WO-2026092688-A1 - METHODS AND APPARATUS FOR SENSING MULTI-TARGET USING MULTIPLE PULSE REPETITION FREQUENCIES IN AN INTEGRATED SENSING AND COMMUNICATION SYSTEM

Abstract

Various solutions for sensing multiple targets using multiple Pulse Repetition Frequencies (PRFs) in an Integrated Sensing and Communication (ISAC) system with respect to an apparatus in mobile communications are described. The apparatus may receive a plurality of pulse sequences having a plurality of PRFs. The apparatus may determine a plurality of frequency peaks associated with the pulse sequences having the plurality of PRFs. The apparatus may determine a plurality of frequency factors based on the plurality of frequency peaks. The apparatus may determine a plurality of target frequencies based on the plurality of frequency factors.

Inventors

• HSU, CHIH-HO
• REN, Jiaying
• TSAI, Shiauhe Shawn

Assignees

• MEDIATEK INC.

Dates

Publication Date

20260507

Application Date

20251031

Priority Date

20241101

Claims (20)

1. A method, comprising: receiving, by a processor of an apparatus, a plurality of pulse sequences having a plurality of pulse repetition frequencies (PRFs) ; determining, by the processor, a plurality of frequency peaks associated with the pulse sequences having the plurality of PRFs; determining, by the processor, a plurality of frequency factors based on the plurality of frequency peaks; and determining, by the processor, a plurality of target frequencies based on the plurality of frequency factors.
2. The method of Claim 1, wherein the determining of the plurality of frequency peaks associated with the pulse sequences further comprises: performing, by the processor, spectral analysis on each of the plurality of pulse sequences to obtain a plurality of frequency domain signals; and determining, by the processor, the plurality of frequency peaks in the frequency domain signals.
3. The method of Claim 2, wherein each of the plurality of frequency peaks includes an erroneous remainder of a corresponding Doppler frequency modulo a corresponding integer-valued PRF.
4. The method of Claim 3, wherein the determining of the plurality of frequency factors based on the plurality of frequency peaks further comprises: determining, by the processor, a plurality of common remainders, wherein each common remainder is derived from a corresponding erroneous remainder modulo a common factor which is nonzero; determining, by the processor, a plurality of quotient remainders, wherein each quotient remainder is derived from a specific value modulo an integer associated with a corresponding integer-valued PRF while the corresponding integer-valued PRF is a product of the integer and the common factor, and the specific value is obtained by dividing the difference between a corresponding erroneous remainder and a corresponding common remainder by the common factor; determining, by the processor, a plurality of coefficients of a polynomial based on the plurality of quotient remainders; and determining, by the processor, a plurality of roots of the polynomial, wherein the plurality of roots are the plurality of frequency factors.
5. The method of Claim 4, wherein the plurality of coefficients of the polynomial are determined based on the plurality of quotient remainders using Chinese remainder theorem (CRT) formula and Vieta's formula.
6. The method of Claim 5, further comprising: determining, by the processor, a mapping between one frequency factor and one set of common remainders.
7. The method of Claim 6, wherein the determining of the mapping between the one frequency factor and the one set of common remainders further comprises: identifying, by the processor, a repeated frequency factor from the plurality of frequency factors, wherein the repeated frequency factor appears z times; selecting, by the processor, a specific pulse sequence associated with a specific integer-valued PRF, wherein the specific pulse sequence has corresponding z quotient remainders equal to a modulo value of the repeated frequency factor with respect to an integer associated with the specific integer-valued PRF while the specific integer-valued PRF is a product of the integer and the common factor; determining, by the processor, a z-dimensional reference vector based on quotient remainders of the specific pulse sequence, wherein each element of the z-dimensional reference vector corresponds to one common remainder, and the one common remainder is associated with one quotient remainder equal to the modulo value; comparing, by the processor, the z-dimensional reference vector with candidate remainders from other pulse sequences to identify, based on a predefined threshold error margin, a matching between each element of the z-dimensional reference vector and the candidate remainders associated with the same frequency factor; and determining, by the processor, the identified matching results as the mapping between the one frequency factor and the set of common remainders, while the one frequency factor is the repeated frequency factor, and the set of common remainders includes the matched candidate remainders and the elements of the z-dimensional reference vector.
8. The method of Claim 6, wherein the determining of the plurality of target frequencies based on the plurality of frequency factors further comprises: determining, by the processor, the plurality of target frequencies based on a corresponding frequency factor, the common factor, and a corresponding set of common remainders.
9. The method of Claim 1, wherein each pulse sequence includes a integer-valued PRF, each integer-valued PRF is a product of an integer and a common factor, and the integers are coprime.
10. A method, comprising: determining, by a processor of an apparatus, a plurality of pulse repetition frequencies (PRFs) ; and transmitting, by the processor, a plurality of pulse sequences having the plurality of PRFs for determining a plurality of frequency peaks associated with the pulse sequences, determining a plurality of frequency factors based on the plurality of frequency peaks, and determining a plurality of target frequencies based on the plurality of frequency factors.
11. The method of Claim 10, wherein each pulse sequence includes integer-valued PRF, each integer-valued PRF is a product of an integer and a common factor, and the integers are coprime.
12. An apparatus, comprising: a transceiver which, during operation, wirelessly communicates with a wireless network; and a processor communicatively coupled to the transceiver such that, during operation, the processor performs operations comprising: receiving, via the processor, a plurality of pulse sequences having a plurality of pulse repetition frequencies (PRFs) ; determining a plurality of frequency peaks associated with the pulse sequences having the plurality of PRFs; determining a plurality of frequency factors based on the plurality of frequency peaks; and determining a plurality of target frequencies based on the plurality of frequency factors.
13. The apparatus of Claim 12, wherein, during operation, the processor further performs operations comprising: performing spectral analysis on each of the plurality of pulse sequences to obtain a plurality of frequency domain signals; and determining the plurality of frequency peaks in the frequency domain signals.
14. The apparatus of Claim 13, wherein each of the plurality of frequency peaks includes an erroneous remainder of a corresponding Doppler frequency modulo a corresponding integer-valued PRFs.
15. The apparatus of Claim 14, wherein, during operation, the processor further performs operations comprising: determining a plurality of common remainders, wherein each common remainder is derived from a corresponding erroneous remainder modulo a common factor which is nonzero; determining a plurality of quotient remainders, wherein each quotient remainder is derived from a specific value modulo an integer associated with a corresponding integer-valued PRF while the corresponding integer-valued PRF is a product of the integer and the common factor, and the specific value is obtained by dividing the difference between a corresponding erroneous remainder and a corresponding common remainder by the common factor; determining a plurality of coefficients of a polynomial based on the plurality of quotient remainders; and determining a plurality of roots of the polynomial, wherein the plurality of roots are the plurality of frequency factors.
16. The apparatus of Claim 15, wherein the plurality of coefficients of the polynomial are determined based on the plurality of quotient remainders using Chinese remainder theorem (CRT) formula and Vieta's formula.
17. The apparatus of Claim 16, wherein, during operation, the processor further performs operations comprising: determining a mapping between one frequency factor and one set of common remainders.
18. The apparatus of Claim 17, wherein, during operation, the processor further performs operations comprising: identifying a repeated frequency factor from the plurality of frequency factors, wherein the repeated frequency factor appears z times; selecting a specific pulse sequence associated with a specific integer-valued PRF, wherein the specific pulse sequence has corresponding z quotient remainders equal to a modulo value of the repeated frequency factor with respect to an integer associated with the specific integer-valued PRF while the specific integer-valued PRF is a product of the integer and the common factor; determining a z-dimensional reference vector based on quotient remainders of the specific pulse sequence, wherein each element of the z-dimensional reference vector corresponds to one common remainder, and the one common remainder is associated with one quotient remainder equal to the modulo value; comparing the z-dimensional reference vector with candidate remainders from other pulse sequences to identify, based on a predefined threshold error margin, a matching between each element of the z-dimensional reference vector and the candidate remainders associated with the same frequency factor; and determining the identified matching results as the mapping between the one frequency factor and the set of common remainders, while the one frequency factor is the repeated frequency factor, and the set of common remainders includes the matched candidate remainders and the elements of the z-dimensional reference vector.
19. The apparatus of Claim 17, wherein, during operation, the processor further performs operations comprising: determining the plurality of target frequencies based on a corresponding frequency factor, the common factor, and a corresponding set of common remainders.
20. The apparatus of Claim 12, wherein each pulse sequence includes an integer-valued PRF, each integer-valued PRF is a product of an integer and a common factor, and the integers are coprime.

Description

METHODS AND APPARATUS FOR SENSING MULTI-TARGET USING MULTIPLE PULSE REPETITION FREQUENCIES IN AN INTEGRATED SENSING AND COMMUNICATION SYSTEM CROSS REFERENCE TO RELATED PATENT APPLICATION (S) The present disclosure is part of a non-provisional application claiming the priority benefit of U.S. Patent Application No. 63/714,955, filed 1 November 2024, the content of which herein being incorporated by reference in its entirety. TECHNICAL FIELD The present disclosure is generally related to an Integrated Sensing and Communication (ISAC) system, and, more particularly, to sensing multi-target using multiple Pulse Repetition Frequencies (PRFs) in an ISAC system. 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 New Radio (NR) mobile communications, the detection of surrounding objects in radar-related environments may typically rely on the measurement of signal delay and Doppler shift. Wireless signals transmitted across frequency, time, and/or spatial domains for communication inherently exhibit radio characteristics similar to those used in radar sensing. Accordingly, radar sensing and communication systems operating in overlapping frequency bands have motivated their integration into a unified system, referred to as an Integrated Sensing and Communication (ISAC) system. A time-division multiplexing approach may be a natural and practical solution for realizing such integration. However, in the context of Doppler ambiguity resolution for multiple targets using pulse-Doppler radar integrated with a communication system in a time-division manner, a high pulse repetition frequency (PRF) may result in excessive system overhead. Conversely, while a low PRF reduces overhead, it may induce significant Doppler frequency aliasing, thereby increasing the level of Doppler ambiguity. Accordingly, balancing system overhead and Doppler ambiguity has become a critical consideration in some network scenarios of modern wireless communication networks (e.g., the ISAC system) . Therefore, there is a recognized need for effective schemes capable of jointly minimizing overhead and mitigating Doppler ambiguity. 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 propose solutions or schemes that address the aforementioned issues pertaining to sensing multi-target using multiple Pulse Repetition Frequencies (PRFs) in an Integrated Sensing and Communication (ISAC) system with respect to apparatus in mobile communications. In one aspect, a method may involve an apparatus receiving a plurality of pulse sequences having a plurality of PRFs. The method may also involve the apparatus determining a plurality of frequency peaks associated with the pulse sequences having the plurality of PRFs. The method may further involve the apparatus determining a plurality of frequency factors based on the plurality of frequency peaks. The method may further involve the apparatus determining a plurality of target frequencies based on the plurality of frequency factors. In one aspect, a method may involve an apparatus determining a plurality of PRFs. The method may also involve the apparatus transmitting a plurality of pulse sequences having the plurality of PRFs for determining a plurality of frequency peaks associated with the pulse sequences, determining a plurality of frequency factors based on the plurality of frequency peaks, and determining a plurality of target frequencies based on the plurality of frequency factors. In one aspect, an apparatus may comprise a transceiver which, during operation, wirelessly communicates with a wireless network. The apparatus may also comprise a processor communicatively coupled to the transceiver. The processor, during operation, may perform operations comprising receiving, via the processor, a plurality of pulse sequences having a plurality of PRFs. The processor may also perform operations comprising determining a plurality of frequency peaks associated with the pulse sequences having the plurality of PRFs. The processor may further perform operations comprising determining a plurality of frequency factors based on the plurality of frequency peaks. The processor may further perform operations comprising determining a plurality of target frequencies based on the plurality of frequency factors. It is noteworthy that, although description provided herein may be in