CN109792415B

CN109792415B - Compressed CSI feedback for WLAN range estimation

Info

Publication number: CN109792415B
Application number: CN201780060111.3A
Authority: CN
Inventors: 蒋锋; 李庆华; Y·阿米斯尔; N·德沃利基; J·塞格夫; 陈晓刚
Original assignee: Intel Corp
Current assignee: Intel Corp
Priority date: 2016-10-24
Filing date: 2017-09-27
Publication date: 2022-05-24
Anticipated expiration: 2037-09-27
Also published as: CN109792415A; WO2018080709A1

Abstract

The apparatus of the wireless device may operate in a CSI feedback protocol to encode the first NDP for transmission to another wireless device and to store a ToD of the first NDP. The apparatus may also decode a second NDP received from another wireless device and determine a ToA of the second NDP. The apparatus may decode a measurement feedback packet received from another wireless device, the measurement feedback packet including a ToD of the second NDP and a downsampled smoothed channel estimate of a channel between the wireless devices, the channel estimate based on the first NDP. The apparatus may also derive a ToA of the first NDP at another wireless device based on the channel estimate, and calculate an RTT between the wireless devices based on the ToD value and the ToA value. The apparatus may also estimate a distance between the wireless devices based on the RTT.

Description

Compressed CSI feedback for WLAN range estimation

Priority requirement

This application claims priority from U.S. provisional patent application No.62/412,106 entitled "Compressed Channel State Information Feedback for Range Estimation in Wireless Local Area Network (WLAN)" filed on 24/10/2016, which is incorporated herein by reference in its entirety.

Technical Field

Embodiments pertain to wireless networks and wireless communications. Some embodiments relate to Wireless Local Area Networks (WLANs) and Wi-Fi networks, including networks operating in accordance with the Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards. Some embodiments relate to IEEE 802.11 ax. Some embodiments relate to IEEE 802.11 az. Some embodiments relate to methods, computer readable media, and apparatuses for distance (range) estimation in a WLAN using compressed channel state information feedback.

Background

Efficient use of the resources of a Wireless Local Area Network (WLAN) is important to provide bandwidth and acceptable response time to users of the WLAN. However, there are often many devices attempting to share the same resources, and some devices may be limited in the communication protocol they use or their hardware bandwidth. Furthermore, wireless devices may need to operate with both newer protocols and legacy device protocols.

Drawings

The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

fig. 1 illustrates a wireless network according to some embodiments;

fig. 2 illustrates a WLAN according to some embodiments;

fig. 3 illustrates a diagram of channel estimation in the frequency domain using a high efficiency long training field (HE-LTF) in a Null Data Packet (NDP), in accordance with some embodiments;

FIG. 4 illustrates a diagram of smoothed frequency domain channel estimates, in accordance with some embodiments;

fig. 5 shows a diagram of downsampling of smoothed channel estimates, in accordance with some embodiments;

fig. 6 shows a diagram of frequency domain channel estimation in accordance with some embodiments;

fig. 7 shows a diagram of interpolating channels on missing tones, in accordance with some embodiments;

fig. 8A illustrates a diagram of frequency domain channels transformed into the time domain using an Inverse Fast Fourier Transform (IFFT), in accordance with some embodiments;

fig. 8B shows a diagram of compressed Channel State Information (CSI) feedback, in accordance with some embodiments;

fig. 9 is a block diagram of a radio architecture according to some embodiments;

figure 10 illustrates front end module circuitry for the radio architecture of figure 9, in accordance with some embodiments;

fig. 11 illustrates a radio Integrated Circuit (IC) circuit for the radio architecture of fig. 9, in accordance with some embodiments;

figure 12 illustrates baseband processing circuitry for the radio architecture of figure 9, in accordance with some embodiments;

FIG. 13 illustrates operations of a distance estimation method according to some embodiments;

FIG. 14 illustrates operations of another distance estimation method according to some embodiments;

fig. 15 illustrates an example scenario for distance estimation between an initiator and a responder using a sounding packet sequence and CSI feedback, in accordance with some embodiments;

fig. 16 illustrates an example multi-user (MU) scenario for distance estimation between a primary station (AP) and a Station (STA) using a sounding packet sequence and CSI feedback, in accordance with some embodiments;

fig. 17 illustrates an example scenario of obtaining channel estimates for a channel from a STA to an AP, in accordance with some embodiments; and

fig. 18 illustrates a block diagram of an example machine on which any one or more of the techniques (e.g., methods) discussed herein may be executed.

Detailed Description

The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in or substituted for those of others. Embodiments set forth in the claims encompass all available equivalents of those claims.

Fig. 1 illustrates a wireless network 100 according to some embodiments. In some embodiments, network 100 may be a High Efficiency (HE) Wireless Local Area Network (WLAN). In some embodiments, network 100 may be a WLAN or Wi-Fi network. However, these embodiments are not limiting, as some embodiments of network 100 may include a combination of such networks. That is, network 100 may support HE devices in some cases, may support non-HE devices in some cases, and may support a combination of HE and non-HE devices in some cases. Thus, it should be understood that while the techniques described herein may refer to either a non-HE device or an HE device, in some cases, such techniques may be applicable to both non-HE devices and HE devices.

Referring to fig. 1, network 100 may include any or all of the components shown, and embodiments are not limited to the number of each component shown in fig. 1. In some embodiments, network 100 may include a master station (AP)102 and may include any number (including zero) of Stations (STAs) 103 and/or HE devices 104. In some embodiments, the AP 102 may receive and/or detect signals from one or more STAs 103 and may transmit data packets to one or more STAs 103. These embodiments will be described in more detail below.

In some embodiments, the AP 102 may be a Basic Service Set (BSS) AP 102 configured to communicate with STAs 103 as part of an Extended Service Set (ESS) network (e.g., network 100). That is, in an embodiment, the network 100 is an ESS network. One or more overlapping bss (obss) APs 105 may be operational but not part of the ESS network 100 and may provide interference to STAs 103. In some embodiments, OBSS AP 105 may be a device with which STA103 may not necessarily communicate. For example, in some cases, STA103 may not be associated with OBSS AP 105, but may still detect/receive packets from OBSS AP 105. It should be noted that in this example, OBSS AP 105 is shown geographically outside ESS network 100, but this is not limiting. In some cases, OBSS AP 105 may be located within the coverage area of ESS network 100 (and/or BSS AP 102 of ESS network 100). These embodiments will be described in more detail below.

AP 102 may be arranged to: communicate with one or more of the components shown in fig. 1 in accordance with one or more IEEE 802.11 standards (including 802.11ax and/or others), other standards, and/or other communication protocols. It should be noted that embodiments are not limited to the use of AP 102. Reference herein to the AP 102 is not limiting, and reference herein to the master station 102 is also not limiting. In some embodiments, STA103, HE device 104, and/or other devices may be configurable to operate as a master station. Thus, in such embodiments, the operations that AP 102 may perform as described herein may be performed by STAs 103, HE devices 104, and/or other devices that may be configured to operate as a master station.

In some embodiments, one or more of STAs 103 may be legacy stations. However, these embodiments are not limiting, as in some embodiments, STA103 may be configured to operate as HE device 104 or may support HE operation. The master station 102 may be arranged to: communicate with STAs 103 and/or HE devices 104 according to one or more IEEE 802.11 standards (including 802.11ax and/or others). In accordance with some HE embodiments, an Access Point (AP) may operate as a master station 102 and may be arranged to: contending for a wireless medium (e.g., during a contention period) to receive exclusive control of the medium for an HE control period (i.e., transmission opportunity (TXOP)). For example, the master station 102 may transmit a primary synchronization or control transmission at the beginning of an HE control period, to indicate which HE devices 104 are scheduled for communication during the HE control period, and so on. During the HE control period, scheduled HE devices 104 may communicate with the primary station 102 according to a non-contention based multiple access technique. This is different from conventional Wi-Fi communications, in which devices communicate according to a contention-based communication technique rather than a non-contention-based multiple access technique. During the HE control period, the primary station (e.g., AP 102) may communicate with the HE device 104 using one or more HE Physical Layer Convergence Protocol (PLCP) protocol data units (PPDUs). During the HE control period, STAs 103 that are not operating as HE devices 104 may suppress communication in some cases. In some embodiments, the primary synchronization transmission may be referred to as a "control and schedule transmission.

In some embodiments, the multiple access technique used during the HE control period may be a scheduled Orthogonal Frequency Division Multiple Access (OFDMA) technique, but this is not a requirement. In some embodiments, the multiple access technique may be a Time Division Multiple Access (TDMA) technique or a Frequency Division Multiple Access (FDMA) technique. In some embodiments, the multiple access technique may be a Spatial Division Multiple Access (SDMA) technique including a multi-user (MU) Multiple Input Multiple Output (MIMO) (MU-MIMO) technique. These multiple access techniques used during the HE control period may be configured for uplink or downlink data communications.

The master station 102 may also communicate with STAs 103 and/or other legacy stations in accordance with legacy IEEE 802.11 communication techniques. In some embodiments, the master station 102 may also be configurable to: according to legacy IEEE 802.11 communication techniques, communication with HE device 104 is outside of the HE control period, but this is not a requirement.

In some embodiments, HE communications during the HE control period may be configured to use one of a 20MHz, 40MHz, or 80MHz contiguous bandwidth or an 80+80MHz (160MHz) non-contiguous bandwidth. In some embodiments, a channel width of 320MHz may be used. In some embodiments, a subchannel bandwidth of less than 20MHz may also be used. In these embodiments, each channel or subchannel of the HE communication may be configured to transmit multiple spatial streams.

In some embodiments, HE wireless technology may be used, although the scope of the embodiments is not limited in this respect. By way of example, techniques included in the 802.11ax standard and/or other standards may be used. According to some embodiments, the master station (e.g., AP 102) and/or HE device 104 may generate the HE packet according to a short preamble format or a long preamble format. The HE packet may include a legacy signal field (L-SIG) followed by one or more HE signal fields (HE-SIG) and a HE long training field (HE-LTF). For short preamble formats, the field may be configured for shorter delay spread channels. For long preamble formats, the field may be configured for longer delay spread channels. These embodiments are described in more detail below. It should be noted that the term "HE" may be used to refer to high efficiency WLAN operation and/or high efficiency Wi-Fi operation.

As used herein, the term "circuitry" may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with, one or more software or firmware modules. In some embodiments, the circuitry may comprise logic operable, at least in part, in hardware. The embodiments described herein may be implemented in a system using any suitably configured hardware and/or software.

Fig. 2 illustrates a WLAN according to some embodiments. The WLAN may include a Basic Service Set (BSS)200, which may include: a master station 202, which may be an AP (e.g., AP 102); a plurality of High Efficiency (HE) (e.g., IEEE 802.11Ax) Stations (STAs) 204; and a plurality of legacy (e.g., IEEE 802.11n/ac) devices 206.

The primary station 202 may be an AP that transmits and receives using one of the IEEE 802.11 protocols. The primary station 202 may be a base station. The master station 202 may use other communication protocols as well as the IEEE 802.11 protocol. The IEEE 802.11 protocol may be IEEE 802.11 ax. The IEEE 802.11 protocol may include the use of OFDMA, TDMA, and/or Code Division Multiple Access (CDMA). The IEEE 802.11 protocol may include multiple access techniques. For example, IEEE 802.11 protocols may include SDMA and/or MU-MIMO. The master station 202 and/or the HE STAs 204 may use one or both of MU-MIMO and OFDMA. There may be more than one master station 202 that is part of an Extended Service Set (ESS). A controller (not shown) may store information common to one or more master stations 202. The controller may access an external network, such as the internet.

Legacy device 206 may operate in accordance with one or more of IEEE 802.11a/b/g/n/ac/ad/af/ah/aj or another legacy wireless communication standard. The legacy device 206 may be an STA or an IEEE 802.11 STA. HE STA 204 may be a wireless transmitting device and a wireless receiving device such as a cellular phone, a smart phone, a handheld wireless device, wireless glasses, a wireless watch, a wireless personal device, a tablet, or another device that may transmit and receive using an IEEE 802.11 protocol (e.g., IEEE 802.11ax) or another wireless protocol (e.g., IEEE 802.11 az). In some embodiments, the HE STAs 204, the master station 202, and/or the legacy devices 206 may be referred to as "wireless devices". In some embodiments, HE STA 204 may be a "group owner" (GO) of a point-to-point mode of operation, where HE STA 204 may perform some operations of the master station 202. In some embodiments, HE STAs 204 may be referred to as "High Efficiency (HE) stations.

The master station 202 may communicate with the legacy device 206 in accordance with legacy IEEE 802.11 communication techniques. In an example embodiment, the master station 202 may be further configured to: communicates with the HE STA 204 in accordance with legacy IEEE 802.11 communication techniques.

In some embodiments, HE frames may be configurable to have the same bandwidth as the channel.

The bandwidth of the channel may be a 20MHz, 40MHz, 80MHz, 160MHz or 320MHz continuous bandwidth or an 80+80MHz (160MHz) discontinuous bandwidth. In some embodiments, the bandwidth of the channel may be 1MHz, 1.25MHz, 2.03MHz, 2.5MHz, 5MHz, or 10MHz, or a combination thereof, or another bandwidth less than or equal to the available bandwidth may also be used. In some embodiments, the bandwidth of the channel may be based on the number of active subcarriers. In some embodiments, the bandwidth of the channel is a multiple of 26 active subcarriers or tones (e.g., 26, 52, 104, etc.) spaced apart by 20 MHz. In some embodiments, the bandwidth of the channel is 26, 52, 104, 242, etc. active data subcarriers or tones separated by 20 MHz. In some embodiments, the bandwidth of the channel is 256 tones separated by 20 MHz. In some embodiments, for a 256-point Fast Fourier Transform (FFT), a 20MHz channel may include 256 tones. In some embodiments, a different number of tones are used. In some embodiments, the OFDMA structure consists of a 26 subcarrier Resource Unit (RU), a 52 subcarrier RU, a 106 subcarrier RU, a 242 subcarrier RU, a 484 subcarrier RU, and a 996 subcarrier RU. The resource allocation for Single User (SU) operation includes 242 subcarriers RU, 484 subcarriers RU, 996 subcarriers RU, and 2x996 subcarriers RU.

The HE frame may be configured to transmit multiple spatial streams, which may be in accordance with MU-MIMO. In some embodiments, the HE frame may be configured for transmission in accordance with one or both of OFDMA and MU-MIMO. In other embodiments, the master station 202, HE STA 204, and/or legacy device 206 may also implement different technologies, such as CDMA 2000, CDMA 20001X, CDMA 2000 evolution data optimized (EV-DO), temporary Standard 2000(IS-2000), temporary Standard 95(IS-95), temporary Standard 856(IS-856), Long Term Evolution (LTE), Global System for Mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE (GERAN), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), and/or the like,

WiGig, or other technologies.

Some embodiments relate to HE communications. According to some IEEE 802.11ax embodiments, the master station 202 may operate as a master station that 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 embodiments, the HE control period may be referred to as a "TXOP". The master station 202 may transmit an HE master sync transmission, which may be a trigger frame or an HE control and schedule transmission, at the beginning of the HE control period. The master station 202 can transmit the duration of the TXOP and channel information. During the HE control period, the HE STAs 204 may communicate with the master station 202 according to non-contention based multiple access techniques, such as OFDMA and/or MU-MIMO. This is different from conventional WLAN communications, in which devices communicate according to a contention-based communication technique rather than a multiple access technique. During the HE control period, the master station 202 may communicate with the HE STAs 204 using one or more HE frames. During the HE control period, HE STAs 204 may operate on a channel that is smaller than the operating range of the master station 202. During the HE control period, legacy stations (e.g., legacy device 206) refrain from communicating.

In accordance with some embodiments, HE STAs 204 may contend for the wireless medium during the primary synchronization transmission, wherein legacy devices 206 are excluded from contending for the wireless medium during the primary synchronization transmission or TXOP. In some embodiments, the trigger frame may indicate an Uplink (UL) UL-MU-MIMO and/or UL OFDMA control period. In some embodiments, the trigger frame may indicate a portion of the TXOP that is contention based and not contention based for some HE STAs 204.

In some embodiments, the multiple access technique used during the HE control period may be a scheduled OFDMA technique, but this is not a requirement. In some embodiments, the multiple access techniques may be TDMA techniques or FDMA techniques. In some embodiments, the multiple access techniques may be SDMA techniques.

In an example embodiment, the HE STA 204 and/or the master station 202 are configured to perform the methods and operations described herein in connection with fig. 3-17.

In some embodiments, the systems, devices, and methods disclosed herein may compress Channel State Information (CSI) feedback for range estimation in WLANs. In some embodiments, in a range estimation protocol based on IEEE 802.11ax, the AP and the STA exchange probe packets first, and the Round Trip Time (RTT) of the probe packets is used as a metric to estimate the range between the AP and the STA. In some embodiments, other metrics, such as angle of arrival (AoA), may be used to estimate the distance between the AP and the STA.

To derive the RTT, the times of arrival (ToA) of the sounding packet on the STA side and the AP side need to be estimated, which may require computationally intensive calculations. To reduce power consumption on the STA side and extend the battery life of the STA, the STA may choose to feed back CSI to the AP, which will then expend the effort to calculate ToA for the STA. In this example, the estimation accuracy of the ToA depends on the signal-to-noise ratio (SNR) of the CSI feedback. In additional or alternative embodiments, the AP may also send CSI to the STAs to reduce the computations performed at the AP in order to reduce power consumption on the AP side. For example, the mobile AP may send CSI feedback to the STAs in order to conserve battery power of the mobile AP.

In some embodiments, the systems, devices, and methods disclosed herein may improve the SNR of CSI feedback while reducing the overhead of CSI feedback.

In some embodiments, the basic principle of the new CSI feedback scheme is to first transform the frequency domain channel estimates to the time domain and then select a portion of the time domain sequence for feedback. Useful information in the CSI is the first path arrival time. The first path is located at the beginning of the channel response in the time domain. In some embodiments, it may be beneficial to be able to significantly reduce the feedback overhead by feeding back only the first channel response.

In some embodiments, IEEE 802.11ax based measurement protocols for distance estimation are still under development and there is no specific definition of the format for CSI feedback. In a first example of the systems, devices, and methods disclosed herein, frequency domain channel estimates may be smoothed to reduce the effects of noise, the smoothed channel response may then be downsampled, and the downsampled CSI may be fed back. By channel smoothing, the SNR of the CSI may be improved and the overhead of CSI feedback may be reduced using downsampling. In a second example of the systems, devices, and methods disclosed herein, the frequency domain channel estimates may be transformed into time domain sequences. Since the signal of interest is concentrated in the first few samples of the time domain sequence, only a part of the sequence will be fed back, the rest of the sequence is mainly noise and will be discarded, so that the SNR of the CSI can be improved and the overhead can be reduced.

Example 1: CSI feedback in compressed frequency domain

Fig. 3 illustrates a diagram of channel estimation 300 in the frequency domain using a high efficiency long training field (HE-LTF) in a Null Data Packet (NDP), according to some embodiments. In additional or alternative embodiments, the frequency domain estimation may be based on a very high throughput long training field (VHT-LTF) in the NDP. In some embodiments, to reduce noise in the channel estimate and improve SNR, the frequency domain channel estimate may be smoothed (filtered) by a linear Minimum Mean Square Error (MMSE) filter.

Fig. 4 shows a diagram of a smoothed frequency domain channel estimate 400 in accordance with some embodiments. In some embodiments, the smoothed channel estimate may be downsampled in order to compress the overhead of the CSI feedback, and the downsampling factor depends on the compression rate and the desired accuracy of the CSI feedback.

Fig. 5 illustrates a diagram of downsampling 500 of smoothed channel estimates, according to some embodiments.

Example 2: compressing CSI feedback in time domain

Fig. 6 shows a diagram of frequency domain channel estimation 600 according to some embodiments. An example frequency-domain channel estimate 600 is shown in the frequency domain using the HE-LTF in NDP. In additional or alternative embodiments, the frequency domain estimation may be performed using VHT-LTFs in the NDPs.

Fig. 7 shows a diagram of interpolating 700 a channel on missing tones, according to some embodiments. In some embodiments, the channel response on the missing tones is interpolated. The interpolation removes side lobes of each signal path response. In some embodiments, extrapolation of edge tones may not be required if an FFT that is not a power of 2 size is not a concern.

Fig. 8A illustrates a diagram of frequency domain channels 800 transformed to the time domain using an Inverse Fast Fourier Transform (IFFT), in accordance with some embodiments. In some embodiments, the frequency domain channel is transformed to the time domain using an IFFT, the signal of interest is only present in the first few samples of the time domain sequence, the rest being the noise and channel response of the later paths that are not of interest.

Fig. 8B shows a diagram of compressed Channel State Information (CSI) feedback 802 in accordance with some embodiments. In some embodiments, only the first few samples are quantized and fed back. Samples consisting of noise and subsequent paths are discarded.

In some embodiments, the window size of the signal of interest is adjustable depending on compression rate and performance requirements. For example, the window size may be equal to a Cyclic Prefix (CP) size. Probing for NDP requires the use of 2 × LTF, while for 2 × LTF (6.4 μ s symbol length) the CP size may be 0.8 μ s or 1.6 μ s, which would give a compression ratio of 8 or 4.

Computational complexity analysis

In some embodiments, the bandwidth is assumed to be 20 MHz. Then, for 2 × LTF, there are 128 tones (including DC and edge tones) in the frequency domain channel estimation. To smooth the frequency domain channel, it may be assumed that the desired tone is smoothed using three adjacent tones on the left and right sides of the desired tone, where the left side corresponds to lower frequencies and the right side corresponds to higher frequencies. In additional or alternative embodiments, the frequency smoothing process may also be used for 40MHz, 80MHz, and 160MHz bandwidths. The example smoothing process described above may be viewed as multiplying each of the desired pitch and neighboring pitches by a complex coefficient and then adding the products together. For example, the computational complexity of smoothing a single pitch is 7 complex multiplications and 6 complex additions, the total complexity of smoothing a pitch is:

128 × (7+6) complex multiplications and additions.

In some embodiments, the computation of the FFT dominates the computational complexity when implementing CSI feedback compression in the time domain. For a 128-point FFT, the computational complexity is:

128×log₂(128) secondary complex multiplication and addition.

In some embodiments, the computational complexity of time-domain and frequency-domain CSI compression are comparable to each other according to the above analysis.

Fig. 9 is a block diagram of a radio architecture 900 according to some embodiments. The radio architecture 900 may include radio Front End Module (FEM) circuitry 904, radio IC circuitry 906, and baseband processing circuitry 908. The illustrated radio architecture 900 includes WLAN functionality and Bluetooth (BT) functionality, but embodiments are not so limited. In this disclosure, "WLAN" and "Wi-Fi" are used interchangeably.

The FEM circuitry 904 may include WLAN or Wi-Fi FEM circuitry 904A and Bluetooth (BT) FEM circuitry 904B. The WLAN FEM circuitry 904A may include a receive signal path that includes circuitry configured to operate on WLAN RF signals received from the one or more antennas 901, amplify the received signals, and provide an amplified version of the received signals to the WLAN radio IC circuitry 906A for further processing. BT FEM circuitry 904B may include a receive signal path, which may include circuitry configured to operate on BT RF signals received from one or more antennas 901, amplify the received signals, and provide amplified versions of the received signals to BT radio IC circuitry 906B for further processing. The WLAN FEM circuitry 904A may also include a transmit signal path, which may include circuitry configured to amplify WLAN signals provided by the WLAN radio IC circuitry 906A for wireless transmission by the one or more antennas 901. Further, BT FEM circuitry 904B may also include a transmit signal path, which may include circuitry configured to amplify BT signals provided by BT radio IC circuitry 906B for wireless transmission by one or more antennas 901. In the embodiment of fig. 9, although WLAN FEM 904A and BT FEM 904B are shown as being different from each other, embodiments are not so limited and include within their scope: FEM circuits (not shown) are used that include transmit and/or receive signal paths for both WLAN and BT signals, or one or more FEM circuits are used, where at least some of the FEM circuits share transmit and/or receive signal paths for both WLAN and BT signals.

The radio IC circuitry 906 as shown may include a WLAN radio IC circuitry 906A and a BT radio IC circuitry 906B. The WLAN radio IC circuitry 906A may include a receive signal path that may include circuitry for down-converting a WLAN RF signal received from the WLAN FEM circuitry 904A and providing a baseband signal to the WLAN baseband processing circuitry 908A. BT radio IC circuitry 906B may then include a receive signal path, which may include circuitry for down-converting BT RF signals received from BT FEM circuitry 904B and providing baseband signals to BT baseband processing circuitry 908B. The WLAN radio IC circuitry 906A may also include a transmit signal path, which may include circuitry to up-convert WLAN baseband signals provided by the WLAN baseband processing circuitry 908A and provide WLAN RF output signals to the WLAN FEM circuitry 904A for subsequent wireless transmission by the one or more antennas 901. The BT radio IC circuitry 906B may also include a transmit signal path, which may include circuitry to up-convert BT baseband signals provided by the BT baseband processing circuitry 908B and provide BT RF output signals to the BT FEM circuitry 904B for subsequent wireless transmission by the one or more antennas 901. In the embodiment of fig. 9, although the radio IC circuits 906A and 906B are shown as being different from each other, embodiments are not so limited and include within their scope: a radio IC circuit (not shown) including a transmit signal path and/or a receive signal path for both WLAN and BT signals is used, or one or more radio IC circuits are used, at least some of which share a transmit signal path and/or a receive signal path for both WLAN and BT signals.

The baseband processing circuitry 908 may include WLAN baseband processing circuitry 908A and BT baseband processing circuitry 908B. The WLAN baseband processing circuit 908A may include a memory, such as a set of Random Access Memory (RAM) arrays in FFT or IFFT blocks (not shown) of the WLAN baseband processing circuit 908A. Each of the WLAN baseband circuitry 908A and the BT baseband circuitry 908B may also include one or more processors and control logic to process signals received from the corresponding WLAN or BT receive signal path of the radio IC circuitry 906 and also to generate corresponding WLAN or BT baseband signals for the transmit signal path of the radio IC circuitry 906. Each of the

baseband processing circuits

908A and 908B may also include physical layer (PHY) and media access control layer (MAC) circuits, and may also interface with an application processor 911 for generating and processing baseband signals and controlling the operation of the radio IC circuits 906.

Still referring to fig. 9, in accordance with the illustrated embodiment, the WLAN-BT coexistence circuit 913 may include logic to provide an interface between the WLAN baseband circuit 908A and the BT baseband circuit 908B to implement use cases requiring WLAN and BT coexistence. Further, a switch 903 may be provided between the WLAN FEM circuit 904A and the BT FEM circuit 904B to allow switching between WLAN and BT radios according to application needs. Further, although the antenna 901 is depicted as being connected to the WLAN FEM circuit 904A and the BT FEM circuit 904B, respectively, embodiments include within their scope: one or more antennas 901 are shared between the WLAN and BT FEM, or more than one antenna 901 connected to each of the

FEMs

904A and 904B is provided.

In some embodiments, the front-end module FEM circuitry 904, the radio IC circuitry 906, and the baseband processing circuitry 908 may be provided on a single radio card (e.g., wireless circuit card 912). In some other embodiments, one or more of the antenna 901, the FEM circuitry 904 and the radio IC circuitry 906 may be provided on a single radio card. In some other embodiments, the radio IC circuitry 906 and the baseband processing circuitry 908 may be provided on a single chip or Integrated Circuit (IC) (e.g., wireless circuit card 912).

In some embodiments, the wireless circuit card 912 may comprise a WLAN radio card and may be configured for Wi-Fi communication, although the scope of the embodiments is not limited in this respect. In some of these embodiments, radio architecture 900 may be configured to receive and transmit Orthogonal Frequency Division Multiplexed (OFDM) or OFDMA communication signals over a multicarrier communication channel. The OFDM or OFDMA signal may include a plurality of orthogonal subcarriers.

In some of these multicarrier embodiments, radio architecture 900 may be part of a Wi-Fi communication Station (STA), such as a wireless Access Point (AP), a base station, or a mobile device that includes a Wi-Fi device. In some of these embodiments, radio architecture 900 may be configured to transmit and receive signals according to particular communication standards and/or protocols, such as any of the IEEE standards, including IEEE 802.11n-2009, IEEE 802.11-2012, IEEE 802.11-2016, IEEE 802.11ac, and/or IEEE 802.11ax standards and/or proposed specifications for WLANs, although the scope of the embodiments is not limited in this respect. The radio architecture 900 may also be adapted to transmit and/or receive communications in accordance with other techniques and standards.

In some embodiments, the radio architecture 900 may be configured for HE Wi-Fi communication according to the IEEE 802.11ax standard. In these embodiments, radio architecture 900 may be configured to communicate in accordance with OFDMA techniques, although the scope of the embodiments is not limited in this respect.

In some other embodiments, radio architecture 900 may be configured to transmit and receive signals 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.

In some embodiments, as further illustrated in fig. 9, the BT baseband processing circuit 908B may conform to a Bluetooth (BT) connection standard, such as bluetooth, bluetooth 4.0, bluetooth 5.0, or any other generation of the bluetooth standard. In embodiments including BT functionality, such as shown in fig. 9, the radio architecture 900 may be configured to establish a BT synchronous connection-oriented (SCO) link and/or a BT low energy (BT LE) link. In some embodiments including BT functionality, the radio architecture 900 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 including BT functionality, radio architecture 900 may be configured to participate in BT Asynchronous Connectionless (ACL) communications, although the scope of the embodiments is not limited in this respect. In some embodiments, as shown in fig. 9, the functionality of the BT radio card and the WLAN radio card may be combined on a single radio card, such as the wireless circuit card 912, although embodiments are not so limited and include within their scope separate WLAN and BT radio cards.

In some embodiments, radio architecture 900 may include other radio cards, such as cellular radio cards configured for cellular (e.g., 3GPP, e.g., LTE-Advanced, or 5G communications).

In some IEEE 802.11 embodiments, radio architecture 900 may be configured for communication over various channel bandwidths, including bandwidths having a center frequency of approximately 900MHz, 2.4GHz, 5GHz, and bandwidths of approximately 1MHz, 2MHz, 2.5MHz, 4MHz, 5MHz, 8MHz, 10MHz, 16MHz, 20MHz, 40MHz, or 80MHz (continuous bandwidth) or 80+80MHz (160MHz) (discontinuous bandwidth). In some embodiments, a 320MHz channel bandwidth may be used. However, the scope of the embodiments is not limited in this regard to the center frequency described above.

Fig. 10 illustrates a front-end module (FEM) circuit 1000 according to some embodiments. FEM circuit 1000 is one example of a circuit that may be suitable for use as WLAN and/or BT FEM circuits 904A/904B (fig. 9), but other circuit configurations may also be suitable.

In some embodiments, FEM circuit 1000 may include a TX/RX switch 1002 to switch between transmit mode and receive mode operation. FEM circuit 1000 may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry 1000 may include a Low Noise Amplifier (LNA)1006 to amplify the received RF signal 1003 and provide an amplified receive RF signal 1007 as an output (e.g., to the radio IC circuitry 906 (fig. 9)). The transmit signal path of the FEM circuit 1000 may include: a Power Amplifier (PA)1010 to amplify an input RF signal 1009 (e.g., provided by radio IC circuitry 906); and one or more filters 1012, such as Band Pass Filters (BPFs), Low Pass Filters (LPFs), or other types of filters, for generating RF signals 1015 for subsequent transmission (e.g., by one or more antennas 901 (fig. 9)).

In some dual-mode embodiments for Wi-Fi communications, FEM circuitry 1000 may be configured to operate in the 2.4GHz spectrum or the 5GHz spectrum. In these embodiments, the receive signal path of FEM circuit 1000 may include a receive signal path duplexer 1014 to separate the signal from each spectrum and provide a separate LNA 1006 for each spectrum, as shown. In these embodiments, the transmit signal path of the FEM circuit 1000 may further include: power amplifier 1010 and filter 1012, such as a BPF, LPF, or other type of filter for each spectrum; and a transmit signal path duplexer 1014 to provide signals of one of the different frequency spectrums onto a single transmit signal path for subsequent transmission by one or more of the antennas 901 (fig. 9). In some embodiments, BT communications may utilize a 2.4GHZ signal path and may utilize the same FEM circuitry 1000 as is used for WLAN communications.

Fig. 11 illustrates a radio IC circuit 1100 according to some embodiments. The radio IC circuit 1100 is one example of a circuit that may be suitable for use as the WLAN or BT radio IC circuits 906A/906B (fig. 9), but other circuit configurations may also be suitable.

In some embodiments, radio IC circuit 1100 may include a receive signal path and a transmit signal path. The receive signal path of radio IC circuit 1100 may include at least a mixer circuit 1102 (e.g., a down-conversion mixer circuit), an amplifier circuit 1106, and a filter circuit 1108. The transmit signal path of the radio IC circuit 1100 may include at least a filter circuit 1112 and a mixer circuit 1114 (e.g., an upconversion mixer circuit). Radio IC circuit 1100 may also include synthesizer circuit 1104 for synthesizing frequency 1105 for use by mixer circuit 1102 and mixer circuit 1114. According to some embodiments, the mixer circuits 1102 and/or 1114 may each be configured to provide direct conversion functionality. The latter type of circuit presents a simpler architecture than standard superheterodyne mixer circuits and any flicker noise caused thereby can be mitigated, for example by using OFDM modulation. Fig. 11 shows only a simplified version of a radio IC circuit, and may include (although not shown) embodiments in which each depicted circuit may include more than one component. For example, mixer circuits 1102 and/or 1114 may each include one or more mixers and filter circuits 1108 and/or 1112 may each include one or more filters, e.g., one or more BPFs and/or LPFs, as desired by the application. For example, when mixer circuits 1102 and/or 1114 are of the direct conversion type, they may each include two or more mixers.

In some embodiments, the mixer circuit 1102 may be configured to: the RF signal 1007 received from the FEM circuitry 1000 (fig. 10) is downconverted based on the synthesized frequency 1105 provided by the synthesizer circuit 1104. The amplifier circuit 1106 may be configured to amplify the downconverted signal, and the filter circuit 1108 may include an LPF configured to: the undesired signal is removed from the down-converted signal to generate an output baseband signal 1107. The output baseband signal 1107 may be provided to baseband processing circuitry 908 (fig. 9) for further processing. In some embodiments, the output baseband signal 1107 may be a zero frequency baseband signal, although this is not a requirement. In some embodiments, mixer circuit 1102 may comprise a passive mixer, although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuit 1114 may be configured to: the input baseband signal 1111 is upconverted based on the synthesized frequency 1105 provided by the synthesizer circuit 1104 to generate an RF output signal 1009 for the FEM circuit 1000 (fig. 10). An input baseband signal 1111 may be provided by the baseband processing circuit 908 and may be filtered by the filter circuit 1112. Filter circuit 1112 may include an LPF or BPF, although the scope of the embodiments is not limited in this respect.

In some embodiments, mixer circuit 1102 and mixer circuit 1114 may each include two or more mixers and may be arranged for quadrature downconversion and/or upconversion, respectively, with the aid of synthesizer circuit 1104. In some embodiments, mixer circuit 1102 and mixer circuit 1114 may each include two or more mixers, each configured for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuit 1102 and the mixer circuit 1114 may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, mixer circuit 1102 and mixer circuit 1114 may be configured for super-heterodyne operation, but this is not required.

According to one embodiment, the mixer circuit 1102 may include: quadrature passive mixers (e.g., for in-phase (I) and quadrature-phase (Q) paths). In such embodiments, the RF input signal 1007 from fig. 10 may be downconverted to provide I and Q baseband output signals to be sent to a baseband processor (e.g., baseband processing circuit 908).

The quadrature passive mixer may be driven by zero and ninety degree time-varying LO switching signals provided by a quadrature circuit, which may be configured to receive an LO frequency (f) from a local oscillator or synthesizer_LO) Such as frequency 1105 of synthesizer circuit 1104 (fig. 11). 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., half the carrier frequency, or one third of the carrier frequency). In some embodiments, zero and ninety degree time varying switching signals may be generated by synthesizer circuit 1004, although the scope of the embodiments is not limited in this respect.

In some embodiments, the LO signal may differ in duty cycle (the percentage of a cycle in which the LO signal is high) and/or offset (the difference between the start of the cycle). In some embodiments, the LO signal may have a duty cycle of 25% and an offset of 50%. In some embodiments, each branch (e.g., I and Q path) of the mixer circuit may operate at a 25% duty cycle, which may result in a significant reduction in power consumption.

The RF signal 1007 (fig. 10) 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 a low noise amplifier (e.g., amplifier circuit 1106) or filter circuit 1108 (fig. 11).

In some embodiments, output baseband signal 1107 and input baseband signal 1111 may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternative embodiments, the output baseband signal 1107 and the input baseband signal 1111 may be digital baseband signals. In these alternative embodiments, the radio IC circuit 1100 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuits.

In some dual-mode embodiments, separate radio IC circuits may be provided for each spectrum, or for other spectra not mentioned herein, for processing signals, although the scope of the embodiments is not limited in this respect.

In some embodiments, synthesizer circuit 1104 may be a fractional-N synthesizer or a fractional-N/N +1 synthesizer, although the scope of embodiments is not so limited as other types of frequency synthesizers may be suitable. For example, the synthesizer circuit 1104 may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase locked loop with a frequency divider. According to some embodiments, synthesizer circuit 1104 may comprise a digital synthesizer circuit. The advantage of using a digital synthesizer circuit is that although it may still include some analog components, its footprint (footprint) may be much reduced compared to the footprint of an analog synthesizer circuit. In some embodiments, the frequency input to the synthesizer circuit 1104 may be provided by a Voltage Controlled Oscillator (VCO), but this is not required. The divider control input may also be provided by the baseband processing circuit 908 (fig. 9) or the application processor 911 (fig. 9), depending on the desired output frequency 1105. In some embodiments, the 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 determined or indicated by the application processor 911.

In some embodiments, the synthesizer circuit 1104 can be configured to generate the carrier frequency as the output frequency 1105, while in other embodiments, the output frequency 1105 can be a fraction of the carrier frequency (e.g.,one half of the carrier frequency, or one third of the carrier frequency). In some embodiments, output frequency 1105 may be the LO frequency (f)_LO)。

Fig. 12 illustrates a functional block diagram of a baseband processing circuit 1200 according to some embodiments. Baseband processing circuit 1200 is one example of a circuit that may be suitable for use as baseband processing circuit 908 (fig. 9), but other circuit configurations may also be suitable. The baseband processing circuit 1200 may include: a receive baseband processor (RX BBP)1202 for processing an output baseband signal 1107 provided by the radio IC circuitry 1100 (fig. 11); and a transmit baseband processor (TX BBP)1204 for generating a transmit baseband signal 1111 for the radio IC circuit 1100 (fig. 11). The baseband processing circuit 1200 may also include control logic 1206 to coordinate the operation of the baseband processing circuit 1200.

In some embodiments (e.g., when analog baseband signals are exchanged between the baseband processing circuitry 1200 and the radio IC circuitry 1100), the baseband processing circuitry 1200 may include an ADC1210 to convert analog baseband signals received from the radio IC circuitry 906 to digital baseband signals for processing by the RX BBP 1202. In these embodiments, the baseband processing circuit 1200 may also include a DAC 1212 to convert the digital baseband signal from the TX BBP 1204 to an analog baseband signal.

In some embodiments, for example, where the OFDM signal or OFDMA signal is communicated by the WLAN baseband processing circuitry 908A, the TX BBP 1204 may be configured to: an OFDM or OFDMA signal suitable for transmission is generated by performing IFFT. RX BBP 1202 may be configured to: the received OFDM signal or OFDMA signal is processed by performing FFT. In some embodiments, RX BBP 1202 may be configured to: the presence of an OFDM signal or an OFDMA signal is detected by performing autocorrelation to detect a preamble such as a short preamble and cross-correlation to detect a long preamble. The preamble may be part of a predetermined frame structure for Wi-Fi communication.

Referring back to fig. 9, in some embodiments, antennas 901 (fig. 9) may each include 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 MIMO embodiments, the antennas may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may be obtained. Antennas 901 may each comprise a set of phased array antennas, although embodiments are not so limited.

Although radio architecture 900 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, a functional element may refer to one or more processes operating on one or more processing elements.

FIG. 13 illustrates operations of a distance estimation method according to some embodiments. In particular, fig. 13 illustrates operations of a distance estimation method 1300 for estimating a distance from a STA to an AP by using transmissions between the AP and the STA, in accordance with some embodiments. It is important to note that embodiments of method 1300 may include additional or even fewer operations or processes than those shown in fig. 13. Furthermore, embodiments of method 1300 are not necessarily limited to the temporal order shown in FIG. 13. In describing the method 1300, reference may be made to fig. 1-12 and 15, but it should be understood that the method 1300 may be practiced with any other suitable systems, interfaces, and components.

Further, although method 1300 and other methods described herein may refer to STAs 103 and AP 102 operating according to IEEE 802.11 or other standards, embodiments of those methods are not limited to only those devices, and may also be practiced on other mobile devices, such as HE STAs, HE APs, evolved node bs (enbs), or User Equipment (UEs). In some embodiments, the STAs 103 described in method 1300 may be HE STAs 103 and the AP 102 may be HE AP 102. Method 1300 and other methods described herein may also be practiced by a wireless device configured to operate in other suitable types of wireless communication systems, including systems configured to operate in accordance with various third generation partnership project (3GPP) Long Term Evolution (LTE) standards. Method 1300 may also refer to an apparatus for STA103 and/or AP 102 or other devices described above.

Additionally, in some embodiments of method 1300 and other methods described herein, the AP 102 may be or may operate as a "beam-forming initiator (beam-former)" and the STA103 may be or may operate as a "beam-forming responder (beam-former)". That is, in some cases, the method 1300 may enable use of a beamformed path for downlink communications between the AP 102 (beamforming initiator) and the STA103 (beamforming responder).

At operation 1302 of method 1300, a wireless device (e.g., AP 102) may smooth a frequency domain channel estimate. In some embodiments, operation 1302 may smooth the frequency domain channel estimates as shown in fig. 3 and 4.

At operation 1304, the wireless device (e.g., AP 102) may downsample the smoothed channel estimate obtained at operation 1302. Operation 1304 may downsample the smoothed channel estimate as shown in fig. 5, according to some embodiments.

At operation 1306, the wireless device (e.g., AP 102) may generate CSI feedback based on the downsampled smoothed channel estimate. In some embodiments, the CSI feedback generated at operation 1306 may be included in a CSI report.

After generating the CSI feedback, the wireless device (e.g., AP 102) may encode the packet including the CSI feedback for transmission to another wireless device (e.g., STA 103) at operation 1308.

In some embodiments, additional optional operations (not shown) may be performed to transmit the encoded packet to another wireless device. For example, after encoding the packet at operation 1308, the wireless device (e.g., AP 102) may transmit the encoded packet to another wireless device (e.g., STA 103). According to these embodiments, after receiving the encoded packet, another wireless device (e.g., STA 103) may determine the transmission parameters based on CSI feedback. In some embodiments, the transmission parameters that may be derived from CSI feedback may include ToA and AoA. For example, after the AP or STA derives these transmission parameters from CSI feedback, the AP and STA may exchange these parameters using a measurement report packet.

In this manner, method 1300 may communicate CSI using encoded packets. Using the encoded packets, the STA103 or AP 102 may derive an RTT that may be used for range estimation.

FIG. 14 illustrates operations of another distance estimation method according to some embodiments. In particular, fig. 14 illustrates the operation of a distance estimation method 1400 to estimate the distance from a STA to an AP by using transmissions between the AP and the STA, in accordance with some embodiments. It is important to note that embodiments of method 1400 may include additional or even fewer operations or processes than those shown in fig. 14. Furthermore, embodiments of method 1400 are not necessarily limited to the temporal order shown in FIG. 14. In describing the method 1400, reference may be made to fig. 1-13 and 15, but it should be understood that the method 1400 may be practiced with any other suitable systems, interfaces, and components.

Further, although method 1400 and other methods described herein may refer to STAs 103 and AP 102 operating according to IEEE 802.11 or other standards, embodiments of those methods are not limited to only those devices, and may also be practiced on other mobile devices, such as HE STAs, HE APs, enbs, or UEs. In some embodiments, the STAs 103 described in method 1400 may be HE STAs 103 and the AP 102 may be HE AP 102. Method 1400 and other methods described herein may also be practiced by wireless devices configured to operate in other suitable types of wireless communication systems, including systems configured to operate in accordance with various 3GPP LTE standards. Method 1400 may also refer to an apparatus for STA103 and/or AP 102 or other devices described above.

Additionally, in some embodiments of the method 1400 and other methods described herein, the AP 102 may be or may operate as a "beamforming initiator" and the STA103 may be or may operate as a "beamforming responder. That is, in some cases, the method 1400 may enable use of beamformed paths for downlink communications between the AP 102 (beamforming initiator) and the STA103 (beamforming responder).

At operation 1402 of method 1400, a wireless device (e.g., AP 102) may interpolate a frequency domain channel estimate over the missing tones. In some embodiments, operation 1402 may interpolate frequency domain channels as shown in fig. 7.

At operation 1404, the wireless device (e.g., AP 102) may transform the interpolated channel estimates into a time-domain sequence with an IFFT. Operation 1404 may transform the interpolated channel estimates into a time domain sequence as shown in fig. 8A, according to some embodiments.

At operation 1406, a wireless device (e.g., AP 102) may generate CSI feedback based on the time-domain sequence. Operation 1406 may generate CSI feedback as shown in fig. 8B, according to some embodiments. In some embodiments, the CSI feedback generated at operation 1406 may be included in a CSI report.

After generating the CSI feedback, the wireless device (e.g., AP 102) may encode the packet including the CSI feedback for transmission to another wireless device (e.g., STA 103) at operation 1408.

In some embodiments, additional optional operations (not shown) may be performed to transmit the encoded packet to another wireless device. For example, after encoding the packet at operation 1408, the wireless device (e.g., AP 102) may transmit the encoded packet to another wireless device (e.g., STA 103). According to these embodiments, after receiving the encoded packet, other wireless devices (e.g., STA 103) may determine transmission parameters based on CSI feedback. In some embodiments, the transmission parameters that may be derived from CSI feedback may include ToA and AoA. For example, after the AP or STA derives these transmission parameters from CSI feedback, the AP and STA may exchange these parameters using a measurement report packet.

In this way, the method 1400 may communicate CSI using the encoded packet. Using the encoded packets, the STA103 or AP 102 may derive an RTT that may be used for range estimation.

FIG. 15 shows an example scenario 1500 of a single user distance estimation process. Scenario 1500 uses sounding packet sequences and CSI feedback for distance estimation between initiator 1501 and responder 1506. In the example of fig. 15, a single user sounding sequence in IEEE 802.11az is shown. As shown, the scenario 1500 includes: transmission of Null Data Packet Advertisements (NDPA)1502, NDPs 1504, NDPs 1508, and measurement feedback packets 1510 are transmitted between the initiator 1501 and the responder 1506. In some embodiments, the initiator 1501 may be an STA (e.g., STA 103) and the responder 1506 may be an AP (e.g., AP 102). In additional or alternative embodiments, the initiator 1501 may be an AP and the responder 1506 may be a STA.

As described above, in the single user scenario 1500 shown in fig. 15, the initiator 1501 may be a STA and the responder 1506 may be an AP, or vice versa. Example steps of a single-user distance estimation process performed in scene 1500 are described below with continued reference to FIG. 15.

An example single-user distance estimation process begins with: the initiator 1501 sends the NDPA 1502 to the responder 1506 to let the responder 1506 know that there will be an NDP after a short interframe space (SIFS). SIFS is the amount of time (e.g., in microseconds) required for a wireless interface (e.g., the wireless interface of the initiator 1501 or responder 1506) to process a received frame and respond with a response frame. In the example scenario 1500, the NDPA 1502 may also include some parameter information about the measurement report feedback packet. For example, a reporting feedback type of a report to be included in the measurement feedback packet 1510 may be indicated in the NDPA 1502.

As shown in the example of fig. 15, the initiator 1501 sends the NDP 1504 after SIFS 1503 has passed after sending the NDPA 1502.

Next, after the responder 1506 receives the NDPA 1502, the responder 1506 will be ready to receive the NDP 1504 from the initiator 1501. Based on the NDP 1504, the responder 1506 may obtain CSI for a channel from the initiator 1501 to the responder 1506.

Then, after receiving SIFS 1505 of NDP 1504 from the initiator 1501, the responder 1506 may send NDP 1508 to the initiator 1501. After the NDP 1508, the responder 1506 may send a measurement feedback packet 1510. In some embodiments, the measurement feedback packet 1510 may include CSI and a time-of-departure (ToD) of the NDP 1508 from the responder 1506.

Next, after the initiator 1501 receives the measurement feedback packet 1510, the initiator 1501 may use the CSI to derive the arrival time (ToA) of the NDP 1504 from the initiator 1501 to the responder 1506. In addition, based on the CSI obtained from the NDP 1508 (i.e., the second NDP), the initiator 1501 may derive a ToA of the second NDP (i.e., the NDP 1508). When the initiator 1501 sends an NDP 1504 (i.e., a first NDP), the initiator 1501 may record the ToD of the NDP 1504. Based on the toas and tods of the

NDPs

1504 and 1508, the initiator 1501 may calculate a Round Trip Time (RTT) between the initiator 1501 and the responder 1506. In this way, distance information (e.g., an estimated distance between the initiator 1501 and the responder 1506) may be derived by the initiator 1501.

After SIFS 1505 has elapsed, the responder 1506 sends an NDP 1508 to the initiator 1501. Then, after SIFS + X1509 elapses, the responder 1506 transmits a measurement feedback packet 1510 to the initiator 1501. In the example scenario 1500, the measurement feedback packet 1510 may include CSI of the NDP 1504 from the initiator 1501 to the responder 1506. When X is 0, the measurement feedback packet 1510 is in the same TXOP as the NDPA 1502, NDP 1504, and NDP 1508, and when X >0, the measurement feedback packet 1510 is in a different TXOP than the NDPA 1502, NDP 1504, and NDP 1508. In some embodiments, the measurement feedback packet 1510 may also include a time-of-departure (ToD) from the responder 1506 to the initiator 1501's NDP 1508.

After the initiator 1501 receives the measurement feedback packet 1510, the initiator 1501 may use the CSI to derive ToA and AoA information for the NDP 1504 from the initiator 1501 to the responder 1506.

The initiator 1501 may also have a ToA from the responder 1506 sent to the NDP 1508 of the initiator 1501 and a ToD sent from the initiator 1501 to the NDP 1504 of the responder 1506. Using ToD information of an NDP 1504 sent from the initiator 1501 to the responder 1506 and ToA information of an NDP 1508 sent from the responder 1506 to the initiator 1501, the initiator 1501 can derive round trip information (e.g., RTT) that can be used for distance estimation.

Two further examples of CSI feedback for MU scenarios in 802.11az are described below with reference to fig. 16.

Figures 16 and 17 show a multi-user scenario for distance estimation.

Fig. 16 shows a scenario 1600 of a use case for a STA to feed CSI back to an AP. Example steps of the multi-user distance estimation process performed in scene 1600 are described below with continued reference to FIG. 16.

As shown in scenario 1600 of fig. 16, as part of an Uplink (UL) sounding portion 1602, the AP first sends a Trigger Frame (TF)1604 to request an uplink NDP (UL NDP 1606) from one or more STAs.

Next, upon receiving TF 1604, each of the one or more STAs polled by TF 1604 may transmit a respective UL NDP 1606. After SIFS 1605, UL NDP 1606 is received from the STA. Based on UL NDP 1606, the AP may obtain CSI of the channel between the AP and the STA and estimate the ToA of UL NDP 1606.

As part of the Downlink (DL) sounding portion 1608, after receiving SIFS 1607 of the UL NDP 1606, the AP may send a Downlink (DL) NDPA 1610 to inform one or more STAs to be ready for a DL NDP 1612. After one or more STAs receive the respective DL NDPs 1612, the one or more STAs may obtain CSI for various channels from the AP to the one or more STAs.

Next, after SIFS + X1613, the AP uses the second TF 1616 to request a corresponding Location Measurement Report (LMR) packet 1618 from one or more STAs. As shown in fig. 16, the LMR packet 1618 may be part of the STA to AP LMR feedback portion 1614. For each of the one or more STAs, LMR packet 1618 may include CSI of DL NDP 1612 and ToD of UL NDP 1606. In fig. 16, for SIFS + X1613, if X is 0, two data packets before and after SIFS + X1613 are both in the same TXOP, and if X >0, two data packets before and after SIFS + X1613 are in different TXOPs.

Next, after SIFS 1617, the AP receives LMR feedback portion 1614, and the AP may use the CSI to derive the ToA of DL NDP 1612. When the AP transmits the DL NDP (1612), it stores the ToD of the DL NDP. Based on the ToA and ToD of UL NDP 1606 and DL NDP 1612, the AP may calculate a round-trip time between the AP and each of the one or more STAs. In this way, the AP may determine range information between the AP and one or more STAs.

Fig. 17 shows an example scenario 1700 in which an AP may use a UL sounding portion 1702, a DL sounding portion 1708, and a unicast packet 1714 transmitted from the AP to one or more STAs to obtain channel estimates for the channel from the STAs to the AP. Scenario 1700 illustrates a use case where an AP feeds CSI back to one or more STAs.

As part of the UL sounding portion 1702, the AP first transmits a TF 1704 to request a corresponding UL NDP 1706 from one or more STAs.

Next, after SIFS 1705 and after receiving TF 1704, one or more STAs polled by TF 1704 may transmit a corresponding UL NDP 1706. Based on the corresponding UL NDP 1706, the AP may obtain CSI of a channel between the AP and one or more STAs.

Next, as part of the DL sounding portion 1708, after receiving SIFS 1707 of UL NDP 1706, the AP may send DL NDPA 1710 to inform one or more STAs to be ready for DL NDP 1712. After SIFS 1711, the STA receives DL NDP 1712. Based on the DL NDP 1712, each of the one or more STAs may obtain CSI for a channel from the AP to the one or more STAs. At this time, one or more STAs may use the CSI to derive the ToA of the DL NDP 1712.

Next, after SIFS + X1713, unicast packet 1714 is sent from the AP to one or more STAs. As part of the unicast packet 1714, the AP may use the LMR packet 1716 to feed back CSI of the UL NDP 1706 and ToD of the DL NDP 1712 to one or more STAs. Based on the CSI of UL NDP 1706, one or more STAs may derive a ToA of UL NDP 1706. When each STA of the one or more STAs transmits UL NDP 1706, the STA records the ToD of UL NDP 1706. Based on the ToA and ToD of UL NDP 1706 and DL NDP 1712, respectively, the STA may calculate RTT and calculate distance information between the STA and the AP.

In fig. 17, for SIFS + X1713, if X is 0, two data packets before and after SIFS + X1713 are in the same TXOP, and if X >0, two data packets before and after SIFS + X1713 are in different TXOPs.

Fig. 18 illustrates a block diagram of an example machine 1800 on which any one or more of the techniques (e.g., methods) discussed herein may be performed. In alternative embodiments, the machine 1800 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 1800 may operate in the role of a server machine, a client machine, or both, in server-client network environments. In an example, machine 1800 may act as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. The machine 1800 may be the master station 102, the HE device 104, a Personal Computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a mobile telephone, a smart phone, a web appliance, a network router, network switch, network bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), other computer cluster configurations.

The examples described herein may include, or may operate on, logic or multiple components, modules, or mechanisms. A module is a tangible entity (e.g., hardware) capable of performing specified operations and may be configured or arranged in a particular manner. In an example, a circuit can be arranged (e.g., internally or with respect to an external entity such as other circuits) as a module in a specified manner. In an example, all or a portion of one or more computer systems (e.g., a stand-alone, client, or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, application portions, or applications) as a module that operates to perform specified operations. In an example, the software may reside on a machine-readable medium. In an example, software, when executed by underlying hardware of a module, causes the hardware to perform specified operations.

Thus, the term "module" is understood to encompass a tangible entity, whether physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transiently) configured (e.g., programmed) to operate in a specified manner or to perform some or all of any of the operations described herein. Considering the example of temporarily configuring modules, it is not necessary to instantiate each module at any one time. For example, where the modules include a general purpose hardware processor configured using software, the general purpose hardware processor may be configured as various different modules at different times. The software may accordingly configure the hardware processor, for example, to constitute a particular module at one instance in time and to constitute a different module at a different instance in time.

The machine (e.g., computer system) 1800 may include a hardware processor 1802 (e.g., a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), a hardware processor core, or any combination thereof), a main memory 1804, and a static memory 1806, some or all of which may communicate with each other via an interconnect link or interconnect (e.g., bus) 1808. The machine 1800 may also include a display device 1810, an input device 1812 (e.g., a keyboard), and a User Interface (UI) navigation device 1814 (e.g., a mouse). In an example, the display device 1810, the input device 1812, and the UI navigation device 1814 may be a touch screen display. The machine 1800 may additionally include mass storage (e.g., a drive unit) 1816, a signal generation device 1818 (e.g., a speaker), a network interface device 1820, and one or more sensors 1821 (e.g., a Global Positioning System (GPS) sensor, compass, accelerometer, or other sensor). The machine 1800 may include an output controller 1828, such as a serial connection (e.g., Universal Serial Bus (USB)), a parallel connection, or other wired or wireless connection (e.g., Infrared (IR), Near Field Communication (NFC)), or the like, to communicate with or control one or more peripheral devices (e.g., a printer, card reader, or the like). In some embodiments, hardware processor 1802 and/or instructions 1824 may include processing circuitry and/or transceiver circuitry.

Mass storage 1816 may include a machine-readable medium 1822 on which is stored one or more sets of data structures or instructions 1824 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 1824 may also reside, completely or at least partially, within the main memory 1804, within the static memory 1806, and/or within the hardware processor 1802 during execution thereof by the machine 1800. In an example, one or any combination of the hardware processor 1802, the main memory 1804, the static memory 1806, or the mass storage 1816 may constitute machine-readable media.

While the machine-readable medium 1822 is shown to be a single medium, the term "machine-readable medium" can include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that are configured to store the one or more instructions 1824.

The devices of the machine 1800 may be one or more of a hardware processor 1802 (e.g., a CPU, GPU, hardware processor core, or any combination thereof), a main memory 1804, and a static memory 1806, some or all of which may communicate with each other via an interconnection link (e.g., bus) 1808.

The term "machine-readable medium" may include any medium that is capable of storing, encoding or carrying instructions for execution by the machine 1800 and that cause the machine 1800 to perform any one or more of the techniques of this disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting examples of machine-readable media may include solid-state memory and optical and magnetic media. Specific examples of the machine-readable medium may include: non-volatile memories such as semiconductor memory devices (e.g., electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; a magnetic optical disk; a RAM; and CD-ROM and DVD-ROM disks. In some examples, the machine-readable medium may include a non-transitory machine-readable medium. In some examples, a machine-readable medium may include a machine-readable medium that is not a transitory propagating signal.

Multiple transport protocols (e.g., frame relay, Internet Protocol (IP), transport) may also be utilizedAny of Transmission Control Protocol (TCP), User Datagram Protocol (UDP), hypertext transfer protocol (HTTP), etc.) sends or receives instructions 1824 over a communication network 1826 using a transmission medium via a network interface device 1820. Example communication networks can include a Local Area Network (LAN), a Wide Area Network (WAN), a packet data network (e.g., the internet), a mobile telephone network (e.g., a cellular network), a Plain Old Telephone (POTS) network, and a wireless data network (e.g., referred to as

Of the Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards, referred to as

IEEE 802.16 family of standards), IEEE 802.15.4 family of standards, LTE family of standards, Universal Mobile Telecommunications System (UMTS) family of standards, and peer-to-peer (P2P) networks, among others.

In an example, the network interface device 1820 may include one or more physical jacks (e.g., ethernet jacks, coaxial jacks, or telephone jacks) or one or more antennas to connect to the communication network 1826. In an example, the network interface device 1820 can include one or more antennas 1860 to wirelessly communicate using at least one of single-input multiple-output (SIMO), MIMO, or multiple-input single-output (MISO) techniques. In some examples, the network interface device 1820 may communicate wirelessly using MU-MIMO techniques. The term "transmission medium" may be considered to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine 1800, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

Various embodiments may be implemented in whole or in part in software and/or firmware. The 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 computer-readable media may include any tangible, non-transitory medium for storing information in one or more computer-readable forms, such as, but not limited to, Read Only Memory (ROM); a RAM; a magnetic disk storage medium; an optical storage medium; flash memory, etc.

Examples of the invention

The following examples pertain to further embodiments.

Example 1 is an apparatus of a wireless device, the apparatus comprising: a memory; and processing circuitry coupled to the memory, the processing circuitry configured to: operate with a Channel State Information (CSI) feedback protocol to: encoding a first Null Data Packet (NDP) for transmission to another wireless device; storing a time-of-departure (ToD) of the first NDP in the memory; decoding a second NDP received from the other wireless device; determining a time of arrival (ToA) of the second NDP; decoding a measurement feedback packet received from the other wireless device, the measurement feedback packet comprising a ToD of the second NDP and a downsampled smoothed channel estimate of a channel between the other wireless device and the wireless device, the channel estimate based on the first NDP; deriving a ToA of the first NDP at the other wireless device based on the channel estimate; calculating a Round Trip Time (RTT) between the wireless device and the other wireless device based on the ToD of the first NDP, the ToA of the first NDP, the ToD of the second NDP, and the ToA of the second NDP; and estimating a distance between the wireless device and the other wireless device based on the RTT.

In example 2, the subject matter of example 1 includes: wherein the measurement feedback packet further comprises CSI feedback, and wherein the processing circuitry is further configured to: determining an angle of arrival (AoA) of the first NDP; and deriving a location of the wireless device based on the AoA of the first NDP and the distance.

In example 3, the subject matter of examples 1-2 includes: wherein the processing circuit is further configured to: storing the CSI feedback in the memory.

In example 4, the subject matter of examples 1-3 includes: wherein the frequency domain channel estimation is based on a high efficiency long training field (HE-LTF) in the first NDP.

In example 5, the subject matter of examples 1-4 includes: wherein the frequency domain channel estimation is based on a very high throughput long training field (VHT-LTF) in the first NDP.

In example 6, the subject matter of examples 1-5 includes an access point.

In example 7, the subject matter of examples 1-6 includes: wherein the wireless device and the other wireless device are configured to: operating in a High Efficiency (HE) wireless local area network that supports beamforming for the CSI feedback.

In example 8, the subject matter of examples 1-7 includes: a transceiver circuit coupled to the processing circuit; and one or more antennas coupled to the transceiver circuitry for transmitting the first NDP and receiving the second NDP and the measurement feedback packet.

Example 9 is an apparatus of a wireless device, the apparatus comprising: a memory; and processing circuitry coupled to the memory, the processing circuitry configured to: operate with a Channel State Information (CSI) feedback protocol to: decoding a first Null Data Packet (NDP) received from another wireless device; encoding the second NDP for transmission to the other wireless device; storing a time-of-departure (ToD) of the second NDP in the memory; estimating a frequency-domain channel estimate for a channel between the other wireless device and the wireless device based at least in part on the decoded first NDP, the frequency-domain channel estimate comprising CSI feedback for the channel; smoothing the frequency domain channel estimate; down-sampling the smoothed frequency domain channel estimate; and encoding a measurement feedback packet for transmission to the other wireless device, the measurement feedback packet comprising the ToD and the downsampled smoothed channel estimate.

In example 10, the subject matter of example 9, comprising: wherein the processing circuitry is further configured to: the smoothed frequency domain channel estimate is downsampled using a downsampling factor.

In example 11, the subject matter of example 10 includes: wherein the processing circuit is further configured to: determining the downsampling factor based on a compression rate and a desired accuracy of the CSI feedback.

In example 12, the subject matter of examples 9-11 includes: wherein the processing circuit is further configured to: smoothing the frequency domain channel estimate by using a linear Minimum Mean Square Error (MMSE) filter to reduce noise in the frequency domain channel estimate and improve a signal-to-noise ratio (SNR) of the CSI feedback.

In example 13, the subject matter of examples 9-12 includes: wherein the processing circuit is further configured to: including the CSI feedback and the ToD in a Location Measurement Report (LMR).

In example 14, the subject matter of examples 9-13 includes: wherein the frequency domain channel estimation is based on a high efficiency long training field (HE-LTF) in the first NDP.

In example 15, the subject matter of examples 9-14 includes: wherein the frequency domain channel estimation is based on a very high throughput long training field (VHT-LTF) in the first NDP.

Example 16 is an apparatus of a wireless device, the apparatus comprising: a memory; and processing circuitry coupled to the memory, the processing circuitry configured to: operate with a Channel State Information (CSI) feedback protocol to: decoding a first Null Data Packet (NDP) received from another wireless device; encoding the second NDP for transmission to the other wireless device; storing a time-of-departure (ToD) of the second NDP in the memory; estimating a frequency domain channel estimate of a channel between the other wireless device and the wireless device based at least in part on the decoded first NDP; interpolating the frequency domain channel estimate on the missing tones; transforming the interpolated frequency domain channel estimates into time domain sequences with an Inverse Fast Fourier Transform (IFFT); generating CSI feedback based on the time domain sequence; and encoding a measurement feedback packet comprising the CSI feedback and the ToD for transmission to the other wireless device.

In example 17, the subject matter of example 16, comprising: wherein the frequency domain channel estimation is based on a high efficiency long training field (HE-LTF) in the first NDP.

In example 18, the subject matter of examples 16-17 includes: wherein the frequency domain channel estimation is based on a very high throughput long training field (VHT-LTF) in the first NDP.

In example 19, the subject matter of examples 16-18 includes: an access point.

In example 20, the subject matter of examples 16-19 includes: wherein the wireless device and the other wireless device are configured to: operating in a High Efficiency (HE) wireless local area network that supports beamforming for the CSI feedback.

In example 21, the subject matter of examples 16-20 includes: a transceiver circuit coupled to the processing circuit; and one or more antennas coupled to the transceiver circuitry to receive the first NDP and to transmit the second NDP and the measurement feedback packet.

Example 22 is a method performed by a wireless device, the method comprising: operate with a Channel State Information (CSI) feedback protocol to: encoding a first Null Data Packet (NDP) for transmission to another wireless device; storing a time-of-departure (ToD) of the first NDP in the memory; decoding a second NDP received from the other wireless device; determining a time of arrival (ToA) of the second NDP; decoding a measurement feedback packet received from the other wireless device, the measurement feedback packet comprising a ToD of the second NDP and a downsampled smoothed channel estimate of a channel between the other wireless device and the wireless device, the channel estimate based on the first NDP; deriving a ToA of the first NDP at the other wireless device based on the downsampled smoothed channel estimate; calculating a Round Trip Time (RTT) between the wireless device and the other wireless device based on the ToD of the first NDP, the ToA of the first NDP, the ToD of the second NDP, and the ToA of the second NDP; and estimating a distance between the wireless device and the other wireless device based on the RTT.

In example 23, the subject matter of example 22 includes: wherein the frequency domain channel estimation is based on a high efficiency long training field (HE-LTF) in the first NDP.

In example 24, the subject matter of examples 22-23 includes: wherein the frequency domain channel estimation is based on a very high throughput long training field (VHT-LTF) in the first NDP.

In example 25, the subject matter of examples 22-24 includes: an access point.

In example 26, the subject matter of examples 22-25 includes: wherein the wireless device and the other wireless device are configured to: operating in a High Efficiency (HE) wireless local area network that supports beamforming for the CSI feedback.

Example 27 is a non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of a wireless device to perform operations that configure the one or more processors to operate in a Channel State Information (CSI) feedback protocol to: decoding a first Null Data Packet (NDP) received from another wireless device; encoding the second NDP for transmission to the other wireless device; storing a time-of-departure (ToD) of the second NDP in the memory; estimating a frequency domain channel estimate of a channel between the other wireless device and the wireless device based at least in part on the decoded first NDP; interpolating the frequency domain channel estimate on the missing tones; transforming the interpolated frequency domain channel estimates into time domain sequences with an Inverse Fast Fourier Transform (IFFT); generating CSI feedback based on the time domain sequence; and encode a measurement feedback packet comprising the ToD of the second NDP and the CSI feedback for transmission to the other wireless device.

In example 28, the subject matter of example 27, comprising: the operations further configure the one or more processors to: estimating a time of arrival (ToA) of the first NDP, wherein an accuracy of the estimated ToA depends on a signal-to-noise ratio (SNR) of CSI feedback based on the first NDP.

In example 29, the subject matter of example 28 includes: the operations further configure the one or more processors to: calculating a Round Trip Time (RTT) between the wireless device and the other wireless device based on the estimated ToA, the ToD of the first NDP, and the ToD of the second NDP.

In example 30, the subject matter of examples 27-29 includes: wherein the channel estimation is a frequency domain channel estimation based on a high efficiency long training field (HE-LTF) in the first NDP.

In example 31, the subject matter of examples 27-30 includes: wherein the channel estimation is a frequency domain channel estimation based on a very high throughput long training field (VHT-LTF) in the first NDP.

In example 32, the subject matter of examples 27-31 includes: an access point.

In example 33, the subject matter of examples 27-32 includes: wherein the wireless device and the other wireless device are configured to: operating in a High Efficiency (HE) wireless local area network that supports beamforming for the CSI feedback.

In example 34, the subject matter of examples 27-33 includes: the wireless device further comprises: a transceiver circuit coupled to the processing circuit; and one or more antennas coupled to the transceiver circuitry to receive the first NDP and to transmit the second NDP and the measurement feedback packet.

Example 35 is at least one machine readable medium comprising instructions that, when executed by processing circuitry, cause the processing circuitry to perform operations to implement any of examples 1-34.

Example 36 is an apparatus comprising means to implement any of examples 1-34.

Example 37 is a system to perform the operations of any of examples 1-34.

Example 38 is a method to perform the operations of any of examples 1-34.

Functions, operations, components, and/or features described herein with reference to one or more embodiments may be combined with or used in conjunction with one or more other functions, operations, components, and/or features described herein with reference to one or more other embodiments, and vice versa.

While certain features have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.

Claims

1. An apparatus of a wireless device, the apparatus comprising: a memory; and processing circuitry coupled to the memory, the processing circuitry configured to: operate with a Channel State Information (CSI) feedback protocol to:

encoding a first Null Data Packet (NDP) for transmission to another wireless device;

storing a time-of-departure (ToD) of the first NDP in the memory;

decoding a second NDP received from the other wireless device;

determining a time of arrival (ToA) of the second NDP;

decoding a measurement feedback packet received from the other wireless device, the measurement feedback packet comprising a ToD of the second NDP and a down-sampled smoothed frequency-domain channel estimate of a channel between the other wireless device and the wireless device, the frequency-domain channel estimate based on the first NDP;

deriving a ToA of the first NDP at the other wireless device based on the frequency-domain channel estimate;

calculating a Round Trip Time (RTT) between the wireless device and the other wireless device based on the ToD of the first NDP, the ToA of the first NDP, the ToD of the second NDP, and the ToA of the second NDP; and

estimating a distance between the wireless device and the other wireless device based on the RTT.

2. The apparatus of claim 1, wherein the measurement feedback packet further comprises CSI feedback,

and wherein the processing circuitry is further configured to:

determining an angle of arrival (AoA) of the first NDP; and

deriving a location of the wireless device based on the AoA of the first NDP and the distance.

3. The apparatus of claim 2, wherein the processing circuitry is further configured to:

storing the CSI feedback in the memory.

4. The apparatus of claim 1, wherein the frequency domain channel estimation is based on a high efficiency long training field (HE-LTF) in the first NDP.

5. The apparatus of claim 1, wherein the frequency domain channel estimation is based on a very high throughput long training field (VHT-LTF) in the first NDP.

6. The apparatus of claim 1, wherein the wireless device and the other wireless device are each one of the group of: an Institute of Electrical and Electronics Engineers (IEEE)802.11ax access point, an IEEE 802.11ax station, an IEEE 802.11 station, and an IEEE 802.11 access point.

7. The apparatus of claim 1, wherein the wireless device and the other wireless device are configured to:

operating in a High Efficiency (HE) wireless local area network that supports beamforming for the CSI feedback.

8. The apparatus of any of claims 1-7, further comprising:

a transceiver circuit coupled to the processing circuit; and

one or more antennas coupled to the transceiver circuitry to transmit the first NDP and to receive the second NDP and the measurement feedback packet.

9. An apparatus of a wireless device, the apparatus comprising: a memory; and processing circuitry coupled to the memory, the processing circuitry configured to: operate with a Channel State Information (CSI) feedback protocol to:

decoding a first Null Data Packet (NDP) received from another wireless device;

encoding the second NDP for transmission to the other wireless device;

storing a time-of-departure (ToD) of the second NDP in the memory;

estimating a frequency domain channel estimate of a channel between the other wireless device and the wireless device based at least in part on the decoded first NDP, the frequency domain channel estimate comprising CSI feedback for the channel;

smoothing the frequency domain channel estimate;

down-sampling the smoothed frequency domain channel estimate; and

encoding a measurement feedback packet for transmission to the other wireless device, the measurement feedback packet comprising the ToD and the downsampled smoothed channel estimate.

10. The apparatus of claim 9, wherein the processing circuitry is further configured to:

the smoothed frequency domain channel estimate is downsampled using a downsampling factor.

11. The apparatus of claim 10, wherein the processing circuitry is further configured to:

determining the downsampling factor based on a compression rate and a desired accuracy of the CSI feedback.

12. The apparatus of claim 9, wherein the processing circuitry is further configured to:

smoothing the frequency domain channel estimate by using a linear Minimum Mean Square Error (MMSE) filter to reduce noise in the frequency domain channel estimate and improve a signal-to-noise ratio (SNR) of the CSI feedback.

13. The apparatus of claim 9, wherein the processing circuitry is further configured to:

including the CSI feedback and the ToD in a Location Measurement Report (LMR).

14. An apparatus of a wireless device, the apparatus comprising: a memory; and processing circuitry coupled to the memory, the processing circuitry configured to: operate with a Channel State Information (CSI) feedback protocol to:

decoding a first Null Data Packet (NDP) received from another wireless device;

encoding the second NDP for transmission to the other wireless device;

storing a time-of-departure (ToD) of the second NDP in the memory;

estimating a frequency domain channel estimate of a channel between the other wireless device and the wireless device based at least in part on the decoded first NDP;

interpolating the frequency domain channel estimate on the missing tones;

transforming the interpolated frequency domain channel estimates into time domain sequences with an Inverse Fast Fourier Transform (IFFT);

generating CSI feedback based on the time domain sequence; and

encoding a measurement feedback packet comprising the CSI feedback and the ToD for transmission to the other wireless device.

15. The apparatus of claim 14, wherein the frequency domain channel estimation is based on a high efficiency long training field (HE-LTF) in the first NDP.

16. The apparatus of claim 14, wherein the frequency domain channel estimation is based on a very high throughput long training field (VHT-LTF) in the first NDP.

17. The apparatus of claim 14, wherein the wireless device and the other wireless device are configured to:

18. The apparatus of claim 14, further comprising:

a transceiver circuit coupled to the processing circuit; and

one or more antennas coupled to the transceiver circuitry to receive the first NDP and to transmit the second NDP and the measurement feedback packet.

19. A method performed by a wireless device, the method comprising:

operate with a Channel State Information (CSI) feedback protocol to:

storing a time-of-departure (ToD) of the first NDP in a memory;

decoding a second NDP received from the other wireless device;

determining a time of arrival (ToA) of the second NDP;

deriving a ToA of the first NDP at the other wireless device based on the downsampled smoothed frequency-domain channel estimate;

20. The method of claim 19, wherein the frequency domain channel estimation is based on a high efficiency long training field (HE-LTF) in the first NDP.

21. The method of claim 19, wherein the frequency domain channel estimation is based on a very high throughput long training field (VHT-LTF) in the first NDP.

22. At least one machine-readable medium comprising instructions that, when executed by a machine, cause the machine to perform operations of any one of the methods of claims 19-21.

23. A computer-readable storage medium that stores instructions for execution by one or more processors of a wireless device to perform operations that configure the one or more processors to operate in a Channel State Information (CSI) feedback protocol to:

decoding a first Null Data Packet (NDP) received from another wireless device;

encoding the second NDP for transmission to the other wireless device;

storing a time-to-departure (ToD) of the second NDP in a memory;

interpolating the frequency domain channel estimate on the missing tones;

generating CSI feedback based on the time domain sequence; and

encoding a measurement feedback packet comprising the ToD of the second NDP and the CSI feedback for transmission to the other wireless device.

24. The computer-readable storage medium of claim 23, the operations further to configure the one or more processors to:

estimating a time of arrival (ToA) of the first NDP, wherein an accuracy of the estimated ToA depends on a signal-to-noise ratio (SNR) of CSI feedback based on the first NDP; and

calculating a Round Trip Time (RTT) between the wireless device and the other wireless device based on the estimated ToA, the ToD of the first NDP, and the ToD of the second NDP.

25. An apparatus of a wireless device, the apparatus comprising:

means for operating with a Channel State Information (CSI) feedback protocol to:

storing a time-of-departure (ToD) of the first NDP in a memory;

decoding a second NDP received from the other wireless device;

determining a time of arrival (ToA) of the second NDP;

decoding a measurement feedback packet received from the other wireless device, the measurement feedback packet comprising a ToD of the second NDP and a downsampled smoothed channel estimate of a channel between the other wireless device and the wireless device, the channel estimate based on the first NDP;

deriving a ToA of the first NDP at the other wireless device based on the downsampled smoothed channel estimate;