Estimation of orthogonal frequency division multiplexing channels using frequency-modulated continuous waveforms.

Abstract

A method, system, and device for wireless communication are described. A first wireless device receives a first frequency-modulated continuous waveform (FMCW) signal from a second wireless device over an orthogonal frequency division multiplexing (OFDM) channel. The first wireless device generates a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The first wireless device combines the first and second FMCW signals, filters the combined FMCW signal, and samples the combined, filtered FMCW signal in the time domain. The first wireless device estimates a frequency-domain OFDM channel based on sampling the combined, filtered FMCW signal. The first and second wireless devices communicate the OFDM signal over the OFDM channel based on the estimate.

Description

[Technical Field]

[0001] The following relates to wireless communications, including estimating orthogonal frequency division multiplexing (OFDM) channels using frequency modulated continuous waveforms (FMCWs). [Background technology]

[0002] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasts, and so on. These systems may allow for communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth-generation (4G) systems, such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth-generation (5G) systems, sometimes referred to as New Radio (NR) systems. These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM), etc. A wireless multiple-access communication system may include one or more base stations that each support wireless communication for communication devices, which may be known as user equipment (UE).

[0003] In some systems, a receiving device, such as a UE, a network entity, or both, may estimate an Orthogonal Frequency Division Multiplexing (OFDM) channel based on one or more received OFDM signals. The receiving device may receive the OFDM signals in analog format, convert the analog OFDM signals to digital format, and transform the digital OFDM signals into frequency-domain signals. The receiving device may perform OFDM channel estimation in the frequency domain based on the frequency-domain signals. Summary of the Invention

[0004] The described techniques relate to improved methods, systems, devices, and apparatuses that support estimating orthogonal frequency division multiplexing (OFDM) channels using frequency modulated continuous waveforms (FMCWs). For example, the described techniques provide for a wireless device receiving an FMCW signal via an OFDM channel and estimating a frequency-domain OFDM channel based on the FMCW signal using time-domain signal processing. To implement the FMCW-based OFDM channel estimation techniques described herein, a first wireless device may receive a first FMCW signal from a second wireless device via the OFDM channel. The first wireless device may generate a second FMCW signal (e.g., a local FMCW signal) at the first wireless device based on one or more FMCW parameters associated with the first FMCW signal. The first wireless device may combine the first FMCW signal and the second FMCW signal in the time domain and filter the combined FMCW signal. The first wireless device may sample the combined, filtered FMCW signal (e.g., using an analog-to-digital converter (ADC)) using a sampling rate based on one or more parameters of the OFDM channel. The first wireless device may estimate a value for each subband of a plurality of subbands across the frequency domain of the OFDM channel based on the sampling. The receiving device may thereby estimate the frequency-domain OFDM channel using time-domain signal processing and a relatively low sampling rate. In some examples, the first wireless device and the second wireless device may exchange one or more capability messages, control messages, or both to facilitate FMCW-based OFDM channel estimation.

[0005] A method for wireless communication in a first wireless device is described. The method may include receiving a first FMCW signal over an OFDM channel, generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, and estimating the OFDM channel based on samples of the combined FMCW signal in a time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

[0006] An apparatus for wireless communication is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive a first FMCW signal over an OFDM channel, generate a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, and estimate an OFDM channel in a time domain based on samples of the combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal.

[0007] Another apparatus for wireless communication in a first wireless device is described, which may include means for receiving a first FMCW signal over an OFDM channel, means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, and means for estimating the OFDM channel in a time domain based on samples of the combined FMCW signal, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

[0008] A non-transitory computer-readable medium storing code for wireless communication in a first wireless device is described, wherein the code may include instructions executable by a processor to receive a first FMCW signal over an OFDM channel, generate a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, and estimate an OFDM channel in a time domain based on samples of the combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal.

[0009] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, estimating the OFDM channel may include operations, features, means, or instructions for filtering the combined FMCW signal and, after filtering, sampling the combined FMCW signal in the time domain using a sampling rate that may be based on a subband frequency range of the OFDM channel, and the estimating includes estimating a respective value of the OFDM channel for each subband of a set of multiple subbands in the frequency domain of the OFDM channel based on the sampling.

[0010] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving one or more OFDM signals time division multiplexed with the first FMCW signal in an OFDM channel.

[0011] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting a capability message indicating that the first wireless device may be capable of estimating an OFDM channel using the time-domain FMCW signal, the first wireless device including user equipment (UE).

[0012] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving a capability message indicating that the second wireless device may be capable of transmitting an FMCW signal for OFDM channel estimation, where the first wireless device includes a network entity.

[0013] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving a control message indicating whether one or more symbols of the OFDM channel may be allocated for FMCW signals, wherein the first FMCW signal may be received within one symbol of the set of one or more symbols that may be indicated as being allocated for FMCW signals, and wherein the first wireless device includes a UE.

[0014] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting a control message indicating whether one or more symbols of the OFDM channel may be allocated for an FMCW signal or an OFDM signal, wherein the first FMCW signal may be received within one symbol of the set of one or more symbols that may be allocated for the FMCW signal based on the control message, and wherein the first wireless device includes a network entity.

[0015] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving a control message indicating a set of FMCW parameters including a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof, where the slope may be based on the bandwidth of the first FMCW signal and a duration of a symbol within which the first FMCW signal may be received.

[0016] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting a control message indicating a set of FMCW parameters including a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof, where the slope may be based on the bandwidth of the first FMCW signal and a duration of a symbol within which the first FMCW signal may be received, and receiving the first FMCW signal may be based on the set of FMCW parameters.

[0017] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for a first wireless device to receive a control message including a trigger for performing OFDM channel estimation using the FMCW signal, where estimating the OFDM channel using the first FMCW signal and the second FMCW signal may be based on the trigger, and the first wireless device includes a UE.

[0018] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for the first wireless device receiving a control message including a trigger for transmitting a channel state information report based on the first FMCW signal, and transmitting a channel state information report including a set of channel state information parameters based on receiving the trigger and estimating the OFDM channel.

[0019] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting a control message including a trigger for the second wireless device to transmit the first FMCW signal.

[0020] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first wireless device includes a UE or a network entity.

[0021] A method for wireless communication in a second wireless device is described that may include generating an FMCW signal for estimation of an OFDM channel by a first wireless device, transmitting the FMCW signal over the OFDM channel, and communicating the OFDM signal with the first wireless device over the OFDM channel based on the estimation of the OFDM channel.

[0022] An apparatus for wireless communication is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to generate an FMCW signal for estimation of an OFDM channel by a first wireless device, transmit the FMCW signal over the OFDM channel, and communicate the OFDM signal with the first wireless device over the OFDM channel based on the estimation of the OFDM channel.

[0023] Another apparatus for wireless communication in a second wireless device is described, which may include means for generating an FMCW signal for estimation of an OFDM channel by a first wireless device, means for transmitting the FMCW signal over the OFDM channel, and means for communicating the OFDM signal with the first wireless device over the OFDM channel based on the estimation of the OFDM channel.

[0024] A non-transitory computer-readable medium storing code for wireless communication at a second wireless device is described, wherein the code may include instructions executable by a processor to generate an FMCW signal for estimation of an OFDM channel by a first wireless device, transmit the FMCW signal over the OFDM channel, and communicate the OFDM signal with the first wireless device over the OFDM channel based on the estimation of the OFDM channel.

[0025] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting one or more OFDM signals time division multiplexed with an FMCW signal within an OFDM channel.

[0026] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting a capability message indicating that a second wireless device may be capable of transmitting an FMCW signal for OFDM channel estimation, where the second wireless device includes a UE.

[0027] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving a capability message indicating that the first wireless device may be capable of estimating an OFDM channel using a time-domain FMCW signal, and the second wireless device includes a network entity.

[0028] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving a control message indicating whether one or more symbols of the OFDM channel may be allocated for an FMCW signal, and the FMCW signal may be transmitted within one symbol of the set of one or more symbols that may be allocated for the FMCW signal based on the control message, and the second wireless device includes a UE.

[0029] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting a control message indicating whether one or more symbols of the OFDM channel may be allocated for an FMCW signal or an OFDM signal, wherein the FMCW signal may be transmitted within one symbol of the one or more symbols that may be allocated for the FMCW signal, and wherein the second wireless device includes a network entity.

[0030] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving a control message indicating a set of FMCW parameters that may be associated with the FMCW signal, including a starting frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, where the slope may be based on the bandwidth of the FMCW signal and a duration of a symbol in which the FMCW signal may be transmitted, and transmitting the FMCW signal may be based on the set of FMCW parameters.

[0031] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for transmitting a control message indicating a set of FMCW parameters that may be associated with the FMCW signal, including a starting frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, where the slope may be based on the bandwidth of the FMCW signal and a duration of a symbol in which the FMCW signal may be transmitted, and where the estimation of the OFDM channel may be based on the set of FMCW parameters.

[0032] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for the first wireless device to transmit a control message including a trigger for performing OFDM channel estimation using the FMCW signal, where the estimation of the OFDM channel may be based on the trigger, and the second wireless device includes a network entity.

[0033] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for the first wireless device to transmit a control message including a trigger for transmitting a channel state information report, which may be based on an FMCW signal, and to receive a channel state information report including a set of channel state information parameters based at least in part on the trigger.

[0034] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for the second wireless device to receive a control message including a trigger for transmitting an FMCW signal, where transmitting the FMCW signal may be based on the trigger.

[0035] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second wireless device includes a UE or a network entity. [Brief explanation of the drawings]

[0036] [Figure 1] 1 illustrates an example of a wireless communication system that supports estimating an Orthogonal Frequency Division Multiplexing (OFDM) channel using Frequency Modulated Continuous Waveforms (FMCWs), in accordance with one or more aspects of the present disclosure. [Figure 2] 1 illustrates an example of an OFDM channel estimation scheme that supports estimating an OFDM channel using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 3]1 illustrates an example of an OFDM channel estimation scheme that supports estimating an OFDM channel using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 4] 1 illustrates an example of a wireless communication system that supports estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 5] 1 illustrates an example process flow that supports estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 6] 1 illustrates an example process flow that supports estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 7] 1 illustrates a block diagram of a device that supports estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 8] 1 illustrates a block diagram of a device that supports estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 9] 1 illustrates a block diagram of a communications manager that supports estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 10] 1 illustrates a diagram of a system including a UE that supports estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 11] 1 illustrates a diagram of a system including network entities that support estimating OFDM channels using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 12] 1 shows a flow diagram illustrating a method for supporting OFDM channel estimation using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 13] 1 shows a flow diagram illustrating a method for supporting OFDM channel estimation using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 14]1 shows a flow diagram illustrating a method for supporting OFDM channel estimation using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 15] 1 shows a flow diagram illustrating a method for supporting OFDM channel estimation using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 16] 1 shows a flow diagram illustrating a method for supporting OFDM channel estimation using FMCW, in accordance with one or more aspects of the present disclosure. [Figure 17] 1 shows a flow diagram illustrating a method for supporting OFDM channel estimation using FMCW, in accordance with one or more aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0037] In some systems, a wireless device may estimate an Orthogonal Frequency Division Multiplexing (OFDM) channel based on one or more received signals to improve the reliability and throughput of transmission and reception by the wireless device. The wireless device may receive an OFDM signal via an OFDM channel in some cases. The wireless device may use an analog-to-digital converter (ADC) to convert the received analog OFDM signal to a digital signal. The received signal may be a time-domain signal. The wireless device may then perform a fast Fourier transform (FFT) on the time-domain digital signal to convert the time-domain digital signal to one or more frequency-domain signals. The wireless device may estimate the OFDM channel in the frequency domain using the frequency-domain signals. In some examples, the sampling rate of the ADC in the wireless device may be relatively high to accurately convert the analog OFDM signal to digital form. Additionally or alternatively, performing an FFT to convert the time-domain signal to the frequency domain is relatively complex.

[0038] The techniques, systems, and devices described herein provide improved OFDM channel estimation using a frequency modulated continuous waveform (FMCW) signal. A transmitting device may transmit a first FMCW signal for channel estimation over an OFDM channel. A receiving device may receive the first FMCW signal and generate a second (e.g., local) FMCW signal using a set of FMCW parameters associated with the first FMCW signal. The receiving device may combine the first FMCW signal and the second FMCW signal and filter the combined signal (e.g., using a low pass filter (LPF) or some other type of filter). The receiving device may estimate a frequency-domain OFDM channel by sampling the combined FMCW signal using a relatively low sampling rate. The sampling rate used by the receiving device may be based on one or more parameters of the OFDM channel, such as the bandwidth or subband frequency size of the OFDM channel.

[0039] In some examples, the transmitting device and the receiving device may exchange signaling to facilitate OFDM channel estimation using FMCW signals. For example, one of the devices (e.g., user equipment (UE)) may transmit a capability message to indicate that the device supports FMCW for channel estimation or supports FMCW transmission. In some examples, one or both of the devices may transmit one or more control messages that allocate symbols in an OFDM channel (e.g., an OFDM resource grid) for FMCW transmission, indicate FMCW parameters, trigger transmission of an FMCW signal, trigger channel estimation using an FMCW signal, or any combination thereof. In some examples, the signaling exchanged between the devices may be based on the type of device. The transmitting device and the receiving device may each be a UE, a network entity, some other type of device, or any combination thereof.

[0040] Accordingly, the described techniques may support estimation of a frequency-domain OFDM channel based on an FMCW signal, which may be referred to in some aspects herein as FMCW-based OFDM channel estimation. The sampling rate applied by a receiving device to estimate a frequency-domain OFDM channel using an FMCW-based OFDM channel estimation technique may be lower than the sampling rate used by the receiving device to estimate a frequency-domain OFDM channel based on an OFDM signal (e.g., channel state information reference signals (CSI-RSs), sounding reference signals (SRSs), demodulation reference signals (DMRSs), or any combination thereof). Additionally or alternatively, the receiving device may estimate the frequency-domain OFDM channel in the time domain using time-domain signal processing based on the FMCW signal (e.g., the receiving device may refrain from performing an FFT), which may reduce complexity and power consumption compared to OFDM-based estimation techniques in which an FFT is applied.

[0041] Aspects of the present disclosure are first described in the context of a wireless communication system. Additional aspects are described with reference to OFDM channel estimation schemes and process flows. Aspects of the present disclosure are further illustrated by and described with reference to apparatus, system, and flow diagrams relating to estimating OFDM channels using FMCW.

[0042] 1 illustrates an example of a wireless communication system 100 that supports estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The wireless communication system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a network operating in accordance with a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, a New Radio (NR) network, or other systems and radio technologies, including future systems and radio technologies not explicitly mentioned herein.

[0043] The network entities 105 may be dispersed throughout a geographic area to form the wireless communication system 100 and may include devices of different forms or with different capabilities. In various examples, the network entities 105 may be referred to as network elements, mobility elements, radio access network (RAN) nodes, or network equipment, among other nomenclature. In some examples, the network entities 105 and the UEs 115 may communicate wirelessly via one or more communication links 125 (e.g., radio frequency (RF) access links). For example, the network entities 105 may support a coverage area 110 (e.g., a geographic coverage area) over which the UEs 115 and the network entities 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which the network entities 105 and the UEs 115 may support communication of signals via one or more radio access technologies (RATs).

[0044] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile or both at different times. The UEs 115 may be devices of different types or with different capabilities. Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be capable of supporting communication with various types of devices, such as other UEs 115 or network entities 105, as shown in FIG. 1.

[0045] As described herein, a node of the wireless communication system 100, which may be referred to as a network node or a wireless node, may be a network entity 105 (e.g., any network entity described herein), a UE 115 (e.g., any UE described herein), a network controller, an apparatus, a device, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, a node may be a UE 115. As another example, a node may be a network entity 105. As another example, a first node may be configured to communicate with a second node or a third node. In one aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a UE 115. In another aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a network entity 105. In still other aspects of this example, the first node, the second node, and the third node may vary relative to these examples. Similarly, references to a UE 115, a network entity 105, an apparatus, a device, a computing system, etc. may include disclosure of the UE 115, the network entity 105, the apparatus, the device, the computing system, etc. as being nodes. For example, a disclosure that a UE 115 is configured to receive information from a network entity 105 also discloses that a first node is configured to receive information from a second node.

[0046] In some examples, the network entities 105 may communicate with the core network 130, with each other, or with both. For example, the network entities 105 may communicate with the core network 130 via one or more backhaul communication links 120 (e.g., according to an S1, N2, N3, or other interface protocol). In some examples, the network entities 105 may communicate with each other either directly (e.g., directly between the network entities 105), or indirectly (e.g., via the core network 130) via the backhaul communication links 120 (e.g., according to an X2, Xn, or other interface protocol). In some examples, the network entities 105 may communicate with each other via midhaul communication links 162 (e.g., according to a midhaul interface protocol) or fronthaul communication links 168 (e.g., according to a fronthaul interface protocol), or any combination thereof. The backhaul communication link 120, the midhaul communication link 162, or the fronthaul communication link 168 may be or include, among other examples or various combinations thereof, one or more wired links (e.g., electrical links, optical fiber links), one or more wireless links (e.g., radio links, wireless optical links). The UE 115 may communicate with the core network 130 via the communication link 155.

[0047] One or more of the network entities 105 described herein may include or may be referred to as a base station 140 (e.g., base transceiver station, radio base station, NR base station, access point, radio transceiver, NodeB, eNodeB (eNB), next-generation NodeB or giga-NodeB (all may be referred to as gNB), 5G NB, next-generation eNB (ng-eNB), Home NodeB, Home eNodeB, or other suitable terminology). In some examples, the network entities 105 (e.g., base stations 140) may be implemented in an aggregated (e.g., monolithic, standalone) base station architecture that may be configured to utilize protocol stacks that are physically or logically integrated within a single network entity 105 (e.g., a single RAN node such as base station 140).

[0048] In some examples, the network entities 105 may be implemented in a disaggregated architecture (e.g., a disaggregated base station architecture, a disaggregated RAN architecture) that may be configured to utilize a protocol stack that is physically or logically distributed between two or more network entities 105, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a virtualized RAN (vRAN) (e.g., cloud RAN (C-RAN)). For example, the network entity 105 may include one or more of a central unit (CU) 160, a distributed unit (DU) 165, a radio unit (RU) 170, a RAN Intelligent Controller (RIC) 175 (e.g., a Near-Real Time RIC (Near-RT RIC), a Non-Real Time RIC (Non-RT RIC)), a Service Management and Orchestration (SMO) 180 system, or any combination thereof. The RU 170 may also be referred to as a radio head, a smart radio head, a remote radio head (RRH), a remote radio unit (RRU), or a transmission reception point (TRP). One or more components of the network entity 105 in a disaggregated RAN architecture may be co-located, or one or more components of the network entity 105 may be located in distributed locations (e.g., separate physical locations).In some examples, one or more network entities 105 of the disaggregated RAN architecture may be implemented as a virtual unit (e.g., a virtual CU (VCU), a virtual DU (VDU), a virtual RU (VRU)).

[0049] The division of functionality among the CU 160, the DU 165, and the RU 170 is flexible and may support different functions depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combination thereof) are implemented in the CU 160, the DU 165, or the RU 170. For example, a functional division of a protocol stack may be adopted between the CU 160 and the DU 165 such that the CU 160 can support one or more layers of the protocol stack and the DU 165 can support one or more different layers of the protocol stack. In some examples, the CU 160 may host upper protocol layer (e.g., Layer 3 (L3), Layer 2 (L2)) functions and signaling (e.g., Radio Resource Control (RRC), service data adaptation protocol (SDAP), Packet Data Convergence Protocol (PDCP)). The CU 160 may be connected to one or more DUs 165 or RUs 170, which may host lower protocol layers such as Layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functions and signaling, each of which may be at least partially controlled by the CU 160. Additionally or alternatively, a functional division of the protocol stack may be employed between the DU 165 and the RU 170, such that the DU 165 can support one or more layers of the protocol stack, and the RU 170 can support one or more different layers of the protocol stack. The DU 165 may support one or more different cells (e.g., via one or more RUs 170).In some cases, the functional division between the CU 160 and the DU 165 or between the DU 165 and the RU 170 may be within a protocol layer (e.g., some functions for a protocol layer may be performed by one of the CU 160, the DU 165, or the RU 170, while other functions of the protocol layer are performed by a different one of the CU 160, the DU 165, or the RU 170). The CU 160 may be further functionally divided into a CU control plane (CU-CP) function and a CU user plane (CU-UP) function. The CU 160 may be connected to one or more DUs 165 via midhaul communication links 162 (e.g., F1, F1-c, F1-u), and the DUs 165 may be connected to one or more RUs 170 via fronthaul communication links 168 (e.g., an open fronthaul (FH) interface). In some examples, the midhaul communication link 162 or the fronthaul communication link 168 may be implemented according to an interface (e.g., a channel) between layers of a protocol stack supported by the respective network entities 105 communicating over such communication link.

[0050] In a wireless communication system (e.g., wireless communication system 100), infrastructure and spectrum resources for radio access can supplement wired backhaul connections to support wireless backhaul link capabilities and provide an IAB network architecture (e.g., to the core network 130). In some cases, in an IAB network, one or more network entities 105 (e.g., IAB nodes 104) may be partially controlled by each other. One or more IAB nodes 104 may be referred to as donor entities or IAB donors. One or more DUs 165 or one or more RUs 170 may be partially controlled by one or more CUs 160 associated with the donor network entity 105 (e.g., donor base station 140). One or more donor network entities 105 (e.g., IAB donors) may communicate with one or more additional network entities 105 (e.g., IAB nodes 104) via supported access links and backhaul links (e.g., backhaul communication links 120). An IAB node 104 may include an IAB mobile termination (IAB-MT) controlled (e.g., scheduled) by the DU 165 of the associated IAB donor. The IAB-MT may include an independent set of antennas for relaying communications with the UE 115, or may share the same antenna (e.g., of the RU 170) of the IAB node 104 used for access via the DU 165 of the IAB node 104 (e.g., referred to as a virtual IAB-MT (vIAB-MT)). In some examples, the IAB node 104 may include a DU 165 that supports communication links with additional entities (e.g., the IAB node 104, the UE 115) in an access network (e.g., downstream) relay chain or configuration. In such cases, one or more components of the disaggregated RAN architecture (e.g., one or more IAB nodes 104 or components of the IAB node 104) may be configured to operate in accordance with the techniques described herein.

[0051] For example, an access network (AN) or RAN may include communication between an access node (e.g., an IAB donor), an IAB node 104, and one or more UEs 115. The IAB donor may facilitate a connection between the core network 130 and an AN (e.g., via a wired or wireless connection to the core network 130). That is, an IAB donor may refer to a RAN node that has a wired or wireless connection to the core network 130. The IAB donor may include a CU 160 and at least one DU 165 (e.g., and / or an RU 170), where the CU 160 may communicate with the core network 130 over an interface (e.g., a backhaul link). The IAB donor and IAB node 104 may communicate over an F1 interface according to a protocol (e.g., an F1 AP protocol) that defines signaling messages. Additionally or alternatively, CU160 may communicate with the core network via an interface, which may be an example of a portion of a backhaul link, and may communicate with other CU160 (e.g., CU160 associated with an alternative IAB donor) via an Xn-C interface, which may be an example of a portion of a backhaul link.

[0052] An IAB node 104 may refer to a RAN node that provides IAB functionality (e.g., access to the UE 115, wireless self-backhaul capabilities). The DU 165 may act as a distributed scheduling node for a child node associated with the IAB node 104, and the IAB-MT may act as a scheduled node for a parent node associated with the IAB node 104. That is, an IAB donor may be referred to as a parent node that communicates with one or more child nodes (e.g., an IAB donor may relay a transmission for a UE through one or more other IAB nodes 104). Additionally or alternatively, an IAB node 104 may also be referred to as a parent node or a child node for other IAB nodes 104, depending on the relay chain or configuration of the AN. Thus, the IAB-MT entity of the IAB node 104 can provide a Uu interface for the child IAB node 104 to receive signaling from the parent IAB node 104, and the DU interface (e.g., DU 165) can provide a Uu interface for the parent IAB node 104 to signal to the child IAB node 104 or UE 115.

[0053] For example, the IAB node 104 may be referred to as a parent node supporting communication for a child IAB node, or as a child IAB node associated with an IAB donor, or both. The IAB donor may include a CU 160 having a wired or wireless connection (e.g., backhaul communication link 120) to the core network 130 and may act as a parent node for the IAB node 104. For example, the DU 165 of the IAB donor may relay transmissions to the UE 115 via the IAB node 104, or may directly signal transmissions to the UE 115, or both. The CU 160 of the IAB donor may signal communication link establishment to the IAB node 104 via the F1 interface, and the IAB node 104 may schedule transmissions (e.g., transmissions to the UE 115 relayed from the IAB donor) via the DU 165. That is, data may be relayed to and from the IAB node 104 via signaling over the NR Uu interface to the MT of the IAB node 104. Communications with the IAB node 104 may be scheduled by the DU 165 of the IAB donor, and communications with the IAB node 104 may be scheduled by the DU 165 of the IAB node 104.

[0054] For the techniques described herein applied in the context of a disaggregated RAN architecture, one or more components of the disaggregated RAN architecture may be configured to support estimating OFDM channels using FMCW, as described herein. For example, some operations described as being performed by the UE 115 or a network entity 105 (e.g., a base station 140) may additionally or alternatively be performed by one or more components of the disaggregated RAN architecture (e.g., an IAB node 104, a DU 165, a CU 160, an RU 170, a RIC 175, an SMO 180).

[0055] The UE 115 may include or be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, and a “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. The UE 115 may also include or be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, the UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various items, such as an appliance, a vehicle, a meter, or the like.

[0056] The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115, which may act as relays, as shown in FIG. 1, as well as network entities 105 and network equipment, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples.

[0057] The UE 115 and the network entity 105 may wirelessly communicate with each other over one or more communication links 125 (e.g., access links) using resources associated with one or more carriers. The term “carrier” may refer to a set of RF spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier used for the communication link 125 may include a portion (e.g., a bandwidth part (BWP)) of an RF spectrum band operated according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling coordinating operation on the carrier, user data, or other signaling. The wireless communication system 100 may support communication with the UE 115 using carrier aggregation or multi-carrier operation. The UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers. Communication between a network entity 105 and another device may refer to communication between a device and any portion (e.g., entity, sub-entity) of the network entity 105. For example, when referring to a network entity 105, the terms "transmit," "receive," or "communicate" may refer to any portion of the network entity 105 (e.g., base station 140, CU 160, DU 165, RU 170) of the RAN that communicates with another device (e.g., directly or via one or more other network entities 105).

[0058] In some examples, such as carrier aggregation configurations, carriers may also have acquisition or control signaling to coordinate operation with other carriers. Carriers may be associated with frequency channels (e.g., evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute RF channel numbers (EARFCN)) and may be identified according to a channel raster for discovery by the UE 115. Carriers may be operated in a standalone mode, where initial acquisition and connection may be made by the UE 115 via the carrier, or the carrier may be operated in a non-standalone mode, where connection is anchored using a different carrier (e.g., of the same or different radio access technology).

[0059] The communication links 125 shown in the wireless communication system 100 may include, among other transmission configurations, downlink transmissions (e.g., forward link transmissions) from the network entity 105 to the UE 115, uplink transmissions (e.g., reverse link transmissions) from the UE 115 to the network entity 105, or both. A carrier may carry downlink or uplink communications (e.g., in FDD mode) or may be configured to carry downlink and uplink communications (e.g., in TDD mode).

[0060] A carrier may be associated with a particular bandwidth of the RF spectrum, although in some examples, the carrier bandwidth may be referred to as the carrier or the “system bandwidth” of the wireless communication system 100. For example, the carrier bandwidth may be one of a set of bandwidths of a carrier of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)). Devices of the wireless communication system 100 (e.g., the network entity 105, the UE 115, or both) may have a hardware configuration that supports communication using a particular carrier bandwidth or may be configurable to support communication using one of the set of carrier bandwidths. In some examples, the wireless communication system 100 may include a network entity 105 or a UE 115 that supports simultaneous communication using carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate using a portion (e.g., a sub-band, BWP) or all of the carrier bandwidth.

[0061] A signal waveform transmitted on a carrier may be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as OFDM or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may refer to a resource of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and the subcarrier spacing may have an inverse proportional relationship. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both), such that a relatively large number of resource elements (e.g., during a transmission duration) and a relatively high order of the modulation scheme may correspond to a relatively higher communication rate. Wireless communication resources may refer to a combination of RF spectrum resources, time resources, and spatial resources (e.g., spatial layers, beams), where the use of multiple spatial resources may further increase the data rate or data integrity for communication with the UE 115.

[0062] One or more numerologies for a carrier may be supported, and a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs with the same or different numerologies. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP of a carrier may be active at a given time, and communication for the UE 115 may be limited to one or more active BWPs.

[0063] The time interval for the network entity 105 or the UE 115 is, for example, T s =1 / (Δf max N f ) seconds, where Δf max may represent the supported subcarrier spacing, and N fmay represent the supported discrete Fourier transform (DFT) sizes. The communication resource time intervals may be organized according to radio frames, each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., in the range of 0 to 1023).

[0064] Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a certain number of slots. Alternatively, each frame may include a variable number of slots, where the number of slots may depend on the subcarrier spacing. Each slot may include a certain number of symbol periods (e.g., depending on the length of a cyclic prefix prepended to each symbol period). In some wireless communication systems 100, a slot may be further divided into multiple minislots, which are associated with one or more symbols. Excluding the cyclic prefix, each symbol period may include one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the frequency band of operation.

[0065] A subframe, slot, minislot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., among bursts of shortened TTIs (sTTIs)).

[0066] Physical channels may be multiplexed for communication using carriers according to various techniques. Physical control channels and physical data channels may be multiplexed for signaling over downlink carriers using, for example, one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by a set of symbol periods and may span the system bandwidth of the carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESET) may be configured for a set of UEs 115. For example, one or more of the UEs 115 may monitor or search the control region for control information according to one or more search space sets, where each search space set may include one or more control channel candidates at one or more aggregation levels arranged in a cascaded manner. The aggregation level for control channel candidates may refer to the amount of control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for sending control information to multiple UEs 115 and a UE-specific search space set for sending control information to a specific UE 115.

[0067] The network entity 105 may provide communication coverage via one or more cells, e.g., macro cells, small cells, hot spots, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used for communication with the network entity 105 (e.g., using a carrier) and may be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), or other) for distinguishing neighboring cells. In some examples, a cell may also refer to a coverage area 110 or a portion (e.g., a sector) of a coverage area 110 in which the logical communication entity operates. Such a cell may range from a smaller area (e.g., a structure, a subset of a structure) to a larger area, depending on various factors such as the capabilities of the network entity 105. For example, a cell may be or include a building, a subset of a building, or an outer space between or overlapping with the coverage area 110, among other examples.

[0068] A macro cell generally covers a relatively large geographic area (e.g., a few kilometers in radius) and may allow unrestricted access by UEs 115 that subscribe to service with the network provider that supports the macro cell. A small cell may be associated with a lower-power network entity 105 (e.g., a lower-power base station 140) compared to a macro cell, and the small cell may operate using the same or a different (e.g., licensed, unlicensed) frequency band as the macro cell. A small cell may provide unrestricted access to UEs 115 that subscribe to service with the network provider, or may provide restricted access to UEs 115 that have an association with the small cell (e.g., UEs 115 in a closed subscriber group (CSG), UEs 115 associated with users in a home or office). The network entity 105 may support one or more cells and may also support communication via one or more cells using one or more component carriers.

[0069] In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that may provide access to different types of devices.

[0070] In some examples, the network entities 105 (e.g., base stations 140, RUs 170) may be mobile and thus may provide communication coverage for moving coverage areas 110. In some examples, different coverage areas 110 associated with different techniques may overlap, but the different coverage areas 110 may be supported by the same network entity 105. In some other examples, overlapping coverage areas 110 associated with different techniques may be supported by different network entities 105. The wireless communication system 100 may include a heterogeneous network, for example, where different types of network entities 105 provide coverage to various coverage areas 110 using the same or different radio access technologies.

[0071] The wireless communications system 100 may support synchronous or asynchronous operation. For synchronous operation, the network entities 105 (e.g., base stations 140) may have similar frame timing, and transmissions from different network entities 105 may be approximately aligned in time. For asynchronous operation, the network entities 105 may have different frame timing, and transmissions from different network entities 105 may, in some examples, not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operation.

[0072] Some UEs 115, such as MTC or IoT devices, may be low-cost or low-complexity devices and may provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technologies that enable devices to communicate with each other or with a network entity 105 (e.g., a base station 140) without human intervention. In some examples, M2M communication or MTC may include communication from devices that incorporate sensors or meters to measure or capture information and relay that information to a central server or application program that uses such information or presents the information to a human who interacts with the application program. Some UEs 115 may be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business billing.

[0073] Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception, but not simultaneous transmission and reception). In some examples, half-duplex communication may be implemented at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power-saving deep sleep mode when not engaged in active communication, operating using a limited bandwidth (e.g., pursuant to narrowband communication), or a combination of these techniques. For example, some UEs 115 may be configured for operation using a narrowband protocol type associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of the carrier, or outside of a carrier.

[0074] The wireless communication system 100 may be configured to support ultra-reliable or low-latency communications, or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communications (URLLC). The UE 115 may be designed to support ultra-reliable, low-latency, or critical functionality. Ultra-reliable communications may include private or group communications, and may be supported by one or more services such as push-to-talk, video, data, etc. Support for ultra-reliable, low-latency functionality may include service prioritization, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency may be used interchangeably herein.

[0075] In some examples, the UEs 115 may be configured to support direct communication with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., according to a peer-to-peer (P2P), D2D, or sidelink protocol). In some examples, one or more UEs 115 of a group conducting D2D communication may be within the coverage area 110 of a network entity 105 (e.g., a base station 140, an RU 170), which may support aspects of such D2D communication configured (e.g., scheduled) by the network entity 105. In some examples, one or more UEs 115 of such a group may be outside the coverage area 110 of the network entity 105, or may otherwise be unable or not configured to receive transmissions from the network entity 105. In some examples, a group of UEs 115 communicating via D2D communication may support a one-to-many (1:M) system, with each UE 115 transmitting to each of the other UEs 115 in the group. In some examples, the network entity 105 may facilitate scheduling of resources for D2D communication. In some other examples, D2D communication may occur between UEs 115 without the involvement of the network entity 105.

[0076] In some systems, the D2D communication link 135 may be an example of a communication channel between vehicles (e.g., UEs 115), such as a sidelink communication channel. In some examples, the vehicles may communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination thereof. The vehicles may signal information associated with traffic conditions, signal scheduling, weather, safety, emergency situations, or some other information related to the V2X system. In some examples, the vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, with the network via one or more network nodes (e.g., network entities 105, base stations 140, RUs 170) using vehicle-to-network (V2N), or both.

[0077] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5G core, 5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) that manages access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (PDN gateway (P-GW), or a user plane function (UPF)) that routes packets or interconnects to external networks. The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for UEs 115 served by network entities 105 (e.g., base stations 140) associated with the core network 130. User IP packets may be forwarded through a user plane entity, which may provide IP address allocation and other functions. The user plane entity may connect to IP services 150 for one or more network operators. The IP services 150 may include access to the Internet, intranet(s), IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0078] The wireless communication system 100 may operate using one or more frequency bands, which may range from 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the 300 MHz to 3 GHz region is known as the ultra-high frequency (UHF) region or decimeter band because wavelengths range in length from approximately 1 decimeter to 1 meter. Although UHF waves may be blocked or redirected by buildings and environmental features, sometimes referred to as clusters, the waves can penetrate structures sufficiently for a macrocell to serve UEs 115 located indoors. Communications using UHF waves may be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers) compared to communications using lower frequency and longer waves in the shortwave (high frequency (HF)) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0079] The wireless communication system 100 may also operate using the super high frequency (SHF) region, also known as the centimeter band, which may range from 3 GHz to 30 GHz, or the extremely high frequency (EHF) region of the spectrum, also known as the millimeter band (e.g., 30 GHz to 300 GHz). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communications between the UE 115 and the network entity 105 (e.g., base station 140, RU 170), although the EHF antennas on each device may be smaller and more closely spaced than UHF antennas. In some examples, such techniques may facilitate the use of antenna arrays within the device. However, propagation of EHF transmissions may experience greater attenuation and shorter distances than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency ranges, and the designated use of bands across these frequency ranges may vary by country or regulatory body.

[0080] The wireless communication system 100 may utilize both licensed and unlicensed RF spectrum bands. For example, the wireless communication system 100 may employ License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or an NR technology using an unlicensed band, such as the 5 GHz industrial, scientific, and medical (ISM) band. While operating using the unlicensed RF spectrum band, the network entity 105 and devices such as the UE 115 may employ carrier sensing for collision detection and avoidance. In some examples, operations using the unlicensed band may be based on a carrier aggregation configuration in conjunction with component carriers operating using a licensed band (e.g., LAA). Operations using the unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

[0081] A network entity 105 (e.g., base station 140, RU 170) or a UE 115 may be equipped with multiple antennas that can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the network entity 105 or UE 115 may be arranged in one or more antenna arrays or antenna panels that can support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be collocated in an antenna assembly such as an antenna tower. In some examples, antennas or antenna arrays associated with the network entity 105 may be located in various geographic locations. The network entity 105 may include an antenna array having a set of rows and columns of antenna ports that the network entity 105 can use to support beamforming of communications with the UE 115. Similarly, the UE 115 may include one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support RF beamforming for signals transmitted through the antenna ports.

[0082] The network entity 105 or the UE 115 may use MIMO communications to exploit multipath signal propagation and increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques are sometimes referred to as spatial multiplexing. Multiple signals may be transmitted by a transmitting device, for example, via different antennas or different combinations of antennas. Similarly, multiple signals may be received by a receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry information associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), in which multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO), in which multiple spatial layers are transmitted to multiple devices.

[0083] Beamforming, sometimes referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting or receiving device (e.g., network entity 105, UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming may be achieved by combining signals communicated through antenna elements of an antenna array such that some signals propagating along a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjusting signals communicated through antenna elements may include the transmitting or receiving device applying an amplitude offset, a phase offset, or both to signals carried through the antenna elements associated with the device. The adjustment associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the antenna array of the transmitting or receiving device, or to some other orientation).

[0084] The network entity 105 or the UE 115 may use beam sweeping techniques as part of a beamforming operation. For example, the network entity 105 (e.g., base station 140, RU 170) may use multiple antennas or antenna arrays (e.g., antenna panels) to perform a beamforming operation for directional communication with the UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by the network entity 105 along different directions. For example, the network entity 105 may transmit signals according to different beamforming weight sets associated with different directions of transmission. The transmissions along different beam directions may be used to identify beam directions (e.g., by a transmitting device such as the network entity 105 or by a receiving device such as the UE 115) for subsequent transmission or reception by the network entity 105.

[0085] Some signals, such as data signals associated with a particular receiving device, may be transmitted by a transmitting device (e.g., transmitting network entity 105, transmitting UE 115) along a single beam direction (e.g., a direction associated with a receiving device, such as receiving network entity 105 or receiving UE 115). In some examples, the beam direction associated with a transmission along a single beam direction may be determined based on signals transmitted along one or more beam directions. For example, UE 115 may receive one or more of the signals transmitted by network entity 105 along different directions, but may report to network entity 105 an indication of the signal that UE 115 received with the highest signal quality or otherwise acceptable signal quality.

[0086] In some examples, transmission by a device (e.g., by the network entity 105 or the UE 115) may be performed using multiple beam directions, but the device may use a combination of digital precoding or beamforming to generate a combined beam for transmission (e.g., from the network entity 105 to the UE 115). The UE 115 may report feedback indicating precoding weights for one or more beam directions, but the feedback may correspond to a configured set of beams across the system bandwidth or one or more subbands. The network entity 105 may transmit a reference signal (e.g., a cell-specific reference signal (CRS), CSI-RS) that may be precoded or unprecoded. The UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination type codebook, a port selection type codebook). Although these techniques are described with reference to signals transmitted along one or more directions by the network entity 105 (e.g., base station 140, RU 170), the UE 115 may employ similar techniques to transmit a signal multiple times along different directions (e.g., to identify a beam direction for subsequent transmission or reception by the UE 115) or to transmit a signal along a single direction (e.g., to transmit data to a receiving device).

[0087] A receiving device (e.g., UE 115) may perform receiving operations according to multiple receiving configurations (e.g., directional intercepts) when receiving various signals from a receiving device (e.g., network entity 105), such as a synchronization signal, a reference signal, a beam selection signal, or other control signals. For example, a receiving device may perform receiving according to multiple receiving directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (e.g., different directional intercept weight sets) applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as “intercepting” according to different receiving configurations or receiving directions. In some examples, a receiving device may use a single receiving configuration to receive along a single beam direction (e.g., when receiving a data signal). A single receive configuration may be aligned along a beam direction determined based on interception from different receive configuration directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on interception from multiple beam directions).

[0088] The wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communications at the bearer or PDCP layer may be IP-based. The RLC layer may perform packet segmentation and reassembly for communications over logical channels. The MAC layer may perform priority handling and multiplexing of logical channels onto transport channels. The MAC layer may also implement error detection, error correction, or both to support retransmissions and improve link efficiency. In the control plane, the RRC layer may provide establishment, configuration, and maintenance of the RRC connection between the UE 115 and the network entity 105 or the core network 130 supporting radio bearers for user plane data. The PHY layer may map transport channels to physical channels.

[0089] The UE 115 and the network entity 105 may support retransmission of data to increase the likelihood that the data is successfully received. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is correctly received over a communication link (e.g., communication link 125, D2D communication link 135). HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device may support same-slot HARQ feedback, in which case the device may provide HARQ feedback for data received via a previous symbol in a particular slot. In some other examples, the device may provide HARQ feedback in a subsequent slot or according to some other time interval.

[0090] Waveforms and multiple access designs used for wireless communications may be configured to support a relatively wide variety of use cases, such as mobile broadband, the metaverse, massive Internet of Things (IoT), sidelink, massive spectrum aggregation or duplexing, UE cooperation, other use cases, or any combination thereof. In some examples, waveforms and multiple access designs may support a relatively wide variety of technologies, such as full-duplex technologies, radio frequency sensing, positioning, physical layer security, other technologies, or any combination thereof. Additionally or alternatively, waveforms and multiple access designs may be supported across multiple frequency ranges (e.g., mmW and above) as use cases and technologies expand. In some examples, waveforms and multiple access designs may be configured to support a relatively large amount of connectivity and a relatively high cell capacity (e.g., the waveforms and multiple access designs may provide relatively efficient support of channel access for a relatively large number of users).

[0091] The one or more waveforms used for wireless communications may be based on multiple design metrics, which may include, for example, spectral efficiency, energy efficiency (e.g., power amplifier efficiency and processing power efficiency at transmitting and receiving devices, respectively), waveform processing complexity and latency, radio frequency impairments (e.g., error vector magnitude (EVM), etc.), spectrum confinement by power amplifier model (e.g., in-band and out-of-band emissions), and support for relatively efficient multi-user or MIMO multiple access. The one or more waveforms may be designed to support one or more channel conditions, such as fading (e.g., time-varying or inter-symbol-interference (ISI)), phase noise, power amplifier nonlinearity, or any combination thereof. In some examples, one or more waveforms may be designed based on advances in digital pre-distortion (DPD) and digital post-distortion (DPoD) technology, spectral confinement for full duplex, joint sensing and common (JSAC) use cases, or any combination thereof.

[0092] The techniques, systems, and devices described herein may provide support for using FMCW to improve channel estimation in OFDM systems. One or more devices in the wireless communication system 100 may support the FMCW-based OFDM channel estimation techniques described herein. For example, a transmitting device (e.g., a UE 115 or a network entity 105) may transmit a first FMCW signal over an OFDM channel. A receiving device (e.g., a UE 115 or a network entity 105 communicating with the transmitting device) may receive the first FMCW signal. The receiving device may generate a second FMCW signal (e.g., a local FMCW signal) based on a set of one or more FMCW parameters associated with the first FMCW signal. The set of one or more FMCW parameters may include a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof. The receiving device may combine the first FMCW signal and the second FMCW signal and filter the combined FMCW signal (e.g., using a low-pass filter (LPF)). The receiving device may sample the combined FMCW signal using a sampling rate that may be based on one or more parameters associated with the OFDM channel. The receiving device may use the samples to estimate the frequency-domain OFDM channel using time-domain signal processing techniques, which may reduce latency, reduce processing complexity, and improve channel estimation reliability.

[0093] 2 illustrates an example of an OFDM channel estimation scheme 200 that supports estimating an OFDM channel using FMCW in accordance with one or more aspects of the present disclosure. In some examples, the OFDM channel estimation scheme 200 may implement aspects of the wireless communication system 100 described with reference to FIG. 1. In this example, a transmitting device 205 (e.g., a UE, a base station, a RU, a DU, a CU, an IAB node, or some other device) and a receiving device 210 (e.g., a UE, a base station, a RU, a DU, a CU, an IAB node, or some other device) may exchange OFDM signals over a wireless channel 235, which may be an OFDM channel. The receiving device 210 may estimate the wireless channel 235 using frequency-domain signal processing.

[0094] The transmitting device 205 and the receiving device 210 may establish a connection for wireless communication over a wireless channel 235. The transmitting device 205 may generate an OFDM signal for transmission to the receiving device 210 over the wireless channel 235. To generate the OFDM signal, the transmitting device 205 may identify data scheduled for transmission to the receiving device 210. The data may be transmitted over a set of frequency domain signals 215 (e.g., {X(0), X(1), ... X(N c The transmitting device 205 may include or be converted to a time-domain signal (e.g., X(m)). The transmitting device 205 may perform an inverse fast Fourier transform (IFFT) 220 on the frequency-domain signal 215 to convert the frequency-domain signal 215 to a time-domain signal (e.g., X(m)).

[0095] The transmitting device 205 can perform cyclic prefix addition 225 to the time-domain signal. For example, the transmitting device 205 may add a cyclic prefix to the time-domain signal to generate an OFDM signal. The transmitting device 205 can then convert the time-domain signal from a digital signal to an analog signal using a digital-to-analog converter (DAC) 230. In some examples, the transmitting device 205 may separately convert the real and imaginary parts of the digital time-domain signal to the analog domain. The transmitting device 205 can transmit the analog time-domain OFDM signal to the receiving device 210 over a wireless channel 235.

[0096] The receiving device 210 can receive the analog time-domain OFDM signal and convert the received signal to the digital domain using an ADC 240 in the receiving device 210. In some examples, the receiving device 210 may convert the real and imaginary parts of the analog signal to the digital domain separately. After using the ADC 240, the receiving device 210 can perform cyclic prefix removal 245 to remove cyclic prefix(es) from the time-domain digital signal. After removing the cyclic prefix(es), the receiving device 210 can perform an FFT 250 on the digital time-domain signal. The FFT 250 can convert the time-domain signal to the frequency domain. That is, the FFT 250 can create a set of frequency-domain signals 255.

[0097] The receiving device 210 can estimate a frequency-domain OFDM channel (e.g., the frequency domain of the wireless channel 235) using the set of frequency-domain signals 255 created by the FFT 250. In some examples, to estimate the frequency-domain OFDM channel based on the OFDM signal, as described with reference to FIG. 2, the ADC 240 in the receiving device 210 can be a relatively high-rate ADC 240. That is, the sampling rate of the ADC 240 can be relatively high to accurately convert the analog OFDM signal to a digital OFDM signal.

[0098] Exemplary sampling rates of ADC 240 that may be used for different configured subcarrier spacing (SCS) values ​​are shown in Table 1.

[0099] [Table 1]

[0100] The sampling rate may be defined in units of mega samples per second (Msps). The sampling rate may be calculated based on the SCS values ​​and respective FFT sizes, and may be related to the respective number of subcarriers (sc) (e.g., in the number of physical resource blocks (PRBs)). For example, the sampling rate may be calculated based on the SCS and N FFT It may be equal to the product of the frequency and the size (for example, 15KHz*2048=30.72MHz).

[0101] In some examples, performing the FFT 250 by the receiving device 210 may be associated with relatively high processing and complexity. Additionally or alternatively, the ADC 240 in the receiving device 210 may be a relatively high-rate ADC 240. The sampling rate used to convert the received analog signal to digital form, such as the sampling rates shown in Table 1, may be relatively high in order for the receiving device 210 to accurately convert the OFDM signal and then perform the FFT 250.

[0102] The techniques, systems, and devices described herein provide a transmitting device 205 and a receiving device 210 for exchanging FMCW signals over a wireless channel 235. The FMCW signal may be configured for channel estimation of an OFDM channel and may support reduced processing complexity at the receiver. For example, the FMCW signal may be sampled at a reduced sampling rate compared to the OFDM signal and used to estimate a frequency-domain OFDM channel using time-domain signal processing, such that the receiving device 210 may refrain from performing an FFT 250, which may reduce complexity compared to using the OFDM signal to estimate the OFDM channel. FMCW-based channel estimation techniques are described in further detail elsewhere herein, including with reference to FIGS. 3-6.

[0103] 3 illustrates an example of an OFDM channel estimation scheme 300 that supports estimating an OFDM channel using FMCW in accordance with one or more aspects of the present disclosure. In some examples, the OFDM channel estimation scheme 300 may implement aspects of the wireless communications system 100 described with reference to FIG. 1. In this example, a transmitting device 305 (e.g., a UE, a base station, a RU, a DU, a CU, an IAB node, or some other device) and a receiving device 310 (e.g., a UE, a base station, a RU, a DU, a CU, an IAB node, or some other device) may exchange FMCW signals over an OFDM channel 315. The FMCW signals may be used to facilitate channel estimation of the frequency-domain OFDM channel by the receiving device 310.

[0104] The transmitting device 305 and the receiving device 310 may establish a connection for wireless communication over an OFDM channel 315. The devices may be the UE 115, the network entity 105, other devices, or any combination thereof. In some examples, the devices may exchange one or more capability messages, control messages, or both to initiate the FMCW-based OFDM channel estimation procedures described herein. Such signaling may be described in further detail elsewhere herein, including with reference to FIGS. 4-6.

[0105] After the FMCW-based OFDM channel estimation procedure is initiated, the transmitting device 305 may generate an FMCW signal 320 (e.g., a first FMCW signal). In some examples, the transmitting device 305 may generate the FMCW signal 320 in the analog domain using a voltage controlled oscillator (VCO) 345. The transmitting device 305 may transmit the FMCW signal 320 over the OFDM channel 315 using at least one antenna element in the transmitting device 305. The analog domain FMCW signal 320 generated and transmitted by the transmitting device 305 may be expressed as x RF,Tx (t) and is shown in Equation 1.

number

[0106] As shown in Equation 1, the FMCW signal 320 may be a time-domain signal (e.g., a function of time (t)). In the example of Equation 1, f c may represent the starting frequency 390 of the FMCW signal 320, S may represent the slope 385 of the FMCW signal 320, and φ Tx may represent the phase of the transmitting device 305.

[0107] 3, the FMCW signal 320 may be associated with a waveform signal transmitted over symbols 380 of the OFDM channel 315 in the time domain and a bandwidth 370 (e.g., BW) of the OFDM channel 315 in the frequency domain. The bandwidth 370 may include one or more resource blocks 375 in the frequency domain. In some examples, each resource block 375 may include a set of resource elements in the frequency domain. The OFDM channel 315 may include multiple symbols 380 in the time domain. The duration or length of each symbol 380 may correspond to the length of an OFDM symbol, or the length of an OFDM symbol and a respective cyclic prefix duration, or a partial length of an OFDM symbol, or a partial length of an OFDM symbol and a respective cyclic prefix duration, or some other length longer than the length of an OFDM symbol and the length of an OFDM symbol and a cyclic prefix duration, or some other symbol duration, or any combination thereof. The FMCW signal 320 may span frequencies between a start frequency 390 and the sum of the start frequency 390 and a bandwidth 370 (e.g., {f c ,f c +BW}). The slope 385 of the FMCW signal 320 may correspond to the quotient of the bandwidth 370 and the duration of the symbol 380 in which the FMCW signal 320 is transmitted, as shown by Equation 2.

number

[0108] In the example of Equation 2, T sym may represent the duration of the symbol 380, and N RE may represent the quantity of resource elements in the bandwidth 370, and Δf may represent the SCS. In this example, the slope may be calculated based on a symbol duration, which corresponds to the length of an OFDM symbol. For example, the duration of the symbol 380 may be calculated as the inverse of the SCS (e.g.,

number

[0109] The radio frequency FMCW signal 325 received by the receiving device 310 over the OFDM channel 315 in response to the FMCW signal 320 transmitted by the transmitting device 305 is expressed as y RF,Rx (t) and is shown in Equation 3.

number

[0110] In the example of Equation 3, P may represent the quantity of channel delay paths (e.g., the quantity of multipaths) associated with the OFDM channel 315, and τ p A may represent a given channel delay with index p. That is, the received FMCW signal 325 may be sampled over a range of channel delays (e.g., p=0 to p-1). p n(t) may represent the conditions of the OFDM channel 315, and n(t) may represent the channel noise. In some examples, the channel noise may be associated with a relatively small value relative to the other values ​​defining the radio frequency FMCW signal 325 received by the receiving device 310 in Equation 3.

[0111] As described herein, the receiving device 310 may generate the FMCW signal 330 at the receiving device. The FMCW signal 330 generated at the receiving device 310 may be referred to as a second FMCW signal or a local FMCW signal. The receiving device 310 may generate the FMCW signal 330 in the analog domain using a VCO 355 at the receiving device 310. The receiving device 310 may generate the FMCW signal 330 simultaneously with or after receiving the FMCW signal 325. The FMCW signal 330 generated by the receiving device 310 may be a frequency domain signal (FMCW) of x RF,Rx (t) and is shown in Equation 4.

number

[0112] As shown in Equation 4, the receiving device 310 may generate the FMCW signal 320 based on a set of FMCW parameters associated with the FMCW signal 330 transmitted by the transmitting device 305. The set of FMCW parameters may include, for example, a starting frequency 390 (f c ), the slope 385 (S) of the FMCW signal 320, the initial phase of the transmitting device (e.g., φ Tx ), or any combination thereof. That is, the FMCW signal 330 generated by the receiving device 310 may have the same start frequency 390 and slope 385 as the FMCW signal 320 generated by the transmitting device 305. In the example of Equation 4, φ Rx may represent the phase of the receiving device 310. In some examples, the phase of the receiving device may be the same as the phase of the transmitting device (e.g., φ Tx =φ RxIn some examples, the transmitting device 305 may transmit a control message indicating a set of FMCW parameters for generation of the FMCW signal 330 by the receiving device 310. Additionally or alternatively, the receiving device 310 may transmit a control message indicating a set of FMCW parameters for generation of the FMCW signal 320 by the transmitting device 305 and for generation of the FMCW signal 330 by the receiving device 310, as described in further detail elsewhere herein, including with reference to FIGS.

[0113] The FMCW signal 320 transmitted by the transmitting device 305 and the FMCW signal 330 generated at the receiving device 310 may have a similar FMCW structure. For example, both signals may be wideband signals (e.g., spanning the entire bandwidth 370 of the OFDM channel 315), may span the duration of a symbol 380 in the OFDM channel 315, may be associated with a start frequency 390, and may be associated with a slope 385. In some examples, the FMCW signal 320 transmitted by the transmitting device 305 may be a real signal. For example, the FMCW signal 320 may include a single stream (e.g., a cosine stream as shown in Equation 1). The FMCW signal 330 generated by the receiving device 310 may include two streams (e.g., a sine stream and a cosine stream) for channel estimation. That is, an exponential function in the FMCW signal 330 generated by the receiving device 310 may be designed for channel estimation. In some examples, the receiving device 310 may be configured with the capability to generate an FMCW signal 330 for channel estimation, or the receiving device 310 may receive a control message indicating the capability to generate an FMCW signal 330 for channel estimation.

[0114] After generating the FMCW signal 330 configured for channel estimation, the receiving device 310 receives a synthesized FMCW signal 335 (e.g., y mixed(t)). To generate a combined FMCW signal 335, the receiving device 310 may combine the FMCW signal 325 received at the receiving device 310 with the locally generated FMCW signal 330 using a mixer 350. The mixer 350 may represent an example of one or more components (e.g., hardware, software, or both) of the receiving device 310 configured to combine two or more time-domain FMCW signals. In some examples, combining may include multiplying the FMCW signals (e.g., y mixed (t)=y RF,Rx (t)x RF,Rx (t)).

[0115] The receiving device 310 can filter the combined FMCW signal 335 using an LPF 360 at the receiving device 310. The LPF 360 filters the combined filtered FMCW signal 340 (e.g., y mixed,LPF (t)). LPF 360 may represent an example of a component of receiving device 310 configured to filter a signal, or a function supported by receiving device 310, or both. For example, receiving device 310 may apply an LPF function to combined FMCW signal 335 (e.g., y mixed,LPF (t)=LPF[y RF,Rx (t)x RF,UE (t)]). The combined filtered FMCW signal 340 may be represented by Equation 5:

number

[0116] Equation 5 can be simplified according to Equation 6:

number

[0117] In some instances, β pThe second exponential function in may represent the channel estimation error, which may be ignored to further simplify Equation 6. For example, p Half the second exponential of (e.g.,

number

number

number

[0118] After combining and filtering the FMCW signal, the receiving device 310 can perform frequency-domain OFDM channel estimation using time-domain signal processing based on sampling the combined and filtered FMCW signal 340. The receiving device 310 can sample the combined and filtered FMCW signal 340 in the time domain using an ADC 365. The sampling rate used to sample the combined and filtered FMCW signal 340 can be based on one or more parameters associated with the OFDM channel 315. For example, the sampling rate may be based on the frequency range of one or more subbands in the OFDM channel 315 (e.g., sampling rate

number

number

[0119] The sampling by the receiving device 310 as part of the OFDM channel estimation is performed using the sampling sequence D Rx (k), which may represent a set of values ​​associated with the OFDM channel estimate. subband For example, D Rx Each value of (k) may represent an example of an estimate for a respective frequency subband of the OFDM channel 315. Rx (k) is shown by Equation 7.

number

[0120] In the example of Equation 7, F s may represent a sampling rate used by the receiving device 310 to estimate the OFDM channel 315. K may represent the total number of subbands in the OFDM channel 315, which may also correspond to the total number of samples in the sampling sequence. Thus, each value of k may represent the index of a respective subband among the total number of subbands. In one example, the subband frequency range f of the OFDM channel 315 may be subband If f is equal to one resource element, the sampling sequence may include a respective sample or estimate for each resource element in the OFDM channel 315 (e.g., per comb). In some examples, the subband frequency range f subbandmay be some other granularity, such as a set of two or more resource elements, a resource block, or some other frequency range.

[0121] Thereby, the receiving device 310 uses time domain signal processing based on the FMCW signal 325 received at the receiving device 310 and the FMCW signal 330 generated by the receiving device 310 to calculate f subband The described FMCW-based OFDM channel estimation technique may be implemented by the receiving device 310 in the time domain using time-domain signal processing. That is, the receiving device 310 may refrain from applying an FFT or other frequency transform when estimating the frequency-domain OFDM channel 315 using the FMCW signal. By performing OFDM channel estimation in the time domain, the receiving device 310 may reduce processing complexity, latency, and power consumption compared to other OFDM channel estimation techniques that are implemented at least partially in the frequency domain (e.g., using an FFT). Additionally or alternatively, the receiving device 310 may estimate the frequency-domain OFDM channel 315 using both wideband and narrowband radio frequency processing. For example, the FMCW signal 325 received at the receiving device 310 may be a wideband signal in radio frequencies, and after the LPF 360, the combined and filtered FMCW signal 340 may be a narrowband signal for baseband processing.

[0122] The sampling rate used by the receiving device 310 to estimate the frequency-domain OFDM channel 315 using the FMCW signal may be relatively low. The sampling rate described herein is determined by the slope 385 of the FMCW signal and the frequency granularity f subband For example, the sampling rate may be based on

number

number

[0123] As shown by Equation 8, the ratio of the sampling rate of the FMCW-based OFDM channel estimation technique to the OFDM-based OFDM channel estimation technique may be relatively low. That is, the sampling rate of the FMCW-based OFDM channel estimation technique may be relatively low compared to the OFDM-based OFDM channel estimation technique. In one example, 273 FMCWs are used in a bandwidth of 370 FMCWs. * There are 12 resource elements (e.g., N RE =273*12), if each subband contains a single resource element (e.g., k subband =1), the ratio may be equal to 0.8. That is, in such a case, the FMCW-based OFDM channel estimation technique may create an ADC sampling gain of approximately 20 percent. In some examples, such as in scenarios where a receiving device (e.g., UE 115) reports channel state information (CSI) or a precoding matrix indicator (PMI), the subband size may be at least N because the maximum number of subbands (e.g., N) that may be reported via a CSI or PMI report may be 37.

number

[0124] Table 2 includes a comparison of example sampling rates for achieving an accurate estimation of the frequency-domain OFDM channel 315 using the FMCW-based OFDM channel estimation techniques described herein with example sampling rates for achieving an accurate estimation of the frequency-domain OFDM channel 315 using other OFDM channel estimation techniques in the frequency domain, such as those described with reference to Figure 2. The example sampling rates shown in Table 2 represent example sampling rates that may be used by the receiving device 310 to accurately estimate the OFDM channel 315 at a granularity of four resource blocks 375 when the channel bandwidth 370 is 50 MHz.

[0125] [Table 2]

[0126] As shown in Table 2, the FMCW-based channel estimation techniques described herein may reduce the sampling rate by a relatively large amount relative to OFDM-based channel estimation. For example, when the channel bandwidth 370 is 50 MHz and an FMCW signal is used, the sampling rate used by the receiving device 310 to estimate the OFDM channel 315 at a granularity of four resource blocks 375 may be approximately 1.69 percent of the sampling rate that would be used by the receiving device 310 if OFDM-based channel estimation were implemented in the same scenario.

[0127] The FMCW-based OFDM channel estimation described herein can reliably estimate the frequency-domain OFDM channel 315 using a reduced sampling rate. For example, the accuracy of the FMCW-based OFDM channel estimation techniques can be relatively similar to that of OFDM-based OFDM channel estimation techniques using frequency-domain reference signals across a range of packet delay protocols, SCS values, and bandwidths when compared to benchmark values. That is, the described techniques can maintain or improve the accuracy and reliability of the estimation of the frequency-domain OFDM channel 315 while reducing processing and power consumption.

[0128] 4 illustrates an example wireless communication system 400 that supports estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The wireless communication system 400 may implement or be implemented by aspects of the wireless communication system 100 or OFDM channel estimation scheme 300 described with reference to FIGS. 1 and 3. For example, the wireless communication system 400 may include a network entity 105-a and a UE 115-a, which may represent examples of the network entity 105 and the UE 115 described with reference to FIGS. 1-3. The network entity 105-a may communicate with the UE 115-a within the geographic coverage area 110-a via an uplink communication link 410 and a downlink communication link 415. In this example, the network entity 105-a may transmit an FMCW signal 430 to the UE 115-a for use in estimating the OFDM channel.

[0129] The network entity 105-a and the UE 115-a may represent examples of a transmitting device and a receiving device. As used herein, a transmitting device may refer to a wireless device that transmits the FMCW signal 430, and a receiving device may refer to a wireless device that receives the FMCW signal 430. Thus, in the example shown in FIG. 4, the network entity 105-a may be the transmitting device and the UE 115-a may be the receiving device, which may represent examples of the transmitting device 305 and the receiving device 310 described with reference to FIG. 3. While the network entity 105-a is shown as a transmitting device in the example shown in FIG. 4, it should be understood that in some examples, the UE 115-a may be the transmitting device and transmit the FMCW signal 430 to the network entity 105-a, as described in more detail elsewhere herein, including with reference to FIG. 6.

[0130] The UE 115-a may establish a connection with the network entity 105-a for wireless communication via an uplink communication link 410 and a downlink communication link 415. After establishing the connection, the UE 115-a may send a capability message 420 to the network entity 105-a via the uplink communication link 410. The capability message 420 may indicate that the UE 115-a is capable of receiving the FMCW signal 430. The capability message 420 may be an example of an uplink control information (UCI) message, a medium access control-control element (MAC-CE), or some other type of uplink signaling. The UE 115-a may send multiple capability messages 420 dynamically or semi-persistently, in some examples.

[0131] The network entity 105-a may receive the capability message 420 and determine that the UE 115-a is capable of receiving the FMCW signal 430 and performing OFDM channel estimation based on the FMCW signal 430. The network entity 105-a may thereby determine to initiate an FMCW-based OFDM channel estimation procedure. The network entity 105-a may transmit one or more control messages 425 to the UE 115-a via the downlink communication link 415 to facilitate the FMCW-based OFDM channel estimation procedure. The one or more control messages 425 may include, for example, symbol allocation information, FMCW parameter information, a channel estimation trigger, or any combination thereof.

[0132] In some examples, the first control message 425 may indicate whether each symbol of a set of symbols in the OFDM channel is allocated for the FMCW signal 430 or the OFDM signal 435. The FMCW signal 430 and the OFDM signal 435 may be multiplexed in the time domain across the symbols of the OFDM channel, and the first control message 425 may indicate which symbols are allocated for which type of signaling. The second control message 425 may indicate a set of one or more FMCW parameters 445 that the network entity 105-a intends to use to transmit the FMCW signal 430. The set of FMCW parameters 445 may include a bandwidth of the FMCW signal 430, a starting frequency of the FMCW signal 430, a slope of the FMCW signal 430, an initial phase of the FMCW signal 430, or any combination thereof, as described in further detail elsewhere herein, including with reference to FIG. 3 . In some examples, the network entity 105-a may send an RRC configuration to the UE 115-a after establishing communication with the UE 115-a, and the RRC configuration may configure one or more sets of FMCW parameters 445. In such a case, the second control message 425 may be configured to indicate (e.g., via a pointer) an index of one of the multiple configured sets 445 of FMCW parameters.

[0133] In some examples, the third control message 425 transmitted by the network entity 105-a to the UE 115-a may include a trigger (e.g., a request or other trigger information) for the UE 115-a to perform OFDM channel estimation using the FMCW signal 430. In some examples, the network entity 105-a may transmit a single control message including symbol allocation information, a set of FMCW parameters 445, and an OFDM channel estimation trigger. The control message 425 may be a downlink control information (DCI) message, an RRC message, MAC-CE signaling, another type of downlink message, or any combination thereof. The network entity 105-a may transmit the one or more control messages 425 dynamically or semi-statically. In some examples, the network entity 105-a may transmit the one or more control messages 425 based on (e.g., in response to, or after) receiving the capability message 420 from the UE 115-a. That is, the network entity 105-a may transmit a control message 425 to facilitate an FMCW-based OFDM channel estimation procedure based on the UE 115-a indicating that the UE 115-a is capable of receiving the FMCW signal 430.

[0134] The network entity 105-a may then transmit a first FMCW signal 430 to the UE 115-a via downlink communication link 415. The network entity 105-a may transmit the first FMCW signal 430 based on (e.g., using, in accordance with) the set of FMCW parameters 445 indicated via at least one of the one or more control messages 425. The first FMCW signal 430 may be transmitted over an OFDM channel and may be configured to assist the UE 115-a in estimating the frequency-domain OFDM channel.

[0135] The UE 115-a may receive the first FMCW signal 430 via the OFDM channel, and the UE 115-a may generate a second FMCW signal (e.g., a local FMCW signal). The UE 115-a may estimate the OFDM channel based on samples of a combined FMCW signal that includes a combination of the first FMCW signal 430 and the second FMCW signal. The sampling rate used by the UE 115-a to sample the combined FMCW signal and estimate the frequency-domain OFDM channel may be relatively low, as described in further detail elsewhere herein, including with reference to FIG. 3.

[0136] In some examples, the UE 115-a may transmit a report, such as a CSI report 440, indicating information associated with an OFDM channel estimate based on the FMCW signal. The network entity 105-a may transmit a control message 425 including a trigger or request for the UE 115-a to transmit the CSI report 440, and the UE 115-a may generate and transmit the CSI report 440 via the uplink communication link 410 based on the trigger. The network entity 105-a and the UE 115-a may adjust one or more parameters for subsequent communications based on the channel estimate, which may improve the throughput and reliability of subsequent communications between the network entity 105-a and the UE 115-a.

[0137] 4 is shown as the transmitting device, it should be understood that in some examples, the UE 115-a may be the transmitting device. For example, the UE 115-a may transmit a first FMCW signal 430 to the network entity 105-a via the uplink communication link 410, and the network entity 105-a may generate a local FMCW signal and estimate a frequency-domain OFDM channel based on the first FMCW signal 430 and time-domain samples of the local FMCW signal. In such a case, the capability message 420 transmitted by the UE 115-a may indicate that the UE 115-a is capable of transmitting the FMCW signal 430. The control message 425 transmitted by the network entity 105-a may include symbol allocation information, a set of FMCW parameters 445, and a trigger for the UE 115-a to transmit the first FMCW signal 430 (e.g., via the uplink communication link 410). The UE 115-a may transmit a first FMCW signal 430 over the symbols allocated for FMCW based on the indicated set of FMCW parameters 445 and the trigger.

[0138] Devices in the wireless communication system 400 may thereby exchange FMCW signals 430 configured for frequency-domain OFDM channel estimation using time-domain signal processing (e.g., without performing an FFT) and a relatively low sampling rate. The network entity 105-a may determine to transmit one or more control messages or other signaling to facilitate FMCW-based OFDM channel estimation based on the ability of the UE 115-a to either transmit or receive the FMCW signals 430. Examples of signaling that may be exchanged between transmitting and receiving devices are described in further detail elsewhere herein, including with reference to FIGS. 5 and 6.

[0139] 5 illustrates an example process flow 500 supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. Process flow 500 may implement, or may be implemented by, aspects of wireless communication systems 100 and 400 or OFDM channel estimation scheme 300. For example, process flow 500 illustrates communication between a first wireless device 505 and a second wireless device 510, which may represent aspects of the corresponding devices described with reference to FIGS. 1-4. In this example, first wireless device 505 may represent an example of UE 115, and second wireless device 510 may represent an example of network entity 105. In some examples, the devices may exchange signaling to support FMCW-based OFDM channel estimation.

[0140] In the following description of process flow 500, operations between the first wireless device 505 and the second wireless device 510 may be performed in a different order or at different times. Some operations may be omitted from process flow 500, or other operations may be added. Although the first wireless device 505 and the second wireless device 510 are shown performing the operations of process flow 500, some aspects of some operations may also be performed by one or more other wireless devices.

[0141] At 515, the first wireless device 505 may transmit a capabilities message to the second wireless device 510. The capabilities message may indicate whether the first wireless device 505 is capable of receiving an FMCW signal (e.g., FMCW reception capability). In some examples, the capabilities message may indicate whether the first wireless device 505 is capable of estimating a frequency-domain OFDM channel based on the FMCW signal.

[0142] At 520, the second wireless device 510 may transmit a first control message, which may be referred to in some aspects herein as a symbol allocation control message. The first control message may indicate whether one or more symbols of the OFDM channel are allocated for FMCW signals or for OFDM signals. For example, the first control message may include a bitmap or one or more indices configured to allocate a first set of symbols for transmission and reception of OFDM signals and a second set of symbols for transmission and reception of FMCW signals. The OFDM signals and FMCW signals may be time division multiplexed across the symbols of the OFDM channel. The second wireless device 510 may dynamically or semi-persistently transmit the first control message to the first wireless device 505 to indicate the symbol allocation to the first wireless device 505. The first control message may be, for example, a DCI message, a MAC-CE, an RRC message, or any combination thereof.

[0143] At 525, the second wireless device 510 may transmit a second control message, which may be referred to in some aspects herein as an FMCW parameter control message. The second control message may indicate a set of FMCW parameters associated with the first FMCW signal to be transmitted by the second wireless device 510. The set of FMCW parameters may include a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof (e.g., {f c}, {BW}, {S}). The start frequency, bandwidth, and slope may represent examples of the corresponding parameters described with reference to FIG. 3. In some examples, the slope may be based on the bandwidth of the first FMCW signal and the duration of the symbol in which the first FMCW signal is to be transmitted.

[0144] As described in further detail with reference to FIG. 4 , the second control message may be a DCI message, a MAC-CE, an RRC message, some other type of control signaling, or any combination thereof. The second wireless device 510 may transmit the second control message (e.g., an indication of FMCW parameters) dynamically or semi-persistently. In some examples, the second wireless device 510 may transmit one or more RRC messages that may each configure (e.g., pre-configure) a set of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling that indicates to the first wireless device 505 an index for one of the sets of FMCW signals. Additionally or alternatively, the second wireless device 510 may transmit a single RRC message that configures multiple sets of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling that indicates to the first wireless device 505 an index for one of the sets of FMCW signals.

[0145] At 530, the second wireless device 510 may transmit a third control message to the first wireless device 505. The third control message may be referred to as a channel estimation trigger in some aspects herein. The channel estimation trigger may trigger the first wireless device 505 to perform channel estimation with FMCW. That is, the channel estimation trigger may include a request, command, or instruction to trigger the first wireless device 505 to begin monitoring an FMCW signal for use in estimating a frequency-domain OFDM channel.

[0146] Although the symbol allocation control message, the FMCW parameter control message, and the channel estimation trigger (e.g., the first control message through the third control message) are shown as separate control messages, it should be understood that the second wireless device 510 may transmit any quantity of control messages to indicate any combination of the described symbol allocation, FMCW parameters, and channel estimation trigger. In some examples, the second wireless device 510 may transmit a single control message (e.g., a single DCI, MAC-CE, or RRC message) indicating each of the symbol allocation for FMCW, the set of FMCW parameters, and the channel estimation trigger. Additionally or alternatively, the second wireless device 510 may transmit two control messages to indicate the symbol allocation for FMCW and the set of FMCW parameters, respectively. In some examples, receipt by the first wireless device 505 of the symbol allocation for FMCW, the set of FMCW parameters, or both may trigger the first wireless device 505 to perform OFDM channel estimation using the FMCW signal.

[0147] At 535, the second wireless device 510 may generate a first FMCW signal for estimation of an OFDM channel by the first wireless device 505. In some examples, the first FMCW signal may be generated or configured to support frequency-domain OFDM channel estimation. The second wireless device 510 may generate the first FMCW signal as a time-domain signal. The second wireless device 510 may generate the first FMCW signal based on some or all of the information conveyed via the first control message, the second control message, and the third control message. For example, the second wireless device 510 may generate the first FMCW signal based on a set of FMCW parameters indicated via the second control message. In some examples, the second wireless device 510 may generate the first FMCW signal based on (e.g., in response to, or subsequently to) receiving a capability message from the first wireless device 505, based on transmitting any of the first control message through the third control message, or any combination thereof.

[0148] At 540, the second wireless device 510 may transmit the first FMCW signal over the OFDM channel to the first wireless device 505. The first wireless device 505 may receive the first FMCW signal as an analog time-domain signal over the OFDM channel.

[0149] At 545, the first wireless device 505 may generate a second FMCW signal, which may be referred to as a local signal in some examples herein. The first wireless device 505 may generate the second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal (e.g., indicated via the second control message at 525). For example, the first wireless device 505 may generate the second FMCW signal based on the same starting frequency, slope, and bandwidth as the first FMCW signal, as described in further detail elsewhere herein, including with reference to FIG. 3. Generating the second FMCW signal by the first wireless device 505 may be based on one or more configured rules or procedures for FMCW-based OFDM channel estimation. For example, the second FMCW signal may be generated based on FMCW functionality configured to support improved OFDM channel estimation.

[0150] At 550, the first wireless device 505 may estimate an OFDM channel based on the first FMCW signal and the second FMCW signal. To estimate the frequency-domain OFDM channel, the first wireless device 505 may, in some examples, combine the first FMCW signal and the second FMCW signal to generate a combined FMCW signal. The first wireless device 505 may filter the combined FMCW signal (e.g., using an LPF). After filtering, the first wireless device 505 may estimate a sub-band frequency range (e.g., f subband The combined FMCW signal may be sampled in the time domain using a sampling rate based on one or more parameters of the OFDM channel, such as the OFDM frequency, the OFDM time, ...

[0151] The first wireless device 505 can estimate the frequency-domain OFDM channel by estimating a respective value of the OFDM channel for each of a plurality of subbands in the frequency domain of the OFDM channel based on the sampling. For example, the sampling can create a sampling sequence, and each value in the sampling sequence is associated with a respective subband of the OFDM channel. By adjusting the sampling rate used by the first wireless device 505 based on the subband frequency range (e.g., frequency estimation granularity), the first wireless device 505 can change the number of subbands estimated (e.g., the first wireless device 505 can make the frequency-domain OFDM channel estimation finer or coarser granularity). The sampling rate used to sample the combined and filtered FMCW signal can be relatively low (e.g., lower than the sampling rate used to estimate the OFDM channel based on the OFDM signal), which can reduce processing complexity and power consumption in the device.

[0152] At 555, in some examples, the second wireless device 510 may transmit a control message including a trigger (e.g., a request) for the first wireless device 505 to transmit a CSI report or some other report indicative of an OFDM channel estimate. The first wireless device 505 may generate a CSI report based on the CSI report trigger and an OFDM channel estimate based on the FMCW signal. At 560, the first wireless device 505 may transmit the CSI report to the second wireless device 510.

[0153] At 565, the second wireless device 510 and the first wireless device 505 may communicate OFDM signals over the OFDM channel based on the estimate of the frequency-domain OFDM channel. For example, the second wireless device 510 and the first wireless device 505 may transmit and receive uplink data, downlink data, sidelink data, or any combination thereof, where the data may be conveyed via the OFDM signal. Thus, the FMCW-based frequency-domain OFDM channel estimation techniques described herein can provide the first wireless device 505 with reliable and accurate estimation of the frequency-domain OFDM channel using time-domain signal processing and a relatively low sampling rate. By estimating the OFDM channel based on the FMCW signal, the first wireless device 505 can improve throughput, communication reliability, and inter-device coordination while maintaining or reducing processing complexity, latency, and power consumption.

[0154] 6 illustrates an example process flow 600 supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. Process flow 600 may implement, or may be implemented by, aspects of wireless communication systems 100 and 400 or OFDM channel estimation scheme 300. For example, process flow 600 illustrates communication between a first wireless device 605 and a second wireless device 610, which may represent aspects of the corresponding devices described with reference to FIGS. 1-5. In this example, the first wireless device 605 may represent an example of network entity 105, and the second wireless device 610 may represent an example of UE 115. The devices may exchange signaling to support FMCW-based OFDM channel estimation.

[0155] In the following description of process flow 600, operations between the first wireless device 605 and the second wireless device 610 may be performed in a different order or at different times. Some operations may be omitted from process flow 600, or other operations may be added. Although the first wireless device 605 and the second wireless device 610 are shown performing the operations of process flow 600, some aspects of some operations may also be performed by one or more other wireless devices.

[0156] At 615, the second wireless device 610 may transmit a capabilities message to the first wireless device 605. The capabilities message may indicate whether the second wireless device 610 is capable of transmitting FMCW signals (e.g., FMCW transmit capabilities). In some examples, the capabilities message may indicate whether the second wireless device 610 is capable of transmitting FMCW signals configured for frequency-domain OFDM channel estimation.

[0157] At 620, the first wireless device 605 may transmit a first control message, which may be referred to in some aspects herein as a symbol allocation control message. The first control message may indicate whether one or more symbols of the OFDM channel are allocated for FMCW signals or for OFDM signals. For example, the first control message may include a bitmap or one or more indices configured to allocate a first set of symbols for transmission and reception of OFDM signals and a second set of symbols for transmission and reception of FMCW signals. The OFDM signals and FMCW signals may be time division multiplexed across the symbols of the OFDM channel. The first wireless device 605 may dynamically or semi-persistently transmit the first control message to the second wireless device 610 to indicate the symbol allocation to the second wireless device 610. The first control message may be, for example, a DCI message, a MAC-CE, an RRC message, or any combination thereof. In some examples, the first wireless device 605 may transmit a symbol allocation control message based on (e.g., in response to, subsequently to) a capability message from the second wireless device 610.

[0158] At 625, the first wireless device 605 may transmit a second control message, which may be referred to in some aspects herein as an FMCW parameter control message. The second control message may indicate a set of FMCW parameters associated with the first FMCW signal to be transmitted by the second wireless device 610. The set of FMCW parameters may include a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof (e.g., {f c}, {BW}, {S}). The start frequency, bandwidth, and slope may represent examples of the corresponding parameters described with reference to FIG. 3. In some examples, the slope may be based on the bandwidth of the first FMCW signal and the duration of the symbol in which the first FMCW signal is to be transmitted.

[0159] As described in further detail with reference to FIG. 4 , the second control message may be a DCI message, a MAC-CE, an RRC message, some other type of control signaling, or any combination thereof. The first wireless device 605 may transmit the second control message (e.g., an indication of FMCW parameters) dynamically or semi-persistently. In some examples, the first wireless device 605 may transmit one or more RRC messages that may each configure (e.g., pre-configure) a set of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling that indicates to the second wireless device 610 an index for one of the sets of FMCW signals. Additionally or alternatively, the first wireless device 605 may transmit a single RRC message that configures multiple sets of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling that indicates to the second wireless device 610 an index for one of the sets of FMCW signals.

[0160] At 630, the first wireless device 605 may transmit a third control message to the second wireless device 610. The third control message may be referred to as an FMCW transmit trigger in some aspects herein. The FMCW transmit trigger may trigger the second wireless device 610 to transmit an FMCW signal. That is, the FMCW transmit trigger may include a request, command, or instruction to trigger the second wireless device 610 to generate and transmit an FMCW signal that estimates the frequency-domain OFDM channel.

[0161] Although the symbol allocation control message, the FMCW parameter control message, and the FMCW transmission trigger (e.g., the first control message through the third control message) are shown as separate control messages, it should be understood that the first wireless device 605 may transmit any quantity of control messages to indicate any combination of the described symbol allocations, FMCW parameters, and FMCW transmission triggers. In some examples, the first wireless device 605 may transmit a single control message (e.g., a single DCI, MAC-CE, or RRC message) indicating each of the symbol allocation for FMCW, the set of FMCW parameters, and the FMCW transmission trigger. Additionally or alternatively, the first wireless device 605 may transmit two control messages to indicate the symbol allocation for FMCW and the set of FMCW parameters, respectively. In some examples, receipt by the second wireless device 610 of a symbol assignment for FMCW, a set of FMCW parameters, or both, may trigger the second wireless device 610 to transmit an FMCW signal for channel estimation (e.g., via the assigned symbols and using the indicated FMCW parameters). In some examples, any one or more of the first through third control messages may be transmitted by the first wireless device 605 based on (e.g., in response to, subsequent to) a capabilities message from the second wireless device 610 indicating that the second wireless device 610 supports FMCW transmission.

[0162] At 635, the second wireless device 610 may generate a first FMCW signal for estimation of an OFDM channel by the first wireless device 605. In some examples, the first FMCW signal may be generated or configured to support frequency-domain OFDM channel estimation. The second wireless device 610 may generate the first FMCW signal as a time-domain signal. The second wireless device 610 may generate the first FMCW signal based on some or all of the information conveyed via the first control message, the second control message, and the third control message. For example, the second wireless device 610 may generate the first FMCW signal based on a set of FMCW parameters received via the second control message. In some examples, the second wireless device 610 may generate the first FMCW signal based on (e.g., in response to or thereafter) transmitting a capability message, based on receiving any of the first control message through the third control message, or any combination thereof.

[0163] At 640, the second wireless device 610 may transmit the first FMCW signal over the OFDM channel to the first wireless device 605. The first wireless device 605 may receive the first FMCW signal as an analog time-domain signal over the OFDM channel.

[0164] At 645, the first wireless device 605 may generate a second FMCW signal, which may be referred to as a local signal in some examples herein. The first wireless device 605 may generate the second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal (e.g., indicated via the second control message at 625). For example, the first wireless device 605 may generate the second FMCW signal based on the same starting frequency, slope, and bandwidth as the first FMCW signal, as described in further detail elsewhere herein, including with reference to FIG. 3. Generating the second FMCW signal by the first wireless device 605 may be based on one or more configured rules or procedures for FMCW-based OFDM channel estimation. For example, the second FMCW signal may be generated based on FMCW functionality configured to support improved OFDM channel estimation.

[0165] At 650, the first wireless device 605 may estimate an OFDM channel based on the first FMCW signal and the second FMCW signal. To estimate the frequency-domain OFDM channel, the first wireless device 605 may, in some examples, combine the first FMCW signal and the second FMCW signal to generate a combined FMCW signal. The first wireless device 605 may filter the combined FMCW signal (e.g., using an LPF). After filtering, the first wireless device 605 may estimate a subband frequency range or size (e.g., f subband The combined FMCW signal may be sampled in the time domain using a sampling rate that is based on one or more parameters of the OFDM channel, such as the frequency of the OFDM channel (frequency), the time domain (frequency), or the frequency of the OFDM channel (frequency). In some examples, the first wireless device 605 may sample the combined FMCW signal using an ADC, as described in further detail elsewhere herein, including with reference to FIG.

[0166] The first wireless device 605 can estimate the frequency-domain OFDM channel by estimating a respective value of the OFDM channel for each of a plurality of subbands in the frequency domain of the OFDM channel based on the sampling. For example, the sampling can create a sampling sequence, and each value in the sampling sequence is associated with a respective subband of the OFDM channel. By adjusting the sampling rate used by the first wireless device 605 based on the subband frequency range (e.g., frequency estimation granularity), the first wireless device 605 can change the number of estimated subbands (e.g., the first wireless device 605 can make the frequency-domain OFDM channel estimation finer or coarser granularity). The sampling rate used to sample the combined and filtered FMCW signal can be relatively low (e.g., lower than the sampling rate used to estimate the OFDM channel based on the OFDM signal), which can reduce processing complexity and power consumption in the device.

[0167] At 655, the first wireless device 605 and the second wireless device 610 may communicate OFDM signals over an OFDM channel based on the frequency-domain OFDM channel estimate. For example, the first wireless device 605 may transmit one or more follow-up data transmissions to the second wireless device 610 after estimating the frequency-domain OFDM channel. The follow-up data transmissions may be OFDM signals indicative of the channel estimate or other information associated with the frequency-domain OFDM channel estimate. The first wireless device 605 and the second wireless device 610 may transmit and receive uplink data, downlink data, sidelink data, or any combination thereof, and the data may be conveyed via OFDM signals.

[0168] Thus, the FMCW-based frequency-domain OFDM channel estimation techniques described herein can provide the first wireless device 605 with reliable and accurate estimation of the frequency-domain OFDM channel using time-domain signal processing and a relatively low sampling rate. By estimating the OFDM channel based on the FMCW signal, the first wireless device 605 can improve throughput, communication reliability, and inter-device coordination while maintaining or reducing processing complexity, latency, and power consumption.

[0169] 7 shows a block diagram 700 of a device 705 that supports estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The device 705 may be an example of an aspect of a UE 115 or a network entity 105 described herein. The device 705 may include a receiver 710, a transmitter 715, and a communications manager 720. The device 705 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0170] The receiver 710 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various traffic channels (e.g., control channels, data channels, traffic channels related to estimating an OFDM channel using FMCW). The information may be passed to other components of the device 705. The receiver 710 may utilize a single antenna or a set of multiple antennas.

[0171] The transmitter 715 may provide a means for transmitting signals generated by other components of the device 705. For example, the transmitter 715 may transmit information such as packets associated with various traffic channels (e.g., control channels, data channels, traffic channels related to estimating an OFDM channel using FMCW), user data, control information, or any combination thereof. In some examples, the transmitter 715 may be collocated with the receiver 710 in a transceiver module. The transmitter 715 may utilize a single antenna or a set of multiple antennas.

[0172] The communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be examples of means for implementing various aspects of estimating an OFDM channel using FMCW, as described herein. For example, the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may support a method for implementing one or more of the functions described herein.

[0173] In some examples, the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry). The hardware may include a processor, a digital signal processor (DSP), a central processing unit (CPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a microcontroller, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting means for performing the functions described in this disclosure. In some examples, the processor and memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

[0174] Additionally or alternatively, in some examples, the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communications management software or firmware). If implemented in code executed by a processor, the functionality of the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be performed by a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, a microcontroller, or any combination of these or other programmable logic devices (e.g., which may be configured as or otherwise support a means for performing the functions described in this disclosure).

[0175] In some examples, communications manager 720 may be configured to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting) using or otherwise cooperating with receiver 710, transmitter 715, or both. For example, communications manager 720 may receive information from receiver 710 and send information to transmitter 715, or may be integrated in combination with receiver 710, transmitter 715, or both to acquire information, output information, or perform various other operations described herein.

[0176] Communications manager 720 may support wireless communications in a first wireless device according to examples disclosed herein. For example, communications manager 720 may be configured as or otherwise support a means for receiving a first FMCW signal over an OFDM channel. Communications manager 720 may be configured as or otherwise support a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. Communications manager 720 may be configured as or otherwise support a means for estimating an OFDM channel based on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal in the time domain.

[0177] Additionally or alternatively, communications manager 720 may support wireless communications at a second wireless device according to examples disclosed herein. For example, communications manager 720 may be configured as or otherwise support a means for generating an FMCW signal for estimation of an OFDM channel by a first wireless device. Communications manager 720 may be configured as or otherwise support a means for transmitting an FMCW signal over an OFDM channel. Communications manager 720 may be configured as or otherwise support a means for communicating an OFDM signal with a first wireless device over an OFDM channel based on estimation of the OFDM channel.

[0178] By including or configuring a communications manager 720 according to examples described herein, the device 705 (e.g., a processor controlling or otherwise coupled to the receiver 710, the transmitter 715, the communications manager 720, or a combination thereof) may support techniques for reduced processing, reduced power consumption, and more efficient utilization of communications resources.

[0179] 8 shows a block diagram 800 of a device 805 that supports estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The device 805 may be an example of an aspect of a device 705, a UE 115, or a network entity 105 described herein. The device 805 may include a receiver 810, a transmitter 815, and a communications manager 820. The device 805 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0180] The receiver 810 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various traffic channels (e.g., control channels, data channels, traffic channels related to estimating an OFDM channel using FMCW). The information may be passed to other components of the device 805. The receiver 810 may utilize a single antenna or a set of multiple antennas.

[0181] The transmitter 815 may provide a means for transmitting signals generated by other components of the device 805. For example, the transmitter 815 may transmit information such as packets associated with various traffic channels (e.g., control channels, data channels, traffic channels related to estimating an OFDM channel using FMCW), user data, control information, or any combination thereof. In some examples, the transmitter 815 may be collocated with the receiver 810 in a transceiver module. The transmitter 815 may utilize a single antenna or a set of multiple antennas.

[0182] Device 805 or its various components may be an example of a means for implementing various aspects of estimating an OFDM channel using FMCW as described herein. For example, communications manager 820 may include an FMCW signal component 825, an FMCW signal generation component 830, an OFDM estimation component 835, an OFDM signal component 840, or any combination thereof. Communications manager 820 may be an example of an aspect of communications manager 720 as described herein. In some examples, communications manager 820, or its various components, may be configured to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting) using or otherwise cooperating with receiver 810, transmitter 815, or both. For example, communications manager 820 may receive information from receiver 810 and send information to transmitter 815, or may be integrated in combination with receiver 810, transmitter 815, or both to acquire information, output information, or perform various other operations as described herein.

[0183] The communications manager 820 may support wireless communications in a first wireless device according to examples disclosed herein. The FMCW signal component 825 may be configured as or otherwise support a means for receiving a first FMCW signal over an OFDM channel. The FMCW signal generation component 830 may be configured as or otherwise support a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The OFDM estimation component 835 may be configured as or otherwise support a means for estimating an OFDM channel based on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal in the time domain.

[0184] Additionally or alternatively, communications manager 820 may support wireless communications with a second wireless device according to examples disclosed herein. FMCW signal generation component 830 may be configured as or otherwise support a means for generating an FMCW signal for OFDM channel estimation by the first wireless device. FMCW signal component 825 may be configured as or otherwise support a means for transmitting an FMCW signal over an OFDM channel. OFDM signal component 840 may be configured as or otherwise support a means for communicating an OFDM signal with the first wireless device over an OFDM channel based on the OFDM channel estimation.

[0185] 9 shows a block diagram 900 of a communications manager 920 that supports estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. Communications manager 920 may be an example of aspects of communications manager 720, communications manager 820, or both, described herein. Communications manager 920 or its various components may be an example of a means for implementing various aspects of estimating OFDM channels using FMCW, described herein. For example, communications manager 920 may include an FMCW signal component 925, an FMCW signal generation component 930, an OFDM estimation component 935, an OFDM signal component 940, a filtering component 945, an FMCW sampling component 950, an FMCW capability component 955, a symbol allocation component 960, an FMCW parameters component 965, a CSI component 970, an FMCW component 975, or any combination thereof. Each of these components may communicate directly or indirectly with one another (e.g., via one or more buses), which may include communication within a protocol layer of a protocol stack, communication associated with a logical channel of a protocol stack (e.g., between protocol layers of a protocol stack, within a device, component, or virtualization component associated with network entity 105, between devices, components, or virtualization components associated with network entity 105), or any combination thereof.

[0186] The communications manager 920 may support wireless communications in a first wireless device according to examples disclosed herein. The FMCW signal component 925 may be configured as or otherwise support a means for receiving a first FMCW signal over an OFDM channel. The FMCW signal generation component 930 may be configured as or otherwise support a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The OFDM estimation component 935 may be configured as or otherwise support a means for estimating an OFDM channel based on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal in the time domain.

[0187] In some examples, to support estimating the OFDM channel, filtering component 945 may be configured as or otherwise support a means for filtering the combined FMCW signal. In some examples, to support estimating the OFDM channel, FMCW sampling component 950 may be configured as or otherwise support a means for sampling the combined FMCW signal in the time domain after filtering using a sampling rate based on a subband frequency range of the OFDM channel, where estimating includes estimating a respective value of the OFDM channel for each subband of a set of multiple subbands in the frequency domain of the OFDM channel based on the sampling.

[0188] In some examples, the OFDM signal component 940 may be configured as or otherwise support a means for receiving one or more OFDM signals time division multiplexed with the first FMCW signal within an OFDM channel.

[0189] In some examples, the FMCW capability component 955 may be configured as or otherwise support a means for transmitting a capability message indicating that the first wireless device is capable of estimating an OFDM channel using a time-domain FMCW signal, and the first wireless device comprises a UE. In some examples, the FMCW capability component 955 may be configured as or otherwise support a means for receiving a capability message indicating that the second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, and the first wireless device comprises a network entity.

[0190] In some examples, the symbol allocation component 960 may be configured with or otherwise support a means for receiving a control message indicating whether one or more symbols of the OFDM channel are allocated for FMCW signals, the first FMCW signal being received within one symbol of the one or more symbols indicated as allocated for FMCW signals, and the first wireless device including a UE.

[0191] In some examples, the symbol allocation component 960 may be configured with or otherwise support a means for transmitting a control message indicating whether one or more symbols of the OFDM channel are allocated for an FMCW signal or an OFDM signal, wherein the first FMCW signal is received within one of the one or more symbols allocated for the FMCW signal based on the control message, and the first wireless device includes a network entity.

[0192] In some examples, the FMCW parameters component 965 may be configured as or otherwise support a means for receiving a control message indicating a set of FMCW parameters including a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof, where the slope is based on the bandwidth of the first FMCW signal and the duration of the symbol in which the first FMCW signal is received.

[0193] In some examples, the FMCW parameters component 965 may be configured as or otherwise support a means for transmitting a control message indicating a set of FMCW parameters including a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof, where the slope is based on the bandwidth of the first FMCW signal and the duration of the symbol at which the first FMCW signal is received, and where receiving the first FMCW signal is based on the set of FMCW parameters.

[0194] In some examples, the OFDM estimation component 935 may be configured with or otherwise support a means for a first wireless device to receive a control message including a trigger for performing OFDM channel estimation using the FMCW signal, where estimating the OFDM channel using the first FMCW signal and the second FMCW signal is based on the trigger, and where the first wireless device includes a UE.

[0195] In some examples, the CSI component 970 may be configured or otherwise support a means for receiving a control message including a trigger for the first wireless device to transmit a channel state information report based on the first FMCW signal. In some examples, the CSI component 970 may be configured or otherwise support a means for transmitting a channel state information report including a set of channel state information parameters based on receiving the trigger and estimating the OFDM channel.

[0196] In some examples, the FMCW signal component 925 may be configured with or otherwise support a means for the second wireless device to transmit a control message including a trigger for the second wireless device to transmit the first FMCW signal. In some examples, the first wireless device includes a UE or a network entity.

[0197] Additionally or alternatively, communications manager 920 may support wireless communications with a second wireless device in accordance with examples disclosed herein. In some examples, FMCW signal generation component 930 may be configured as or otherwise support a means for generating an FMCW signal for estimation of an OFDM channel by the first wireless device. In some examples, FMCW signal component 925 may be configured as or otherwise support a means for transmitting an FMCW signal over an OFDM channel. OFDM signal component 940 may be configured as or otherwise support a means for communicating an OFDM signal with the first wireless device over an OFDM channel based on the estimation of the OFDM channel.

[0198] In some examples, OFDM signal component 940 may be configured with or otherwise support a means for transmitting one or more OFDM signals time division multiplexed with an FMCW signal within an OFDM channel.

[0199] In some examples, the FMCW capability component 955 may be configured with or otherwise support a means for transmitting a capability message indicating that the second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, where the second wireless device comprises a UE.

[0200] In some examples, the FMCW capability component 955 may be configured as or otherwise support a means for receiving a capability message indicating that the first wireless device is capable of estimating an OFDM channel using a time-domain FMCW signal, and the second wireless device includes a network entity.

[0201] In some examples, the symbol allocation component 960 may be configured with or otherwise support a means for receiving a control message indicating whether one or more symbols of the OFDM channel are allocated for an FMCW signal, the FMCW signal being transmitted within one of the one or more symbols allocated for the FMCW signal based on the control message, and the second wireless device including a UE.

[0202] In some examples, the symbol allocation component 960 may be configured with or otherwise support a means for transmitting a control message indicating whether one or more symbols of the OFDM channel are allocated for an FMCW signal or an OFDM signal, the FMCW signal being transmitted within one of the one or more symbols allocated for the FMCW signal, and the second wireless device includes a network entity.

[0203] In some examples, the FMCW parameters component 965 may be configured as or otherwise support a means for receiving a control message indicating a set of FMCW parameters associated with the FMCW signal, including a starting frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, where the slope is based on the bandwidth of the FMCW signal and the duration of the symbol in which the FMCW signal is transmitted, and where transmitting the FMCW signal is based on the set of FMCW parameters.

[0204] In some examples, the FMCW parameters component 965 may be configured as or otherwise support a means for transmitting a control message indicating a set of FMCW parameters associated with the FMCW signal, including a starting frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, where the slope is based on the bandwidth of the FMCW signal and the duration of the symbol in which the FMCW signal is transmitted, and where the estimation of the OFDM channel is based on the set of FMCW parameters.

[0205] In some examples, the OFDM estimation component 935 may be configured or otherwise support a means for the first wireless device to transmit a control message including a trigger for performing OFDM channel estimation using the FMCW signal, the estimation of the OFDM channel being based on the trigger, and the second wireless device including the network entity.

[0206] In some examples, the CSI component 970 may be configured or otherwise support a means for transmitting a control message including a trigger for the first wireless device to transmit a channel state information report based on the FMCW signal. In some examples, the CSI component 970 may be configured or otherwise support a means for receiving a channel state information report including a set of channel state information parameters based at least in part on the trigger.

[0207] In some examples, the FMCW component 975 may be configured or otherwise support a means for the second wireless device to receive a control message including a trigger to transmit an FMCW signal, where transmitting the FMCW signal is based on the trigger.

[0208] In some examples, the second wireless device includes a UE or a network entity.

[0209] 10 shows a diagram of a system 1000 including a device 1005 that supports estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The device 1005 may be an example of or include components of a device 705, a device 805, or a UE 115 described herein. The device 1005 may communicate (e.g., wirelessly) with one or more network entities 105, one or more UEs 115, or any combination thereof. The device 1005 may include components for two-way voice and data communication, including components for transmitting and receiving communications, such as a communications manager 1020, an input / output (I / O) controller 1010, a transceiver 1015, an antenna 1025, a memory 1030, code 1035, and a processor 1040. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., bus 1045).

[0210] The I / O controller 1010 may manage input and output signals for the device 1005. The I / O controller 1010 may also manage peripheral devices not integrated into the device 1005. In some cases, the I / O controller 1010 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 1010 may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another well-known operating system. Additionally or alternatively, the I / O controller 1010 may represent or be able to interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 1010 may be implemented as part of a processor, such as the processor 1040. In some cases, a user may interact with the device 1005 through the I / O controller 1010 or through hardware components controlled by the I / O controller 1010 .

[0211] In some cases, the device 1005 may include a single antenna 1025. However, in some other cases, the device 1005 may have two or more antennas 1025 that may be capable of simultaneously transmitting or receiving multiple wireless transmissions. The transceiver 1015 may communicate bidirectionally via one or more antennas 1025, a wired link, or a wireless link as described herein. For example, the transceiver 1015 may represent a wireless transceiver, but may communicate bidirectionally with another wireless transceiver. The transceiver 1015 may also include a modem for modulating packets, providing the modulated packets to one or more antennas 1025 for transmission, and demodulating packets received from the one or more antennas 1025. The transceiver 1015, or the transceiver 1015 and one or more antennas 1025, may be an example of the transmitter 715, transmitter 815, receiver 710, receiver 810, or any combination thereof or component thereof, as described herein.

[0212] The memory 1030 may include random access memory (RAM) and read-only memory (ROM). The memory 1030 may store computer-readable computer-executable code 1035, which includes instructions that, when executed by the processor 1040, cause the device 1005 to perform various functions described herein. The code 1035 may be stored on a non-transitory computer-readable medium, such as system memory or another type of memory. In some cases, the code 1035 may not be directly executable by the processor 1040, but may instead cause a computer to perform (e.g., when compiled and executed) the functions described herein. In some cases, the memory 1030 may include a basic I / O system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices, among other things.

[0213] The processor 1040 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 1040 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated into the processor 1040. The processor 1040 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1030) to cause the device 1005 to perform various functions (e.g., functions or tasks supporting estimating an OFDM channel using FMCW). For example, the device 1005 or components of the device 1005 may include the processor 1040 and the memory 1030 coupled to or associated with the processor 1040, where the processor 1040 and the memory 1030 are configured to perform various functions described herein.

[0214] Communications manager 1020 may support wireless communications in a first wireless device according to examples disclosed herein. For example, communications manager 1020 may be configured as or otherwise support a means for receiving a first FMCW signal over an OFDM channel. Communications manager 1020 may be configured as or otherwise support a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. Communications manager 1020 may be configured as or otherwise support a means for estimating an OFDM channel based on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal in the time domain.

[0215] Additionally or alternatively, communications manager 1020 may support wireless communications at a second wireless device according to examples disclosed herein. For example, communications manager 1020 may be configured as or otherwise support a means for generating an FMCW signal for estimation of an OFDM channel by a first wireless device. Communications manager 1020 may be configured as or otherwise support a means for transmitting an FMCW signal over an OFDM channel. Communications manager 1020 may be configured as or otherwise support a means for communicating an OFDM signal with a first wireless device over an OFDM channel based on the estimation of the OFDM channel.

[0216] By including or configuring a communications manager 1020 in accordance with examples described herein, the device 1005 may support techniques for improved communication reliability, reduced latency, improved user experience related to reduced processing, reduced power consumption, more efficient use of communications resources, improved coordination between devices, and longer battery life.

[0217] In some examples, communications manager 1020 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with transceiver 1015, one or more antennas 1025, or any combination thereof. Although communications manager 1020 is shown as a separate component, in some examples, one or more functions described with reference to communications manager 1020 may be supported by or performed by processor 1040, memory 1030, code 1035, or any combination thereof. For example, code 1035 may include instructions executable by processor 1040 to cause device 1005 to perform various aspects of estimating OFDM channels using FMCW as described herein, or processor 1040 and memory 1030 may be otherwise configured to perform or support such operations.

[0218] 11 shows a diagram of a system 1100 including a device 1105 that supports estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The device 1105 may be an example of or include components of a device 705, a device 805, or a network entity 105 described herein. The device 1105 may communicate with one or more network entities 105, one or more UEs 115, or any combination thereof, which may include communication via one or more wired interfaces, one or more wireless interfaces, or a combination thereof. The device 1105 may include components that support outputting and obtaining communications, such as a communications manager 1120, a transceiver 1110, an antenna 1115, a memory 1125, code 1130, and a processor 1135. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., bus 1140).

[0219] The transceiver 1110 may support bidirectional communication via a wired link, a wireless link, or both, as described herein. In some examples, the transceiver 1110 may include a wired transceiver and may communicate bidirectionally with another wired transceiver. Additionally or alternatively, in some examples, the transceiver 1110 may include a wireless transceiver and may communicate bidirectionally with another wireless transceiver. In some examples, the device 1105 may include one or more antennas 1115 that may be capable of transmitting or receiving (e.g., simultaneously) wireless transmissions. The transceiver 1110 may also include a modem for modulating signals, providing the modulated signals for transmission (e.g., by one or more antennas 1115 or by a wired transmitter), receiving the modulated signals (e.g., from one or more antennas 1115 or from a wired receiver), and demodulating the signals. In some implementations, the transceiver 1110 may include one or more interfaces, such as one or more interfaces coupled with one or more antennas 1115 configured to support various receive or acquisition operations, or one or more interfaces coupled with one or more antennas 1115 configured to support various transmit or output operations, or a combination thereof. In some implementations, the transceiver 1110 may include or be configured to couple to one or more processors or memory components operable to perform or support operations based on received or acquired information or signals, or to generate information or other signals for transmission or other output, or any combination thereof. In some implementations, the transceiver 1110, or the transceiver 1110 and one or more antennas 1115, or the transceiver 1110 and one or more antennas 1115 and one or more processors or memory components (e.g., the processor 1135, or the memory 1125, or both) may be included on a chip or chip assembly installed on the device 1105.In some examples, the transceiver may be operable to support communication over one or more communication links (e.g., communication link 125, backhaul communication link 120, midhaul communication link 162, fronthaul communication link 168).

[0220] The memory 1125 may include RAM and ROM. The memory 1125 may store computer-readable computer-executable code 1130, which includes instructions that, when executed by the processor 1135, cause the device 1105 to perform various functions described herein. The code 1130 may be stored on a non-transitory computer-readable medium, such as system memory or another type of memory. In some cases, the code 1130 may not be directly executable by the processor 1135, but may instead cause a computer (e.g., when compiled and executed) to perform functions described herein. In some cases, the memory 1125 may include a BIOS, which may control basic hardware or software operations, such as interaction with peripheral components or devices, among other things.

[0221] The processor 1135 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA, a microcontroller, a programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof). In some cases, the processor 1135 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated into the processor 1135. The processor 1135 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1125) to cause the device 1105 to perform various functions (e.g., functions or tasks supporting estimating an OFDM channel using FMCW). For example, the device 1105 or a component of the device 1105 may include the processor 1135 and the memory 1125 coupled to the processor 1135, where the processor 1135 and the memory 1125 are configured to perform various functions described herein. Processor 1135 may be an example of a cloud computing platform (e.g., one or more physical nodes and supporting software such as an operating system, virtual machine, or container instance) that may host functionality (e.g., by executing code 1130) to perform the functionality of device 1105. Processor 1135 may be any one or more suitable processors capable of executing scripts or instructions of one or more software programs stored on device 1105 (e.g., in memory 1125). In some implementations, processor 1135 may be a component of a processing system. A processing system may generally refer to a system or set of machines or components that receives input, processes the input, and produces a set of output (e.g., that may be passed to other systems or components of device 1105).For example, the processing system of device 1105 may refer to a system that includes various other components or subcomponents of device 1105, such as processor 1135, or transceiver 1110, or communications manager 1120, or other components or combinations of components of device 1105. The processing system of device 1105 may interface with other components of device 1105 and process information (such as input or signals) received from other components or output information to other components. For example, a chip or modem of device 1105 may include a processing system and one or more interfaces for outputting information, acquiring information, or both. The one or more interfaces may be implemented as or otherwise include a first interface configured to output information and a second interface configured to acquire information, or the same interface configured to output information and acquire information, among other implementations. In some implementations, the one or more interfaces refer to an interface between the processing system and a transmitter of the chip or modem, such that device 1105 may transmit information output from the chip or modem. Additionally or alternatively, in some implementations, the one or more interfaces refer to an interface between a processing system and a receiver of a chip or modem, such that the device 1105 obtains information or signal input, and that information can be passed to the processing system. Those skilled in the art will readily recognize that the first interface can also obtain information or signal input, and the second interface can also output information or signal output.

[0222] In some examples, bus 1140 may support communication of (e.g., within) protocol layers of a protocol stack. In some examples, bus 1140 may support communication associated with logical channels of a protocol stack (e.g., between protocol layers of the protocol stack), which may include communication conducted within a component of device 1105 or between different components of device 1105, which may be collocated or located in different locations (e.g., device 1105 may refer to a system in which one or more of communications manager 1120, transceiver 1110, memory 1125, code 1130, and processor 1135 may be located in one of or split among different components).

[0223] In some examples, the communications manager 1120 may manage aspects of communications with the core network 130 (e.g., over one or more wired or wireless backhaul links). For example, the communications manager 1120 may manage the forwarding of data communications for client devices, such as one or more UEs 115. In some examples, the communications manager 1120 may manage communications with other network entities 105 and may include a controller or scheduler for cooperating with the other network entities 105 to control communications with the UEs 115. In some examples, the communications manager 1120 may support an X2 interface within LTE / LTE-A wireless communications network technologies to provide communications between network entities 105.

[0224] Communications manager 1120 may support wireless communications in a first wireless device according to examples disclosed herein. For example, communications manager 1120 may be configured as or otherwise support a means for receiving a first FMCW signal over an OFDM channel. Communications manager 1120 may be configured as or otherwise support a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. Communications manager 1120 may be configured as or otherwise support a means for estimating an OFDM channel based on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal in the time domain.

[0225] Additionally or alternatively, communications manager 1120 may support wireless communications at a second wireless device according to examples disclosed herein. For example, communications manager 1120 may be configured as or otherwise support a means for generating an FMCW signal for estimation of an OFDM channel by a first wireless device. Communications manager 1120 may be configured as or otherwise support a means for transmitting an FMCW signal over an OFDM channel. Communications manager 1120 may be configured as or otherwise support a means for communicating an OFDM signal with a first wireless device over an OFDM channel based on the estimation of the OFDM channel.

[0226] By including or configuring a communications manager 1120 in accordance with examples described herein, the device 1105 may support techniques for improved communication reliability, reduced latency, improved user experience related to reduced processing, reduced power consumption, more efficient utilization of communications resources, and improved coordination between devices.

[0227] In some examples, communications manager 1120 may be configured to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting) using or otherwise cooperating with transceiver 1110, one or more antennas 1115 (e.g., if applicable), or any combination thereof. Although communications manager 1120 is shown as a separate component, in some examples, one or more functions described with reference to communications manager 1120 may be supported or implemented by transceiver 1110, processor 1135, memory 1125, code 1130, or any combination thereof. For example, code 1130 may include instructions executable by processor 1135 to cause device 1105 to perform various aspects of estimating OFDM channels using FMCW as described herein, or processor 1135 and memory 1125 may be otherwise configured to perform or support such operations.

[0228] FIG. 12 shows a flow diagram illustrating a method 1200 for supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The operations of method 1200 may be implemented by a UE or network entity described herein or components thereof. For example, the operations of method 1200 may be performed by the UE 115 or network entity described with reference to FIGS. 1 through 11. In some examples, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the described functionality. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functionality.

[0229] At 1205, the method may include receiving a first FMCW signal over an OFDM channel. The operations of 1205 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1205 may be performed by FMCW signal component 925 described with reference to FIG. 9.

[0230] At 1210, the method may include generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The operations of 1210 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1210 may be performed by FMCW signal generation component 930 described with reference to FIG. 9.

[0231] At 1215, the method may include estimating an OFDM channel based on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal in the time domain. The operations of 1215 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1215 may be performed by OFDM estimation component 935 described with reference to FIG. 9.

[0232] FIG. 13 shows a flow diagram illustrating a method 1300 for supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The operations of method 1300 may be implemented by a UE or network entity described herein or components thereof. For example, the operations of method 1300 may be performed by a UE 115 or network entity described with reference to FIGS. 1 through 11. In some examples, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the described functionality. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functionality.

[0233] At 1305, the method may include receiving a first FMCW signal over an OFDM channel. The operations of 1305 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1305 may be performed by FMCW signal component 925 described with reference to FIG. 9.

[0234] At 1310, the method may include generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The operations of 1310 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1310 may be performed by FMCW signal generation component 930 described with reference to FIG. 9.

[0235] At 1315, the method may include filtering, in the time domain, a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal. The operations of 1315 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1315 may be performed by filtering component 945 described with reference to FIG. 9.

[0236] At 1320, the method may include sampling the combined FMCW signal in the time domain after filtering using a sampling rate based on the subband frequency range of the OFDM channel. The operations of 1320 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1320 may be performed by FMCW sampling component 950 described with reference to FIG. 9.

[0237] At 1325, the method may include estimating, based on the sampling, a respective value of the OFDM channel for each subband of the set of subbands in the frequency domain of the OFDM channel. The operations of 1325 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1325 may be performed by OFDM estimation component 935 described with reference to FIG. 9.

[0238] FIG. 14 shows a flow diagram illustrating a method 1400 for supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The operations of method 1400 may be implemented by a UE or a network entity or components thereof described herein. For example, the operations of method 1400 may be performed by a UE 115 or a network entity described with reference to FIGS. 1 through 11. In some examples, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the described functionality. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functionality.

[0239] At 1405, the method may include receiving a first FMCW signal over an OFDM channel. The operations of 1405 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1405 may be performed by FMCW signal component 925 described with reference to FIG. 9.

[0240] At 1410, the method may include receiving one or more OFDM signals time division multiplexed with the first FMCW signal in an OFDM channel. The operations of 1410 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1410 may be performed by OFDM signal component 940 described with reference to FIG. 9.

[0241] At 1415, the method may include generating a second FMCW signal based on the set of FMCW parameters associated with the first FMCW signal. The operations of 1415 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1415 may be performed by FMCW signal generation component 930 described with reference to FIG. 9.

[0242] At 1420, the method may include estimating an OFDM channel in the time domain based on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal. The operations of 1420 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1420 may be performed by OFDM estimation component 935 described with reference to FIG. 9.

[0243] FIG. 15 shows a flow diagram illustrating a method 1500 for supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The operations of method 1500 may be implemented by a UE or a network entity or components thereof described herein. For example, the operations of method 1500 may be performed by a UE 115 or a network entity described with reference to FIGS. 1 through 11. In some examples, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the described functionality. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functionality.

[0244] At 1505, the method may include generating an FMCW signal for estimation of the OFDM channel by the first wireless device. The operations of 1505 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1505 may be performed by FMCW signal generation component 930 described with reference to FIG. 9.

[0245] At 1510, the method may include transmitting an FMCW signal over an OFDM channel. The operations of 1510 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1510 may be performed by the FMCW signal component 925 described with reference to FIG. 9.

[0246] At 1515, the method may include communicating an OFDM signal with the first wireless device over the OFDM channel based on the estimate of the OFDM channel. The operations of 1515 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1515 may be performed by OFDM signal component 940 described with reference to FIG. 9.

[0247] FIG. 16 shows a flow diagram illustrating a method 1600 for supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The operations of method 1600 may be implemented by a UE or network entity described herein or components thereof. For example, the operations of method 1600 may be performed by a UE 115 or network entity described with reference to FIGS. 1 through 11. In some examples, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the described functionality. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functionality.

[0248] At 1605, the method may include generating an FMCW signal for estimation of the OFDM channel by the first wireless device. The operations of 1605 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1605 may be performed by FMCW signal generation component 930 described with reference to FIG. 9.

[0249] At 1610, the method may include transmitting an FMCW signal over an OFDM channel. The operations of 1610 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1610 may be performed by the FMCW signal component 925 described with reference to FIG. 9.

[0250] At 1615, the method may include transmitting one or more OFDM signals time division multiplexed with the FMCW signal in the OFDM channel. The operations of 1615 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1615 may be performed by OFDM signal component 940 described with reference to FIG. 9.

[0251] At 1620, the method may include communicating an OFDM signal with the first wireless device over the OFDM channel based on the estimate of the OFDM channel. The operations of 1620 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1620 may be performed by OFDM signal component 940 described with reference to FIG. 9.

[0252] FIG. 17 shows a flow diagram illustrating a method 1700 for supporting estimating OFDM channels using FMCW in accordance with one or more aspects of the present disclosure. The operations of method 1700 may be implemented by a UE or network entity described herein or components thereof. For example, the operations of method 1700 may be performed by a UE 115 or network entity described with reference to FIGS. 1 through 11. In some examples, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the described functionality. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functionality.

[0253] At 1705, the method may include transmitting a capability message indicating that the second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, the second wireless device including a UE. The operations of 1705 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1705 may be performed by the FMCW capability component 955 described with reference to FIG. 9.

[0254] At 1710, the method may include generating an FMCW signal for estimation of the OFDM channel by the first wireless device. The operations of 1710 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1710 may be performed by FMCW signal generation component 930 described with reference to FIG. 9.

[0255] At 1715, the method may include transmitting an FMCW signal over the OFDM channel. The operations of 1715 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1715 may be performed by FMCW signal component 925 described with reference to FIG. 9.

[0256] At 1720, the method may include communicating an OFDM signal with the first wireless device over the OFDM channel based on the estimate of the OFDM channel. The operations of 1720 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1720 may be performed by OFDM signal component 940 described with reference to FIG. 9.

[0257] The following provides a summary of aspects of the present disclosure.

[0258] Aspect 1: A method for wireless communication in a first wireless device, the method including: receiving a first FMCW signal via an OFDM channel; generating a second FMCW signal based at least in part on a set of FMCW parameters associated with the first FMCW signal; and estimating an OFDM channel in a time domain based at least in part on samples of a combined FMCW signal that includes a combination of the first FMCW signal and the second FMCW signal.

[0259] Aspect 2: The method of aspect 1, wherein estimating the OFDM channel includes filtering the combined FMCW signal and, after filtering, sampling the combined FMCW signal in the time domain using a sampling rate based at least in part on a subband frequency range of the OFDM channel, and wherein estimating includes estimating respective values ​​of the OFDM channel for each subband of a plurality of subbands in the frequency domain of the OFDM channel based at least in part on the sampling.

[0260] Aspect 3: The method of aspect 1 or 2, further comprising receiving one or more OFDM signals time division multiplexed with the first FMCW signal in an OFDM channel.

[0261] Aspect 4: The method of any one of aspects 1 to 3, further comprising: transmitting a capability message indicating that the first wireless device is capable of estimating the OFDM channel using the time-domain FMCW signal, wherein the first wireless device comprises a UE.

[0262] Aspect 5: The method of any one of aspects 1 to 3, further comprising receiving a capability message indicating that the second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, and wherein the first wireless device includes a network entity.

[0263] Aspect 6: The method of any of Aspects 1 to 4, further comprising receiving a control message indicating whether one or more symbols of the OFDM channel are allocated for FMCW signals, wherein the first FMCW signal is received within one symbol of the set of one or more symbols indicated as allocated to FMCW signals, and the first wireless device comprises a UE.

[0264] Aspect 7: The method of any of Aspects 1 to 3 and 5, further comprising transmitting a control message indicating whether one or more symbols of the OFDM channel are allocated for FMCW signals or for OFDM signals, wherein the first FMCW signal is received within one symbol of the set of one or more symbols allocated for FMCW signals based at least in part on the control message, and wherein the first wireless device includes a network entity.

[0265] Aspect 8: The method of any of Aspects 1 to 4 and 6, further comprising receiving a control message indicating a set of FMCW parameters including a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof, wherein the slope is based at least in part on the bandwidth of the first FMCW signal and a duration of the symbol in which the first FMCW signal is received.

[0266] Aspect 9: The method of any of Aspects 1 to 3, 5, and 7, further including transmitting a control message indicating a set of FMCW parameters including a starting frequency of the first FMCW signal, a bandwidth of the first FMCW signal, a slope of the first FMCW signal, or any combination thereof, wherein the slope is based at least in part on the bandwidth of the first FMCW signal and the duration of the symbol in which the first FMCW signal is received, and wherein receiving the first FMCW signal is based at least in part on the set of FMCW parameters.

[0267] Aspect 10: The method of any of aspects 1 to 4, 6, and 8, further comprising: a first wireless device receiving a control message including a trigger to perform OFDM channel estimation using the FMCW signal; estimating the OFDM channel using the first FMCW signal and the second FMCW signal based at least in part on the trigger; and the first wireless device including a UE.

[0268] Aspect 11: The method of any of aspects 1 to 4, 6, 8, and 10, further including: receiving, by the first wireless device, a control message including a trigger for transmitting a CSI report based at least in part on the first FMCW signal; and transmitting, based at least in part on receiving the trigger and estimating the OFDM channel, the CSI report including the set of CSI parameters.

[0269] Aspect 12: The method of any of aspects 1 to 3, 5, 7, and 9, further comprising: the second wireless device transmitting a control message including a trigger to transmit the first FMCW signal.

[0270] Aspect 13: The method of any of aspects 1 to 12, wherein the first wireless device includes a UE or a network entity.

[0271] Aspect 14: A method for wireless communication in a second wireless device, the method including: generating an FMCW signal for estimation of an OFDM channel by a first wireless device; transmitting the FMCW signal over the OFDM channel; and communicating the OFDM signal with the first wireless device over the OFDM channel based at least in part on the estimation of the OFDM channel.

[0272] Aspect 15: The method of aspect 14, further comprising transmitting one or more OFDM signals time division multiplexed with the FMCW signal in an OFDM channel.

[0273] Aspect 16: The method of aspect 14 or 15, further comprising: transmitting a capability message indicating that the second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, wherein the second wireless device includes a UE.

[0274] Aspect 17: The method of aspect 14 or 15, further comprising receiving a capability message indicating that the first wireless device is capable of estimating the OFDM channel using the time-domain FMCW signal, and the second wireless device includes a network entity.

[0275] Aspect 18: The method of any of aspects 14 to 16, further comprising receiving a control message indicating whether one or more symbols of the OFDM channel are allocated for an FMCW signal, wherein the FMCW signal is transmitted within one symbol of the set of one or more symbols allocated for the FMCW signal based at least in part on the control message, and the second wireless device includes a UE.

[0276] Aspect 19: The method of any of Aspects 14, 15, and 17, further comprising: transmitting a control message indicating whether one or more symbols of the OFDM channel are allocated for an FMCW signal or an OFDM signal, wherein the FMCW signal is transmitted within one of the one or more symbols allocated for the FMCW signal, and the second wireless device includes a network entity.

[0277] Aspect 20: The method of any of aspects 14, 16, and 18, further including receiving a control message indicating a set of FMCW parameters associated with the FMCW signal, the set of FMCW parameters including a starting frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, wherein the slope is based at least in part on the bandwidth of the FMCW signal and a duration of a symbol in which the FMCW signal is transmitted, and wherein transmitting the FMCW signal is based at least in part on the set of FMCW parameters.

[0278] Aspect 21: The method of any of aspects 14, 15, 17, and 19, further comprising: transmitting a control message indicating a set of FMCW parameters associated with the FMCW signal, the set including a starting frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, wherein the slope is based at least in part on the bandwidth of the FMCW signal and a duration of a symbol in which the FMCW signal is transmitted, and wherein the estimation of the OFDM channel is based at least in part on the set of FMCW parameters.

[0279] Aspect 22: The method of any of aspects 14, 15, 17, 19, and 21, further comprising: the first wireless device transmitting a control message including a trigger to perform OFDM channel estimation using the FMCW signal, wherein the estimation of the OFDM channel is based at least in part on the trigger; and the second wireless device including a network entity.

[0280] Aspect 23: The method of any of aspects 14, 15, 17, 19, 21, and 22, further including: the first wireless device transmitting a control message including a trigger for transmitting a CSI report based at least in part on the FMCW signal; and receiving, based at least in part on the trigger, a CSI report including the set of CSI parameters.

[0281] Aspect 24: The method of any of aspects 14, 16, 18, and 20, further comprising: the second wireless device receiving a control message including a trigger to transmit an FMCW signal, wherein transmitting the FMCW signal is based at least in part on the trigger.

[0282] Aspect 25: The method of any of aspects 14 to 24, wherein the second wireless device includes a UE or a network entity.

[0283] Aspect 26: An apparatus for wireless communication, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory, the instructions executable by the processor to cause the apparatus to perform a method described in any of aspects 1 to 13.

[0284] Aspect 27: An apparatus for wireless communication in a first wireless device, the apparatus comprising at least one means for performing the method of any of aspects 1 to 13.

[0285] Aspect 28: A non-transitory computer-readable medium storing code for wireless communication in a first wireless device, the code comprising instructions executable by a processor to perform a method described in any of aspects 1 to 13.

[0286] Aspect 29: An apparatus for wireless communication, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory, the instructions being executable by the processor to cause the apparatus to perform a method described in any of aspects 14 to 25.

[0287] Aspect 30: An apparatus for wireless communication in a second wireless device, the apparatus comprising at least one means for performing the method of any of aspects 14 to 25.

[0288] Aspect 31: A non-transitory computer-readable medium storing code for wireless communication in a second wireless device, the code comprising instructions executable by a processor to perform a method described in any of aspects 14 to 25.

[0289] It should be noted that the methods described herein describe possible implementations, that operations and steps may be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects from two or more of these methods may be combined.

[0290] Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described as examples, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used throughout much of the description, the techniques described herein may be applicable to networks other than LTE, LTE-A, LTE-A Pro, or NR. For example, the described techniques may be applicable to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0291] The information and signals described herein may be represented using any of a wide variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0292] The various example blocks and components described in connection with the disclosure herein may be implemented or performed using a general purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0293] The functions described herein may be implemented using hardware, software executed by a processor, firmware, or any combination thereof. If implemented using software executed by a processor, the functions may be stored on or transmitted using one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. The features implementing the functions may also be physically located in various locations, including being distributed such that portions of the functions are implemented in different physical locations.

[0294] Computer-readable media includes both non-transitory computer storage media and communication media, including any medium that facilitates transfer of a computer program from one location to another. Non-transitory storage media may be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer or processor. Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of computer-readable media. As used herein, disk and disc include CDs, laser disks, optical disks, digital versatile discs (DVDs), floppy disks, and Blu-ray discs. Disks may reproduce data magnetically, and discs may reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media.

[0295] As used herein, including in the claims, "or" as used in a list of items (e.g., a list of items followed by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such as, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase "based on" should not be construed as referring to a closed set of conditions. For example, an example step described as "based on condition A" could be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" is to be interpreted the same as the phrase "based at least in part on."

[0296] The terms "determine" or "determining" encompass various actions, and thus "determining" can include calculating, computing, processing, deriving, investigating, looking up (such as via looking up in a table, database, or other data structure), ascertaining, and the like. "Determining" can also include receiving (e.g., receiving information), accessing (e.g., accessing data stored in a memory), and the like. "Determining" can also include resolving, obtaining, selecting, choosing, establishing, and other similar actions.

[0297] In the accompanying figures, similar components or features may have the same reference label. Furthermore, various components of the same type may be distinguished by following the reference label with a dash and a second label that distinguishes between the similar components. If only a first reference label is used herein, the description is applicable to any of the similar components having the same first reference label, regardless of a second reference label, or other subsequent reference label.

[0298] The descriptions set forth herein with reference to the accompanying drawings describe exemplary configurations and do not necessarily represent every example that may be implemented or fall within the scope of the claims. As used herein, the term "example" means "serving as an example, instance, or illustration," and does not mean "preferred" or "advantageous over other examples." The detailed description includes specific details for the purpose of providing an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0299] The description herein is provided to enable any person skilled in the art to make or use the disclosure. Various modifications of the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. A method for wireless communication in a first wireless device, comprising: receiving a first frequency modulated continuous waveform signal over an orthogonal frequency division multiplexing channel; generating a second frequency-modulated continuous waveform signal based at least in part on a set of frequency-modulated continuous waveform parameters associated with the first frequency-modulated continuous waveform signal; estimating the orthogonal frequency division multiplexing channel based at least in part on samples of a combined frequency modulated continuous waveform signal in a time domain, the combined frequency modulated continuous waveform signal comprising a combination of the first frequency modulated continuous waveform signal and the second frequency modulated continuous waveform signal; A method comprising:

2. estimating the orthogonal frequency division multiplexing channel, filtering the synthesized frequency modulated continuous wave signal; sampling the synthesized frequency-modulated continuous waveform signal in the time domain after the filtering using a sampling rate based at least in part on subband frequency ranges of the orthogonal frequency division multiplexing channel; 2. The method of claim 1 , wherein the estimating comprises estimating a respective value of the orthogonal frequency division multiplexing channel for each subband of a plurality of subbands in a frequency domain of the orthogonal frequency division multiplexing channel based at least in part on the sampling.

3. receiving one or more orthogonal frequency division multiplexed signals time division multiplexed with the first frequency modulated continuous wave signal within the orthogonal frequency division multiplexed channel; The method of claim 1 further comprising:

4. transmitting a capability message indicating that the first wireless device is capable of estimating the orthogonal frequency division multiplexing channel using a time-domain frequency modulated continuous waveform signal; 10. The method of claim 1, further comprising: wherein the first wireless device comprises a user equipment (UE).

5. receiving a capability message indicating that the second wireless device is capable of transmitting a frequency modulated continuous waveform signal for orthogonal frequency division multiplexing channel estimation; 10. The method of claim 1, further comprising: wherein the first wireless device comprises a network entity.

6. receiving a control message indicating whether one or more symbols of the orthogonal frequency division multiplexing channel are allocated for a frequency modulated continuous wave signal; 10. The method of claim 1, further comprising: wherein the first frequency-modulated continuous waveform signal is received within one symbol of the one or more symbols indicated as allocated for the frequency-modulated continuous waveform signal; and wherein the first wireless device comprises user equipment (UE).

7. transmitting a control message indicating whether one or more symbols of the orthogonal frequency division multiplexing channel are allocated for a frequency modulated continuous wave signal or for an orthogonal frequency division multiplexing signal.

10. The method of claim 1, further comprising: receiving the first frequency-modulated continuous waveform signal within one of the one or more symbols allocated for the frequency-modulated continuous waveform signal based at least in part on the control message; and wherein the first wireless device comprises a network entity.

8. receiving a control message indicating the set of frequency modulated continuous waveform parameters, the set of frequency modulated continuous waveform parameters including a start frequency of the first frequency modulated continuous waveform signal, a bandwidth of the first frequency modulated continuous waveform signal, a slope of the first frequency modulated continuous waveform signal, or any combination thereof; 2. The method of claim 1 , further comprising: wherein the slope is based at least in part on the bandwidth of the first frequency-modulated continuous waveform signal and a duration of a symbol by which the first frequency-modulated continuous waveform signal is received.

9. Transmitting a control message indicating the set of frequency modulated continuous waveform parameters, the set of frequency modulated continuous waveform parameters including a start frequency of the first frequency modulated continuous waveform signal, a bandwidth of the first frequency modulated continuous waveform signal, a slope of the first frequency modulated continuous waveform signal, or any combination thereof.

2. The method of claim 1 , further comprising: wherein the slope is based at least in part on the bandwidth of the first frequency-modulated continuous waveform signal and a duration of a symbol by which the first frequency-modulated continuous waveform signal is received; and wherein receiving the first frequency-modulated continuous waveform signal is based at least in part on the set of frequency-modulated continuous waveform parameters.

10. receiving a control message including a trigger for the first wireless device to perform orthogonal frequency division multiplexing channel estimation using a frequency modulated continuous waveform signal; 2. The method of claim 1 , further comprising: estimating the orthogonal frequency division multiplexing channel using the first frequency modulated continuous waveform signal and the second frequency modulated continuous waveform signal based at least in part on the trigger; and wherein the first wireless device comprises user equipment (UE).

11. receiving a control message including a trigger for the first wireless device to transmit a channel state information report based at least in part on the first frequency-modulated continuous waveform signal; transmitting the channel state information report, the channel state information report including a set of channel state information parameters, based at least in part on receiving the trigger and estimating the orthogonal frequency division multiplexing channel; The method of claim 1 further comprising:

12. transmitting a control message including a trigger for a second wireless device to transmit the first frequency-modulated continuous waveform signal; The method of claim 1 further comprising:

13. The method of claim 1 , wherein the first wireless device comprises a user equipment (UE) or a network entity.

14. 1. A method for wireless communication in a second wireless device, comprising: generating a frequency modulated continuous waveform signal for estimation of an orthogonal frequency division multiplexing channel by a first wireless device; transmitting the frequency modulated continuous wave signal over the orthogonal frequency division multiplexing channel; communicating an orthogonal frequency division multiplexing signal with the first wireless device over the orthogonal frequency division multiplexing channel based at least in part on the estimate of the orthogonal frequency division multiplexing channel; A method comprising:

15. transmitting one or more orthogonal frequency division multiplexed signals time division multiplexed with said frequency modulated continuous wave signal within said orthogonal frequency division multiplexed channel; The method of claim 14 further comprising:

16. transmitting a capability message indicating that the second wireless device is capable of transmitting a frequency modulated continuous waveform signal for orthogonal frequency division multiplexing channel estimation.

15. The method of claim 14, further comprising: wherein the second wireless device comprises a user equipment (UE).

17. receiving a capability message indicating that the first wireless device is capable of estimating the orthogonal frequency division multiplexing channel using a time-domain frequency modulated continuous waveform signal; 15. The method of claim 14, further comprising: wherein the second wireless device comprises a network entity.

18. receiving a control message indicating whether one or more symbols of the orthogonal frequency division multiplexing channel are allocated for a frequency modulated continuous wave signal; 15. The method of claim 14, further comprising: wherein the frequency-modulated continuous waveform signal is transmitted within one symbol of the one or more symbols allocated for the frequency-modulated continuous waveform signal based at least in part on the control message; and wherein the second wireless device comprises user equipment (UE).

19. transmitting a control message indicating whether one or more symbols of the orthogonal frequency division multiplexing channel are allocated for a frequency modulated continuous wave signal or for an orthogonal frequency division multiplexing signal.

15. The method of claim 14, further comprising: wherein the frequency-modulated continuous waveform signal is transmitted within one symbol of the one or more symbols allocated for the frequency-modulated continuous waveform signal; and wherein the second wireless device comprises a network entity.

20. receiving a control message indicating a set of frequency modulated continuous waveform parameters associated with the frequency modulated continuous waveform signal, the set of frequency modulated continuous waveform parameters including a start frequency of the frequency modulated continuous waveform signal, a bandwidth of the frequency modulated continuous waveform signal, a slope of the frequency modulated continuous waveform signal, or any combination thereof; 15. The method of claim 14, further comprising: wherein the slope is based at least in part on the bandwidth of the frequency modulated continuous waveform signal and a duration of a symbol by which the frequency modulated continuous waveform signal is transmitted; and wherein transmitting the frequency modulated continuous waveform signal is based at least in part on the set of frequency modulated continuous waveform parameters.

21. transmitting a control message indicating a set of frequency modulated continuous waveform parameters associated with the frequency modulated continuous waveform signal, the set of frequency modulated continuous waveform parameters including a start frequency of the frequency modulated continuous waveform signal, a bandwidth of the frequency modulated continuous waveform signal, a slope of the frequency modulated continuous waveform signal, or any combination thereof.

15. The method of claim 14, further comprising: wherein the slope is based at least in part on the bandwidth of the frequency modulated continuous waveform signal and a duration of a symbol transmitted by the frequency modulated continuous waveform signal; and wherein the estimate of the orthogonal frequency division multiplexing channel is based at least in part on the set of frequency modulated continuous waveform parameters.

22. transmitting a control message including a trigger for the first wireless device to perform orthogonal frequency division multiplexing channel estimation using a frequency modulated continuous waveform signal; 15. The method of claim 14, further comprising: wherein the estimation of the orthogonal frequency division multiplexing channel is based at least in part on the trigger; and wherein the second wireless device comprises a network entity.

23. transmitting a control message including a trigger for the first wireless device to transmit a channel state information report based at least in part on the frequency modulated continuous waveform signal; receiving the channel state information report, the channel state information report including a set of channel state information parameters, based at least in part on the trigger; The method of claim 14 further comprising:

24. receiving a control message including a trigger for the second wireless device to transmit the frequency modulated continuous waveform signal; 15. The method of claim 14, further comprising: transmitting the frequency-modulated continuous waveform signal based at least in part on the trigger.

25. The method of claim 14 , wherein the second wireless device comprises a user equipment (UE) or a network entity.

26. 1. An apparatus for wireless communication, comprising: a processor; a memory coupled to the processor; instructions stored in the memory; and wherein the instructions cause the device to: receiving a first frequency modulated continuous waveform signal over an orthogonal frequency division multiplexing channel; generating a second frequency-modulated continuous waveform signal based at least in part on a set of frequency-modulated continuous waveform parameters associated with the first frequency-modulated continuous waveform signal; estimating the orthogonal frequency division multiplexing channel based at least in part on samples of a combined frequency modulated continuous waveform signal in a time domain, the combined frequency modulated continuous waveform signal comprising a combination of the first frequency modulated continuous waveform signal and the second frequency modulated continuous waveform signal; executable by the processor to cause Device.

27. The instructions for estimating the orthogonal frequency division multiplexing channel may include: filtering the synthesized frequency modulated continuous wave signal; sampling the synthesized frequency-modulated continuous waveform signal in the time domain after the filtering using a sampling rate based at least in part on subband frequency ranges of the orthogonal frequency division multiplexing channel; 27. The apparatus of claim 26, wherein the estimating comprises estimating a respective value of the orthogonal frequency division multiplexing channel for each subband of a plurality of subbands in a frequency domain of the orthogonal frequency division multiplexing channel based at least in part on the sampling.

28. The instructions cause the device to: receiving one or more orthogonal frequency division multiplexed signals time division multiplexed with the first frequency modulated continuous wave signal within the orthogonal frequency division multiplexed channel; further executable by the processor to cause 27. The apparatus of claim 26.

29. 1. An apparatus for wireless communication, comprising: a processor; a memory coupled to the processor; instructions stored in the memory; and wherein the instructions cause the device to: generating a frequency modulated continuous waveform signal for estimation of an orthogonal frequency division multiplexing channel by a first wireless device; transmitting the frequency modulated continuous wave signal over the orthogonal frequency division multiplexing channel; communicating an orthogonal frequency division multiplexing signal with the first wireless device over the orthogonal frequency division multiplexing channel based at least in part on the estimate of the orthogonal frequency division multiplexing channel; executable by the processor to cause Device.

30. The instructions cause the device to: transmitting one or more orthogonal frequency division multiplexed signals time division multiplexed with said frequency modulated continuous wave signal within said orthogonal frequency division multiplexed channel; further executable by the processor to cause 30. The apparatus of claim 29.

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