ADAPTIVE REFERENCE SIGNAL DESIGN FOR DETECTION UNDER CHANGING DOPPLER REQUIREMENTS

Abstract

The invention relates to a method and a system, which is a Doppler-aware sensing framework based on adaptive control of HFM reference signal parameters.

Description

1 TARIFF FOR DETECTION UNDER CHANGING DOPPLER REQUIREMENTS ADAPTIVE REFERENCE SIGNAL DESIGN Technical Area The invention is a Doppler-based adaptive control of HFM reference signal parameters. It is related to a method and a system that is a framework of conscious perception. Previous Technique Integrated wireless detection and communication (ISAC) in 5G-Advanced and 6G systems. The development in this direction, in addition to traditional data transmission of cellular infrastructure, includes environmental sensing. This requires supporting its functions. Current systems have very poor sensing capabilities. To a certain extent, it was initially designed for channel estimation, synchronization, and communication reliability. Communication-oriented reference signals, such as pilot and positioning signals, are being re-evaluated. This is achieved through the use of these reference signals, via signal processing techniques. Although it allows for the acquisition of delay and Doppler information, their structure and its configuration is fundamentally communication-focused rather than perception-optimized 20 It remains. The first technical challenge is accurate and uncertainty-controlled combined delay-Doppler estimation. This stems from the requirement. Maximum uncertainty in OFDM-based sensing systems. The non-existent range depends on signal bandwidth and frequency space allocation, with a maximum of 25. Unambiguous Doppler, by the time-domain repetition interval of the reference signal Doppler resolution and estimation variance are also determined by the phase evolution that is accumulated. It depends on the coherent processing range, which is the effective observation window. Reference signal Inappropriate configuration of the periodicity leads to Doppler overlap, Insufficient observation time reduces speed resolution and increases estimation error. 30 In contrast, extending the observation window improves Doppler accuracy, but the system This increases the delay and can violate channel coherence constraints. Therefore, it is correct. Combined latency-Doppler estimation inherently involves uncertainty and performance degradation. 2 To prevent this, the periodicity of the reference signal and the observation time must be carefully considered. It requires checking. The second technical challenge stems from the heterogeneous nature of the sensing scenarios and their varying Doppler values. This stems from the requirements. Specific detection tasks, radar search mode, target 5. Doppler robustness, such as presence detection and initial acquisition under unknown velocity conditions. These scenarios prioritize robustness and speed against Doppler discordance. It requires immunity to uncertainty. Other sensing tasks include micro-Doppler. analysis, fine detail motion tracking and high-resolution, low-variance speed estimation Doppler accuracy is 10, as required for combined positioning and velocity estimation. This requires a Doppler-aware adaptation of the current reference signal configurations. It does not include a mechanism and therefore the Doppler varies across detection scenarios. time-domain structures depending on robustness or Doppler accuracy requirements It does not provide a mechanism for dynamic adjustment. However, existing communication-oriented reference signals are reused for sensing. It is configured as static or semi-static, with time-domain periodicity and density. or adapting the effective observation window according to scenario-dependent Doppler requirements It does not provide a mechanism for this. Resource allocation and signal processing techniques delay- While it allows for the acquisition of Doppler data, the underlying reference signal is 20 This does not allow for dynamic control of its structure. From a waveform theory perspective... When viewed in this context, uncertainty function analysis is related to Doppler robustness and estimation accuracy. This reveals a fundamental trade-off between them: Linear Frequency Modulation. (LFM) type structures exhibit Doppler behavior due to their ridge behavior in the delay-Doppler plane. It offers strong resilience under the mismatch, whereas hyperbolic curvature Fisher information 25 This increases and reduces the Cramér–Rao lower bound (CRLB), resulting in a combined yield of lower variance. This enables delay-Doppler estimation. Current systems allow for this controllable... It does not use trade-offs within standardized signaling frameworks. Prior to this invention, sensing capabilities in cellular systems were primarily limited to an initial 30 Communication-focused reference designed for synchronization, channel estimation, and positioning. This is achieved through the reuse of signals. In 5G-based ISAC frames, Positioning Reference Signals (PRS), Demodulation Reference Signals (DMRS), and Channel Stateful Reference Signals (CSI-RS), channel pulse response (CIR) reconstruction and two 3 To obtain delay and Doppler information through three-dimensional time-frequency processing. These approaches are used [1], [2]. These approaches are new standardized communication reference signals. It can support range and speed estimation without introducing waveform structures. It shows. CIR-based positioning algorithms using downlink pilots perform geometric processing. and to improve range estimation accuracy through multi-base station coordination It is also recommended [3]. In addition, energy accumulation across multiple PRS transmissions, coherent Improving weak target detection and reducing estimation variance by extending the processing interval. It is used to reduce [4]. Discussions on pilot-based ISAC signaling 10 It also highlights the deterministic-random trade-off, the perception of sparse pilot allocation. limiting resolution, while increasing pilot density improves communication efficiency. It is stated that it lowers [5]. Although these methods improve perception performance within existing communication structures, 15 constant reference signal periodicity and predefined frame configurations It depends on the Doppler resolution and the maximum unambiguous Doppler, static repetition. These are limited to certain intervals; improvements mainly involve extending the observation period or This is achieved by increasing resource allocation. The periodicity of the reference signal or Doppler robustness or Doppler accuracy depending on the scenario and density is 20 any mechanism for dynamically adapting to its requirements It is not provided. Consequently, current designs simultaneously offer a non-ambiguous combined delay–Doppler. It is unable to provide estimation and scenario-aware Doppler optimization, which is the case for 25 either the detection accuracy deteriorates under high mobility conditions or it is low. This leads to unnecessary signaling load in mobility scenarios. Consequently, Doppler control at the waveform level with communication-compatible signaling structures. There is a need for an integrated, sensing-focused reference signal design framework. The present invention improves Doppler robustness and Doppler accuracy by 30 in next-generation ISAC systems. dynamically adjusting waveform parameters to achieve a balanced trade-off between them adaptive Hyperbolic Frequency Modulation (HFM) reference signal that regulates It addresses this need by introducing its mechanism. 4 To address the inherent Doppler limitations of traditional OFDM signaling, an alternative approach was developed. Delay–Doppler domain approaches are proposed. Especially for high mobility. Enhanced in their environments by performing delay-Doppler field detection. OTFS-based ISAC to enable combined range-speed estimation with robustness. frameworks are presented [6]. These techniques significantly improve Doppler resolution and robustness 5 This increases it considerably, but typically requires dedicated resource allocation and additional It introduces a signaling load. The waveform configuration is predetermined. It remains, and is not dynamically adapted to heterogeneous sensing targets. In parallel with communication-focused developments, radar-focused techniques include waveform design and 10 Addressing combined delay–Doppler estimation through Doppler labeling mechanisms. It obtains high accuracy using uniquely identifiable Doppler labels. Range estimation is shown in radar-based systems [7], [8] and multi-target range- Doppler estimation is studied in FMCW radar frames [9]. Hyperbolic chirp uncertainty function analysis and waveform optimization, including studies on wave 15 He also investigates the relationship between the form structure and the Doppler tolerance

[10] . Low additional load Comb-type sensing reference signal configurations provide communication efficiency while maintaining it. It is also recommended to reduce uncertainty

[11] . These radar-focused and delay-Doppler waveform studies investigate uncertainty behavior and estimation. 20 Although it provides important insights into its limits, Doppler robustness and estimation This also reveals a fundamental trade-off between accuracy and performance. Under narrow band conditions, LFM type waveforms are essentially a shift in Doppler along the uncertainty ridge. It exhibits strong Doppler tolerance, resulting in a stable correlation peak. It provides protection and enables reliable detection even under large frequency shifts. This includes 25 In contrast, hyperbolic chirp structures provide improved latency-Doppler conditioning and lower CRLB provides the estimated variance around the true delay-Doppler parameters. This results in a reduction

[10] . However, these properties are generally static. It is analyzed in configured radar systems, standardized communication reference. The signal structures are not integrated into the system. As a result, current approaches apply to scenario 30 waveform behavior according to the required Doppler uncertainty and estimation accuracy. It does not provide a unified adaptive mechanism for regulation. In summary, current solutions either reuse reference signals focused on fixed communication, either extends the coherent observation period to improve estimation accuracy, or It offers alternative delay-Doppler signaling schemes or radar-focused waveforms. It implements optimization. None of these approaches are suitable for heterogeneous sensing scenarios. Dynamically control Doppler uncertainty, Doppler resolution, and estimation accuracy. 5 Current systems do not provide a unified adaptive reference signal frame. High sensitivity combined with Doppler robustness for reliable detection at unknown speeds. A scenario-aware approach to Doppler accuracy for delay-Doppler estimation. This does not make adaptation possible. This unresolved limitation is addressed by the present invention. This creates a technical gap. 10 In conclusion, all the problems mentioned above necessitate an innovation in the relevant technical field. It makes it necessary. Brief Description and Purpose of the Invention 15 The primary objective of the present invention is to enable the wireless detection of a target in a communication system. adaptively modulating a parameter of a hyperbolic frequency-modulated reference signal. The aim is to provide a method that enables Doppler-aware sensing by controlling it. Specifically, the invention addresses a Doppler requirement related to the target hyperbolic frequency of 20. Doppler robustness by selecting the final baseband frequency of the modulated waveform. It aims to regulate the trade-off between accuracy and Doppler estimation. Another objective of the invention is to adapt the final baseband frequency of a base station to the Doppler requirement. depending on the transmitted waveform, it has increased robustness against Doppler uncertainty. 25 Improved delay-Doppler for displaying or accurately estimating target parameters. The goal is to enable him to choose in a way that will allow him to make the distinction. Another objective of the invention is to set the base station's final baseband frequency to a predetermined one. It selects based on the threshold value, thus operating in Doppler robust mode, Doppler accuracy mode, or 30. by gradually adapting the final baseband frequency throughout successive transmissions a scenario-dependent detection method that makes it possible to work in a combined mode to provide. 6 Another aim of the invention is target presence detection and coarse delay under Doppler uncertainty. with detection-based sensing, including prediction, and improved sensitivity. Predictive sensing, including positioning and velocity estimation, in a unified waveform. The aim is to support it within its formal framework. Another objective of the invention is to transmit signals without altering signal duration or bandwidth and in an orthogonal manner. Adaptive while maintaining compatibility with frequency division multiplex-based communication systems. The goal is to obtain Doppler behavior. Another aim of the invention is to meet different sensing requirements with a single waveform at the base station. by adjusting the parameter, without increasing the signal load or system complexity. an efficient and scalable sensing system suitable for heterogeneous mobility conditions that can be met. The goal is to provide a solution. Description of the Forms of the Invention 15 The necessary figures and relevant explanations are provided below to facilitate a better understanding of the subject matter of the invention. is provided. Figure 1. Schematic representation of the system showing different requirements in the sensing process. 20 is provided. Detailed Description of the Invention The invention is a Doppler 25 based on adaptive control of HFM reference signal parameters. It is related to a method and a system that is a framework of conscious perception. An integrated sensing and communication system is being considered, where a base station and a wireless The downlink transmits a reference signal over the channel; the transmitted signal has range and speed. It is used for detecting a target, including estimation. The transmitted waveform is 30 It propagates across a multipath wireless medium, and the received signal follows different propagation paths. It includes corresponding delayed and Doppler-shifted copies. Detection channel Delay is modeled as a Doppler multipath channel. Dominant K propagation paths. Under this assumption, the received baseband signal can be expressed as follows: 7 𝑟(𝑡) = ∑ 𝛼𝑘𝑠(𝑡 − 𝜏𝑘)𝑒 𝑗2𝜋𝜈𝑘𝑡 + 𝑤(𝑡) 𝐾 k=1 Here, 𝜏𝑘 and 𝜈𝑘 represent the delay and Doppler shift associated with the k-th propagation path, respectively. This shows that 𝑎𝑘 represents complex path gain including path loss and scattering effects. 5 and 𝑤(𝑡) represents the additive noise. The delay parameter is the propagation distance. While related to the carrier frequency, the Doppler shift is determined by the relative motion and carrier frequency. From this channel model, the sensing performance depends on the varying mobility of the transmitted waveform. The ability to distinguish and estimate delay-Doppler parameters under these conditions is 10. It appears that this has been determined. In cases where Doppler shifts are large or unclear, Despite waveform frequency shifts, it retains stable correlation properties. This... In contrast, waveform estimation is used in situations where accurate parameter extraction is required. It provides strong delay-Doppler separation to minimize bias and variance. Accordingly, different sensing applications have heterogeneous Doppler requirements. 15 It imposes search mode operation or under unknown or uncompensated Doppler. Detection-oriented tasks, such as target presence detection, prioritize Doppler robustness. Estimation methods such as combined positioning and tracking, fine velocity estimation, and micro-Doppler analysis. Focused tasks prioritize Doppler estimation accuracy. A single fixed reference point The waveform cannot optimally meet both requirements simultaneously. 20 To address this, the base station is to be used as the downlink reference signal. It produces an adaptive hyperbolic frequency modulated waveform with a duration of T. The continuous-time analytical representation of the waveform is given below. ?̂?(𝑡) = 1 √T exp (𝑗2𝜋 a 𝑘 ln (1 + 𝑘𝑡)) Rect ( 𝑡 T ) 𝑒𝑗2𝜋𝑓0𝑡 , along with the instantaneous frequency f(t) = 𝑎𝑘 1 + 𝑘𝑡 + f0. 30 8 f1 and f2 represent the starting and ending baseband frequencies, respectively. Constant signal duration. For bandwidth T and B = f1 − f2, the parameters satisfy the following condition: f1 = 𝑎𝑘, 𝑘 = f1 − f2 𝑇𝑓2 . The final baseband frequency f2 directly controls the curvature of the hyperbolic modulation. When f2 takes relatively large values, the time-frequency trajectory exhibits linear behavior. is approaching and the waveform is a linear frequency modulated waveform. This is similar to the case for scenarios with large or subtle Doppler shifts. It provides suitable, improved Doppler robustness. 10 when f2 takes relatively small values. However, the curvature increases, making it suitable for fine tracking and positioning. Improved delay-Doppler separation and increased Doppler estimation accuracy are achieved. is being done. Accordingly, the base station will have a Doppler requirement associated with a target. 15 It is configured in this way. The Doppler requirement ensures the Doppler robustness of the detection. whether to prioritize Doppler estimation accuracy or both This is demonstrated. Depending on this Doppler requirement, the base station has Doppler robustness. The final baseband is used to regulate the trade-off between Doppler estimation accuracy and other factors. It chooses frequency f2. 20 In the present invention, a predetermined threshold value is used to distinguish between operating regimes. It is defined. When the Doppler requirement demonstrates Doppler robustness, the base station the final baseband frequency f2 will be greater than a predetermined threshold value It selects. When the Doppler requirement indicates the accuracy of Doppler estimation, the base station 25 the final baseband frequency f2 will be less than a predetermined threshold value It chooses this because both Doppler robustness and Doppler estimation accuracy are required. In such cases, the base station initially sets f2 greater than a predetermined threshold value. It selects the value of f2 in such a way that it is pre-selected throughout successive transmissions. It reduces the initial detection phase until it falls below a defined threshold, thus reducing it to 30. This subsequently enables an improved estimation phase. 9 For practical applications, the HFM waveform is discretized and orthogonally frequency-divided. The multiplexing is embedded within the transmission frame. The sampled HFM sequence is in hyperbolic phase. It preserves its evolution and includes inverse fast Fourier transform processing and cyclic prefix addition. It is integrated into the OFDM modulation chain via this method. The base station is OFDM compatible. HFM transmits the reference signal over a delay-Doppler multipath wireless channel. 5 Referring to Figure 1; initially, the base station f2 parameter is determined based on the Doppler requirement. It configures the Doppler ultrasound corresponding to detection under large or unknown Doppler ultrasound. In a robust scenario, a value of f2 greater than the predetermined threshold is selected. Doppler accuracy corresponding to positioning, tracking, or micro-Doppler analysis is 10. In this scenario, a f2 value smaller than the predetermined threshold value is selected. Hybrid In one scenario, the base station initially selects a f2 value greater than the threshold value, and It then reduces this value across successive frames. During the transmission process, the configured HFM waveform is transmitted. The waveform is 15 miles from the target. It is reflected and reaches the receiver. After the waveform is received by the receiver, the receiver experiences a delay. and delay by applying correlation or coupled filters on Doppler hypotheses. It performs Doppler processing. When f2 is greater than a predetermined threshold value, receiver target detection, coarse delay estimation, and estimation of a wide Doppler uncertainty range. It performs this. When f2 is less than the predetermined threshold value, the receiver optionally activates 20 a narrowed search area limited by previously obtained rough estimates It performs fine combined delay-Doppler estimation. In the hybrid scenario, coarse The estimation results are used to narrow down the fine-tuning phase, so that While computational complexity is reduced, prediction accuracy is increased. For continuous sensing, Doppler uncertainty can be estimated from previous predictions. and the f2 parameter can be adjusted accordingly throughout successive transmissions, so Doppler with Doppler robust operation without changing signal duration or bandwidth. Dynamic switching between accuracy-based operations is made possible. SOURCES [1]. Z. Wei et al., “5G PRS-Based Sensing: A Sensing Reference Signal Approach for Joint Sensing and Communication System," in IEEE Transactions on Vehicular Technology, cilt. 72, no. 3, s. 3250-3263, Mart 2023. 5 [2]. M. Wypich vd., "5G-Based Passive Radar Utilizing Channel Response Estimated via Reference Signals," in IEEE Transactions on Radar Systems, cilt. 3, s. 511-519, 2025. [3]. X. Gao vd., "Channel Impulse Response-Based Sensing Algorithm for Localization Using Downlink Pilots in 5G NR: Theory and Applications," in IEEE Transactions on Cognitive Communications and Networking, cilt. 11, no. 5, s. 3000-3015, Ekim 2025. 10 [4]. X. Wang vd., "Energy Accumulation in 5G PRS-Based Weak Target Sensing," in IEEE Wireless Communications Letters, cilt. 14, no. 9, s. 2688-2692, Eylül 2025. [5]. Y. Li vd., "Rethinking Signaling Design for ISAC: From Pilot-Based to Payload-Based Sensing," in IEEE Communications Standards Magazine, 2025. [6]. J. Wang vd., "Range-Velocity Estimation Assisted by Delay-Doppler Domain for B5G / 6G 15 ISAC," in IEEE Internet of Things Journal, cilt. 12, no. 14, s. 27618-27627, 15 Temmuz 2025. [7]. T. Antes vd., "Identification and High-Accuracy Range Estimation With Doppler Tags in Radar Applications," in IEEE Transactions on Radar Systems, cilt. 3, s. 260-271, 2025. [8]. T. Antes vd., "Radar-Based 3D Spatial Estimation using Uniquely Identifiable Doppler Tags," in IEEE Transactions on Radar Systemsm, 2026. 20 [9]. C. Rai vd., "Multi-Target Range, Doppler and Angle Estimation in MIMO-FMCW Radar With Limited Measurements," in IEEE Transactions on Signal Processing, cilt. 73, s. 3762- 3778, 2025.

[10] . A. Balleri vd., “Ambiguity Function and Accuracy of the Hyperbolic Chirp: Comparison with the Linear Chirp” in IET radar, sonar & navigation, cilt. 11, s.142-153, 2017. 25

[11] . W. Liu vd., "Low-Overhead Sensing RS Design for Integrated Sensing and Communication (ISAC)," 2025 IEEE Wireless Communications and Networking Conference (WCNC), Milano, İtalya, 2025, s. 1-6.

Claims

11 REQUESTS 1. A method for wirelessly detecting a target in a communication system. It is characterized by the following: • hyperbolic frequency modulated waveform by the base station 5 The generation here involves a hyperbolic frequency modulated waveform as the starting base. It includes baseband frequency f1 and the final baseband frequency f2, • Orthogonal frequency-division multiplexing (OFDM) waveform of the HFM reference signal it needs to be configured for transmission and the embedded signal can be transmitted over the wireless channel. transmission, 10 • receiving the reflections of the signal transmitted from the target at the receiver and • Delay-Doppler processing for estimating target parameters to be carried out, Here; base station, target Doppler robustness and / or Doppler estimation accuracy 15 It has a Doppler requirement associated with the need and Doppler robustness. To regulate the balance between Doppler accuracy, Doppler It selects the final baseband frequency f2 according to its requirements, and The base station's final baseband frequency is determined based on the Doppler requirement as follows: It selects as follows: 20 Doppler reliability requirement by Doppler requirement When shown, the last baseband frequency f2 is above the predetermined threshold value. to be chosen in such a way that it will be large or the Doppler requirement by the Doppler estimation accuracy requirement When shown, the last baseband frequency f2 is 25 degrees above the predetermined threshold value. to be chosen in a small way or both the Doppler requirement and the Doppler estimation accuracy requirement and the final baseband when Doppler stability requirements are demonstrated. frequency f2 will be greater than a predetermined threshold value and 30 until f2 is less than the predetermined threshold value. reduction. 12 2. The final baseband frequency f2 will be greater than a predetermined threshold value. the way it was selected and the Doppler requirement is related to the detection of the target's presence Method according to claim 1.

3. The final baseband frequency f2 shall be less than the predetermined threshold value of 5 the choice and Doppler requirement are related to the target's positioning and / or velocity. that is, the method according to Claim 1.

4. The final baseband frequency f2 shall be greater than the predetermined threshold value. 10 where selected and 𝑓2 is reduced until it is less than a predetermined threshold value and the Doppler requirement is related to tracking a moving target, according to Claim 1. method.

5. Hyperbolic frequency modulated waveform IFFT processing and cyclic prefixing It was incorporated into the OFDM modulation chain by way of addition, according to Claim 15 method.

6. The final baseband frequency f2 shall be greater than the predetermined threshold value. selected and target detection, coarse delay estimation and wide Doppler uncertainty range The method applied according to Claim 1. 20 7. The final baseband frequency f2 shall be greater than the predetermined threshold value. where selected and reduced until f2 is less than a predetermined threshold value, target detection, coarse delay estimation, and wide Doppler uncertainty range are applied, and Fine combined estimation, constrained by coarse delay and Doppler limits, is applied, 25 Method according to claim 1.

8. The final baseband frequency f2 shall be less than a predetermined threshold value. The method selected and applied using combined estimation, according to Claim 1.

9. To perform the steps of the method according to any of claims 1 through 8. A data processing device containing a configured processor. 13 10. When executed by a data processing device, the data processing device must comply with Claim 1 to Instructions that enable the method to perform its steps according to any of the 8. a computer program containing.

11. According to claim 10, the computer on which the product of the computer program is stored is 5. a data carrier that can be read by the robot.

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