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US-12627351-B2 - MIMO joint ToA and AoA estimation for Wi-Fi systems

US12627351B2US 12627351 B2US12627351 B2US 12627351B2US-12627351-B2

Abstract

Techniques pertaining to multiple-input-multiple-output (MIMO) joint time of arrival (ToA) and angle of arrival (AoA) for Wi-Fi systems in wireless communications are described. An apparatus performs channel estimation to obtain a plurality of multiple-input-multiple-output (MIMO) channel state information (CSI). The apparatus then calculates weighted MIMO CSI and determines a time of arrival (ToA) or the ToA and an angle of arrival (AoA) based at least on the weighted MIMO CSI.

Inventors

  • CHING-CHIA CHENG
  • Yen-Wen Yang

Assignees

  • MEDIATEK INC.

Dates

Publication Date
20260512
Application Date
20231128

Claims (15)

  1. 1 . A method, comprising: performing, by a processor of an apparatus, channel estimation to obtain a plurality of multiple-input-multiple-output (MIMO) channel state information (CSI); calculating, by the processor, weighted MIMO CSI; and determining, by the processor, a time of arrival (ToA) or the ToA and an angle of arrival (AoA) based at least on the weighted MIMO CSI, wherein the calculating of the weighted MIMO CSI comprises, for each MIMO CSI of the plurality of MIMO CSI: calculating a weighting factor; and applying the weighting factor to the respective MIMO CSI, wherein the calculating of the weighting factor comprises calculating the weighting factor based on at least one of a signal-to-interference-and-noise ratio (SINR), a received signal strength indicator (RSSI) and a root-mean-square deviation (RMSD), wherein the applying of the weighting factor comprises: responsive to a respective SINR of the respective MIMO CSI being lower than a signal-to-noise ratio (SNR) threshold, de-weighting the respective MIMO CSI; or responsive to the respective SINR being equal to or higher than the SNR threshold, applying a predetermined weighting factor to the respective MIMO CSI.
  2. 2 . A method, comprising: performing, by a processor of an apparatus, channel estimation to obtain a plurality of multiple-input-multiple-output (MIMO) channel state information (CSI); calculating, by the processor, weighted MIMO CSI; and determining, by the processor, a time of arrival (ToA) or the ToA and an angle of arrival (AoA) based at least on the weighted MIMO CSI, wherein the determining of the ToA or the ToA and the AoA based at least on the weighted MIMO CSI further comprises, for each MIMO CSI of the plurality of MIMO CSI: calculating a subcarrier or subband validation mask; combining the weighted MIMO CSI and the subcarrier or subband validation mask; and determining the ToA or the ToA and the AoA based on the combined weighted MIMO CSI and the subcarrier or subband validation mask.
  3. 3 . The method of claim 2 , wherein the calculating of the subcarrier or subband validation mask comprises calculating the subcarrier or subband validation mask based on either or both of a respective signal-to-interference-and-noise ratio (SINR) and a respective noise profile associated with a respective subcarrier or subband.
  4. 4 . The method of claim 2 , wherein the combining of the weighted MIMO CSI and the subcarrier or subband validation mask comprises disregarding the subcarrier or subband validation mask responsive to a respective signal-to-interference-and-noise ratio (SINR) associated with a respective subcarrier or subband being higher than a SINR threshold.
  5. 5 . The method of claim 1 , wherein the determining of the ToA or the ToA and the AoA comprises iteratively extracting a channel impulse response (CIR) from the plurality of MIMO CSI to search the ToA or the ToA and the AoA.
  6. 6 . The method of claim 5 , wherein the iteratively extracting of the CIR from the plurality of MIMO CSI to search the ToA or the ToA and the AoA comprises, during each iteration: searching for one or more new possible tap candidates for each of one or more candidates; cancelling one or more peak components individually; keeping one or more most possible candidates to a next iteration; and checking whether any of the one or more most possible candidates passes termination criteria.
  7. 7 . The method of claim 1 , further comprising: performing, by the processor, two-way ranging with the ToA or the ToA and the AoA.
  8. 8 . An apparatus, comprising: a transceiver configured to communicate wirelessly; and a processor coupled to the transceiver and configured to perform operations comprising: performing, via the transceiver, channel estimation to obtain a plurality of multiple-input-multiple-output (MIMO) channel state information (CSI); calculating weighted MIMO CSI; and determining a time of arrival (ToA) or the ToA and an angle of arrival (AoA) based at least on the weighted MIMO CSI, wherein the determining of the ToA or the ToA and the AoA comprises iteratively extracting a channel impulse response (CIR) from the plurality of MIMO CSI to search the ToA or the ToA and the AoA, wherein the iteratively extracting of the CIR from the plurality of MIMO CSI to search the ToA or the ToA and the AoA comprises, during each iteration: searching for one or more new possible tap candidates for each of one or more candidates; cancelling one or more peak components individually; keeping one or more most possible candidates to a next iteration; and checking whether any of the one or more most possible candidates passes termination criteria.
  9. 9 . The apparatus of claim 8 , wherein the calculating of the weighted MIMO CSI comprises, for each MIMO CSI of the plurality of MIMO CSI: calculating a weighting factor; and applying the weighting factor to the respective MIMO CSI.
  10. 10 . The apparatus of claim 9 , wherein the calculating of the weighting factor comprises calculating the weighting factor based on at least one of a signal-to-interference-and-noise ratio (SINR), a received signal strength indicator (RSSI) and a root-mean-square deviation (RMSD).
  11. 11 . The apparatus of claim 10 , wherein the applying of the weighting factor comprises: responsive to a respective SINR of the respective MIMO CSI being lower than a signal-to-noise ratio (SNR) threshold, de-weighting the respective MIMO CSI; or responsive to the respective SINR being equal to or higher than the SNR threshold, applying a predetermined weighting factor to the respective MIMO CSI.
  12. 12 . The apparatus of claim 8 , wherein the determining of the ToA or the ToA and the AoA based at least on the weighted MIMO CSI further comprises, for each MIMO CSI of the plurality of MIMO CSI: calculating a subcarrier or subband validation mask; combining the weighted MIMO CSI and the subcarrier or subband validation mask; and determining the ToA or the ToA and the AoA based on the combined weighted MIMO CSI and the subcarrier or subband validation mask.
  13. 13 . The apparatus of claim 12 , wherein the calculating of the subcarrier or subband validation mask comprises calculating the subcarrier or subband validation mask based on either or both of a respective signal-to-interference-and-noise ratio (SINR) and a respective noise profile associated with a respective subcarrier or subband.
  14. 14 . The apparatus of claim 12 , wherein the combining of the weighted MIMO CSI and the subcarrier or subband validation mask comprises disregarding the subcarrier or subband validation mask responsive to a respective signal-to-interference-and-noise ratio (SINR) associated with a respective subcarrier or subband being higher than a SINR threshold.
  15. 15 . The apparatus of claim 8 , wherein the processor is further configured to perform operations comprising: performing, via the transceiver, two-way ranging with the ToA or the ToA and the AoA.

Description

CROSS REFERENCE TO RELATED PATENT APPLICATION The present disclosure is part of a non-provisional patent application claiming the priority benefit of U.S. Provisional Patent Application No. 63/385,637, filed 1 Dec. 2022, the content of which being herein incorporated by reference in its entirety. TECHNICAL FIELD The present disclosure is generally related to wireless communications and, more particularly, to multiple-input-multiple-output (MIMO) joint time of arrival (ToA) and angle of arrival (AoA) for Wi-Fi systems in wireless communications. BACKGROUND Unless otherwise indicated herein, approaches described in this section are not prior art to the claims listed below and are not admitted as prior art by inclusion in this section. In wireless communications such as Wi-Fi (or WiFi) and wireless local area networks (WLANs) in accordance with upcoming Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard(s), devices compliant with IEEE 802.11mc and IEEE 802.11az are allowed to measure the distance to a nearby access point (AP) through a two-way ranging technology. To achieve the two-way ranging, both the AP and the device (e.g., station (STA)) need to estimate the ToA. Typically, the device can obtain trilateration of its location with three or more APs. On the other hand, with AoA, the device would be able to calculate its location with a single AP. In indoor environments, there tend to be many clusters that cause reflection paths between the device and the AP. In order to determine or obtain information of the device's accurate location, a channel impulse response (CIR) needs to be extracted from a receiver (Rx) channel state information (CSI) with estimation of only the ToA and AoA of a headmost path. However, the perfect CIR extraction is difficult for Wi-Fi systems in a dense environment, since the Wi-Fi channel bandwidth is only up to 160 MHz such that timing difference of less than 6.25 nanoseconds (ns) between any two paths would create a fake path in CSI and thus would be difficult to separate. For example, for 160 MHz, the time resolution=1/channel bandwidth=6.25 ns, and range resolution=C*time resolution=3*108 m/s*6.25 ns=1.875 m. To enhance accuracy, there are two approaches. One approach involves MIMO channel joint search in that the same ToA and AoA are contained in the CSI of all transmit (Tx) and receive (Rx) pairs. Another approach involves maintaining possibilities that found paths are fake paths created by nearby true paths. Nevertheless, there is still room for improvement in the quality of channel estimation and enhancement in ToA and AoA accuracy. Therefore, there is a need for a solution of MIMO joint ToA and AoA for Wi-Fi systems. SUMMARY The following summary is illustrative only and is not intended to be limiting in any way. That is, the following summary is provided to introduce concepts, highlights, benefits and advantages of the novel and non-obvious techniques described herein. Select implementations are further described below in the detailed description. Thus, the following summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter. An objective of the present disclosure is to provide schemes, concepts, designs, techniques, methods and apparatuses pertaining to MIMO joint ToA and AoA for Wi-Fi systems in wireless communications. It is believed that the aforementioned issue(s) may be avoided or otherwise alleviated by implementation of one or more of the various proposed schemes described herein. In one aspect, a method may involve performing channel estimation to obtain a plurality of MIMO CSI. The method may also involve calculating weighted MIMO CSI. The method may further involve determining a ToA or the ToA and a AoA based at least on the weighted MIMO CSI. In another aspect, an apparatus may include a transceiver configured to communicate wirelessly and a processor coupled to the transceiver. The processor may perform channel estimation to obtain a plurality of MIMO CSI. The processor may also calculate weighted MIMO CSI. The processor may further determine a ToA or the ToA and an AoA based at least on the weighted MIMO CSI. It is noteworthy that, although description provided herein may be in the context of certain radio access technologies, networks and network topologies such as, Wi-Fi, the proposed concepts, schemes and any variation(s)/derivative(s) thereof may be implemented in, for and by other types of radio access technologies, networks and network topologies such as, for example and without limitation, Bluetooth, ZigBee, 5th Generation (5G)/New Radio (NR), Long-Term Evolution (LTE), LTE-Advanced, LTE-Advanced Pro, Internet-of-Things (IoT), Industrial IoT (IIoT) and narrowband IoT (NB-IoT). Thus, the scope of the present disclosure is not limited to the examples described herein. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawing