Signal processing for OFDM radar systems

Abstract

In embodiments of signal processing for an OFDM radar system, an OFDM transceiver of an ISAC system operates in a full duplex mode during a downlink communication phase. The ISAC system generates a sensing symbol for an OFDM radar system by combining an OFDM communication symbol and a repetition of the OFDM communication symbol into the sensing symbol. The OFDM transceiver attenuates subcarriers of a received sense symbol for processing by the OFDM radar system to increase a signal to noise ratio of the received sense symbol.

Description

Technical Field

[0001] The invention relates to a signal processing method for an OFDM radar system. Background Art

[0002] The ISAC system utilizes wireless communication systems and sensor systems to facilitate both communication and radar sensing, so that information collected from the radar sensing system can be effectively transmitted to other devices or systems via the communication system. When implementing ISAC, there are usually at least some tradeoffs between sensing applications and communication applications. For example, radar sensing using sensing symbols is an additional overhead of the communication system. In another example of a tradeoff, a technique for reducing such overhead of the communication system can introduce a low target signal-to-noise ratio for target estimation in the sensing system. Summary of the invention

[0003] The present disclosure may be better understood in view of the following examples considered individually or in various combinations.

[0004] Example 1: A method, comprising: operating an orthogonal frequency division multiplexing (OFDM) transceiver in full-duplex mode during a downlink communication phase by an ISAC system; generating, by the ISAC system, a sensing symbol for an OFDM radar system by combining a communication symbol and a repetition of the communication symbol into a sensing symbol.

[0005] Example 2: The method according to Example 1 further includes: attenuating subcarriers of the received sensing symbols by the OFDM transceiver in the full-duplex mode for processing by the OFDM radar system to increase the signal-to-noise ratio of the received sensing symbols.

[0006] Example 3: The method of Example 1, wherein attenuating the subcarrier removes the subcarrier from the received sensing symbol.

[0007] Example 4: The method of Example 1, wherein the subcarrier is attenuated at one or both of a transmitter and a receiver of the OFDM transceiver.

[0008] Example 5: The method of Example 1, wherein the subcarriers are attenuated and complex conjugate multiplication (CCM) is used to obtain channel information.

[0009] Example 6: The method of Example 5, wherein the subcarrier is attenuated based on having an amplitude greater than a high amplitude threshold.

[0010] Example 7: The method of Example 1, wherein the subcarriers are attenuated and spectral division (SD) is used to obtain channel information.

[0011] Example 8: The method of Example 7, wherein the subcarrier is attenuated based on having an amplitude less than a low amplitude threshold.

[0012] Example 9: The method of Example 1, further comprising: processing the received sensed symbols based on minimum mean square error (MMSE) estimation.

[0013] Example 10: An ISAC system comprising: an OFDM radar system configured to process a sensing symbol generated by combining a communication symbol and a repetition of the communication symbol into the sensing symbol; and an OFDM transceiver configured to operate in a full-duplex mode in a downlink communication phase.

[0014] Example 11: The ISAC system of Example 10, wherein the OFDM transceiver is further configured to: attenuate subcarriers of received sensing symbols for processing by the OFDM radar system to increase a signal-to-noise ratio of the received sensing symbols.

[0015] Example 12: The ISAC system of Example 10, wherein the subcarrier is attenuated at one or both of a transmitter and a receiver of the OFDM transceiver.

[0016] Example 13: The ISAC system of Example 10, wherein the subcarrier is attenuated using CCM based on having an amplitude greater than a high amplitude threshold.

[0017] Example 14: The ISAC system of Example 10, wherein the subcarrier uses SD attenuation based on having an amplitude less than a low amplitude threshold.

[0018] Example 15: The ISAC system of Example 10, wherein attenuating the subcarrier removes the subcarrier from the received sensing symbol.

[0019] Example 16: The ISAC system of Example 10, wherein the OFDM radar is configured to process the received sensing symbols based on MMSE estimation.

[0020] Example 17: A non-transitory computer-readable medium storing a set of executable instructions for manipulating at least one processor to: operate an OFDM transceiver of an ISAC system in full-duplex mode during a downlink communication phase; generate sensing symbols for an OFDM radar system of the ISAC system by combining communication symbols and repetitions of the communication symbols into the sensing symbols; and attenuate subcarriers of received sensing symbols for processing by the OFDM radar system to increase the signal-to-noise ratio of the received sensing symbols.

[0021] Example 18 The non-transitory computer-readable medium of Example 17, wherein the subcarrier is attenuated using CCM based on having an amplitude greater than a high amplitude threshold.

[0022] Example 19 The non-transitory computer-readable medium of Example 17, wherein the subcarrier uses SD attenuation based on having an amplitude less than a low amplitude threshold.

[0023] Example 20 The non-transitory computer-readable medium of Example 17, wherein the set of executable instructions is configured to additionally manipulate the at least one processor to: process the received sensed symbols based on MMSE estimation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] By referring to the accompanying drawings, the present disclosure may be better understood and its numerous features and advantages made apparent to those skilled in the art. The use of the same reference symbols in different drawings indicates similar or identical items.

[0025] Figure 1 is a diagram illustrating an ISAC or Joint Communications and Sensing (JCAS) system utilizing OFDM signaling for both communications and radar sensing in accordance with some embodiments.

[0026] Figure 2 is a diagram illustrating an OFDM transceiver of an ISAC system according to some embodiments.

[0027] Figure 3 is a diagram illustrating the combination of OFDM communication symbols and repetitions of OFDM communication symbols into sensing symbols according to some embodiments.

[0028] Figure 4 is a diagram illustrating attenuated subcarriers for processing by an OFDM radar system to improve signal-to-noise ratio for target estimation in accordance with some embodiments.

[0029] Figure 5 is a flow chart of a method of repeating communication OFDM symbols to compose sensing symbols and removing data information from received sensing symbols according to some embodiments.

[0030] Figure 6 is a graph illustrating average target signal-to-noise ratio after applying signal processing for an OFDM radar system according to some embodiments.

[0031] Figure 7 is a diagram illustrating an example hardware implementation of an ISAC system in accordance with some embodiments. DETAILED DESCRIPTION

[0032] The ISAC system can facilitate both communications and radar sensing so that information collected from radar sensing can be efficiently communicated to other devices or systems. For example, an ISAC system including a base station that utilizes range and Doppler measurements as part of a radar sensing system estimates the distance and velocity of objects (e.g., pedestrians) in the local environment, and the ISAC system then communicates the estimated distance and velocity to an autonomous vehicle via a communication system. In this example, the autonomous vehicle receives and processes the communicated information to improve adaptive cruise control, collision warning functionality, etc.

[0033] The ISAC system includes a transmission device that generates and transmits an OFDM signal representing a sequence of OFDM symbols, which in turn represents a set of communication data. The OFDM signal (bit stream) representing the communication data is divided into multiple streams, and multiple orthogonal subcarriers with overlapping spectra are also transmitted, wherein each carrier is modulated with a symbol from an incoming stream, so that multiple symbols are transmitted in parallel. The OFDM signal is received at a receiving device, which processes the OFDM signal to extract the set of communication data represented by the OFDM signal. The OFDM signal is also scattered by at least one object in the local environment of the transmission device. Therefore, the receiving device can also receive the scattered OFDM signal and extract the OFDM symbol represented in the scattered OFDM signal. By comparing the difference between the originally transmitted OFDM symbol and the received OFDM symbol, the transmission device can estimate the distance and speed of the object.

[0034] When implementing an ISAC system, there are typically some tradeoffs between sensing applications and communication applications. In one example of these tradeoffs, symbols reserved for radar sensing are also unavailable for communication, so fewer symbols (and by extension, data) are available for communication. In another example of a tradeoff, a technique for reducing this overhead in a communication system can introduce a low target signal-to-noise ratio for target estimation in a sensing system.

[0035] To overcome the limitations of conventional ISAC systems, in some embodiments, repetition of communication symbols is used as sensing symbols, thereby freeing up more symbols for use as communication symbols. In some embodiments, specific subcarriers are attenuated at the transmitter and / or receiver of the OFDM transceiver of the ISAC system. In an example, specific subcarriers are attenuated by setting them to zero or by designing subcarrier symbols so that the subcarrier symbols do not exhibit relatively small and / or relatively large energy values. In this example, the first technique for CCM or SD is applied.

[0036] In the case of CCM, subcarriers with relatively high amplitude are set to zero to avoid amplification of noise terms and distortion of channel estimation. The CCM case is called optimized CCM (OCCM). In the case of SD, subcarriers with relatively low energy and / or relatively high energy are set to zero to avoid amplification of noise terms. The SD case is called optimized SD (OSD).

[0037] A second technique utilizing an MMSE approach is combined with the first technique to produce an optimized MMSE (OMMSE). According to some embodiments of the second technique, if the noise power is high, the estimate tends toward CCM, and if the noise power is low, the estimate tends toward SD. Evaluations of OSD, OCCM, and OMMSE exhibit similar performance to conventional techniques, and removing subcarriers to be processed can result in an overall reduction in complexity.

[0038] Figure 1 An example ISAC or JCAS system 100 (referred to herein as ISAC system 100) is shown that utilizes integrated or parallel radar sensing and communication with repetition of communication symbols as sensing symbols and attenuation of subcarriers in accordance with some embodiments. ISAC system 100 includes an ISAC device 102 that employs OFDM signaling to transmit data to at least a second device 104 while also performing radar sensing of objects, such as object 106, in a local environment of the ISAC device 102. For illustration, ISAC system 100 may be a cellular system, wherein ISAC device 102 is a base station and device 104 is a user equipment (UE), wherein the base station utilizes OFDM signaling to transmit data to the UE in accordance with, for example, a fourth generation long term evolution (4G LTE) cellular protocol or a third generation partnership protocol (3GPP), fifth generation new radio (5G NR) protocol, while also attempting to sense the distance and velocity of objects in the local environment using the same OFDM signaling. Alternatively, ISAC device 102 may be a UE and device 104 may be a base station. As yet another example, ISAC system 100 may be a wireless local area network (WLAN) system that uses OFDM-based IEEE 802.11 wireless transmissions to communicate data with device 104 in the form of a UE while also using the same OFDM signaling to sense objects in the local environment.

[0039] In operation, ISAC device 102 converts a set of data for transmission to device 104 into a sequence of one or more OFDM symbols, which are then converted into an analog signal, which is modulated with a carrier frequency signal to generate a radio frequency (RF) signal 108, which is transmitted by ISAC device 102 and propagates through the local environment. Device 104 receives the transmitted RF signal 108 and processes the RF signal 108 to extract a data set for further processing. In addition, the transmitted RF signal 108 is scattered by objects in the local environment, such as object 106 (e.g., a vehicle). The resulting scattered RF signal 110 propagates to ISAC device 102, whereupon ISAC device 102 processes the scattered RF signal 110 to determine either or both of the distance (distance) or velocity (as distance / Doppler data 112) of object 106 relative to ISAC device 102 using the techniques described herein. The distance / Doppler data 112 may then be used by the ISAC device 102 to modify one or more of its operations. For example, the distance / Doppler data 112 may inform the ISAC device 102 of the relative position of an interfering object, in response to which the ISAC device 102 may modify one or more of its transmission parameters, such as transmission power, beam direction, etc., to compensate for the interfering object. As another example, the ISAC device 102 may be a vehicle implementing some form of autonomous driving, and the relative distance and speed of the objects identified in the distance / Doppler data 112 may inform one or more driving operations of the vehicle. Furthermore, the ISAC device 102 may transmit the distance / Doppler data 112 to other devices for their own use.

[0040] Figure 2 An example OFDM transceiver 200 of an ISAC system is shown in accordance with some embodiments. The ISAC system is capable of implementing or facilitating wireless communications and sensing applications including radar sensing, and the OFDM transceiver 200 includes an OFDM transmitter path 202 ("transmitter 102") and an OFDM receiver path 204 ("receiver 204"). In accordance with some embodiments, the ISAC system operates the OFDM transceiver 200 in full-duplex mode during a downlink communication phase. In other words, OFDM transmits and receives data simultaneously during a downlink communication phase.

[0041] The transmitter 202 is shown to include symbols S, such as sensed symbols represented in a first domain (e.g., frequency domain). An inverse fast Fourier transform (IFFT) component 206 of the transmitter 202 represents symbols x, such as sensed symbols in a second domain (e.g., time domain). According to some embodiments, the transmitter 202 also includes a cyclic prefix (CP) insertion component 208 and an RF front end 210.

[0042] Receiver 204 is shown as including received subcarrier y. In an example, received subcarrier y may be described as:

[0043] y=h·s+n

[0044] where h represents the frequency channel response (eg, carrying range-Doppler information) and n represents the noise in the frequency domain.

[0045] Receiver 204 also includes a fast Fourier transform (FFT) component 212, a CP removal component 214, and an RF front end 216. RF front ends 210 and 216 are typically implemented using well-known RF hardware such as digital-to-analog converters (DACs), signal generators, modulators / mixers, low pass filters (LPFs), antenna arrays, etc. Components 206, 208, 212, and 214 can each be implemented as hard-coded logic, one or more processors executing software, programmable logic, or a combination thereof.

[0046] Figure 3 An example 300 of combining an OFDM communication symbol with a repetition of an OFDM communication symbol as a sensing symbol is shown in accordance with some embodiments. Example 300 is shown to include an OFDM communication symbol 302 having a length C 304+N306, where N is the FFT size and C is the CP size. According to some embodiments, C≤N and typically C<<N. In order to estimate up to a maximum unambiguous distance for OFDM radar sensing (e.g., a total of 2N samples 308), a signal with N samples may be used, and then the same signal with N samples may be used. In the case where the sensing symbol is not a communication symbol, two OFDM symbols 310 may be reserved in order to reserve 2N samples 308 referred to as a standard sensing symbol.

[0047] If the previous OFDM communication symbol 302 is repeated to include 2N+2C samples (e.g., two OFDM symbols 310), 2N samples 308 (e.g., 2N consecutive samples) may be extracted, where the first N samples are a repetition of the next N samples. In this case, these 2N consecutive samples may be used as sensing symbols, leaving only one OFDM communication symbol 302 for sensing (which is a repetition of the OFDM communication symbol 302).

[0048] Returning to the example, the received subcarrier y can be described as:

[0049] y=h·s+n

[0050] According to some embodiments, two example techniques for extracting channel information h are described. In the first example technique, the CCM of N samples of the sensing subcarrier transmitted by y in the frequency domain can be expressed as:

[0051]

[0052] The amplitude variation of the transmitted subcarrier s affects the channel estimation and noise n, which is suboptimal in situations with high signal-to-noise ratio.

[0053] In a second example technique, SD is used to divide the received subcarrier y by the transmitted subcarrier s in the frequency domain, which can be described as:

[0054]

[0055] The relatively small amplitude of s may increase the noise n, which is suboptimal in situations with low signal-to-noise ratio.

[0056] Figure 4 An example of an attenuated subcarrier 400 for processing by an OFDM radar system to improve the signal-to-noise ratio for target estimation according to some embodiments is shown. In a first attenuation technique, a particular subcarrier is set to zero (or a small value) at the transmitter 202 and / or at the receiver 204. Alternatively, at the transmitter 202, instead of setting a particular subcarrier to zero, the subcarrier symbol may be designed so that the subcarrier symbol does not exhibit relatively small and / or relatively large energy values. In either alternative, the first attenuation technique applies SD or CCM.

[0057] Examples of attenuated subcarriers 400 include representation 402 of inner transmitter 202 subcarriers set to zero; representation 404 of inner receiver 204 subcarriers set to zero; and representation 406 of outer transmitter 202 subcarriers set to zero. In the case of CCM, subcarriers with relatively high amplitudes (e.g., outer rings) are set to zero to avoid amplification of the noise term s*n. This CCM case is referred to as optimized CCM (OCCM).

[0058] In the case of SD, subcarriers with relatively low energy (e.g., inner loop) are set to zero to avoid noise terms. Examples of low energy symbols set to zero at transmitter 202 and at receiver 204 are shown in representations 402 and 404, respectively. This SD case is referred to as optimized SD (OSD).

[0059] In the second attenuation technique, the MMSE method is combined with the first attenuation technique called OMMSE. It can be described as:

[0060]

[0061] If the noise power is relatively high, then tends to follow CCM and avoids dividing y by a relatively small value s; if the noise power is relatively low, then tends to SD and avoids estimating the amplitude h×|s| 2 , and in the example case where no subcarriers are set to zero when OMMSE is applied, the method reduces to MMSE.

[0062] Figure 5 is a flow chart of a method 500 of repeating communication OFDM symbols to compose sensing symbols and removing data information from received sensing symbols in accordance with some embodiments. Figure 5 The method 500 shows Figure 1 and 2 108. A general overview of the operation of ISAC device 102 is provided below. Upon startup or to initiate the process of transmitting an OFDM frame containing OFDM symbols representing communication data, transmitter 202 transmits an OFDM-based RF signal that serves two purposes: as a carrier wave for the communication data for reception by another device; and as a radar signal for radar sensing. Thus, transmitter 202 receives data input in the form of a sequence of symbols representing communication data (e.g., from an application executing at ISAC device 102), and from this data input generates an RF signal (e.g., RF signal 108, which is transmitted into the local environment based on OFDM principles). Figure 1 ). For radar sensing, the ISAC device 102 reuses a portion of the receiver path along with the use of the radar sensing path to perform radar processing on RF signaling received via the receiver path due to scattering / reflection of RF signaling transmitted in parallel by the transmitter path.

[0063] Starting from the transmission process, at block 502, an input of transmission bits of a data stream is received and encoded into data symbols, and the IFFT component 206 performs IFFT on the data symbols to generate OFDM symbols. The transmitter 202 repeats the OFDM communication symbol at block 502, and at block 504, the transmitter 202 uses the OFDM communication symbol and the repeated OFDM communication symbol as a sensing symbol.

[0064] After the IFFT process, the CP insertion component 208 appends (or pre-sets) a CP to each OFDM symbol at block 506. Typically, the CP is a copy of the end portion of the OFDM symbol so that when the receiver performs OFDM demodulation with an FFT, the receiver receiving the resulting RF signal will be able to integrate over an integer number of sinusoidal cycles for each of the multipaths.

[0065] After CP insertion, the OFDM symbol vector is provided to the RF front end 210 of the transmitter path 202, whereby the OFDM symbol vector is converted into analog signaling by a digital / analog (D / A) converter (not shown), the analog signaling is low-pass filtered by a low-pass filter (not shown), and the resulting filtered analog signaling is then transmitted with a frequency f c The carrier signal is modulated to generate an RF signal 108 which is transmitted into the local environment by the antenna array of the RF front end 210. The RF signal 108 then propagates to one or more receiving devices (e.g., device 104, Figure 1 ), whereby each receiving device processes the RF signal 108 to recover the original N symbols.

[0066] While generating and transmitting the RF signal 108, the receiver 204 operates to generate a radar profile of the local environment using scattering / reflection of the RF signal by objects in the local environment. Thus, at block 508, the receiver path 204 is activated in parallel with the transmission in order to receive a scattered representation of the RF signal 108 for radar sensing purposes. For example, when the RF signal 108 encounters the object 106 ( Figure 1 ), object 106 scatters RF signal 108, causing scattered RF signal 110 to propagate back to ISAC device 102 and be received at RF front end 216 of receiver path 204. RF front end 216 converts scattered RF signal 110 from an analog signal to a digital signal, which is parallelized into N channels, where each channel represents a recovered symbol and a corresponding additional CP.

[0067] At block 510, CP removal component 214 removes the CP and component 212 applies FFT. Also at block 510, some high and / or low amplitude subcarriers are attenuated. For example, in some embodiments, if receiver 204 applies CCM to obtain a channel estimate The receiver 204 then sets the loops having amplitudes above the first threshold to zero (or a small value) to avoid amplification of the noise term s*n. For example, in some embodiments, if the receiver 204 applies SD to obtain the channel estimate The receiver 204 then sets the loops having amplitudes below the second threshold to zero (or a small value) to avoid noise terms. If the receiver 204 applies CCM to obtain the channel estimate The method flow then continues to block 512, which indicates OCCM. If the receiver applies SD to obtain the channel estimate The method then continues to block 514, which indicates OSD. If the receiver applies MMSE to obtain the channel estimate The method flow then continues to block 516, representing OMMSE. In some embodiments, at the transmitter 202 side, the subcarrier symbols are designed such that they do not assume small and / or large energy values.

[0068] After applying one of blocks 512, 514, or 516, the result is an estimate of the transfer function of the propagation path, i.e., an estimate of the transfer function of the local environment with scattering object 106. Thus, the radar sensing path operates to extract a representation of this transfer function for the local environment based on the correlation between the original OFDM symbols and the received OFDM symbols, and from this representation of the transfer function, determine one or both of the range and velocity of a scattering object, such as scattering object 106, within the local environment, as described herein.

[0069] Figure 6 An example graph 600 of average target signal-to-noise ratios after applying signal processing for an OFDM radar system according to some embodiments is shown. Graph 600 includes average target signal-to-noise ratios for a given channel signal-to-noise ratio for SD 602, CCM 604, 606, OSD 608, OCCM 610, and OMMSE 612. As shown in the example graph 600, at low channel signal-to-noise ratios, CCM 604 and OMMSE 612 outperform SD 602. At high channel signal-to-noise ratios, SD 602 ​​converges to OMMSE 612, and both SD 602 ​​and OMMSE 612 outperform CCM 604.

[0070] When OSD 608 is applied by setting constellation points below a first energy threshold to zero (e.g., the first energy threshold is heuristically determined based on specific environmental characteristics and / or specific sensing applications, and can be recalibrated based on changes in environmental characteristics and / or sensing applications), OSD 608 closely follows the performance of OMMSE 612 even at low signal-to-noise ratios. When OCCM 610 is applied by setting constellation points above a second energy threshold to zero (e.g., the second energy threshold is heuristically determined based on specific environmental characteristics and / or specific sensing applications, and can be recalibrated based on changes in environmental characteristics and / or sensing applications), the performance of OCCM 610 closely follows CCM 604. Notably, although the performance of OSD 608, OCCM 610, and OMMSE 612 is similar to the performance shown in other curves included in graph 600, removing subcarriers to be processed can result in an overall reduction in complexity (e.g., reduced complexity).

[0071] Figure 7An example hardware implementation 700 of an ISAC system 702 is shown in accordance with some embodiments. In the depicted example, the ISAC system 702 includes at least one application processor 704 (e.g., a central processing unit (CPU) or other general purpose processor), a system memory 706, one or more RF modems 708, a transmitter (TX) RF front end 714 (e.g., an embodiment of the RF front end 210), and a receiver (RX) RF front end 716 (e.g., an embodiment of the RF front end 216). Although a single RF modem 708 is shown supporting the operations of both RF front ends 714 and 716, in other embodiments, each RF front end may have a separate dedicated RF modem 708. The RF modem 708 includes a baseband processor 710 and a memory 712, which may include, for example, flash memory, non-volatile random access memory (NVRAM) or other non-volatile memory, or static RAM (SRAM) or dynamic RAM (DRAM) or other volatile memory, or a combination thereof. In addition, it should be appreciated that the ISAC system 702 may include a plurality of RF modems 708, which are not shown for ease of illustration. Figure 7 Multiple additional components are omitted, including, for example, a transmitter system (e.g., including an encoder, a modulator, an OFDM generator, etc.), a radar sensing system (e.g., including one or more antennas, a duplexer, a radar transceiver, a radar signal processing component, a radar control component, etc.), a receiver system (e.g., including an OFDM demodulator, a decoder, a radar data processing component, etc.), one or more displays, one or more touch screens, a keypad, a mouse, a touchpad, a microphone, a speaker and other user input / output devices, one or more sensors, a battery or other power supply, a graphics processing unit (GPU) or other coprocessor, etc.

[0072] The application processor 704 executes executable instructions from a software stack that includes an operating system (OS) 718 and one or more user software applications, such as user software application 720, and which may additionally include a protocol stack executed by the baseband processor 710 of the RF modem 708. Operating the application processor 704, the OS 718 manages the general operation of the various hardware components of the ISAC system 702, and also supports the execution of one or more user software applications, wherein the executable instructions representing the OS 718 and the user software applications are typically accessed from the system memory 706 for execution by the application processor 704.

[0073] In addition, the memory 712 of the RF modem 708 stores one or more executable instruction sets that, when executed by the baseband processor 710, manipulate the baseband processor 710 to perform various operations in accordance with one or more communication protocols associated with the air interface provided by the RF front ends 714 and 716. These operations may include various OFDM-related operations performed by executing the OFDM software 722, such as the operations described above with reference to components 206, 208, 212, and 214, and radar sensing operations performed by executing the radar sensing software 724. In other embodiments, one or more operations are performed by the application processor 704 (or a dedicated processor, such as a graphics processing unit or GPU) executing software stored in the system memory 706. For example, OFDM-related operations of the transmitter 202 and the receiver 204 may be performed at one or more RF modems 708.

[0074] It should be noted that not all of the activities or elements described above in the general description are required, a part of a particular activity or device may not be required, and one or more additional activities may be performed or one or more additional elements may be included in addition to those described. Furthermore, the order in which the activities are listed is not necessarily the order in which the activities are performed. In addition, concepts have been described with reference to specific embodiments. However, it will be appreciated by those skilled in the art that various modifications and changes may be made without departing from the scope of the present disclosure as set forth in the following claims. Therefore, the description and drawings should be viewed in an illustrative rather than a restrictive sense, and it is expected that all such modifications are included within the scope of the present disclosure.

[0075] The benefits, other advantages, and solutions to problems are described above with respect to specific embodiments. However, these benefits, advantages, solutions to problems, and any features that may make any benefit, advantage, or solution appear or become more prominent should not be understood as key, required, or essential features of any or all claims. In addition, the specific embodiments disclosed above are merely illustrative, as the disclosed subject matter may be modified and practiced in different but equivalent ways that are obvious to those skilled in the art who benefit from the teachings herein. Except as described in the appended claims, it is not intended to limit the details of the construction or design shown herein. Therefore, it is apparent that the specific embodiments disclosed above may be changed or modified, and all such changes are deemed to be within the scope of the disclosed subject matter. Therefore, the protection sought herein is as set forth in the appended claims.

Claims

1. A method, characterized in that include: An orthogonal frequency division multiplexing (OFDM) transceiver is operated in full-duplex mode during the downlink communication phase by the ISAC system; as well as Sensing symbols for an OFDM radar system are generated by the ISAC system by combining communication symbols and repetitions of the communication symbols.

2. The method according to claim 1, characterized in that Also includes: Subcarriers of received sensing symbols are attenuated by the OFDM transceiver in the full-duplex mode for processing by the OFDM radar system.

3. The method according to claim 2, characterized in that The subcarriers are attenuated and a complex conjugate multiplication (CCM) is applied.

4. An ISAC system, characterized in that: include: An orthogonal frequency division multiplication (OFDM) radar system configured to process sensing symbols, the sensing symbols comprising communication symbols and repetitions of the communication symbols; and An OFDM transceiver, the OFDM transceiver being configured to: It operates in full-duplex mode during the downlink communication phase.

5. The ISAC system according to claim 4, characterized in that: The OFDM transceiver is additionally configured to: Subcarriers of received sensing symbols are attenuated for processing by the OFDM radar system to increase a signal-to-noise ratio of the received sensing symbols.

6. The ISAC system according to claim 5, characterized in that: The subcarriers are attenuated using complex conjugate multiplication (CCM) based on having an amplitude greater than a high amplitude threshold.

7. The ISAC system according to claim 5, characterized in that: The subcarriers are attenuated using spectral division (SD) based on having an amplitude less than a low amplitude threshold.

8. A non-transitory computer-readable medium, characterized in that The non-transitory computer-readable medium stores a set of executable instructions for manipulating at least one processor to: Operating the orthogonal frequency division multiplexing (OFDM) transceiver of the ISAC system in full-duplex mode during the downlink communication phase; generating sensing symbols for an OFDM radar system of the ISAC system by combining communication symbols and repetitions of the communication symbols; as well as Subcarriers of received sensing symbols are attenuated for processing by the OFDM radar system to increase a signal-to-noise ratio of the received sensing symbols.

9. The non-transitory computer-readable medium of claim 8, wherein: The subcarriers are attenuated using complex conjugate multiplication (CCM) based on having an amplitude greater than a high amplitude threshold.

10. The non-transitory computer-readable medium of claim 8, wherein: The subcarriers are attenuated using spectral division (SD) based on having an amplitude less than a low amplitude threshold.

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