect. In some of these embodiments, the radio architecture 100 may be configured to receive and transmit orthogonal frequency division multiplexed (OFDM) or orthogonal frequency division multiple access (OFDMA) communication signals over a multicarrier communication channel. The OFDM or OFDMA signals may comprise a plurality of orthogonal subcarriers. Each carrier frequency may be further distinguishable from another channel by use of orthogonal coding techniques such as code-division multiple access (CDMA) or P-matrix code of IEEE 802.1 ln/ac/ax, for instance.

[0038] In some of these multicarrier embodiments, radio architecture 100 may be part of a Wi-Fi communication station (STA) such as a wireless access point (AP), a base station or a mobile device including a Wi-Fi device. In some of these embodiments, radio architecture 100 may be configured to transmit and receive signals in accordance with specific communication standards and/or protocols, such as any of the Institute of Electrical and Electronics Engineers (IEEE) standards including IEEE 802.11n-2009, IEEE 802.11-2012, IEEE 802.11-2016, , IEEE 802.1 lac, and/or IEEE 802.1 lax standards and/or proposed specifications for WLANs, although the scope of embodiments is not limited in this respect. Radio architecture 100 may also be suitable to transmit and/or receive communications in accordance with other techniques and standards.

[0039] In some embodiments, the radio architecture 100 may be configured for high- efficiency (HE) Wi-Fi (HEW) communications in accordance with the IEEE 802.1 lax standard. In these embodiments, the radio architecture 100 may be configured to

communicate in accordance with an OFDMA technique, although the scope of the embodiments is not limited in this respect.

[0040] In some other embodiments, the radio architecture 100 may be configured to transmit and receive signals transmitted using one or more other modulation techniques such as spread spectrum modulation (e.g., direct sequence code division multiple access (DS- CDMA) and/or frequency hopping code division multiple access (FH-CDMA)), time-division multiplexing (TDM) modulation, and/or frequency-division multiplexing (FDM) modulation, although the scope of the embodiments is not limited in this respect.

[0041] In some embodiments, as further shown in FIG. 2, the BT baseband circuitry 108B may be compliant with a Bluetooth (BT) connectivity standard such as Bluetooth, Bluetooth 4.0 or Bluetooth 5.0, or any other iteration of the Bluetooth Standard. In embodiments that include BT functionality as shown for example in FIG. 2, the radio architecture 100 may be configured to establish a BT synchronous connection oriented (SCO) link and/or a BT low energy (BT LE) link. In some of the embodiments that include functionality, the radio architecture 100 may be configured to establish an extended SCO (eSCO) link for BT communications, although the scope of the embodiments is not limited in this respect. In some of these embodiments that include a BT functionality, the radio architecture may be configured to engage in a BT Asynchronous Connection-Less (ACL) communications, although the scope of the embodiments is not limited in this respect. In some embodiments, as shown in FIG. 2, the functions of a BT radio card and WLAN radio card may be combined on a single wireless radio card, such as single wireless radio card 102, although embodiments are not so limited, and include within their scope discrete WLAN and BT radio cards

[0042] In some embodiments, the radio-architecture 100 may include other radio cards, such as a cellular radio card configured for cellular (e.g., 3GPP such as LTE, LTE- Advanced or 5G communications). [0043] In some IEEE 802.11 embodiments, the radio architecture 100 may be configured for communication over various channel bandwidths including band widths having center frequencies of about 900 MHz, 2.4 GHz, 5 GHz, and bandwidths of about 1 MHz, 2 MHz, 2.5 MHz, 4 MHz, 5MHz, 8 MHz, 10 MHz, 16 MHz, 20 MHz, 40MHz, 80MHz (with contiguous bandwidths) or 80+80MHz (160MHz) (with non-contiguous bandwidths). In some embodi ments, a 320 MHz channel bandwidth may be used. The scope of the embodiments is not limited with respectto the above center frequencies however.

[0044] FIG 3 illustrates FEM circuitry 200 in accordance with some embodiments. The FEM circuitry 200 is one example of circuitry that may be suitable for use as the WLAN and/or BT FEM circuitry 104A/104B (FIG. 2), although other circuitry configurations may also be suitable.

[0045] In some embodiments, the FEM circuitry 200 may include a TX/RX switch 202 to switch between transmit mode and receive mode operation. The FEM circuitry 200 may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry 200 may include a low-noise amplifier (LNA) 206 to amplify received RF signals 203 and provide the amplified received RF signals 207 as an output (e.g., to the radio IC circuitry 106 (FIG. 2)). The transmit signal path of the circuitry 200 may include a power amplifier (PA) to amplify input RF signals 209 (e.g., provided by the radio IC circuitry 106), and one or more filters 212, such as band-pass filters (BPFs), low-pass filters (LPFs) or other types of filters, to generate RF signals 215 for subsequent transmission (e.g., by one or more of the antennas 101 (FIG. 2)).

[0046] In some dual-mode embodiments for Wi-Fi communication, the FEM circuitry 200 may be configured to operate in either the 2.4 GHz frequency spectrum or the 5 GHz frequency spectrum. In these embodiments, the recei ve signal path of the FEM circuitry 200 may include a receive signal path duplexer 204 to separate the signals from each spectrum as well as provide a separate LNA 206 for each spectrum as shown. In these embodiments, the transmit signal path of the FEM circuitry 200 may also include a power amplifier 210 and a filter 212, such as a BPF, a LPF or another type of filter for each frequency spectrum and a transmit signal path duplexer 214 to provide the signals of one of the different spectrums onto a single transmit path for subsequent transmission by the one or more of the antennas 101 (FIG. 2). In some embodiments, BT communications may utilize the 2.4 GHZ signal paths and may utilize the same FEM circuitry 200 as the one used for WLAN communications. [0047] FIG. 4A illustrates radio IC circuitry 300 in accordance with some embodiments. The radio IC circuitry 300 is one example of circuitry that may be suitable for use as the WLAN or BT radio IC circuitry 106A/106B (FIG. 2), although other circuitry configurations may also be suitable.

[0048] In some embodiments, the radio IC circuitry 300 may include a receive signal path and a transmit signal path. The receive signal path of the radio IC circuitry 300 may include at least mixer circuitry 302, such as, for example, down-conversion mixer circuitry, amplifier circuitry 306 and filter circuitry 308. The transmit signal path of the radio IC circuitry 300 may include at least filter circuitr ⁷ 312 and mixer circuitry 314, such as, for example, up- conversion mixer circuitry. Radio IC circuitry 300 may also include synthesizer circuitry 304 for synthesizing a frequency 305 for use by the mixer circuitry 302 and the mixer circuitry 314. The mixer circuitry 302 and/or 314 may each, according to some embodiments, be configured to provide direct conversion functionality. The latter type of circuitry presents a much simpler architecture as compared with standard super-heterodyne mixer circuitries, and any flicker noise brought about by the same may be alleviated for example through the use of OFDM modulation. FIG. 4A illustrates only a simplified version of a radio IC circuitry, and may include, although not shown, embodiments where each of the depicted circuitries may include more than one component. For instance, mixer circuitry 320 and/or 314 may each include one or more mixers, and filter circuitries 308 and/or 312 may each include one or more filters, such as one or more BPFs and/or LPFs according to application needs. For example, when mixer circuitries are of the direct-conversion type, they may each include two or more mixers.

[0049] In some embodiments, mixer circuitry 302 may be configured to down-convert RF signals 207 received from the FEM circuitry 104 (FIG. 2) based on the synthesized frequency 305 provided by synthesizer circuitry 304. The amplifier circuitry 306 may be configured to amplify the down-converted signals and the filter circuitry 308 may include a LPF configured to remove unwanted signals from the down-converted signals to generate output baseband signals 307. Output baseband signals 307 may be provided to the baseband processing circuitry 108 (FIG. 2) for further processing. In some embodiments, the output baseband signals 307 may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 302 may comprise passive mixers, although the scope of the embodiments is not limited in this respect. [0050] In some embodiments, the mixer circuitry 314 may be configured to up-convert input baseband signals 311 based on the synthesized frequency 305 provided by the synthesizer circuitry 304 to generate RF output signals 209 for the FEM circuitry 104. The baseband signals 311 may be provided by the baseband processing circuitry 108 and may be filtered by filter circuitry 312. The filter circuitry 312 may include a LPF or a BPF, although the scope of the embodiments is not limited in this respect.

[0051] In some embodiments, the mixer circuitry 302 and the mixer circuitr ⁷ 314 may each include two or more mixers and may be arranged for quadrature down-conversion and/or up- conversion respectively with the help of synthesizer 304. In some embodiments, the mixer circuitry 302 and the mixer circuitry 314 may each include two or more mixers each configured for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 302 and the mixer circuitry 314 may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, the mixer circuitry 302 and the mixer circuitry 314 may be configured for super-heterodyne operation, although this is not a requirement.

[0052] xer circuitry 302 may comprise, according to one embodiment: quadrature passive mixers (e.g., for the in-phase (I) and quadrature phase (Q) paths). In such an embodiment, RF input signal 207 from FIG. 4A may be down-converted to provide I and Q baseband output signals to be sent to the baseband processor

[0053] Quadrature passive mixers may be driven by zero and ninety-degree time-varying LO switching signals provided by a quadrature circuitry which may be configured to receive a LO frequency (fLO) from a local oscillator or a synthesizer, such as LO frequency 305 of synthesizer 304 (FIG. 4A). In some embodiments, the LO frequency may be the carrier frequency, while in other embodiments, the LO frequency may be a fraction of the carrier frequency (e.g., one-half the carrier frequency, one-third the carrier frequency). In some embodiments, the zero and ninety-degree time-varying switching signals may be generated by the synthesizer, although the scope of the embodiments is not limited in this respect.

[0054] In some embodiments, the LO signals may differ in duty cycle (the percentage of one period in which the LO signal is high) and/or offset (the difference between start points of the period). In some embodiments, the LO signals may have a 25% duty cycle and a 50% offset. In some embodiments, each branch of the mixer circuitry (e.g., the in-phase (Γ) and quadrature phase (Q) path) may operate at a 25% duty cycle, which may result in a significant reduction is power consumption. [0055] The RF input signal 207 (FIG. 3) may comprise a balanced signal, although the scope of the embodiments is not limited in this respect. The I and Q baseband output signals may be provided to low-nose amplifier, such as amplifier circuitry 306 (FIG. 4A) or to filter circuitr - 308 (FIG. 4A).

[0056] In some embodiments, the output baseband signals 307 and the input baseband signals 31 1 may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals 307 and the input baseband signals 311 may be digital baseband signals. In these alternate

embodiments, the radio IC circuitry may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry.

[0057] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, or for other spectrums not mentioned here, although the scope of the embodiments is not limited in this respect.

[0058] In some embodiments, the synthesizer circuitry 304 may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 304 may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider. According to some embodiments, the synthesizer circuitry 304 may include digital synthesizer circuitry. An advantage of using a digital synthesizer circuitry is that, although it may still include some analog components, its footprint may be scaled down much more than the footprint of an analog synthesizer circuitry. In some embodiments, frequency input into synthesizer circuity 304 may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. A divider control input may further be provided by either the baseband processing circuitry 108 (FIG. 2) or the application processor 111 (FIG. 2) depending on the desired output frequency 305. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table (e.g., within a Wi-Fi card) based on a channel number and a channel center frequency as determined or indicated by the application processor 111.

[0059] In some embodiments, synthesizer circuitry 304 may be configured to generate a carrier frequency as the output frequency 305, while in other embodiments, the output frequency 305 may be a fraction of the carrier frequency (e.g., one-half the carrier frequency, one-third the carrier frequency). In some embodiments, the output frequency 305 may be a LO frequency (fLO). [0060] FIG. 4B illustrates a functional block diagram of baseband processing circuitry 400 in accordance with some embodiments. The baseband processing circuitry 400 is one example of circuitry that may be suitable for use as the baseband processing circuitry 108 (FIG. 2), although other circuitry configurations may also be suitable. The baseband processing circuitry 400 may include a receive baseband processor (RX BBP) 402 for processing receive baseband signals 309 provided by the radio IC circuitry⁷ 106 (FIG. 2) and a transmit baseband processor (TX BBP) 404 for generating transmit baseband signals 31 1 for the radio IC circuitry 106. The baseband processing circuitry 400 may also include control logi c 406 for coordinating the operations of the baseband processing circuitry 400.

[0061] In some embodiments (e.g., when analog baseband signals are exchanged between the baseband processing circuitry 400 and the radio IC circuitry 106), the baseband processing circuitry 400 may include ADC 410 to convert analog baseband signals received from the radio IC circuitry 106 to digital baseband signals for processing by the RX BBP 402. In these embodiments, the baseband processing circuitry 400 may also include DAC 412 to convert digital baseband signals from the TX BBP 404 to analog baseband signals.

[0062] In some embodiments that communicate OFDM signals or OFDMA signals, such as through baseband processor 108 A,, the transmit baseband processor 404 may be configured to generate OFDM or OFDMA signals as appropriate for transmission by performing an inverse fast Fourier transform (IFFT). The receive baseband processor 402 may be configured to process received OFDM signals or OFDMA signals by performing an FFT. In some embodiments, the receive baseband processor 402 may be configured to detect the presence of an OFDM signal or OFDMA signal by performing an autocorrelation, to detect a preamble, such as a short preamble, and by performing a cross-correlation, to detect a long preamble. The preambles may be part of a predetermined frame structure for Wi-Fi communication.

[0063] Referring back to FIG. 2, in some embodiments, the antennas 101 (FIG. 2) may each compri se one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some multiple-input multiple-output (MDVIO) embodiments, the antennas may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result.

Antennas 101 may each include a set of phased-array antennas, although embodiments are not so limited. [0064] Although the radio-architecture 100 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.

[0065] Examples, as described herein, may include, or may operate on, logic or a number of components, circuits, modules, or engines, which for the sake of brevity may be collectively referred to as engines. Engines are tangible entities (e.g., hardware) capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as an engine. In an example, the whole or part of one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as an engine that operates to perform specified operations. In an example, the software may reside on a machine readable medium. In an example, the software, when executed by the underlying hardware of the engine, causes the hardware to perform the specified operations.

[0066] Accordingly, the term "engine" is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein. Considering examples in which engines are temporarily configured, each of the engines need not be instantiated at any one moment in time. For example, where the engines comprise a general -purpose hardware processor configured using software, the general-purpose hardware processor may be configured as respective different engines at different times. Software may accordingly configure a hardware processor, for example, to constitute a particular engine at one instance of time and to constitute a different engine at a different instance of time.

[0067] Some embodiments may be implemented using software and/or firmware in combination with execution hardware, such as the processing elements described above. This software and/or firmware may take the form of instructions contained in or on a non- transitory computer-readable storage medium. Those instructions may then be read and executed by one or more processors to enable performance of the operations described herein. The instructions may be in any suitable form, such as but not limited to source code, compiled code, interpreted code, executable code, static code, dynamic code, and the like. Such a computer-readable medium may include any tangible non-transitory medium for storing information in a form readable by one or more computers, such as but not limited to read only memory (ROM); random access memory (RAM); magnetic disk storage media; opti cal storage media; a fl ash memory, etc.

[0068] FIG. 5 is a diagram illustrating a MEVIO arrangement utilizing an AP and a STA, each having multiple antennas according to some embodiments. In the example depicted, AP 502 acts as a transmitter, and STA 504 acts as a receiver. It will be understood that the transmitter/receiver roles may be reversed repeatedly according to one or more

communication protocols.

[0069] AP 502 has multiple antennas, as depicted, which may be used in various groupings, and with various signal modifications for each grouping, to effectively produce a plurality of antenna ports P1-P4. Each antenna port Pl-P4 may be associated with a corresponding set of RF circuitry, that may be referred to as an RF chain. In various embodiments within the framework of the illustrated example, each antenna port Pl-P4 may be defined for 1, 2, 3, or 4 antennas. Each antenna port Pl-P4 may correspond to a different spatial configuration such that, when used simultaneously, RF signaling emitted via each port is spatially diverse. . Using the different antenna ports P1-P4, AP 502 may transmit a plurality of MIMO layers. Beamforming techniques, such as codebook-based or non-codebook-based precoding techniques, may be used to enhance spatial diversity between the MIMO layers in certain use cases.

[0070] In other embodiments, there may be more, or fewer, antenna ports available at the AP than the four antenna ports as illustrated in the example shown in FIG. 5. AP 502 may use up to the maximum available number of antenna ports to send signaling over spatially diverse paths. In some examples, the AP may use fewer ports than the maximum number available.

[0071] On the STA side, there are a plurality of receive antenna ports. As illustrated in the example of FIG. 5, there are four receive antenna ports, A1-A4. The multiple receive antenna ports may be used selectively to receive signaling over distinct spatial paths at the same time. In some examples, receive beamforming may be used advantageously to increase the receive antenna gain for the directions) on which desired signals are received, and to suppress interference from neighboring cells, provided of course that the interference is received along different directions than the desired signals. In other examples, the reception of multiple spatially-diverse signals can increase data throughput or signal reliability in some applications. According to some embodiments, the STA may be configured to perform multiple measurements for different spatial transmit/receive configurations.

[0072] In some embodiments, systems, devices, and methods disclosed herein enable AP and STA devices to use their respective MIMO capabilities to improve the range estimation accuracy in the WLAN.

[0073] In related embodiments, the receiver side may use a single receive antenna port with multiple antenna ports being used at the transmitter side as a multiple input single output (MISO) arrangement for range estimation. A MISO arrangement may be suitable for channel sounding since no actual data layer or stream is sent or received and the channel sounding signaling using each antenna port may be sent over orthogonal resources e.g. encoded by P- matrix codes. Accordingly, the receiver is able to separate the sounding signals from different transmit antenna ports.

[0074] In some embodiments, a protocol suitable for, but not necessarily limited in its application to, the next generation positioning in WLAN (e.g., 802.1 iaz) is based on the round trip time (RTT) of a sounding packet exchanged between an STA and one or more APs. In various protocols, the sounding packet may be originated by the AP, or by the STA. The RTT is based on time-of-flight (ToF) of the sounding signal in each direction.

[0075] From the RTT, a distance determination, referred to as ranging, is performed. A combination of measured distances to multiple known locations of AP or STA devices may be used to perform locationing (i.e., determining positioning of a device in question) using techniques such as trilateration, for example, with multiple ranging measurements. In related examples, the angle of arrival (AoA) of the sounding packet i s incorporated by a receiving device in performing its determination of the relative position of the sending device. AoA may be used in combination with multiple ranging-based measurements to improve ranging accuracy. In some cases, AoA in combination with one or two ranging measurements may be used in lieu of a greater number of range-based measurements to determine the location of a STA. In related examples the angle of departure (AoD) information known by the sender as a beam-forming-capable device may be similarly utilized to enhance the location determination. In the present context, for the sake of brevity, the term ranging is used to describe not only single-location RTT measurements, but also multiple-location RTT, AoA, and AoD measurements for locationing.

[0076] In one use case, the channel sounding signal is sent by one party (e.g. AP) and the other parry (e.g. STA), respectively. In another use case, the channel sounding signal is sent by one party (e.g. AP) only. In the second case, instead of the RTT, the difference between two arrival times of the AP's signals may be measured.

[0077] FIGs. 6A-6B are diagrams illustrating position-measurement scenarios according to various examples. FIG. 6A illustrates STA 602 engaging in a ranging protocol with two separate APs, API 604A, and AP2 604B, in respective communication sessions. The ranging message-exchange sessions are performed at different points in time in this example. STA 602 carries out a first ranging session with API 604A, in which RTT of a sounding packet is used to find ranging measurement Rl. API 604A may also use receive beam-forming techniques to find the AoA of the sounding packet (indicated as AoAl). Angle of arrival AoAl is indicated relative to a reference axis 606A as shown in this simplified example. It should be understood that the angle of arrival may include two angles, a heading angle, and an azimuth angle. In similar fashion, STA 602 may carry out a second ranging session with AP2 604B, which is situated at a different location from API 604A. Ranging measurement R2 is made, along with angle of arrival AoA2, which is shown as being relative to reference axis 606B. Each ranging communication session's protocol provides the ranging and AoA information to STA 602. Accordingly, STA 602 may compute its location relative to API 604A and AP2 604B.

[0078] FIG. 6B illustrates a multi-user scenario in which AP 604 serves two separate STA devices, STAl 602A and STA2 602B, simultaneously, or in partial time-overlapping fashion. As depicted, STAl 602A and AP 604 perform ranging measurement Rl , and AP 604 may determine AoA measurement AoAl relative to reference axis 606. Likewise, STA2 602B and AP 604 perform ranging measurement R2, and AP 604 may determine AoA measurement AoA2 relative to reference axis 606. In various examples, the sounding packets from STAl 602A and STA2 602B may be sent or received by AP 604 at the same time, or at different times, according to how communication resource elements are allocated by AP 604. The resource elements in this context may be OFDM or OFDMA symbols, for instance, or OFDM/OFDMA symbols with orthogonal coding specified. More generally, the resource elements may be referred to as channel allocations. In examples where the sounding from each STA device is allocated in different time slots, AP 604 may still temporally overlap other portions of the ranging communications protocol, such as the broadcasting of beacons, negotiation phase messages, trigger frames, and the other messages to make more efficient use of the communication resource elements.

[0079] In a related aspect of the embodiments, the AP and STA devices may use multiple communication resource elements, at the same time, to enhance ranging performance and efficiency of resource utilization. This enhanced functionality is supported with the use of single-user or multi-user ΜΓΜΟ arrangements. Accordingly, the AP may use multiple antenna ports (individually, or in combinations), coupled to corresponding distinct RF chains, to perform sounding packet exchanges with single or multiple antenna ports of individual STA devices, or with multiple STA devices. For the sake of brevity, in the present context, the number, or quantity, of antenna ports refers not only to how many antenna elements are present in a given device, but also to combinations of antennas and the corresponding RF chains, that enable spatial multiplexing of the sounding signaling.

[0080] In ΜΓΜΟ implementations, there may be a separate RF chain for each antenna port allowing multiple RF chains to coexist. MDVIO may facilitate significant improvement in communications throughput and range without additional bandwidth or increased

transmission power. It achieves these benefits by spreading the same total transmission power over the antenna ports to achieve an array gain that improves the spectral efficiency (i.e., more bits per second per hertz of bandwidth) or to achieve a diversity gain that improves the link reliability.

[0081] Therefore, in some embodiments, the transmitter at one end has multiple antenna ports so that the sounding signals go through different spatial channels. Having multiple antenna ports at the receiving end for receiving the sounding signals may enhance the estimation accuracy. However, in some examples the number of receive antenna ports does not need to be known by the transmitter since the sounding signaling is sent over orthogonal resources using the multiple transmit antenna ports and the receiver is able to separate the spatial channels, even with a single receive antenna.

[0082] In related embodiments, the number of spatial streams supported by the receiver may be communicated as part of the antenna-configuration information. For example, knowledge of the number of spatial streams may be used in the measurement feedback phase for increasing the feedback throughput. There may be two indications relating to the spatial streams: number of transmit streams (Tx Nss), and the number of receive spatial streams (Rx Nss). The number of the antenna ports used by the receiver of the channel sounding signal is optional in some protocols. For a given device, the number of transmit antenna ports and the number receive antenna ports may be different. For example, one device may have 2 transmit antenna ports but have 4 receive antenna ports.

[0083] In some embodiments, to facilitate proper use of the MDVIO capability in the ranging measurement, the AP obtains knowledge of the STA's antenna configuration. In related embodiments, the STA obtains knowledge of the AP's antenna configuration. The antenna configuration includes (a) an indication of the total quantity of antenna ports coupled to corresponding distinct RF chains, (b) an indication of the quantity of antenna ports that are currently availableto be used for sounding, where the quantity b is less than or equal to the quantity a, or both indications, (a) and (b). In various examples, which will be described in greater detail below, based on the indications (a), (b), or both, the AP or STA may determine the number of simultaneous sounding packets to use in measurement of ranging or AoA.

[0084] FIG. 7 is a process flow diagram illustrating a sequence of phases of a ranging protocol carried out by AP 604 and one or more STAs 602, according to some embodiments. In each of the phases discussed below, antenna configuration information may be exchanged between the AP and STA according to various examples.

[0085] As shown, the example process includes discovery phase 702, optional association phase 704, negotiation phase 706, and measurement phase 708, with the latter comprising a sounding phase and a measurement feedback phase. Optional association phase 704 is omitted in some use cases in which the example protocol supports location-determination services for unassociated STAs.

[0086] In discovery phase 702, the AP transmits beacon messages at a defined interval, such as every 100 ms. The beacon messages serve to announce the AP's presence to any STA devices within communication range of the AP. The beacon message may carry information identifying the availability, and capability, of the AP to perform ranging or AoA

measurements. Beacons may identify supported ranging protocols such as fine timing measurement (FTM), VHTz, HEWz, or HAYz, or some combination of these. The beacon may also include antenna configuration information that informs recipient STAs about the AP's MUVIO ranging capacity, such as the maximum number of antenna ports that are available. In a more basic example, the AP's MEVIO ranging capacity may be indicated by a yes/no indicator, which may be as simple as a single bit in the beacon message. Upon receiving the antenna configuration information, each STA may determine the number of sounding signals to request from the AP.

[0087] The association phase 704 is used by an STA that intends to associate with the AP for sending and receiving data over the network. In some examples, in addition to the messaging exchanged as part of the association phase, the STA and AP may each

communicate its respective antenna configuration. The association phase 704 is not mandatory in embodiments that support ranging services for unassociated STAs.

[0088] In negotiation phase 706 the STA and AP exchange various parameters in support of the ranging messaging to follow in the measurement phase 708. In an example of negoti ation phase 706, an initiator device, such as the STA, may send a FTM request frame to the AP. The FTM request frame may include a trigger field, and a preference field indicating the preferred protocol for the initiator, as well as a set of proposed parameters. The responder, such as the AP, answers with a FTM response frame. The FTM response frame may include the location configuration information (LCI) or location civic of the responder, a neighbor list of the responder, and FTM or next generation positioning (NGP) parameters to execute the responder' s chosen ranging protocol. Examples of the various transmission-related parameters include modulation and coding scheme (MCS), channel coding (e.g., low-density parity check (LDPC) or binary convolutional code (BCC)), orthogonal frequency division multiple access (OFDMA) support, multi-user MEVIO (MU-MEVIO) support, support for space-time block coding (STBC), beamforming, or beam switching, or security-related parameters. These may be established by the AP and STA according to a defined negotiation protocol to agree upon the ranging, and any other ranging measurements that are to follow and whose measurement results are reported using location measurement report (LMR) packets.

[0089] In some embodiments, physical layer information relating to the antenna

configuration and communications capabilities is also provided in the negotiation phase to permit certain decisions to be made by the STA, AP, or both, regarding transmission resource allocation for channel sounding, from which ranging and other ranging measurements are to be made.

[0090] Measurement phase 708 includes interactive operations between the STA and the AP to sound the channel or channels agreed upon in the negotiation phase 706, measure the RTT and other indicators from which the location may be determined, and report the results of the measurements to the other device. [0091] In an example, measurement phase 708 itself includes two phases: channel sounding, and measurements feedback. A sounding protocol may include an uplink (UL) sounding part, and a downlink (DL) sounding part. For the uplink sounding part as an example, a null data packet (NDP) may be used as the sounding signal, and it may be preceded by a trigger frame (TF). In an example of a downlink sounding part, a NDP announcement packet (NDP- A) responsive to the received UL NDP, followed by a downlink NDP, may be used.

[0092] In the channel sounding operation, the transmitting side, whether for UL sounding or DL sounding, may use multiple antenna ports so that the sounding signals propagate through different spatial channels. In some examples, the quantity of receiving antenna ports on the receiving side does not need to be known by the transmitter. Since the sounding signal is sent over orthogonal resources for the multiple transmit antenna ports, the receiver is able to separate the spatial channels even with a single receive antenna port. In other examples, in which there are multiple antenna ports available at the receiving side, the use of multiple- input reception techniques may enhance the estimation accuracy for ranging.

[0093] The measurements feedback phase may include a LMR packet or a channel state information (CSI) packet. The LMR packet includes the computed time of departure (ToD) or time of arrival (ToA) results, and optionally AoA or AoD results for MEVIO use cases. The CSI packet may each include data from which the ToD/ToA, and AoA/ AoD may be computed. In the case of the LMR packet being used as the measurements feedback, the sender of the feedback assumes the computational load of computing the ToD/ToA,

AoA/AoD resul ts; in the case of the CSI packet being used as the measurements feedback, the computational load for determining these values is passed to the recipient of the feedback

[0094] In some MU-MEVIO embodiments, the antenna configuration information of the AP may be specified in the TF or NDP- A messages. In a related example, the antenna

configuration communicated in the beacon phase is the maximum number of available antenna ports, whereas in the measurement phase the antenna configuration information contains the quantity of transmit antenna ports actually selected to be used to sound the channels, which may be a subset of the maximum number of antenna ports. In some SU- MEVIO embodiments, the actual number of antenna ports (or spatial streams) may be specified in the first frame, or the PPDU header, of the sounding preamble.

[0095] In some embodiments, the antenna configuration for ranging measurement and the antenna configuration for MEVIO data exchange during the measurement phase 708 may be different. For example, the antenna configuration for ranging measurement tells the AP how many transmit antenna ports the STA wants to use for channel sounding; whereas the antenna configuration for MIMO data exchange tells the AP how many data streams the STA can support for the data exchange e.g. the LMR/CSI data exchange.

[0096] In various embodiments, the antenna configuration may be represented as a n-bit field as part of a frame or packet. The number of bits n may be a suitable quantity to represent a number from among 2ⁿ possible values. In an embodiment, the number specified in the antenna configuration is the value of the n-bit field +1. For instance in the example of a 3-bit field, the binary value 000 may represent 1 antenna, whereas the binary value 11 1 may represent 8 antenna ports.

[0097] FIG. 8 is a process flow diagram illustrating an example set of operations that an AP is constructed, programmed, or otherwise configured, to perform, according to some embodiments. At 802, the AP sends a beacon message. This operation may be repeated periodically, such as every second, every 100 ms, etc. The beacon message may include, in addition to beacon-specific identifiers, antenna configuration information of the AP. The antenna configuration information of the beacon message may specify the maximum number of antenna ports available on the AP. In another example, the antenna configuration information of the beacon message may be a simpler indicator, such as a flag, indicating that the AP is capable of MEVIO channel sounding.

[0098] The STA devices that receive the beacon use the antenna configuration information of the AP to determine the quantity of sounding signals that they are able, or prefer, to receive. Based on its preference, each STA responsive to the beacon message sends a request to the AP to initiate a supported location-determination protocol. The responsive message may be a FTM request message, for example. The responsive message may include antenna configuration i nformation of the STA indicating the number of antenna ports that that the STA wishes to use send sounding signals to the AP. In addition, the STA may provide indications regarding the number of receive spatial streams (Rx Nss) and the number of transmit spatial streams (Tx Nss), each of which may be useful for the AP to schedule single- user and multi-user MEVIO in the measurement feedback phase. Accordingly, at 804, the AP receives a responsive message from one or more STAs.

[0099] At decision 806, based on the antenna configuration information of the responsive messages received at 804, the AP determines if there are multiple STAs that may be served at the same time using a MU-MEVIO mode. If there is only a single STA responsive to the beacon, or if the AP determines it is infeasible to support a multi-user (MU) mode, the AP allocates resources in single-user (SU) mode at 808. Otherwise, in the positive case, at 810, the AP initiates resource allocation in MU-MIMO mode. Resource allocation in the present context refers to the AP' s assignment of resources to the STA(s) for the STA(s) to transmit or receive data to or from the AP. The resources can be in frequency and/or space and/or time. For example, a resource may be located at a frequency subband and a spati al stream on the subband. OFDMA is a multiplexing in frequency and MU MIMO is a multiplexing in space.

[0100] At 812, further based on the antenna configuration information of the responsive messages at 804, the AP determines if each responsive STA is capable of transmitting multiple sounding signals at the same time (e.g., if each STA reports multiple antennas available for sending sounding signals). In the negative case, at 814, the AP negotiates parameters for the one or more STAs to each send a single sounding signal. Otherwise, for multi-antenna-available STAs, at 816 the AP negotiates parameters for those STAs to send multiple sounding signals.

[0101] Notably, in various embodiments, there are two modes of MEVIO, single-user (SU) ΜΓΜΟ and multiuser (MU) MEVIO. For SU MEMO, the AP and the STA may sound the channel using multiple antennas for enhancing accuracy. For MU MEVIO, the STA may not need to have multiple antenna ports but the AP uses multiple antenna ports. The AP sounds the channel using multiple antenna ports and each of the STAs sounds the channel using orthogonal resources assigned by the AP. If the orthogonal resources are multiplexed using codes such as CDMA and P-matrix codes, the sounding signals of multiple STAs may be sent simultaneously. If the orthogonal resource are multiplexed using time-division multiple access (TDMA), the sounding signals of the STAs may be sent sequentially.

[0102] At 818, the AP completes the remainder of the negotiation phase with each of the responsive STAs, including exchanging FTM orNGP messages with each STA to determine the types of measurements that are mutually supported (e.g., time of flight, angular, etc.) security provisions, etc., and to establish the protocol and other parameters to be used for the measurements and reporting thereof. In a related embodiment, the parameters negotiated at operation 818 are negotiated together with those at 816.

[0103] At 820, in the measurement phase, the AP sends a TF to command the STAs to sound their allocated channels. The TF may indicate the uplink (UL) sounding resource allocation to the STAs, along with CDMA codes, if appropriate, to those STAs that have negotiated to send multiple simultaneous sounding signals. At 822, the AP receives the UL sounding signals from the STAs according to the allocated and scheduled communication resources and negotiated parameters. At 824, the AP sends a NDP-A message indicating the DL sounding resource allocation, including the actual antenna configuration to be used in the upcoming NDP message. The actual antenna configuration to be used may indicate the same number, or a smaller number of transmit antenna ports than negotiated at 816 in embodiments where the negotiation at 816 serves to establish only the agreed-upon limits. Next, at 826, the AP sends the NDP message containing the DL sounding signal. At 828, the AP receives the measurements feedback message (e.g., LMR or CSI message) containing either the ToF, or AoA/AoD information, or measurements from which these values may be computed.

[0104] FIG. 9 is a flow diagram illustrating an example set of operations that a STA is constructed, programmed, or otherwise configured, to perform, according to some

embodiments. At 902, the STA receives a beacon that was sent by an AP at operation 802 described above with reference to FIG. 8. At 904, the STA checks the beacon message for an indicator of the AP's antenna configuration, or an indicator representing whether the AP supports multi-antenna channel sounding, and determines if the AP supports a MBVIO-based location determination protocol.

[0105] At 906, the STA uses the antenna configuration information of the AP from the beacon to determine the quantity of sounding signals that it is able, or prefers, to receive. The decision by the STA as to the number of sounding signals to receive may be based on a variety of factors. In one example, the STA may be operating in a power-saving mode and accordingly it may exercise a preference for less energy expenditure due to the processing of multiple sounding signals. In another example, the STA may be running a navigation application that calls for maximum accuracy in determining the STA's location, in which case the STA may exercise a preference for greater sounding signal energy that is afforded by receiving multiple sounding signals.

[0106] Based on its preference, the STA sends a request to the AP at 908 to initiate a supported location-determination protocol, such as with a FTM request message, for instance. The responsive message may include antenna configuration information of the STA indicating the number of antenna ports that the STA wishes to use to send sounding signals to the AP, the number of spatial streams that the STA can transmit to the AP, or the number spatial streams that the STA can receive from the AP.

[0107] At 910, the STA negotiates parameters relating to exchanging multiple sounding messages in a multi-antenna sounding and MDVIO data exchange mode with the AP. This negotiation may include the exchange of antenna configuration information that includes the STA's preference for number of sounding signals to send or receive, for example. At 912, the STA exchanges the measurements to be made, protocol, and other parameters with the AP, such as FTM or NGP messaging to determine the types of measurements that are mutually supported (e.g., time of flight, angular, etc.) security provisions, etc., and to establish the protocol and other parameters to be used for the measurements and reporting thereof. In a related embodiment, the parameters negotiated at operation 910 are negotiated together with those at 912.

[0108] At 914 the operations advance to the measurement phase where the STA receives a TF from the AP to command the STA to sound the allocated channels. The TF may indicate the uplink (UL) sounding resource allocation to the STA, along with CDMA codes, if appropriate. The UL sounding resource allocation from the AP is based on the antenna configuration information provided by the STA. At 916, the STA sends a single or multiple UL sounding signals from according to the allocated and scheduled communication resources and negotiated parameters. At 918, the STA receives a NDP-A message indicating the DL sounding resource allocation, including the actual antenna configuration to be used in the upcoming DP message. The actual antenna configuration to be used may indicate the same number, or a smaller number of transmit antenna ports than negotiated at 910 in embodiments where the negotiation at 910 serves to establish only the agreed-upon limits. At 920, the STA configures its receiver, based on the actual antenna configuration information, to receive the DL sounding messages. This may involve configuring the applicable RF and decoder circuitry to monitor the scheduled channels and apply the specified CDMA decoding sequences.

[0109] At 922 the STA receives the NDP message containing the DL sounding signal. At 924, the STA computes the negotiated measurements, if applicable (such as if the STA and AP agreed that the measurements feedback message is to be a LMR). At 926, the STA sends the measurements feedback message (e.g., LMR or CSI message) containing either the ToF, or AoA/AoD information, or measurements from which these values may be computed.

[0110] The examples above illustrating operations of the AP and STA exemplify a general aspect of the embodiments, in which multiple antenna ports or MEVIO is utilized to perform a location determining protocol between two devices in which one device tells the other information about its antenna configuration. The other device may decide to use all of the antenna ports for improving the measurement accuracy. Or, the other device can decide to use a subset of the total amount of antenna ports for saving power or overhead.

[0111] For example, in the MU-MEVIO scenario with an AP, and two STAs, STA1 and STA2, the AP may inform STA1 and STA2 that the AP has 4 Tx antenna ports; STA1 may inform the AP that the STAl has 2 Tx antenna ports; and STA2 may inform the AP that the STA2 has 1 Tx antenna.

[0112] In the MU mode of 802.1 1 az ranging, for example, the AP may allocate two P- matrix codes to STAl and one P-matrix code to STA2 for them to sound channels channel in the example following protocol.

[0113] The AP sends a trigger frame to solicit sounding from STA l and STA2. In the trigger frame, the AP allocates resources for the STAs to sound the channel. The AP exercises one of two options:

[0114] In one option, the AP allocates two sounding resources in total, where a 2x2 P- matrix with only two codes is used. STAl and STA2 each takes one code. As a result, STAl may only sound one of its two Tx antenna ports. This option conserves overhead and power consumption at the cost of accuracy. In another option, the AP allocates 4 sounding resources in total, where a 4x4 P-matrix with four codes is used. STAl takes first two codes and STA2 takes the third code. STAl can sound both Tx antenna ports in this case for higher accuracy. Knowing the numbers of antenna ports at the STAs, the AP can pack the STAs in one burst of sounding to better utilize communication resources.

[0115] The sounding signals of different antenna ports of the STAs share the medium in CDMA fashion. The code length may be 1, 2, 4, 6, or 8. The total number of antenna ports in one burst may be fitted into one of the codes { 1, 2, 4, 6, 8}. In a related example, the antenna ports of the same STA are sounded in the same burst instead of being divided into two or more bursts.

[0116] The STAs sound the channel using the codes specified in the trigger frame.

[0117] The AP sends a sounding announcement frame (e.g., a NDP-A) to inform the STAs about the coming of the AP's sounding signals and the format of the sounding signals. For example, the AP may exercise one of 4 options: the AP may use 1 and 2 resources to sound its 1 and 2 antenna ports, respectively; the AP may use 4 resources to sound 3 or 4 antenna ports. The resource may be in the unit of an OFDM symbol, OFDMA symbol, or a long training field (LTF) symbol. Greater accuracy may be achieved with more antenna ports.

[0118] It should be noted that there is a difference between data transmission and ranging measurement according to the protocols of 802.1 laz, and similar arrangements according to various embodiments. For data transmission, the number of sounding resources may be dictated by the number of data streams. Hence, in the present example, the maximum number of data streams is limited to 3. For ranging measurement, the number of sounding resources is dictated by the number transmit antenna ports. In this example, the AP may choose from among 1, 2, and 4 sounding resources, respectively.

[0119] The AP sounds the channel using the number of resources announced in the previous frame. In an example SU-mode protocol, the STA determines the numbers of sounding resources for the soundings of both the STA and the AP. For instance, the STA may send a NDP-A, trigger frame, or FTM request, in which it specifies the numbers of sounding resources for the sounding of both, the STA, and the AP. The selection of the numbers may be based on the number of AP's antenna ports communicated to the STA previously. The STA (or AP) sounds the channel according to the signal format specified in the previous NDP-A frame. The AP (or STA) sounds the channel according to the signal format specified in the previous NDP-A frame.

[0120] Additional Notes & Examples:

[0121] Example 1 is an apparatus for a client station (STA) for operation in a wireless network, the apparatus comprising: memory; and processing circuitry to: cause the STA to perform a ranging protocol with an access point (AP), wherein a distance between the STA and the AP is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the STA and the AP, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the STA that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and encode a message for transmission to the AP containing antenna configuration information of the STA, the antenna configuration information including at least an indication of an available quantity of antenna ports of the STA; wherein the plurality of concurrent sounding messages to be communicated is selected based on the antenna configuration information.

[0122] In Example 2, the subject matter of Example 1 optionally includes wherein the antenna configuration information includes at least an indication of an available quantity transmit antenna ports of the STA.

[0123] In Example 3, the subject matter of any one or more of Examples 1-2 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of receive spatial streams of the STA. [0124] In Example 4, the subject matter of any one or more of Examples 1-3 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of transmit spatial streams of the STA.

[0125] In Example 5, the subject matter of any one or more of Examples 1-4 optionally include wherein the STA is to execute the ranging protocol while remaining unassociated with the AP.

[0126] In Example 6, the subject matter of any one or more of Examples 1-5 optionally include wherein the concurrent sounding messages are to be sent by the STA to the AP over the distinct antenna ports such that each of the concurrent sounding messages is transmitted over a corresponding antenna port.

[0127] In Example 7, the subject matter of any one or more of Examples 1-6 optionally include wherein the concurrent sounding messages are to be received by the STA from the AP.

[0128] In Example 8, the subject matter of any one or more of Examples 1-7 optionally include wherein the antenna configuration information of the STA is sent by the STA to the AP as part of a request for location service message sent by the STA to the AP in response to a beacon message.

[0129] In Example 9, the subject matter of any one or more of Examples 1-8 optionally include wherein the antenna configuration information of the STA is sent by the STA to the AP as part of a negotiation exchange in which measurement, parameter, and reporting parameters are exchanged.

[0130] In Example 10, the subject matter of any one or more of Examples 1-9 optionally include wherein the processing circuitry is to cause the STA to receive AP antenna configuration information from the AP.

[0131] In Example 1 1 , the subject matter of Example 10 optionally includes wherein the processing circuitry is to determine a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the AP antenna configuration information.

[0132] In Example 12, the subject matter of Example 11 optionally includes wherein the processing circuitry is to determine the quantity of the concurrent sounding messages to be communicated during the ranging protocol based further on a power-save mode of the STA.

[0133] In Example 13, the subject matter of any one or more of Examples 11-12 optionally include wherein the processing circuitry is to determine the quantity of the concurrent sounding messages to be communicated during the ranging protocol based further on a computing load limit of the STA.

[0134] In Example 14, the subject matter of any one or more of Examples 10-13 optionally include wherein the AP antenna configuration information is received by the STA as part of a beacon message broadcast by the AP.

[0135] In Example 15, the subject matter of any one or more of Examples 10-14 optionally include wherein the AP antenna configuration information is received by the STA as part of a negotiation exchange with the AP in which measurement, parameter, and reporting parameters are exchanged.

[0136] In Example 16, the subject matter of any one or more of Examples 10-15 optionally include wherein the AP antenna configuration information is received by the STA as part of as part of a trigger frame sent by the AP, wherein the trigger frame prompts the STA to transmit the concurrent sounding messages.

[0137] In Example 17, the subject matter of any one or more of Examples 10-16 optionally include wherein the AP antenna configuration information is received by the STA as part of an announcement message sent by the AP to indicate scheduling of at least one sounding message to be sent by the AP.

[0138] In Example 18, the subject matter of any one or more of Examples 1-17 optionally include wherein the concurrent sounding messages are communicated on the same frequency and at the same time.

[0139] In Example 19, the subject matter of any one or more of Examples 1-18 optionally include wherein the STA is a high-efficiency wireless (HEW) station and wherein the ranging protocol is a HEWz ranging protocol.

[0140] In Example 20, the subject matter of any one or more of Examples 1-19 optionally include wherein the STA is a very high throughput (VHT) station and wherein the ranging protocol is a VHTz ranging protocol.

[0141] In Example 21, the subject matter of any one or more of Examples 1-20 optionally include wherein the ranging protocol is a fine timing (FTM) ranging protocol.

[0142] In Example 22, the subject matter of any one or more of Examples 1-21 optionally include wherein the ranging protocol is part of a locationing protocol that includes round-trip- time (RTT) measurements between the STA and a plurality of remote devices.

[0143] In Example 23, the subject matter of any one or more of Examples 1-22 optionally include wherein the ranging protocol is part of a locationing protocol that includes angle of arrival (AoA) measurement between the STA and at least one remote device.

[0144] Example 24 is an apparatus for an access point (AP) for operation in a wireless network, the apparatus comprising: memory; and processing circuitry to: cause the AP to perform a ranging protocol with a client station (STA), wherein a distance between the AP and the STA is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the AP and the STA, wherein the concurrent sounding messages are to be transmitted via an antenna configurati on of the AP that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and encode a message for transmission to the STA containing antenna configuration information of the AP, the antenna configuration information including at least an indication of an available quantity of antenna ports of the AP; wherein the AP is to execute the ranging protocol while remaining unassociated with the STA.

[0145] In Example 25, the subject matter of Example 24 optionally includes wherein the antenna configuration information includes at least an indication of an available quantity transmit antenna ports of the AP.

[0146] In Example 26, the subject matter of any one or more of Examples 24-25 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of receive spatial streams of the AP.

[0147] In Example 27, the subject matter of any one or more of Examples 24-26 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of transmit spatial streams of the AP.

[0148] In Example 28, the subject matter of any one or more of Examples 24-27 optionally include wherein the concurrent sounding messages are to be sent by the AP to the STA over the distinct antenna ports such that each of the concurrent sounding messages is transmitted over a corresponding antenna port.

[0149] In Example 29, the subject matter of any one or more of Examples 24-28 optionally include wherein the concurrent sounding messages are to be received by the AP from the STA.

[0150] In Example 30, the subject matter of any one or more of Examples 24-29 optionally include wherein the antenna configuration information of the AP is sent by the AP as part of a beacon message broadcast by the AP.

[0151] In Example 31, the subject matter of any one or more of Examples 24-30 optionally include wherein the antenna configuration information of the AP is sent by the AP as part of a negotiation exchange with the STA in which measurement, parameter, and reporting parameters are exchanged.

[0152] In Example 32, the subject matter of any one or more of Examples 24-31 optionally include wherein the antenna configuration information of the AP is sent by the AP to the STA as part of as part of a trigger frame sent by the AP, wherein the trigger frame prompts the STA to transmit concurrent uplink sounding messages.

[0153] In Example 33, the subject matter of any one or more of Examples 24-32 optionally include wherein the antenna configuration information of the AP is sent by the AP to the STA as part of an announcement message sent by the AP to indicate scheduling of at least one sounding message to be sent by the STA.

[0154] In Example 34, the subject matter of any one or more of Examples 24-33 optionally include wherein the processing circuitry is to cause the AP to receive antenna configuration information from the STA.

[0155] In Example 35, the subject matter of Example 34 optionally includes wherein the processing circuitry is to determine a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the antenna configuration information of the STA.

[0156] In Example 36, the subject matter of any one or more of Examples 24-35 optionally include wherein the concurrent sounding messages are communicated on the same frequency and at the same time.

[0157] In Example 37, the subject matter of any one or more of Examples 24-36 optionally include wherein the AP is a high-efficiency wireless (HEW) station and wherein the ranging protocol is a HEWz ranging protocol.

[0158] In Example 38, the subject matter of any one or more of Examples 24-37 optionally include wherein the AP is a very high throughput (VHT) station and wherein the ranging protocol is a VHTz ranging protocol.

[0159] In Example 39, the subject matter of any one or more of Examples 24-38 optionally include wherein the ranging protocol is a fine timing (FTM) ranging protocol.

[0160] In Example 40, the subject matter of any one or more of Examples 24-39 optionally include wherein the ranging protocol is part of a locationing protocol that includes round-trip- time (RTT) measurements between the AP and a plurality of remote devices.

[0161] In Example 41, the subject matter of any one or more of Examples 24^40 optionally include wherein the ranging protocol is part of a locationing protocol that includes angle of arrival (AoA) measurement between the AP and at least one remote device.

[0162] Example 42 is at least one machine-readable medium comprising instructions that, when executed on a processor of a client station (ST A) for operation in a wireless network, cause the STA to: perform a ranging protocol with an access point (AP), wherein a distance between the STA and the AP is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the STA and the AP, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the STA that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and encode a message for transmission to the AP containing antenna configuration information of the STA, the antenna configuration information including at least an indication of an available quantity of antenna ports of the STA; wherein the plurality of concurrent sounding messages to be communicated is selected based on the antenna configuration information.

[0163] In Example 43, the subject matter of Example 42 optionally includes wherein the antenna configuration information includes at least an indication of an available quantity transmit antenna ports of the STA.

[0164] In Example 44, the subject matter of any one or more of Examples 42-43 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of receive spatial streams of the STA.

[0165] In Example 45, the subject matter of any one or more of Examples 42-44 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of transmit spatial streams of the STA.

[0166] In Example 46, the subject matter of any one or more of Examples 42-45 optionally include wherein the STA is to execute the ranging protocol while remaining unassociated with the AP.

[0167] In Example 47, the subject matter of any one or more of Examples 42-46 optionally include wherein the instructions are to cause the concurrent sounding messages to be sent by the STA to the AP over the distinct antenna ports such that each of the concurrent sounding messages is transmitted over a corresponding antenna port.

[0168] In Example 48, the subject matter of any one or more of Examples 42^17 optionally include wherein the instructions are to cause the concurrent sounding messages to be received by the STA from the AP. [0169] In Example 49, the subject matter of any one or more of Examples 42-48 optionally include wherein the instructions are to cause the antenna configuration information of the STA to be sent by the STA to the AP as part of a request for location service message sent by the STA to the AP in response to a beacon message.

[0170] In Example 50, the subject matter of any one or more of Examples 42-49 optionally include wherein the instructions are to cause the antenna configuration information of the STA to be sent by the STA to the AP as part of a negotiation exchange in which

measurement, parameter, and reporting parameters are exchanged.

[0171] In Example 51, the subject matter of any one or more of Examples 42-50 optionally include wherein the instructions are to cause the STA to receive AP antenna configuration information from the AP.

[0172] In Example 52, the subject matter of Example 51 optionally includes wherein the instructions are to cause the STA to determine a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the AP antenna configuration information.

[0173] In Example 53, the subject matter of Example 52 optionally includes wherein the instructions are to cause the STA to determine the quantity of the concurrent sounding messages to be communicated during the ranging protocol based further on a power-save mode of the STA.

[0174] In Example 54, the subject matter of any one or more of Examples 52-53 optionally include wherein the instructions are to cause the STA to determine the quantity of the concurrent sounding messages to be communicated during the ranging protocol based further on a computing load limit of the STA.

[0175] In Example 55, the subject matter of any one or more of Examples 51-54 optionally include wherein the instructions are to cause the AP antenna configuration information to be received by the STA as part of a beacon message broadcast by the AP.

[0176] In Example 56, the subject matter of any one or more of Examples 51-55 optionally include wherein the instructions are to cause the AP antenna configuration information to be received by the STA as part of a negotiation exchange with the AP in which measurement, parameter, and reporting parameters are exchanged.

[0177] In Example 57, the subject matter of any one or more of Examples 51-56 optionally include wherein the instructions are to cause the AP antenna configuration information to be received by the STA as part of as part of a trigger frame sent by the AP, wherein the trigger frame prompts the STA to transmit the concurrent sounding messages.

[0178] In Example 58, the subject matter of any one or more of Examples 51-57 optionally include wherein the instructions are to cause the AP antenna configuration information to be received by the STA as part of an announcement message sent by the AP to indicate scheduling of at least one sounding message to be sent by the AP.

[0179] In Example 59, the subject matter of any one or more of Examples 42-58 optionally include wherein the instructions are to cause the concurrent sounding messages to be communicated on the same frequency and at the same time.

[0180] In Example 60, the subject matter of any one or more of Examples 42-59 optionally include wherein the ranging protocol is a fine timing (FTM) ranging protocol.

[0181] In Example 61, the subject matter of any one or more of Examples 42-60 optionally include wherein the ranging protocol is part of a locationing protocol that includes round-trip- time (RTT) measurements between the STA and a plurality of remote devices.

[0182] In Example 62, the subject matter of any one or more of Examples 42-61 optionally include wherein the ranging protocol is part of a locationing protocol that includes angle of arrival (AoA) measurement between the STA and at least one remote device.

[0183] Example 63 is at least one machine-readable medium comprising instructions that, when executed on a processor of an access point (AP) for operation in a wireless network, cause the AP to: perform a ranging protocol with a client station (STA), wherein a distance between the AP and the STA is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the AP and the STA, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the AP that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and encode a message for transmi ssion to the STA containing antenna configuration information of the AP, the antenna configuration information including at least an indication of an available quantity of antenna ports of the AP; wherein the AP is to execute the ranging protocol while remaining unassociated with the STA.

[0184] In Example 64, the subject matter of Example 63 optionally includes wherein the antenna configuration information includes at least an indication of an available quantity transmit antenna ports of the AP.

[0185] In Example 65, the subject matter of any one or more of Examples 63-64 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of receive spatial streams of the AP.

[0186] In Example 66, the subject matter of any one or more of Examples 63-65 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of transmit spatial streams of the AP.

[0187] In Example 67, the subject matter of any one or more of Examples 63-66 optionally include wherein the instructions are to cause the concurrent sounding messages to be sent by the AP to the STA over the distinct antenna ports such that each of the concurrent sounding messages is transmitted over a corresponding antenna port.

[0188] In Example 68, the subject matter of any one or more of Examples 63-67 optionally include wherein the instructions are to cause the concurrent sounding messages to be received by the AP from the STA.

[0189] In Example 69, the subject matter of any one or more of Examples 63-68 optionally include wherein the instructions are to cause the antenna configuration information of the AP to be sent by the AP as part of a beacon message broadcast by the AP.

[0190] In Example 70, the subject matter of any one or more of Examples 63-69 optionally include wherein the instructions are to cause the antenna configuration information of the AP to be sent by the AP as part of a negotiation exchange with the STA in which measurement, parameter, and reporting parameters are exchanged.

[0191] In Example 71, the subject matter of any one or more of Examples 63-70 optionally include wherein the instructions are to cause the antenna configuration information of the AP to be sent by the AP to the STA as part of as part of a trigger frame sent by the AP, wherein the trigger frame prompts the STA to transmit concurrent uplink sounding messages.

[0192] In Example 72, the subject matter of any one or more of Examples 63-71 optionally include wherein the instructions are to cause the antenna configuration information of the AP to be sent by the AP to the STA as part of an announcement message sent by the AP to indicate scheduling of at least one sounding message to be sent by the STA.

[0193] In Example 73, the subject matter of any one or more of Examples 63-72 optionally include wherein the instructions are to cause the AP to receive antenna configuration information from the STA.

[0194] In Example 74, the subject matter of Example 73 optionally includes wherein the instructions are to cause the AP to determine a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the antenna configuration information of the STA. [0195] In Example 75, the subject matter of any one or more of Examples 63-74 optionally include wherein the instructions are to cause the concurrent sounding messages to be communicated on the same frequency and at the same time.

[0196] In Example 76, the subject matter of any one or more of Examples 63-75 optionally include wherein the ranging protocol is a fine timing (FTM) ranging protocol.

[0197] In Example 77, the subject matter of any one or more of Examples 63-76 optionally include wherei n the ranging protocol is part of a locationing protocol that includes round-trip- time (RTT) measurements between the AP and a plurality of remote devices.

[0198] In Example 78, the subject matter of any one or more of Examples 63-77 optionally include wherein the ranging protocol is part of a locationing protocol that includes angle of arrival (AoA) measurement between the AP and at least one remote device.

[0199] Example 79 is a client station (STA) for operation in a wireless network, the STA comprising: means for performing a ranging protocol with an access point (AP), wherein a distance between the STA and the AP is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the STA and the AP, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the STA that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and means for encoding a message for transmission to the AP containing antenna configuration information of the STA, the antenna configuration information including at least an indication of an available quantity of antenna ports of the STA; wherein the plurality of concurrent sounding messages to be communicated is selected based on the antenna configuration information.

[0200] In Example 80, the subject matter of Example 79 optionally includes wherein the antenna configuration information includes at least an indication of an available quantity transmi t antenna ports of the STA .

[0201] In Example 81, the subject matter of any one or more of Examples 79-80 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of receive spatial streams of the STA.

[0202] In Example 82, the subject matter of any one or more of Examples 79-81 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of transmit spatial streams of the STA.

[0203] In Example 83, the subject matter of any one or more of Examples 79-82 optionally include wherein the STA is to execute the ranging protocol while remaining unassociated with the AP.

[0204] In Example 84, the subject matter of any one or more of Examples 79-83 optionally include wherein the concurrent sounding messages are to be sent by the STA to the AP over the distinct antenna ports such that each of the concurrent sounding messages is transmitted over a corresponding antenna port.

[0205] In Example 85, the subject matter of any one or more of Examples 79-84 optionally include wherein the concurrent sounding messages are to be received by the STA from the AP.

[0206] In Example 86, the subject matter of any one or more of Examples 79-85 optionally include wherein the antenna configuration information of the STA is sent by the STA to the AP as part of a request for location service message sent by the STA to the AP in response to a beacon message.

[0207] In Example 87, the subject matter of any one or more of Examples 79-86 optionally include wherein the antenna configuration information of the STA is sent by the STA to the AP as part of a negotiation exchange in which measurement, parameter, and reporting parameters are exchanged.

[0208] In Example 88, the subject matter of any one or more of Examples 79-87 optionally include means for receiving AP antenna configuration information from the AP.

[0209] In Example 89, the subject matter of Example 88 optionally includes means for determining a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the AP antenna configuration information.

[0210] In Example 90, the subject matter of Example 89 optionally includes means for determining the quantity of the concurrent sounding messages to be communicated during the ranging protocol based further on a power-save mode of the STA.

[0211] In Example 91 , the subject matter of any one or more of Examples 89-90 optionally include means for determining the quantity of the concurrent sounding messages to be communicated during the ranging protocol based further on a computi ng load limit of the

STA.

[0212] In Example 92, the subject matter of any one or more of Examples 88-91 optionally include wherein the AP antenna configuration information is received by the STA as part of a beacon message broadcast by the AP.

[0213] In Example 93, the subject matter of any one or more of Examples 88-92 optionally include wherein the AP antenna configuration information is received by the STA as part of a negotiation exchange with the AP in which measurement, parameter, and reporting parameters are exchanged.

[0214] In Example 94, the subject matter of any one or more of Examples 88-93 optionally include wherein the AP antenna configuration information is received by the STA as part of as part of a trigger frame sent by the AP, wherein the trigger frame prompts the STA to transmit the concurrent sounding messages.

[0215] In Example 95, the subject matter of any one or more of Examples 88-94 optionally include wherein the AP antenna configuration information is received by the STA as part of an announcement message sent by the AP to indicate scheduling of at least one sounding message to be sent by the AP.

[0216] In Example 96, the subject matter of any one or more of Examples 79-95 optionally include wherein the concurrent sounding messages are communicated on the same frequency and at the same time.

[0217] In Example 97, the subject matter of any one or more of Examples 79-96 optionally include wherein the STA is a high-efficiency wireless (HEW) station and wherein the ranging protocol is a HEWz ranging protocol.

[0218] In Example 98, the subject matter of any one or more of Examples 79-97 optionally include wherein the STA is a very high throughput (VHT) station and wherein the ranging protocol is a VHTz ranging protocol.

[0219] In Example 99, the subject matter of any one or more of Examples 79-98 optionally include wherein the ranging protocol is a fine timing (FTM) ranging protocol.

[0220] In Example 100, the subject matter of any one or more of Examples 79-99 optionally include wherein the ranging protocol is part of a locationing protocol that includes round-trip-time (RTT) measurements between the STA and a plurality of remote devices.

[0221] In Example 101 , the subject matter of any one or more of Examples 79-100 optionally include wherein the ranging protocol is part of a locationing protocol that includes angle of arrival (AoA) measurement between the STA and at least one remote device.

[0222] Example 102 is an access point (AP) for operation in a wireless network, the AP comprising: means for performing a ranging protocol with a client station (STA), wherein a distance between the AP and the STA is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the AP and the STA, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the AP that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and means for encoding a message for transmission to the STA containing antenna configuration information of the AP, the antenna configuration information including at least an indication of an available quantity of antenna ports of the AP; wherein the AP is to execute the ranging protocol while remaining unassociated with the STA.

[0223] In Example 103, the subject matter of Example 102 optionally includes wherein the antenna configuration information includes at least an indication of an available quantity transmit antenna ports of the AP.

[0224] In Example 104, the subject matter of any one or more of Examples 102-103 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of receive spatial streams of the AP.

[0225] In Example 105, the subject matter of any one or more of Examples 102-104 optionally include wherein the antenna configuration information includes at least an indication of an available quantity of transmit spatial streams of the AP.

[0226] In Example 106, the subject matter of any one or more of Examples 102-105 optionally include wherein the concurrent sounding messages are to be sent by the AP to the STA over the distinct antenna ports such that each of the concurrent sounding messages is transmitted over a corresponding antenna port.

[0227] In Example 107, the subject matter of any one or more of Examples 102-106 optionally include wherein the concurrent sounding messages are to be received by the AP from the STA.

[0228] In Example 108, the subject matter of any one or more of Examples 102-107 optionally include wherein the antenna configuration information of the AP is sent by the AP as part of a beacon message broadcast by the AP.

[0229] In Example 109, the subject matter of any one or more of Examples 102-108 optionally include wherein the antenna configuration information of the AP is sent by the AP as part of a negotiation exchange with the STA in which measurement, parameter, and reporting parameters are exchanged.

[0230] In Example 1 10, the subject matter of any one or more of Examples 102-109 optionally include wherein the antenna configuration information of the AP is sent by the AP to the STA as part of as part of a trigger frame sent by the AP, wherein the trigger frame prompts the STA to transmit concurrent uplink sounding messages.

[0231] In Example 1 11, the subject matter of any one or more of Examples 102-110 optionally include wherein the antenna configuration information of the AP is sent by the AP to the STA as part of an announcement message sent by the AP to indicate scheduling of at least one sounding message to be sent by the STA.

[0232] In Example 112, the subject matter of any one or more of Examples 102-1 1 1 optionally include means for receiving antenna configuration information from the STA.

[0233] In Example 1 13, the subject matter of Example 1 12 optionally includes means for determining a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the antenna configuration information of the STA.

[0234] In Example 114, the subject matter of any one or more of Examples 102-1 13 optionally include wherein the concurrent sounding messages are communicated on the same frequency and at the same time.

[0235] In Example 115, the subject matter of any one or more of Examples 102—114 optionally include wherein the AP is a high-efficiency wireless (HEW) station and wherein the ranging protocol is a HEWz ranging protocol.

[0236] In Example 116, the subject matter of any one or more of Examples 102-115 optionally include wherein the AP is a very high throughput (VHT) station and wherein the ranging protocol is a VHTz ranging protocol.

[0237] In Example 117, the subject matter of any one or more of Examples 102-116 optionally include wherein the ranging protocol is a fine timing (FTM) ranging protocol.

[0238] In Example 118, the subject matter of any one or more of Examples 102-117 optionally include wherein the ranging protocol is part of a locationing protocol that includes round- trip-time (RTT) measurements between the AP and a plurality of remote devices.

[0239] In Example 119, the subject matter of any one or more of Examples 102-118 optionally include wherein the ranging protocol is part of a locationing protocol that includes angle of arrival ( AoA) measurement between the AP and at least one remote device.

[0240] The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments that may be practiced. These embodiments are also referred to herein as "examples." Such examples may include elements in addition to those shown or described. However, also contemplated are examples that include the elements shown or described. Moreover, also contemplate are examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0241] Publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) are supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0242] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a nonexclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In the appended claims, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to suggest a numerical order for their objects.

[0243] The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with others. Other embodiments may be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is to allow the reader to quickly ascertain the nature of the technical disclosure and is submitted with the

understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. However, the claims may not set forth features disclosed herein because embodiments may include a subset of said features. Further, embodiments may include fewer features than those disclosed in a particular example. Thus, the following claims are hereby incorporated into the Detailed Description, with a claim standing on its own as a separate embodiment. The scope of the embodiments disclosed herein is to be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

What is claimed is: 1. An apparatus for a client station (ST A) for operation in a wireless network, the apparatus compri sing: memory; and processing circuitry to:

cause the STA to perform a ranging protocol with an access point (AP), wherein a distance between the STA and the AP is determined based on signal propagation of a plurality of concurrent sounding messages communi cated between the STA and the AP, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the STA that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and

encode a message for transmission to the AP containing antenna configuration information of the STA, the antenna configuration information including at least an indication of an available quantity of antenna ports of the STA;

wherein the plurality of concurrent sounding messages to be communicated is selected based on the antenna configuration information.

2. The apparatus of claim 1, wherein the STA is to execute the ranging protocol while remaining unassociated with the AP.

3. The apparatus according to any one of claims 1-2, wherein the antenna configuration information of the STA is sent by the STA to the AP as part of a request for location service message sent by the STA to the AP in response to a beacon message.

4. The apparatus according to any one of claims 1-2, wherein the antenna configuration information of the STA is sent by the STA to the AP as part of a negotiati on exchange in which measurement, parameter, and reporting parameters are exchanged.

5. The apparatus according to any one of claims 1-2, wherein the processing circuitry is to cause the STA to receive AP antenna configuration information from the AP.

6. The apparatus of claim 5, wherein the processing circuitry is to determine a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the AP antenna configuration information.

7. An apparatus for an access point (AP) for operation in a wireless network, the apparatus comprising: memory; and processing circuitry to:

cause the AP to perform a ranging protocol with a client station (STA), wherein a distance between the AP and the STA is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the AP and the STA, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the AP that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and

encode a message for transmission to the STA containing antenna configuration information of the AP, the antenna configuration information including at least an indication of an available quantity of antenna ports of the AP;

wherein the AP is to execute the ranging protocol while remaining unassociated with the STA.

8. The apparatus of claim 7, wherein the antenna configuration information includes at least an indication of an available quantity transmit antenna ports of the AP.

9. The apparatus of claim 7, wherein the antenna configuration information includes at least an indication of an available quantity of receive spatial streams of the AP.

10. The apparatus of claim 7, wherein the antenna configuration information includes at least an indication of an available quantity of transmit spatial streams of the AP.

1 1. The apparatus according to any one of claims 7-10, wherein the antenna configuration information of the AP is sent by the AP as part of a beacon message broadcast by the AP.

12. The apparatus according to any one of claims 7-10, wherein the antenna configuration information of the AP is sent by the AP as part of a negotiation exchange with the STA in which measurement, parameter, and reporting parameters are exchanged.

13. The apparatus according to any one of claims 7-10, wherein the antenna configuration information of the AP is sent by the AP to the STA as part of as part of a trigger frame sent by the AP, wherein the trigger frame prompts the STA to transmit concurrent uplink sounding messages.

14. The apparatus according to any one of claims 7-10, wherein the antenna configuration information of the AP is sent by the AP to the STA as part of an announcement message sent by the AP to indicate scheduling of at least one sounding message to be sent by the STA.

15. The apparatus according to any one of claims 7-10, wherein the processing circuitry is to cause the AP to receive antenna configuration information from the STA.

16. The apparatus of claim 15, wherein the processing circuitry is to determine a quantity of the concurrent sounding messages to be communicated during the ranging protocol in response to the antenna configuration information of the STA.

17. At least one machine-readable medium comprising instructions that, when executed on a processor of a client station (STA) for operation in a wireless network, cause the STA to: perform a ranging protocol with an access point (AP), wherein a distance between the

STA and the AP is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the STA and the AP, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the STA that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and

encode a message for transmission to the AP containing antenna configuration information of the STA, the antenna configuration information including at least an indication of an available quantity of antenna ports of the STA;

wherein the plurality of concurrent sounding messages to be communicated is selected based on the antenna configuration information.

18. The at least one machine-readable medium of claim 17, wherein the STA is to execute the ranging protocol while remaining unassociated with the AP.

19. The at least one machine-readable medium according to any one of claims 17-18, wherein the instructions are to cause the antenna configuration information of the STA to be sent by the STA to the AP as part of a request for locati on service message sent by the STA to the AP in response to a beacon message.

20. The at least one machine-readable medium according to any one of claims 17-18, wherein the instructions are to cause the antenna configuration information of the STA to be sent by the STA to the AP as part of a negotiation exchange in which measurement, parameter, and reporting parameters are exchanged.

21. The at least one machine-readable medium according to any one of claims 17-18, wherein the instructions are to cause the STA to receive AP antenna configuration

information from the AP.

22. The at least one machine-readable medium of claim 21, wherein the instructions are to cause the STA to determine a quantity of the concurrent sounding messages to be

communicated during the ranging protocol in response to the AP antenna configuration information.

23. At least one machine-readable medium comprising instructions that, when executed on a processor of an access point (AP) for operati on in a wireless network, cause the AP to: perform a ranging protocol with a client station (STA), wherein a distance between the AP and the STA is determined based on signal propagation of a plurality of concurrent sounding messages communicated between the AP and the STA, wherein the concurrent sounding messages are to be transmitted via an antenna configuration of the AP that includes distinct radio-frequency (RF) chains coupled to distinct antenna ports such that the concurrent sounding messages are spatially multiplexed; and

encode a message for transmission to the STA containing antenna configuration information of the AP, the antenna configuration information including at least an indication of an available quantity of antenna ports of the AP;

wherein the AP is to execute the ranging protocol while remaining unassociated with the STA.

24. The at least one machine-readable medium of claim 23, wherein the instructions are to cause the AP to receive antenna configuration information from the STA.

25. The at least one machine-readable medium of claim 24, wherein the instructions are to cause the AP to determine a quantity of the concurrent sounding messages to be

communicated during the ranging protocol in response to the antenna configuration information of the STA.