US-20260128928-A1 - SYSTEM AND METHODS FOR SUPPRESSING CHANNEL REPLICA

US20260128928A1US 20260128928 A1US20260128928 A1US 20260128928A1US-20260128928-A1

Abstract

Embodiments of the present disclosure provide a method for suppressing channel replica caused by carrier frequency offset (CFO). The method includes: generating, by an analog-to-digital converter (ADC), a plurality of samples after receiving a sequence of chips by an antenna; accumulating, by an accumulator, the plurality of samples to generate an initial channel impulse response (CIR); comparing the CFO with a threshold value; in response to the CFO being greater than the threshold value, applying a filtering operation on the initial CIR estimate, the filtering operation configured to reduce an intensity of a sidelobe in the initial CIR estimate while maintaining an intensity of a main lobe in the initial CIR estimate; and generating a final estimated CIR based on the filtered initial CIR estimate.

Inventors

Igor Dotlic
Michael McLaughlin

Assignees

QORVO US, INC.

Dates

Publication Date: 20260507
Application Date: 20251028

Claims (20)

1 . A method for suppressing channel replica caused by carrier frequency offset (CFO), comprising: generating, by an analog-to-digital converter (ADC), a plurality of samples after receiving a sequence of chips by an antenna; accumulating, by an accumulator, the plurality of samples to generate an initial channel impulse response (CIR) estimate; comparing the CFO with a threshold value; in response to the CFO being greater than the threshold value, applying a filtering operation on the initial CIR estimate, the filtering operation configured to reduce an intensity of a sidelobe in the initial CIR estimate while maintaining an intensity of a main lobe in the initial CIR estimate; and generating a final estimated CIR based on the filtered initial CIR estimate.
2 . The method of claim 1 , further comprising: determining an ambiguity function of the sequence; determining an analytical model of the initial CIR estimate based on the ambiguity function and a channel response of the sequence; and generating a set of filter coefficient vectors of the filter based on the ambiguity function, wherein the set of the filter coefficient vectors each correspond to a respective one of the plurality of samples.
3 . The method of claim 2 , wherein the applying of the filtering operation comprises generating an inner product of each of the filter coefficient vector with the initial CIR estimate.
4 . The method of claim 2 , wherein the ambiguity function comprises samples arranged in a Toeplitz matrix and comprises a pseudo-circulant matrix.
5 . The method of claim 2 , wherein the generating of the set of filter coefficient vectors comprises: generating one filter coefficient vector of the filter coefficient vectors; and generating an adjacent filter coefficient vector of the one filter coefficient vectors based on the pseudo-circulant matrix.
6 . The method of claim 5 , wherein the generating of the set of filter coefficients comprises: generating a first filter coefficient vector of the filter coefficient vectors; and generating a next filter coefficient vector by: multiplying a last element of a previous filter coefficient vector with a phase factor to generate a product, and shifting the product to be a first element and a remaining of elements by one position to the right.
7 . The method of claim 5 , wherein the generating of the set of filter coefficient vectors comprises: generating a last filter coefficient vector of the filter coefficient vectors; and generating a previous filter coefficient vector by: multiplying a first element of a next filter coefficient vector with a phase factor to generate a product, and shifting the product to be a last element and a remaining of elements by one position to the left.
8 . The method of claim 5 , wherein a first filter coefficient vector or a last filter coefficient vector is pre-computed based on a total sidelobe suppression or a convex optimization.
9 . The method of claim 5 , wherein the shifting is performed in a shift register.
10 . The method of claim 1 , wherein the sequence comprises a synchronization header (SHR) of a radio frequency (RF) packet.
11 . The method of claim 1 , further comprising computing one or more of a time of arrival (ToA) or a position of arrival (PoA) based on the final CIR estimate.
12 . An ultra-wideband (UWB) device, comprising a UWB receiver comprising an analog-to-digital converter (ADC), wherein the UWB receiver is configured to: generate, by the ADC, a plurality of samples after receiving a sequence of chips by an antenna; accumulate, by an accumulator, the plurality of samples to generate an initial channel impulse response (CIR) estimate; compare the CFO with a threshold value; in response to the CFO being greater than the threshold value, apply a filtering operation on the initial CIR, the filtering operation configured to reduce an intensity of a sidelobe in the initial CIR estimate while maintaining an intensity of a main lobe in the initial CIR estimate; and generate a final estimated CIR based on the filtered initial CIR estimate.
13 . The UWB device of claim 12 , wherein the UWB receiver is further configured to: determine an ambiguity function of the sequence; determine an analytical model of the initial CIR estimate based on the ambiguity function; and generate a set of filter coefficient vectors of the filter based on the ambiguity function, wherein the set of the filter coefficient vectors each correspond to a respective one of the plurality of samples.
14 . The UWB device of claim 13 , wherein to apply the filtering operation comprises generating an inner product of each of the filter coefficient vector with a respective part of the initial CIR estimate that corresponds to the respective one of the plurality of samples.
15 . The UWB device of claim 13 , wherein the ambiguity function comprise samples arranged in a Toeplitz matrix and comprises a pseudo-circulant matrix.
16 . The UWB device of claim 13 , wherein to generate the set of filter coefficient vectors comprises: generating one filter coefficient vector of the filter coefficient vectors; and generating an adjacent filter coefficient vector of the one filter coefficient vectors based on the pseudo-circulant matrix.
17 . The UWB device of claim 16 , wherein to generate the set of filter coefficients comprises: generating a first filter coefficient vector of the filter coefficient vectors; and generating a next filter coefficient vector by: multiplying a last element of a previous filter coefficient vector with a phase factor to generate a product, and shifting the product to be a first element and a remaining of elements by one position to the right.
18 . The UWB device of claim 16 , wherein to generate the set of filter coefficient vectors comprises: generating a last filter coefficient vector of the filter coefficient vectors; and generating a previous filter coefficient vector by: multiplying a first element of a next filter coefficient vector with a phase factor to generate a product, and shifting the product to be a last element and a remaining of elements by one position to the left.
19 . The UWB device of claim 16 , wherein the shifting is performed in a shift register.
20 . A non-transitory computer-readable medium (CRM) having program code recorded thereon, the program code comprising: code for causing an ultra-wide band (UWB) device to generate, by an analog-to-digital converter (ADC), a plurality of samples after receiving a sequence of chips by an antenna; code for causing the UWB device to accumulate, by an accumulator, the plurality of samples to generate an initial channel impulse response (CIR); code for causing the UWB device to compare the CFO with a threshold value; code for causing the UWB device to, in response to the CFO being greater than the threshold value, apply a filtering operation on the initial CIR estimate, the filtering operation configured to reduce an intensity of a sidelobe in the initial CIR estimate while maintaining an intensity of a main lobe in the initial CIR estimate; and code for causing the UWB device to generate an estimated CIR based on the filtered initial CIR estimate.

Description

RELATED APPLICATION The present application claims the benefit of U.S. Provisional Application No. 63/716,525, entitled “SYSTEM AND METHODS FOR SUPPRESSING CHANNEL REPLICA” and filed on Nov. 5, 2024, which is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION This disclosure relates to radio frequency (RF) communication technologies. In particular, this disclosure relates to a system and methods for suppressing channel replica. BACKGROUND Ultra-Wideband (UWB) is a wireless communication technology characterized by its ability to transmit data over a wide frequency spectrum, typically greater than 500 MHz. Unlike traditional wireless technologies that use narrow frequency bands, UWB operates by transmitting short, low-power pulses across a broad range of frequencies. This enables high data rates, precise localization capabilities, and low power consumption, making UWB a versatile technology with a wide range of applications such as positioning and localization, consumer electronics, Internet of Things (IoT), security and access control, etc. Synchronization header (SHR) is an important part of a UWB frame structure that helps a receiver synchronize with transmitter, and detect and process the receive UWB signal, in the UWB communication. SHR often includes a preamble and a start frame delimiter (SFD). The preamble includes a sequence of pulses or symbols transmitted at the start of the SHR. The sequence can enable the receiver to detect the presence of the signal, achieve timing synchronization between the receiver and the signal, and estimate and correcting carrier frequency offset (CFO) between the transmitter and the receiver. The sequence can be accumulated to generate a channel impulse response (CIR) which is later used to determine parameters such as time-of-arrival (ToA), for determining a distance between the transmitter and the receiver. However, the CIR can be noisy, and the precision of ToA can be low due to the noise. Therefore, there is a need to improve the precision of CIR to increase the precision of ToA. SUMMARY Embodiments of the present disclosure provide a method for suppressing channel replica caused by carrier frequency offset (CFO). The method includes: generating, by an analog-to-digital converter (ADC), a plurality of samples after receiving a sequence of chips by an antenna; accumulating, by an accumulator, the plurality of samples to generate an initial channel impulse response (CIR); comparing the CFO with a threshold value; in response to the CFO being greater than the threshold value, applying a filtering operation on the initial CIR estimate, the filtering operation configured to reduce an intensity of a sidelobe in the initial CIR estimate while maintaining an intensity of a main lobe in the initial CIR estimate; and generating a final estimated CIR based on the filtered initial CIR estimate. In some embodiments, the method further includes: determining an ambiguity function of the sequence; determining an analytical model of the initial CIR estimate based on the ambiguity function and a channel response of the sequence; and generating a set of filter coefficient vectors of the filter based on the ambiguity function, wherein the set of the filter coefficient vectors each correspond to a respective one of the plurality of samples. In some embodiments, the applying of the filtering operation comprises generating an inner product of each of the filter coefficient vector with the initial CIR estimate. In some embodiments, the ambiguity function comprises samples arranged in a Toeplitz matrix and comprises a pseudo-circulant matrix. In some embodiments, the generating of the set of filter coefficient vectors includes: generating one filter coefficient vector of the filter coefficient vectors; and generating an adjacent filter coefficient vector of the one filter coefficient vectors based on the pseudo-circulant matrix. In some embodiments, the generating of the set of filter coefficients includes: generating a first filter coefficient vector of the filter coefficient vectors; and generating a next filter coefficient vector by: multiplying a last element of a previous filter coefficient vector with a phase factor to generate a product, and shifting the product to be a first element and a remaining of elements by one position to the right. In some embodiments, the generating of the set of filter coefficient vectors includes: generating a last filter coefficient vector of the filter coefficient vectors; and generating a previous filter coefficient vector by: multiplying a first element of a next filter coefficient vector with a phase factor to generate a product, and shifting the product to be a last element and a remaining of elements by one position to the left. In some embodiments, a first filter coefficient vector or a last filter coefficient vector is pre-computed based on a total sidelobe suppression or a convex optimization. In some embodiments, the shifti