Estimating orthogonal frequency division multiplexing channels using frequency modulated continuous waveforms

Abstract

Methods, systems, and devices for wireless communication are described. A first wireless device may receive a first frequency modulated continuous waveform (FMCW) signal from a second wireless device via an orthogonal frequency division multiplexing (OFDM) channel. The first wireless device may generate a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The first wireless device may combine the first FMCW signal and the second FMCW signal, and filter the combined FMCW signal. The first wireless device may sample the combined and filtered FMCW signal in the time domain. The first wireless device may estimate a frequency domain OFDM channel based on sampling the combined and filtered FMCW signal. The first wireless device and the second wireless device may transmit an OFDM signal via an OFDM channel based on the estimation of the frequency domain OFDM channel.

Description

Technical Field

[0001] The following relates to wireless communication, including using frequency-modulated continuous waveform (FMCW) to estimate an orthogonal frequency division multiplexing (OFDM) channel. Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasting, etc. These systems are capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multi-access systems include fourth-generation (4G) systems (e.g., Long Term Evolution (LTE) systems, enhanced LTE (LTE-A) systems, or LTE-A Pro systems) and fifth-generation (5G) systems (which may be referred to as New Radio (NR) systems). These systems may employ technologies 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). A wireless multi-access communication system may include one or more base stations, each supporting wireless communication for communication devices (which may be referred to as user equipment (UE)).

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

[0004] The described technology relates to improved methods, systems, devices, and apparatuses for supporting the use of frequency-modulated continuous wave (FMCW) to estimate an orthogonal frequency-division multiplexing (OFDM) channel. For example, the described technology provides for a wireless device to receive an FMCW signal via an OFDM channel and estimate the frequency-domain OFDM channel using time-domain signal processing based on the FMCW signal. To perform 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 and second FMCW signals and filter the combined FMCW signal in the time domain. The first wireless device may sample the combined and filtered FMCW signal using a sampling rate based on one or more parameters of the OFDM channel (e.g., using an analog-to-digital converter (ADC)). The first wireless device may estimate values for each of a plurality of subbands spanning the frequency domain of the OFDM channel based on the sampling. The receiving device may thus estimate the frequency-domain OFDM channel using time-domain signal processing and a relatively low sampling rate. In some examples, the first and second wireless devices may exchange one or more capability messages, control messages, or both to facilitate FMCW-based OFDM channel estimation.

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

[0007] Describes another apparatus for wireless communication at a first wireless device. The apparatus may include: a unit for receiving a first FMCW signal via an OFDM channel; a unit for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal; and a unit for estimating the OFDM channel based on samples of a combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

[0008] Describes a non-transitory computer-readable medium storing code for wireless communication at a first wireless device. The code may include instructions executable by a processor to: receive a first FMCW signal via an OFDM channel; generate a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal; and estimate the OFDM channel based on samples of a combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

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

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

[0011] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for: transmitting a capability message indicating that the first wireless device is capable of using a time-domain FMCW signal to estimate the OFDM channel, wherein the first wireless device includes a user equipment (UE).

[0012] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a capabilities message indicating that a second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, wherein the first wireless device includes a network entity.

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

[0014] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: sending a control message indicating whether one or more symbols of the OFDM channel can be allocated for the FMCW signal or for the OFDM signal, wherein the first FMCW signal may be received within symbols of a set of the one or more symbols that can 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, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a control message indicating a set of FMCW parameters, the set of FMCW parameters including a start 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 may be based on the bandwidth of the first FMCW signal and a duration of a symbol via which the first FMCW signal can be received.

[0016] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: sending a control message indicating a set of FMCW parameters, the set of FMCW parameters including a start 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 may be based on the bandwidth of the first FMCW signal and a duration of a symbol via which the first FMCW signal can be received, and wherein receiving the first FMCW signal may be based on the set of FMCW parameters.

[0017] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a control message including a trigger for the first wireless device to perform OFDM channel estimation using an FMCW signal, wherein estimating the OFDM channel using the first FMCW signal and the second FMCW signal may be based on the trigger, and wherein the first wireless device includes a UE.

[0018] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a control message including a trigger for the first wireless device to send a channel state information report based on the first FMCW signal; and sending the 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, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: sending a control message including a trigger for a second wireless device to send the first FMCW signal.

[0020] In some examples of the methods, apparatuses, 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 at a second wireless device is described. The method may include: generating an FMCW signal for estimation of an OFDM channel by a first wireless device; transmitting the FMCW signal via the OFDM channel; and communicating an OFDM signal with the first wireless device via 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 perform the following: generating an FMCW signal for estimation of an OFDM channel by a first wireless device; transmitting the FMCW signal via the OFDM channel; and communicating an OFDM signal with the first wireless device via the OFDM channel based on the estimation of the OFDM channel.

[0023] Describes another apparatus for wireless communication at a second wireless device. The apparatus may include: a unit for generating an FMCW signal for estimation of an OFDM channel by a first wireless device; a unit for transmitting the FMCW signal via the OFDM channel; and a unit for transmitting an OFDM signal via the OFDM channel to the first wireless device based on the estimation of the OFDM channel.

[0024] Describes a non-transitory computer-readable medium storing code for wireless communication at a second wireless device. 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 via the OFDM channel; and transmit an OFDM signal via the OFDM channel to the first wireless device based on the estimation of the OFDM channel.

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

[0026] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for: 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.

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

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

[0029] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: sending a control message that indicates whether one or more symbols of the OFDM channel can be allocated for an FMCW signal or for an OFDM signal, wherein the FMCW signal can be transmitted within the symbols of the one or more symbols that can be allocated for the FMCW signal, and wherein the second wireless device includes a network entity.

[0030] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a control message that indicates a set of FMCW parameters that can be associated with the FMCW signal, the set of FMCW parameters including a start frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, wherein the slope can be based on the bandwidth of the FMCW signal and a duration of the symbol via which the FMCW signal can be transmitted, and wherein transmitting the FMCW signal can be based on the set of FMCW parameters.

[0031] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: sending a control message that indicates a set of FMCW parameters that can be associated with the FMCW signal, the set of FMCW parameters including a start frequency of the FMCW signal, a bandwidth of the FMCW signal, a slope of the FMCW signal, or any combination thereof, wherein the slope can be based on the bandwidth of the FMCW signal and a duration of the symbol via which the FMCW signal can be transmitted, and wherein the estimation of the OFDM channel can be based on the set of FMCW parameters.

[0032] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: sending a control message that includes a trigger for the first wireless device to perform OFDM channel estimation using an FMCW signal, wherein the estimation of the OFDM channel can be based on the trigger, and wherein the second wireless device includes a network entity.

[0033] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: sending a control message that includes a trigger for the first wireless device to send a channel state information report that may be based on the FMCW signal; and receiving, at least in part based on the trigger, the channel state information report that includes a set of channel state information parameters.

[0034] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a control message that includes a trigger for the second wireless device to send the FMCW signal, wherein sending the FMCW signal may be based on the trigger.

[0035] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the second wireless device includes a UE or a network entity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Examples of wireless communication systems that support estimating an orthogonal frequency division multiplexing (OFDM) channel using a frequency modulated continuous waveform (FMCW) are shown in accordance with one or more aspects of the present disclosure.

[0037] Figure 2 Examples of OFDM channel estimation schemes that support estimating an OFDM channel using FMCW are shown in accordance with one or more aspects of the present disclosure.

[0038] Figure 3 Examples of OFDM channel estimation schemes that support estimating an OFDM channel using FMCW are shown in accordance with one or more aspects of the present disclosure.

[0039] Figure 4 Examples of wireless communication systems that support estimating an OFDM channel using FMCW are shown in accordance with one or more aspects of the present disclosure.

[0040] Figure 5 Examples of process flows that support estimating an OFDM channel using FMCW are shown in accordance with one or more aspects of the present disclosure.

[0041] Figure 6 Examples of process flows that support estimating an OFDM channel using FMCW are shown in accordance with one or more aspects of the present disclosure.

[0042] Figure 7 and 8A block diagram of a device supporting the use of FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown.

[0043] Figure 9 A block diagram of a communication manager supporting the use of FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown.

[0044] Figure 10 A diagram of a system including a UE supporting the use of FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown.

[0045] Figure 11 A diagram of a system including a network entity supporting the use of FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown.

[0046] Figures 12 to 17 A flowchart illustrating a method supporting the use of FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown. Detailed Description

[0047] 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 of the wireless device. In some cases, the wireless device may receive an OFDM signal via the OFDM channel. The wireless device may use an analog-to-digital converter (ADC) to convert the received analog OFDM signal into 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 into one or more frequency-domain signals. The wireless device may use the frequency-domain signals to estimate the OFDM channel in the frequency domain. In some examples, the sampling rate of the ADC at the wireless device may be relatively high to accurately convert the analog OFDM signal into digital form. Additionally or alternatively, performing the FFT to convert the time-domain signal into the frequency domain is relatively complex.

[0048] The techniques, systems, and devices described herein use frequency-modulated continuous-wave (FMCW) signals to provide improved OFDM channel estimation. A transmitting device may transmit a first FMCW signal for channel estimation via an OFDM channel. A receiving device may receive the first FMCW signal and may 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 may filter the combined signal (e.g., using a low-pass filter (LPF) or some other type of filter). The receiving device may estimate the 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 of the OFDM channel or the sub-band frequency size.

[0049] 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., a user equipment (UE)) may send a capability message to indicate that the device supports FMCW for channel estimation or supports the transmission of FMCW. In some examples, one or both of these devices may send one or more control messages that allocate symbols for FMCW transmission in the OFDM channel (e.g., an OFDM resource grid), indicate FMCW parameters, trigger the 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 the devices. The transmitting device and the receiving device may each be a UE, a network entity, some other type of device, or any combination thereof.

[0050] Thus, the techniques described can support estimating a frequency-domain OFDM channel based on FMCW signals, which in some aspects herein may be referred to as FMCW-based OFDM channel estimation. The sampling rate applied by the receiving device to estimate the frequency-domain OFDM channel using FMCW-based OFDM channel estimation techniques may be lower than the sampling rate used by the receiving device to estimate the frequency-domain OFDM channel based on OFDM signals (e.g., channel state information reference signal (CSI-RS), sounding reference signal (SRS), demodulation reference signal (DMRS), or any combination thereof). Additionally or alternatively, the receiving device may use time-domain signal processing based on FMCW signals to estimate the frequency-domain OFDM channel in the time domain (e.g., the receiving device may avoid performing an FFT), which may reduce complexity and power consumption compared to OFDM-based estimation techniques that apply an FFT.

[0051] 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 apparatus diagrams, system diagrams, and flowcharts that relate to using FMCW to estimate an OFDM channel, and aspects of the present disclosure are described with reference to these diagrams.

[0052] Figure 1 An example of a wireless communication system 100 that supports using FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown. 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 Long Term Evolution (LTE) network, an enhanced LTE (LTE-A) network, an LTE-A Pro network, a New Radio (NR) network, or a network operating according to other systems and radio technologies (including future systems and radio technologies not explicitly mentioned herein).

[0053] The network entities 105 may be dispersed throughout a geographic area to form the wireless communication system 100, and may include devices in different forms or having 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 devices, among other terms. 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 entity 105 may support a coverage area 110 (e.g., a geographic coverage area), and the UE 115 and the network entity 105 may establish one or more communication links 125 over the coverage area 110. The coverage area 110 may be an example of a geographic area over which the network entity 105 and the UE 115 may support transmitting signals according to one or more radio access technologies (RATs).

[0054] The UEs 115 may be dispersed throughout the entire 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 in different forms or have different capabilities. In Figure 1 some example UEs 115 are shown. The UEs 115 described herein are capable of supporting communication with various types of devices (such as other UEs 115 or network entities 105), as Figure 1 shown.

[0055] As described herein, a node (which may be referred to as a network node) or a wireless node of the wireless communication system 100 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, a device, an equipment, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, the node may be a UE 115. As another example, the 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 other aspects of this example, the first node, the second node, and the third node may be different from these examples. Similarly, references to UE 115, network entity 105, device, equipment, computing system, etc. may include the disclosure of UE 115, network entity 105, device, equipment, computing system, etc. as nodes. For example, the 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.

[0056] In some examples, the network entity 105 may communicate with the core network 130, or with each other, or both. For example, the network entity 105 may communicate with the core network 130 via one or more backhaul communication links 120 (e.g., according to S1, N2, N3, or other interface protocols). In some examples, the network entity 105 may communicate with each other directly (e.g., directly between network entities 105) or indirectly (e.g., via the core network 130) via the backhaul communication link 120 (e.g., according to X2, Xn, or other interface protocols). In some examples, the network entity 105 may communicate with each other via a midhaul communication link 162 (e.g., according to a midhaul interface protocol) or a fronthaul communication link 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 one or more wired links (e.g., electrical links, fiber optic links), one or more wireless links (e.g., radio links, wireless optical links), and other examples or various combinations thereof. The UE 115 may communicate with the core network 130 via a communication link 155.

[0057] One or more of the network entities 105 described herein may include or may be referred to as a base station 140 (e.g., a base station transceiver, a radio base station, an NR base station, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a next-generation Node B or a giga Node B (any of which may be referred to as a gNB), a 5G NB, a next-generation eNB (ng-eNB), a home Node B, a home evolved Node B, or other suitable terms). In some examples, the network entity 105 (e.g., the base station 140) may be implemented in an integrated (e.g., monolithic, stand-alone) base station architecture that may be configured to utilize a protocol stack physically or logically integrated within a single network entity 105 (e.g., a single RAN node, such as the base station 140).

[0058] In some examples, the network entity 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 physically or logically distributed among 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., a cloud RAN (C-RAN)). For example, the network entity 105 may include one or more of the following: 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, an intelligent radio head, a remote radio head (RRH), a remote radio unit (RRU), or a transmit receive point (TRP). One or more components of the network entity 105 in the 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 virtual units (e.g., a virtual CU (VCU), a virtual DU (VDU), a virtual RU (VRU)).

[0059] The functional split between the CU 160, DU 165, and RU 170 is flexible and can support different functions, depending on which functions are performed at the CU 160, DU 165, or RU 170 (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combination thereof). For example, a functional split of the protocol stack can 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 can host upper layer 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 can be connected to one or more DU 165s or RU 170s, and one or more DU 165s or RU 170s can host lower protocol layer (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 and can each be at least partially controlled by the CU 160. Additionally or alternatively, a functional split of the protocol stack can be adopted 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 can support one or more different cells (e.g., via one or more RU 170s). In some cases, the functional split between the CU 160 and the DU 165 or between the DU 165 and the RU 170 can be within a protocol layer (e.g., some functions of the protocol layer can be performed by one of the CU 160, DU 165, or RU 170, while other functions of the protocol layer are performed by a different one of the CU 160, DU 165, or RU 170). The CU 160 can be further functionally split into a CU control plane (CU-CP) and a CU user plane (CU-UP) function. The CU 160 can be connected to one or more DU 165s via a mid-range communication link 162 (e.g., F1, F1-c, F1-u), and the DU 165 can be connected to one or more RU 170s via a front-haul communication link 168 (e.g., open front-haul (FH) interface). In some examples, the mid-range communication link 162 or the front-haul communication link 168 can be implemented according to an interface (e.g., a channel) between the layers of the protocol stack, which is supported by the corresponding network entity 105 communicating via such a communication link.

[0060] In a wireless communication system (e.g., wireless communication system 100), the infrastructure and spectrum resources for radio access can support wireless backhaul link capabilities to complement wired backhaul connections, thereby providing an IAB network architecture (e.g., to core network 130). In some cases, in an IAB network, one or more network entities 105 (e.g., IAB nodes 104) can be partially controlled by each other. One or more IAB nodes 104 can be referred to as donor entities or IAB donors. One or more DUs 165 or one or more RUs 170 can be partially controlled by one or more CUs 160 associated with a donor network entity 105 (e.g., donor base station 140). One or more donor network entities 105 (e.g., IAB donors) can communicate with one or more additional network entities 105 (e.g., IAB nodes 104) via the supported access and backhaul links (e.g., backhaul communication link 120). An IAB node 104 can include an IAB mobile terminal (IAB-MT) controlled (e.g., scheduled) by a DU 165 of a coupled IAB donor. The IAB-MT can include a separate set of antennas for relaying communications with a UE 115 or can share the same antennas of the IAB node 104 (e.g., the same antennas of an RU 170) 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, an IAB node 104 can include a DU165 that supports communication links with additional entities (e.g., IAB nodes 104, UEs 115) within the configuration of a relay chain or access network (e.g., downstream). In such cases, one or more components of a split RAN architecture (e.g., one or more IAB nodes 104 or components of an IAB node 104) can be configured to operate according to the techniques described herein.

[0061] For example, the 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 the AN (e.g., via a wired or wireless connection to the core network 130). That is, the IAB donor may refer to a RAN node having 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 an RU 170), in which case the CU 160 may communicate with the core network 130 via an interface (e.g., a backhaul link). The IAB donor and the IAB node 104 may communicate via an F1 interface according to a protocol that defines signaling messages (e.g., the F1 AP protocol). Additionally or alternatively, the CU 160 may communicate with the core network via an interface (which may be an example of a part of the backhaul link), and may communicate with other CUs 160 (e.g., CUs 160 associated with alternative IAB donors) via an Xn-C interface (which may be an example of a part of the backhaul link).

[0062] The IAB node 104 may refer to a RAN node that provides IAB functionality (e.g., access for UEs 115, wireless self-backhauling capabilities). The DU 165 may act as a distributed scheduling node towards sub-nodes associated with the IAB node 104, and the IAB-MT may act as a scheduled node towards a parent node associated with the IAB node 104. That is, the IAB donor may be referred to as a parent node that communicates with one or more sub-nodes (e.g., the IAB donor may relay transmissions for UEs through one or more other IAB nodes 104). Additionally or alternatively, depending on the relay chain or configuration of the AN, the IAB node 104 may also be referred to as a parent node or a sub-node of other IAB nodes. Thus, the IAB-MT entity of the IAB node 104 may provide a Uu interface for sub-IAB nodes 104 to receive signaling from the parent IAB node 104, and a DU interface (e.g., the DU 165) may provide a Uu interface for the parent IAB node 104 to send signals to the sub-IAB nodes 104 or the UEs 115.

[0063] For example, the IAB node 104 may be referred to as a parent node that supports 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 to the core network 130 (e.g., a backhaul communication link 120), and may act as the parent node of the IAB node 104. For example, the DU 165 of the IAB donor may relay a transmission to the UE 115 via the IAB node 104, or may directly signal a transmission to the UE 115, or both. The CU 160 of the IAB donor may signal a communication link establishment to the IAB node 104 via the F1 interface, and the IAB node 104 may schedule a transmission (e.g., a transmission relayed from the IAB donor to the UE 115) 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. Communication with the IAB node 104 may be scheduled by the DU 165 of the IAB donor, and communication with the IAB node 104 may be scheduled by the DU 165 of the IAB node 104.

[0064] In the case of applying the techniques described herein in the context of a split RAN architecture, one or more components of the split RAN architecture may be configured to support estimating an OFDM channel using FMCW as described herein. For example, some operations described as being performed by the UE 115 or the network entity 105 (e.g., the base station 140) may alternatively or additionally be performed by one or more components of the split RAN architecture (e.g., the IAB node 104, the DU 165, the CU 160, the RU 170, the RIC 175, the SMO 180).

[0065] The UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable term, where "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 may 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 communication (MTC) device, among other examples, which may be implemented in various articles such as appliances, or vehicles, meters, and other examples.

[0066] The UE 115 described herein may be capable of communicating with various types of devices, such as other UEs 115 that can sometimes act as relays, as well as network entities 105 and network devices (including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations and other examples), as Figure 1 shown.

[0067] The UE 115 and the network entity 105 may communicate wirelessly with each other via 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 spectral resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier for the communication link 125 may include a portion of an RF spectral band (e.g., a bandwidth part (BWP)) that operates 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 for coordinating the operation of 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. According to a carrier aggregation configuration, the UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used with both frequency division duplex (FDD) component carriers and time division duplex (TDD) component carriers. Communication between the network entity 105 and other devices may refer to communication between any part (e.g., entity, sub-entity) of the device and the network entity 105. For example, when referring to the network entity 105, the terms "transmit", "receive", or "communicate" may refer to any part of the network entity 105 of the RAN (e.g., base station 140, CU 160, DU 165, RU 170) communicating with another device (e.g., directly or via one or more other network entities 105).

[0068] In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling for coordinating the operation of other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunications system terrestrial radio access (E-UTRA) absolute RF channel number (EARFCN)) and may be identified according to a channel raster for discovery by the UE 115. A carrier may operate in standalone mode, in which case the UE 115 may perform initial acquisition and connection via the carrier, or the carrier may operate in non-standalone mode, in which case a different carrier (e.g., of the same or a different radio access technology) is used to anchor the connection.

[0069] The communication link 125 shown in the wireless communication system 100 may include a downlink transmission (e.g., a forward link transmission) from the network entity 105 to the UE 115, an uplink transmission (e.g., a reverse link transmission) from the UE 115 to the network entity 105, or both, as well as other configurations of the transmission. A carrier may carry downlink or uplink communication (e.g., in FDD mode) or may be configured to carry both downlink and uplink communication (e.g., in TDD mode).

[0070] A carrier may be associated with a particular bandwidth of the RF spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or the wireless communication system 100. For example, the carrier bandwidth may be one of a set of bandwidths for 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 a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a network entity 105 or a UE 115 that supports concurrent 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 subband, a BWP) or all of the carrier bandwidth.

[0071] The signal waveform transmitted via 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 an MCM technique, a resource element may refer to the resource of one symbol period (e.g., the duration of one modulated symbol) and one subcarrier, in which case the symbol period and the subcarrier spacing may be inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the decoding rate of the modulation scheme, or both), such that a relatively high number of resource elements (e.g., during the transmission duration) and a relatively high-order modulation scheme may correspond to a relatively high communication rate. Wireless communication resources may refer to a combination of RF spectrum resources, time resources, and space resources (e.g., spatial layers, beams), and the use of multiple space resources may increase the data rate or data integrity for communication with the UE 115.

[0072] One or more numerologies for a carrier can be supported, and a numerology can include a subcarrier spacing (Δf) and a cyclic prefix. The carrier can be divided into one or more BWPs with the same or different numerologies. In some examples, UE 115 can be configured with multiple BWPs. In some examples, a single BWP for a carrier can be active at a given time, and communication for UE 115 can be restricted to one or more active BWPs.

[0073] It can be in terms of a basic time unit, which can for example refer to T s = 1 / (Δf max ·N f ) seconds as the sampling period, where Δf max can represent the supported subcarrier spacing, and N f can represent the supported discrete Fourier transform (DFT) size) multiples to represent the time interval for network entity 105 or UE 115. The time intervals of communication resources can be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0074] Each frame can include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot can have the same duration. In some examples, a frame can be divided (e.g., in the time domain) into subframes, and each subframe can be further divided into a number of time slots. Alternatively, each frame can include a variable number of time slots, and the number of time slots can depend on the subcarrier spacing. Each time slot can include a number of symbol periods (e.g., which depends on the length of the cyclic prefix added in front of each symbol period). In some wireless communication systems 100, a time slot can be further divided into a plurality of mini-slots associated with one or more symbols. Excluding the cyclic prefix, each symbol period can be associated with one or more (e.g., N f ones) sampling periods. The duration of the symbol period can depend on the subcarrier spacing or the operating frequency band.

[0075] A subframe, time slot, mini-slot or symbol can be the smallest scheduling unit (e.g., in the time domain) of wireless communication system 100, and can be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in the TTI) can be variable. Additionally or alternatively, the smallest scheduling unit of wireless communication system 100 can be dynamically selected (e.g., in the form of a burst of shortened TTIs (sTTIs)).

[0076] Physical channels can be multiplexed according to various techniques to communicate using a carrier. For example, one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques can be used to multiplex physical control channels and physical data channels to signal via a downlink carrier. A control region for a physical control channel (e.g., a control resource set (CORESET)) can be defined by a set of symbol periods and can extend across the system bandwidth of a carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESETs) can be configured for a group of UEs 115. For example, one or more of the UEs 115 can monitor or search a control region for control information according to one or more search space sets, and each search space set can include one or more control channel candidates at one or more aggregation levels arranged in a cascaded manner. The aggregation level for a control channel candidate can refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with the coded information for a control information format having a given payload size. The search space set can include a common search space set configured to send control information to multiple UEs 115 and a UE-specific search space set for sending control information to a particular UE 115.

[0077] The network entity 105 can provide communication coverage via one or more cells (e.g., macro cells, small cells, hotspots, or other types of cells, or any combination thereof). The term "cell" can refer to a logical communication entity for communicating with the network entity 105 (e.g., using a carrier) and can be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), or other identifier) for distinguishing adjacent cells. In some examples, a cell can also refer to a coverage area 110 or a portion of the coverage area 110 (e.g., a sector) on which the logical communication entity operates. Depending on various factors (such as the capabilities of the network entity 105), the range of such a cell can vary from a smaller area (e.g., a structure, a subset of a structure) to a larger area. For example, a cell can be or include a building, a subset of a building, or an external space between or overlapping the coverage areas 110, and other examples.

[0078] Macro cells typically cover a relatively large geographical area (e.g., with a radius of several kilometers) and can allow unrestricted access by UEs 115 having a service subscription with the network provider that supports the macro cell. Compared with macro cells, small cells can be associated with a lower-power network entity 105 (e.g., a lower-power base station 140), and small cells can operate using the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells can provide unrestricted access to UEs 115 having a service subscription with the network provider, or can provide restricted access to UEs 115 associated with the small cell (e.g., UEs 115 in a closed subscriber group (CSG), UEs 115 associated with users in a residence or office). The network entity 105 can support one or more cells and can also support communication via one or more cells using one or more component carriers.

[0079] In some examples, a carrier can support multiple cells and can be configured with different cell configurations according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that can provide access for different types of devices.

[0080] In some examples, the network entity 105 (e.g., base station 140, RU 170) can be movable and thus provide communication coverage for a mobile coverage area 110. In some examples, different coverage areas 110 associated with different technologies can overlap, but different coverage areas 110 can be supported by the same network entity 105. In some other examples, overlapping coverage areas 110 associated with different technologies can be supported by different network entities 105. The wireless communication system 100 can include, for example, a heterogeneous network where different types of network entities 105 use the same or different radio access technologies to provide coverage for respective coverage areas 110.

[0081] The wireless communication system 100 can support synchronous or asynchronous operation. For synchronous operation, the network entities 105 (e.g., base stations 140) can have similar frame timings, and transmissions from different network entities 105 can be approximately aligned in time. For asynchronous operation, the network entities 105 can have different frame timings, and in some examples, transmissions from different network entities 105 can not be aligned in time. The techniques described herein can be used for synchronous or asynchronous operation.

[0082] Some UEs 115 (e.g., MTC or IoT devices) can be low-cost or low-complexity devices and can provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC can refer to data communication technologies that allow devices to communicate with each other or with network entity 105 (e.g., base station 140) without human intervention. In some examples, M2M communication or MTC can include communication from devices integrated with sensors or meters to measure or capture information and relay such information to a central server or application that utilizes the information or presents the information to a human interacting with the application. Some UEs 115 can be designed to collect information or implement automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, device monitoring, healthcare monitoring, wildlife monitoring, climate and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business billing.

[0083] Some UEs 115 can be configured to operate in power-saving modes, e.g., half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception rather than simultaneous transmission and reception). In some examples, half-duplex communication can be performed at a reduced peak rate. Other power-saving techniques for UEs 115 include entering a power-saving deep sleep mode when not participating in active communication, when operating with limited bandwidth (e.g., according to narrowband communication), or a combination of these techniques. For example, some UEs 115 can be configured for operation using a narrowband protocol type associated with a defined portion or range within a carrier, within a guard band of the carrier, or external to the carrier (e.g., a set of subcarriers or resource blocks (RBs)).

[0084] Wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, wireless communication system 100 can be configured to support ultra-reliable low-latency communication (URLLC). UEs 115 can be designed to support ultra-reliable, low-latency, or critical functions. Ultra-reliable communication can include private communication or group communication and can be supported by one or more services such as push-to-talk, video, or data. Support for ultra-reliable, low-latency functions can include prioritization of services, and such services can be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency can be used interchangeably herein.

[0085] In some examples, UE 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 performing D2D communication may be within the coverage area 110 of a network entity 105 (e.g., base station 140, RU 170), and the network entity 105 may support aspects of such D2D communication configured (e.g., scheduled) by the network entity 105. In some examples, one or more UEs 115 in 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, groups of UEs 115 communicating via D2D communication may support a one-to-many (1:M) system, where each UE 115 transmits to each of the other UEs 115 in the group. In some examples, the network entity 105 may facilitate the scheduling of resources for D2D communication. In some other examples, D2D communication may be performed between UEs 115 without involving the network entity 105.

[0086] In some systems, the D2D communication link 135 may be an example of a communication channel (such as a sidelink communication channel) between vehicles (e.g., UE 115). In some examples, vehicles may communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination of these. Vehicles may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information related to the V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure (such as a roadside unit), or communicate with the network via one or more network nodes (e.g., network entity 105, base station 140, RU 170) using vehicle-to-network (V2N) communication, or perform both operations.

[0087] The core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 can be an Evolved Packet Core (EPC) or a 5G Core (5GC), which can include at least one control plane entity that manages access and mobility (e.g., a Mobility Management Entity (MME), an Access and Mobility Management Function (AMF)) and at least one user plane entity that routes packets to or interconnects with an external network (e.g., a Serving Gateway (S-GW), a Packet Data Network (PDN) Gateway (P-GW), or a User Plane Function (UPF)). The control plane entity can manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management for a UE 115 served by a network entity 105 (e.g., a base station 140) associated with the core network 130. User IP packets can be transmitted through the user plane entity, which can provide IP address allocation and other functions. The user plane entity can be connected to an IP service 150 for one or more network operators. The IP service 150 can include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or a packet-switched streaming service.

[0088] The wireless communication system 100 can operate using one or more frequency bands, which can be in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is known as the Ultra-High Frequency (UHF) region or the decimeter band because the wavelength range is approximately from one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, which can be referred to as clutter, but the waves can be sufficient to penetrate structures to serve an indoor UE 115 in a macro cell. Compared to communication using smaller frequencies and longer waves in the High Frequency (HF) or Very High Frequency (VHF) portions of the spectrum below 300 MHz, communication using UHF waves can be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers).

[0089] The wireless communication system 100 may also operate using the super high frequency (SHF) region of the spectrum in the range from 3 GHz to 30 GHz (also known as the centimeter band) or using the extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) (also known as the millimeter band). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communication between the UE 115 and network entities (e.g., the base station 140, the RU 170), and the EHF antennas of the corresponding devices may be smaller and more closely spaced compared to UHF antennas. In some examples, such techniques may facilitate the use of antenna arrays within the device. However, the propagation of EHF transmissions may suffer even greater attenuation and shorter distances compared to SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency regions, and the designation of the frequency bands across these frequency regions may vary according to the country or regulatory authority.

[0090] The wireless communication system 100 may utilize both licensed and unlicensed RF spectrum bands. For example, the wireless communication system 100 may employ licensed-assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology using an unlicensed frequency band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating using an unlicensed RF spectrum band, devices (such as the network entity 105 and the UE 115) may employ carrier sensing for collision detection and avoidance. In some examples, the operation using an unlicensed frequency band may be based on a carrier aggregation configuration that combines the use of a component carrier operating in a licensed frequency band (e.g., LAA). The operation using unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer (P2P) transmissions, or device-to-device (D2D) transmissions, among other examples.

[0091] The network entity 105 (e.g., base station 140, RU 170) or the UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of the network entity 105 or the UE 115 may be located within one or more antenna arrays or antenna panels, which may support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (e.g., an antenna tower). In some examples, the antennas or antenna arrays associated with the network entity 105 may be located at different geographical 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 may use to support beamforming for communication with the UE 115. Similarly, the UE 115 may include one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support RF beamforming for signals transmitted via the antenna ports.

[0092] The network entity 105 or the UE 115 may use MIMO communication to exploit multipath signal propagation and improve spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. For example, a transmitting device may transmit multiple signals via different antennas or different combinations of antennas. Similarly, a receiving device may receive multiple signals 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 for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) (where multiple spatial layers are transmitted to the same receiving device) and multi-user MIMO (MU-MIMO) (where multiple spatial layers are transmitted to multiple devices).

[0093] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., network entity 105, UE 115) to form or direct an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals transmitted via the 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 the signals transmitted via the antenna elements can include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to the signals carried via the antenna elements associated with the device. The adjustment associated with each antenna element in the antenna elements can be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0094] Network entity 105 or UE 115 can use beam scanning techniques as part of beamforming operations. For example, network entity 105 (e.g., base station 140, RU 170) can use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communication with UE 115. Network entity 105 can transmit some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) multiple times along different directions. For example, network entity 105 can transmit signals according to different sets of beamforming weights associated with different transmission directions. Transmissions along different beam directions can be used (e.g., by a transmitting device such as network entity 105 or by a receiving device such as UE115) to identify the beam direction for subsequent transmission or reception by network entity 105.

[0095] A transmitting device (e.g., transmitting network entity 105, transmitting UE 115) can transmit some signals (e.g., data signals associated with a particular receiving device) along a single beam direction (e.g., a direction associated with a particular receiving device (e.g., receiving network entity 105 or receiving UE 115)). In some examples, the beam direction associated with transmission along a single beam direction can be determined based on signals transmitted along one or more beam directions. For example, UE 115 can receive one or more of the signals transmitted by network entity 105 along different directions and can report to network entity 105 an indication of the signal received by UE 115 that has the highest signal quality or otherwise acceptable signal quality.

[0096] In some examples, multiple beam directions can be used to perform transmissions by a device (e.g., by network entity 105 or UE 115), and the device can use a combination of digital precoding or beamforming to generate a combined beam for transmission (e.g., from network entity 105 to UE 115). UE 115 can report feedback indicating precoding weights for one or more beam directions, and the feedback can correspond to a configured set of beams across the system bandwidth or one or more subbands. Network entity 105 can send reference signals that can be precoded or not precoded (e.g., cell-specific reference signal (CRS), CSI-RS). UE 115 can provide feedback for beam selection, which can be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., multi-panel type codebook, linear combination type codebook, port selection type codebook). Although these techniques are described with reference to signals sent by network entity 105 (e.g., base station 140, RU 170) along one or more directions, UE 115 can employ similar techniques to send signals multiple times along different directions (e.g., for identifying beam directions for subsequent transmissions or receptions by UE 115) or to send signals along a single direction (e.g., for sending data to a receiving device).

[0097] When receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from a receiving device (e.g., network entity 105), the receiving device (e.g., UE 115) can perform receiving operations according to multiple receiving configurations (e.g., directional listening). For example, the receiving device can perform receiving by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of the antenna array (e.g., different sets of directional listening weights), or by processing received signals according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of the antenna array (any of the above operations can be referred to as "listening" according to different receiving configurations or receiving directions), so as to perform receiving according to multiple receiving directions. In some examples, the receiving device can use a single receiving configuration to receive along a single beam direction (e.g., when receiving a data signal). The single receiving configuration can be aligned along a beam direction determined based on listening according to different receiving configuration directions (e.g., a beam direction determined to have the highest signal strength, the highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening according to multiple beam directions).

[0098] The wireless communication system 100 can be a packet-based network that operates according to a layered protocol stack. In the user plane, communication at the bearer or PDCP layer can be IP-based. The RLC layer can perform packet segmentation and reassembly for communication via logical channels. The MAC layer can perform priority handling and multiplexing of logical channels to transport channels. The MAC layer can also implement error detection techniques, error correction techniques, or both to support retransmissions to improve link efficiency. In the control plane, the RRC layer can provide the establishment, configuration, and maintenance of an RRC connection (which supports radio bearers for user plane data) between the UE 115 and the network entity 105 or the core network 130. The PHY layer can map transport channels to physical channels.

[0099] The UE 115 and the network entity 105 can support retransmissions of data to increase the likelihood that the data is successfully received. Hybrid automatic repeat request (HARQ) feedback is a technique for increasing the likelihood that data is correctly received via a communication link (e.g., communication link 125, D2D communication link 135). HARQ can include a combination of error detection (e.g., using cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device can support same-slot HARQ feedback, in which case the device can provide HARQ feedback for data received via a previous symbol in a particular slot in that slot. In some other examples, the device can provide HARQ feedback in a subsequent slot or according to some other time interval.

[0100] The waveform and multiple access design for wireless communication can 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, the waveform and multiple access design can support a relatively wide variety of technologies, such as full-duplex technology, radio frequency sensing, positioning, physical layer security, other technologies, or any combination thereof. Additionally or alternatively, as use cases and technologies expand, the waveform and multiple access design can be supported across multiple frequency ranges (e.g., mmW and above). In some examples, the waveform and multiple access design can be configured to support a relatively large number of connections and a relatively high cell capacity (e.g., the waveform and multiple access design can provide relatively efficient channel access support for a relatively large number of users).

[0101] One or more waveforms for wireless communication can be based on multiple design metrics. Design metrics can include, for example, spectral efficiency, energy efficiency (e.g., power amplifier and processing power efficiency at the transmitting and receiving devices, respectively), waveform processing complexity and latency, radio frequency impairments (e.g., error vector magnitude (EVM), etc.), spectral limitations with power amplifier models (e.g., in-band and out-of-band emissions), and support for relatively efficient multi-user or MIMO multiple access. One or more waveforms can 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 non-linearity, or any combination thereof. In some examples, one or more waveforms can be designed based on advances in digital pre-distortion (DPD) and digital post-distortion (DPoD) techniques, spectral limitations of full-duplex, joint sensing and common (JSAC) use cases, or any combination thereof.

[0102] The techniques, systems, and devices described herein can provide support for using FMCW to improve channel estimation in OFDM systems. One or more devices in wireless communication system 100 can support the FMCW-based OFDM channel estimation techniques described herein. For example, a transmitting device (e.g., UE 115 or network entity 105) can transmit a first FMCW signal via an OFDM channel. A receiving device (e.g., UE 115 or network entity 105 communicating with the transmitting device) can receive the first FMCW signal. The receiving device can 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 can include the start frequency of the first FMCW signal, the bandwidth of the first FMCW, the slope of the first FMCW signal, or any combination thereof. The receiving device can combine the first and second FMCW signals and filter the combined FMCW signal (e.g., using a low-pass filter (LPF)). The receiving device can sample the combined FMCW signal using a sampling rate that can be based on one or more parameters associated with the OFDM channel. The receiving device can use the sampling to estimate the frequency-domain OFDM channel using time-domain signal processing techniques, which can reduce latency, reduce processing complexity, and improve channel estimation reliability.

[0103] Figure 2 An example of an OFDM channel estimation scheme 200 that supports using FMCW to estimate an OFDM channel is shown in accordance with one or more aspects of the present disclosure. In some examples, OFDM channel estimation scheme 200 can be implemented with reference to Figure 1Aspects of the described wireless communication system 100. In this example, a transmitting device 205 (e.g., a UE, a base station, an RU, a DU, a CU, an IAB node, or some other device) and a receiving device 210 (e.g., a UE, a base station, an RU, a DU, a CU, an IAB node, or some other device) may exchange OFDM signals via a wireless channel 235, which may be an OFDM channel. The receiving device 210 may use frequency-domain signal processing to estimate the wireless channel 235.

[0104] The transmitting device 205 and the receiving device 210 may establish a connection for wireless communication via the wireless channel 235. The transmitting device 205 may generate an OFDM signal for transmission to the receiving device 210 via 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 include or be converted into a set of frequency-domain signals 215 (e.g., {X(0), X(1),... X(N c -1)}). The transmitting device 205 may perform an inverse fast Fourier transform (IFFT) 220 on the frequency-domain signals 215 to convert the frequency-domain signals 215 into time-domain signals (e.g., X(m)).

[0105] The transmitting device 205 may perform cyclic prefix addition 225 on 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 may then use a digital-to-analog converter (DAC) 230 to convert the time-domain signal from a digital signal to an analog signal. In some examples, the transmitting device 205 may convert the real and imaginary parts of the digital time-domain signal to the analog domain separately. The transmitting device 205 may transmit the analog time-domain OFDM signal to the receiving device 210 via the wireless channel 235.

[0106] The receiving device 210 may receive the analog time-domain OFDM signal and convert the received signal to the digital domain using an ADC 240 at 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. The receiving device 210 may perform cyclic prefix removal 245 after using the ADC 240 to remove the cyclic prefix from the time-domain digital signal. After removing the cyclic prefix, the receiving device 210 may perform an FFT 250 on the digital time-domain signal. The FFT 250 may convert the time-domain signal to the frequency domain. That is, the FFT 250 may produce a set of frequency-domain signals 255.

[0107] The receiving device 210 can use the set of frequency-domain signals 255 generated by the FFT 250 to estimate the frequency-domain OFDM channel (e.g., the frequency domain of the wireless channel 235). In some examples, to estimate the frequency-domain OFDM channel based on the OFDM signal, as referenced Figure 2 As described, the ADC 240 at 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 into a digital OFDM signal.

[0108] Table 1 shows example sampling rates of the ADC 240 for subcarrier spacing (SCS) values that can be used for different configurations.

[0109]

[0110] Table 1 - FFT size, subcarriers (sc), and sampling rate per SCS

[0111] The sampling rate can be defined in millions of samples per second (Msps). The sampling rate can be calculated based on the SCS value and the corresponding FFT size and can be associated with the corresponding number of subcarriers (sc) (e.g., in terms of the number of physical resource blocks (PRBs)). For example, the sampling rate can be equal to the product of the SCS and the N FFT size (e.g., 115 KHz * 2048 = 30.72 MHz).

[0112] 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 at the receiving device 210 can be a relatively high-rate ADC 240. The sampling rate for converting the received analog signal into digital form (such as the sampling rates shown in Table 1) may be relatively high for the receiving device 210 to accurately convert the OFDM signal and subsequently perform the FFT 250.

[0113] The techniques, systems, and devices described herein provide for the transmitting device 205 and the receiving device 210 to exchange FMCW signals via the wireless channel 235. The FMCW signals can be configured for channel estimation of the OFDM channel and can support reducing the processing complexity at the receiver. For example, compared to the OFDM signal, the FMCW signal can be sampled at a reduced sampling rate and can be used to estimate the frequency-domain OFDM channel using time-domain signal processing, such that the receiving device 210 can avoid performing the FFT 250, which can reduce complexity compared to using the OFDM signal to estimate the OFDM channel. The FMCW-based channel estimation techniques are described in further detail elsewhere herein, including reference Figures 3 - 6 .

[0114] Figure 3 illustrates an example of an OFDM channel estimation scheme 300 that supports using FMCW to estimate an OFDM channel according to one or more aspects of the present disclosure. In some examples, the OFDM channel estimation scheme 300 may implement aspects of the wireless communication system 100 described with reference to Figure 1 In this example, a transmitting device 305 (e.g., a UE, a base station, an RU, a DU, a CU, an IAB node, or some other device) and a receiving device 310 (e.g., a UE, a base station, an RU, a DU, a CU, an IAB node, or some other device) may exchange FMCW signals via 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.

[0115] The transmitting device 305 and the receiving device 310 may establish a connection for wireless communication via the OFDM channel 315. The devices may be a UE 115, a 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 process described herein. Such signaling may be described in further detail elsewhere herein, including with reference to Figures 4 - 6 .

[0116] After initiating the FMCW-based OFDM channel estimation process, 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 via the OFDM channel 315 using at least one antenna element at the transmitting device 305. The analog-domain FMCW signal 320 generated and transmitted by the transmitting device 305 may be represented by x RF,Tx (t), as shown in Equation 1.

[0117]

[0118] 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.

[0119] As Figure 3As shown, the FMCW signal 320 can be associated with the waveform signal transmitted via the symbols 380 of the OFDM channel 315 in the time domain and the bandwidth 370 (e.g., BW) of the OFDM channel 315 in the frequency domain. The bandwidth 370 can include one or more resource blocks 375 in the frequency domain. In some examples, each resource block 375 can include a set of resource elements in the frequency domain. The OFDM channel 315 can include a plurality of symbols 380 in the time domain. The duration or length of each symbol 380 can correspond to the length of an OFDM symbol, or the length of an OFDM symbol and the corresponding cyclic prefix duration, or a partial length of an OFDM symbol, or a partial length of an OFDM symbol and the corresponding cyclic prefix duration, or some other length longer than the length of an OFDM symbol and the length of an OFDM symbol and cyclic prefix duration, or some other symbol duration, or any combination thereof. The FMCW signal 320 can span the frequency between the starting frequency 390 and the sum of the starting frequency 390 and the bandwidth 370 (e.g., {f c ,f c +BW}). The slope 385 of the FMCW signal 320 can correspond to the quotient of the bandwidth 370 and the duration of the symbol 380 via which the FMCW signal 320 is transmitted, as shown in Equation 2.

[0120]

[0121] In the example of Equation 2, T sym can represent the duration of the symbol 380, N RE can represent the number of resource elements in the bandwidth 370, and Δf can represent the SCS. In this example, the slope can be calculated based on the symbol duration corresponding to the length of the OFDM symbol. For example, the duration of the symbol 380 can be the reciprocal of the SCS (e.g., ).

[0122] The radio frequency FMCW signal 325 received by the receiving device 310 via the OFDM channel 315 in response to the FMCW signal 320 transmitted by the transmitting device 305 can be represented by y RF,Rx (t), as shown in Equation 3.

[0123]

[0124] In the example of Equation 3, P can represent the number of channel delay paths associated with the OFDM channel 315 (e.g., the number of multipaths), and τ p can represent a given channel delay with index P. That is, the received FMCW signal 325 can be sampled at various channel delays (e.g., p = 0 to P - 1). A pThe condition of the OFDM channel 315 can be represented, and n(t) can represent the channel noise. In some examples, the channel noise can be associated with a value that is relatively small compared to other values with respect to the received radio frequency FMCW signal 325 received by the receiving device 310 as defined in Equation 3.

[0125] As described herein, the receiving device 310 can generate an FMCW signal 330 at the receiving device. The FMCW signal 330 generated at the receiving device 310 can be referred to as a second FMCW signal or a local FMCW signal. The receiving device 310 can generate the FMCW signal 330 in the analog domain using the VCO 355 at the receiving device 310. The receiving device 310 can generate the FMCW signal 330 while or after receiving the FMCW signal 325. The FMCW signal 330 generated by the receiving device 310 can be represented by x RF,Rx (t)(t) as shown in Equation 4.

[0126]

[0127] As shown in Equation 4, the receiving device 310 can generate the FMCW signal 330 based on a set of FMCW parameters associated with the FMCW signal 320 transmitted by the transmitting device 305. The set of FMCW parameters can include, for example, the start frequency 390 (f c ) of the FMCW signal 320, 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 can 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 can represent the phase of the receiving device 310. In some examples, the phase of the receiving device can be the same as the phase of the transmitting device (e.g., φ tx = φ Rx ). In some examples, the transmitting device 305 can transmit a control message indicating the set of FMCW parameters for generating the FMCW signal 330 by the receiving device 310. Additionally or alternatively, the receiving device 310 can transmit a control message that indicates the set of FMCW parameters for generating the FMCW signal 320 by the transmitting device 305 and for generating the FMCW signal 330 by the receiving device 310, as described in further detail elsewhere herein (including references Figures 4 to 6 ).

[0128] 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 can be wideband signals (e.g., can span the full bandwidth 370 of the OFDM channel 315), can span the duration of the symbol 380 in the OFDM channel 315, can be associated with the starting frequency 390, and can be associated with the slope 385. In some examples, the FMCW signal 320 transmitted by the transmitting device 305 can be a real signal. For example, the FMCW signal 320 can include a single stream (e.g., a cosine stream, as shown in Equation 1). The FMCW signal 330 generated by the receiving device 310 can include two streams for channel estimation (e.g., a sine stream and a cosine stream). That is, the exponential function in the FMCW signal 330 generated by the receiving device 310 can be designed for channel estimation. In some examples, the receiving device 310 can be configured with a function for generating the FMCW signal 330 for channel estimation, or the receiving device 310 can receive a control message indicating the function for generating the FMCW signal 330 for channel estimation.

[0129] After generating the FMCW signal 330 configured for channel estimation, the receiving device 310 can generate a combined FMCW signal 335 (e.g., y mixed (t)). To generate the combined FMCW signal 335, the receiving device 310 can use a mixer 350 to combine the FMCW signal 325 received at the receiving device 310 with the locally generated FMCW signal 330. The mixer 350 can represent an example of one or more components (e.g., hardware, software, or both) of the receiving device 310 that are configured to combine two or more time-domain FMCW signals. In some examples, the combination can include multiplying the FMCW signals (e.g., y mixed (t) = y RF,Rx (t) x RF,Rx (t)).

[0130] The receiving device 310 can filter the combined FMCW signal 335 at the receiving device 310 using an LPF 360. The LPF 360 can generate a combined and filtered FMCW signal 340 (e.g., y mixed,LPF (t)). The LPF 360 can represent an example of a component of the receiving device 310 that is configured to filter a signal, or a function supported by the receiving device 310, or both. For example, the receiving device 310 can apply an LPF function to the combined FMCW signal 335 (e.g., y mixed,LPF (t) = LPF[y RF,Rx (t) x RF,UE(t)]). The combined and filtered FMCW signal 340 can be represented by Equation 5.

[0131]

[0132] Equation 5 can be simplified according to Equation 6.

[0133]

[0134] In some examples, the quadratic exponential function in β p can represent the channel estimation error, which can be ignored to further simplify Equation 6. For example, half of the quadratic exponential function of β p (e.g., ) may be associated with the channel estimation error. However, if the value of τ p is relatively small, the channel estimation error may also be relatively small (e.g., negligible). In some examples, including in the radio frequency FMCW signal 325 received by the receiving device 310 (e.g., y RF,Rx (t)), the channel noise can be represented by after the signal is combined with the generated FMCW signal 330 and filtered using the LPF 360. As described with reference to Equation 3, the channel noise can be associated with values that are relatively small compared to other values defining the combined and filtered FMCW signal 340 shown in Equations 5 and 6.

[0135] 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 the ADC 365. The sampling rate for sampling 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 can be based on the frequency range of one or more sub - bands in the OFDM channel 315 (e.g., the sampling rate can be equal to the reciprocal of). The sub - band frequency range f subband can represent the granularity at which the receiving device 310 can estimate the OFDM channel 315 in the frequency domain.

[0136] As part of the OFDM channel estimation, sampling by the receiving device 310 can produce a sampling sequence D Rx (k), which can represent a set of values associated with the OFDM channel estimation. The sampling sequence can have the granularity of f subband . For example, D Rx(k) Each value can represent an example of an estimated value of a corresponding frequency sub-band of the OFDM channel 315. The sampling sequence D Rx (k) is shown by Equation 7.

[0137]

[0138] In the example of Equation 7, F s can represent the sampling rate used by the receiving device 310 to estimate the OFDM channel 315. K can represent the total number of sub-bands in the OFDM channel 315, which can also correspond to the total number of samples in the sampling sequence. Thus, each value of k can represent the index of a corresponding sub-band in the total number of sub-bands. In one example, if the sub-band frequency range f subband of the OFDM channel 315 is equal to one resource element, the sampling sequence can include corresponding samples or estimated values for each resource element (e.g., each comb) in the OFDM channel 315. In some examples, the sub-band frequency range f subband can be any other granularity, such as a set of two or more resource elements, a resource block, or some other frequency range.

[0139] The receiving device 310 can thus estimate the frequency-domain OFDM channel 315 using 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, and at a granularity of f subband . The described FMCW-based OFDM channel estimation technique can be performed by the receiving device 310 in the time domain using time-domain signal processing. That is, when using an FMCW signal to estimate the frequency-domain OFDM channel 315, the receiving device 310 can avoid applying an FFT or other frequency transformation. By performing OFDM channel estimation in the time domain, the receiving device 310 can reduce processing complexity, latency, and power consumption compared to other OFDM channel estimation techniques that are performed at least partially in the frequency domain (e.g., using an FFT). Additionally or alternatively, the receiving device 310 can use both wideband radio frequency processing and narrowband radio frequency processing to estimate the frequency-domain OFDM channel 315. For example, the FMCW signal 325 received at the receiving device 310 can be a wideband signal in the radio frequency, and after the LPF 360, the combined and filtered FMCW signal 340 can be a narrowband signal for baseband processing.

[0140] The sampling rate used by the receiving device 310 to estimate the frequency-domain OFDM channel 315 using an FMCW signal may be relatively low. The sampling rate described herein can be based on the slope 385 of the FMCW signal and the frequency granularity f subband . For example, the sampling rate can be equal to where k subbandIndicates the number of resource elements in each frequency sub - band (e.g., each sampled portion of the frequency - domain OFDM channel 315). The sampling rate of some OFDM - based OFDM channel estimation techniques (e.g., as described in reference Figure 2 can be equal to the product of the FFT size N FFT and the SCS Δf (e.g., N FFT ·Δf). Thus, the ratio of the sampling rate of the FMCW - based OFDM channel estimation described herein to that of OFDM - based OFDM channel estimation techniques can be represented by γ, as shown in Equation 8.

[0141]

[0142] As shown in Equation 8, the ratio between the sampling rates of the FMCW - based OFDM channel estimation technique and the OFDM - based OFDM channel estimation technique may be relatively low. That is, compared with the OFDM - based OFDM channel estimation technique, the sampling rate of the FMCW - based OFDM channel estimation technique may be relatively low. In one example, if there are 273*12 resource elements in the bandwidth 370 (e.g., N RE = 273*12), and each sub - band includes a single resource element (e.g., k subband = 1), then the ratio can be equal to 0.8. That is, in such a case, the FMCW - based OFDM channel estimation technique can produce an ADC sampling gain of approximately 20%. In some examples, for example, for the scenario where a receiving device (e.g., UE 115) reports channel state information (CSI) or a precoding matrix indicator (PMI), the minimum value of the sub - band size can be equal to because the maximum number of sub - bands (e.g., N3) that can be reported via CSI or PMI reporting can be 37.

[0143] Table 2 includes the example sampling rates for accurately estimating the frequency - domain OFDM channel 315 using the FMCW - based OFDM channel estimation technique described herein compared to example sampling rates for accurately estimating the frequency - domain OFDM channel 315 using other OFDM channel estimation techniques in the frequency domain, as described in reference Figure 2 The example sampling rates shown in Table 2 represent the example sampling rates that the receiving device 310 can use to accurately estimate the OFDM channel 315 at the granularity of four resource blocks 375 when the channel bandwidth 370 is 50 MHz.

[0144]

[0145] Table 2 - Comparison of Sampling Rates for Different Channel Estimation Techniques

[0146] As shown in Table 2, the FMCW-based channel estimation techniques described herein can 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 at which the receiving device 310 estimates the OFDM channel 315 at the granularity of four resource blocks 375 can be approximately 1.69% of the sampling rate that could be used by the receiving device 310 in the case of performing OFDM-based channel estimation in the same scenario.

[0147] The FMCW-based OFDM channel estimation described herein can reliably estimate the frequency-domain OFDM channel 315 using a reduced sampling rate. For example, when compared to a baseline value, the accuracy of the FMCW-based OFDM channel estimation technique can be relatively similar to that of an OFDM-based OFDM channel estimation technique using a frequency-domain reference signal across a range of packet delay protocols, SCS values, and bandwidths. 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.

[0148] Figure 4 An example of a wireless communication system 400 that supports using FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown. The wireless communication system 400 may implement aspects of the wireless communication system 100 or the OFDM channel estimation scheme 300 as described with reference to Figure 1 and Figure 3 or may be implemented thereby. 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 as described with reference to Figures 1 - 3 The network entity 105-a may be within a geographic coverage area 110-a and communicate with the UE 115-a via an uplink communication link 410 and a downlink communication link 415. In this example, the network entity 105-a may send an FMCW signal 430 to the UE 115-a for estimating the OFDM channel.

[0149] 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 Figure 4 example shown, 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 Figure 3 Although in Figure 4In the example shown, network entity 105-a is shown as the transmitting device, but it should be understood that in some examples, UE 115-a can be the transmitting device and can send FMCW signal 430 to network entity 105-a, as described in further detail elsewhere in this document (including references to Figure 6 ).

[0150] UE 115-a can establish a connection for wireless communication with network entity 105-a via uplink communication link 410 and downlink communication link 415. UE 115-a can send a capability message 420 to network entity 105-a via uplink communication link 410 after establishing the connection. Capability message 420 can indicate that UE 115-a is capable of receiving FMCW signal 430. Capability message 420 can be an example of an uplink control information (UCI) message, a media access control control element (MAC-CE), or some other type of uplink signaling. In some examples, UE 115-a can send multiple capability messages 420 dynamically or semi-persistently.

[0151] Network entity 105-a can receive capability message 420 and determine that UE 115-a is capable of receiving FMCW signal 430 and performing OFDM channel estimation based on FMCW signal 430. Network entity 105-a can thus determine to initiate an FMCW-based OFDM channel estimation process. Network entity 105-a can send one or more control messages 425 to UE 115-a via downlink communication link 415 to facilitate the FMCW-based OFDM channel estimation process. One or more control messages 425 can include, for example, symbol assignment information, FMCW parameter information, channel estimation trigger, or any combination thereof.

[0152] In some examples, the first control message 425 can indicate whether each symbol in a set of symbols in the OFDM channel is assigned for FMCW signal 430 or OFDM signal 435. FMCW signal 430 and OFDM signal 435 can be multiplexed across the symbols of the OFDM channel in the time domain, and the first control message 425 can indicate which symbols are assigned for which type of signaling. The second control message 425 can indicate a set of one or more FMCW parameters 445 that network entity 105-a will use to transmit FMCW signal 430. The set of FMCW parameters 445 can include the bandwidth of FMCW signal 430, the starting frequency of FMCW signal 430, the slope of FMCW signal 430, the initial phase of FMCW signal 430, or any combination thereof, as described in further detail elsewhere in this document (including references to Figure 3) is described in further detail. In some examples, network entity 105-a may send an RRC configuration to UE 115-a after establishing communication with 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 of FMCW parameters 445.

[0153] In some examples, the third control message 425 sent by network entity 105-a to UE 115-a may include a trigger (e.g., a request or other trigger information) for UE 115-a to perform OFDM channel estimation using the FMCW signal 430. In some examples, network entity 105-a may send a single control message that includes symbol assignment 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, other types of downlink messages, or any combination thereof. Network entity 105-a may send one or more control messages 425 dynamically or semi-statically. In some examples, network entity 105-a may send one or more control messages 425 based on receiving a capability message 420 from UE 115-a (e.g., in response to receiving a capability message 420 from UE 115-a or after receiving a capability message 420 from UE 115-a). That is, network entity 105-a may send the control message 425 based on UE 115-a indicating that UE 115-a is capable of receiving the FMCW signal 430 to facilitate the FMCW-based OFDM channel estimation process.

[0154] Network entity 105-a may then send a first FMCW signal 430 to UE 115-a via the downlink communication link 415. Network entity 105-a may send the first FMCW signal 430 based on (e.g., using, according to) 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 sent via an OFDM channel and may be configured to assist UE 115-a in estimating the frequency-domain OFDM channel.

[0155] UE 115-a can receive a first FMCW signal 430 via an OFDM channel, and UE 115-a can generate a second FMCW signal (e.g., a local FMCW signal). UE 115-a can 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 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 Figure 3 ).

[0156] In some examples, UE 115-a can send a report (such as CSI report 440) that indicates information associated with the OFDM channel estimation based on the FMCW signal. The network entity 105-a can send a control message 425 that includes a trigger or request for UE 115-a to send the CSI report 440, and UE 115-a can generate the CSI report 440 based on the trigger and send the CSI report 440 via the uplink communication link 410. The network entity 105-a and UE 115-a can adjust one or more parameters for subsequent communication based on the channel estimation, which can improve the throughput and reliability of subsequent communication between the network entity 105-a and UE 115-a.

[0157] Although the network entity 105-a is shown as a transmitting device in the example of Figure 4 , it should be understood that in some examples, UE 115-a can be the transmitting device. For example, UE 115-a can send the first FMCW signal 430 to the network entity 105-a via the uplink communication link 410, and the network entity 105-a can generate a local FMCW signal and estimate the frequency-domain OFDM channel based on time-domain samples of the first FMCW signal 430 and the local FMCW signal. In such a case, the capability message 420 sent by UE 115-a can indicate that UE 115-a is capable of sending the FMCW signal 430. The control message 425 sent by the network entity 105-a can include symbol allocation information, a set of FMCW parameters 445, and a trigger for UE 115-a to send the first FMCW signal 430 (e.g., via the uplink communication link 410). UE 115-a can send the first FMCW signal 430 via the symbols allocated for FMCW based on the indicated set of FMCW parameters 445 and the trigger.

[0158] Devices in the wireless communication system 400 can thus exchange FMCW signals 430 that are configured to estimate the frequency-domain OFDM channel using time-domain signal processing (e.g., without performing an FFT) and a relatively low sampling rate. The network entity 105-a can determine to send one or more control messages or other signaling based on the ability of the UE 115-a to transmit or receive the FMCW signal 430 to facilitate FMCW-based OFDM channel estimation. Elsewhere in this document (including with reference to Figure 5 and Figure 6 ), examples of signaling that can be exchanged between the transmitting device and the receiving device are described in further detail.

[0159] Figure 5 FIG. shows an example of a process flow 500 that supports estimating an OFDM channel using FMCW, in accordance with one or more aspects of the present disclosure. The process flow 500 can implement aspects of, or be implemented by, the wireless communication systems 100 and 400 or the OFDM channel estimation scheme 300. For example, the process flow 500 shows communication between a first wireless device 505 and a second wireless device 510 (which can represent aspects of corresponding devices as described with reference to Figures 1 - 4 ). In this example, the first wireless device 505 can represent an example of the UE 115, and the second wireless device 510 can represent an example of the network entity 105. In some examples, the devices can exchange signaling to support FMCW-based OFDM channel estimation.

[0160] In the following description of the process flow 500, the operations between the first wireless device 505 and the second wireless device 510 can be performed in a different order or at different times. Some operations can also be excluded from the process flow 500, or other operations can be added. Although the first wireless device 505 and the second wireless device 510 are shown as performing the operations of the process flow 500, some aspects of some operations can also be performed by one or more other wireless devices.

[0161] At 515, the first wireless device 505 can send a capabilities message to the second wireless device 510. The capabilities message can 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 can indicate whether the first wireless device 505 is capable of estimating the frequency-domain OFDM channel based on the FMCW signal.

[0162] At 520, the second wireless device 510 may send a first control message, which may be referred to as a symbol allocation control message in some aspects of the present disclosure. The first control message may indicate whether one or more symbols of an OFDM channel are allocated for an FMCW signal or an OFDM signal. 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 an OFDM signal and a second set of symbols for transmission or reception of an FMCW signal. The OFDM signal and the FMCW signal may be time-division multiplexed across the symbols of the OFDM channel. The second wireless device 510 may send the first control message to the first wireless device 505 dynamically or semi-persistently to indicate 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.

[0163] At 525, the second wireless device 510 may send a second control message, which may be referred to as an FMCW parameter control message in some aspects of the present disclosure. The second control message may indicate a set of FMCW parameters associated with a first FMCW signal to be sent by the second wireless device 510. The set of FMCW parameters may include the start frequency of the first FMCW signal, the bandwidth of the first FMCW, the 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 in the reference Figure 3 . In some examples, the slope may be based on the bandwidth of the first FMCW signal and the duration of the symbol via which the first FMCW signal will be sent.

[0164] As described in further detail in the reference Figure 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 send the second control message (e.g., an indication of FMCW parameters) dynamically or semi-persistently. In some examples, the second wireless device 510 may send one or more RRC messages, each of which may 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 an index for one of the sets of FMCW signals to the first wireless device 505. Additionally or alternatively, the second wireless device 510 may send 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 an index for one of the sets of FMCW signals to the first wireless device 505.

[0165] At 530, the second wireless device 510 may send a third control message to the first wireless device 505. In some aspects herein, this third control message may be referred to as a channel estimation trigger. The channel estimation trigger may trigger the first wireless device 505 to perform channel estimation via FMCW. That is, the channel estimation trigger may include a request, instruction, or indication for triggering the first wireless device 505 to start monitoring FMCW signals for estimating the frequency-domain OFDM channel.

[0166] Although the symbol assignment control message, the FMCW parameter control message, and the channel estimation trigger (e.g., the first to third control messages) are shown as separate control messages, it should be understood that the second wireless device 510 may send any number of control messages to indicate any combination of the described symbol assignment, FMCW parameters, and channel estimation trigger. In some examples, the second wireless device 510 may send a single control message (e.g., a single DCI, MAC-CE, or RRC message) that indicates each of the symbol assignment for FMCW, the set of FMCW parameters, and the channel estimation trigger. Additionally or alternatively, the second wireless device 510 may send two control messages to indicate the symbol assignment for FMCW and the set of FMCW parameters, respectively. In some examples, receipt by the first wireless device 505 of the symbol assignment 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.

[0167] At 535, the second wireless device 510 may generate a first FMCW signal for use by the first wireless device 505 in estimating the OFDM channel. 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 transmitted via the first, second, and third control messages. For example, the second wireless device 510 may generate the first FMCW signal based on the 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 receiving a capabilities message from the first wireless device 505 (e.g., in response to receiving a capabilities message from the first wireless device 505 or after receiving a capabilities message from the first wireless device 505), based on sending any of the first to third control messages, or any combination thereof.

[0168] At 540, the second wireless device 510 may send the first FMCW signal to the first wireless device 505 via the OFDM channel. The first wireless device 505 may receive the first FMCW signal as an analog time-domain signal via the OFDM channel.

[0169] 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., as indicated via a second control message at 525). For example, the first wireless device 505 may generate the second FMCW signal based on the same start frequency, slope, and bandwidth as the first FMCW signal, as described in further detail elsewhere herein (including with reference to Figure 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 an FMCW function configured to support improved OFDM channel estimation.

[0170] At 550, the first wireless device 505 may estimate the OFDM channel based on the first and second FMCW signals. To estimate the frequency-domain OFDM channel, in some examples, the first wireless device 505 may combine the first and second FMCW signals 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 sample the combined FMCW signal in the time domain using a sampling rate based on one or more parameters of the OFDM channel, such as the sub-band frequency range of the OFDM channel (e.g., f subband ). In some examples, the first wireless device 505 may sample the combined FMCW signal using an ADC, as described in further detail elsewhere herein (including with reference to Figure 3 ).

[0171] The first wireless device 505 may estimate the frequency-domain OFDM channel by estimating the respective values of the OFDM channel for each of a plurality of sub-bands in the frequency domain of the OFDM channel based on the sampling. For example, the sampling may produce a sampling sequence, where each value in the sampling sequence is associated with a respective sub-band of the OFDM channel. By adjusting the sampling rate used by the first wireless device 505 based on the sub-band frequency range (e.g., the frequency estimation granularity), the first wireless device 505 may vary the number of sub-bands estimated (e.g., the first wireless device 505 may make the frequency-domain OFDM channel estimation have a greater or smaller granularity). The sampling rate used to sample the combined and filtered FMCW signal may be relatively low (e.g., less than the sampling rate used to estimate the OFDM channel based on an OFDM signal), which may reduce the processing complexity and power consumption at the device.

[0172] At 555, in some examples, the second wireless device 510 may send a control message that includes a trigger (e.g., a request) for the first wireless device 505 to send a CSI report or some other report indicating an OFDM channel estimate. The first wireless device 505 may generate a CSI report based on the CSI report trigger and the OFDM channel estimate based on the FMCW signal. At 560, the first wireless device 505 may send the CSI report to the second wireless device 510.

[0173] At 565, the second wireless device 510 and the first wireless device 505 may transmit OFDM signals via 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 send and receive uplink data, downlink data, sidelink data, or any combination thereof, where the data may be transmitted via the OFDM signal. The FMCW-based frequency-domain OFDM channel estimation techniques described herein may thus provide the first wireless device 505 with the ability to reliably and accurately estimate 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 may improve throughput, communication reliability, and coordination between devices while maintaining or reducing processing complexity, latency, and power consumption.

[0174] Figure 6 An example of a process flow 600 that supports the use of FMCW to estimate an OFDM channel is shown in accordance with one or more aspects of the present disclosure. The process flow 600 may implement aspects of or be implemented by the wireless communication systems 100 and 400 or the OFDM channel estimation scheme 300. For example, the process flow 600 shows communication between a first wireless device 605 and a second wireless device 610 (which may represent aspects of corresponding devices as described with reference to Figures 1 - 5 In this example, the first wireless device 605 may represent an example of the network entity 105, and the second wireless device 610 may represent an example of the UE 115. In some examples, the devices may exchange signaling to support FMCW-based OFDM channel estimation.

[0175] In the following description of the process flow 600, the 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 also be excluded from the process flow 600, or other operations may be added. Although the first wireless device 605 and the second wireless device 610 are shown as performing the operations of the process flow 600, some aspects of some operations may also be performed by one or more other wireless devices.

[0176] At 615, the second wireless device 610 may send a capabilities message to the first wireless device 605. The capabilities message may indicate whether the second wireless device 610 is capable of sending an FMCW signal (e.g., FMCW transmission capability). In some examples, the capabilities message may indicate whether the second wireless device 610 is capable of sending an FMCW signal configured for frequency-domain OFDM channel estimation.

[0177] At 620, the first wireless device 605 may send a first control message, which in some aspects herein may be referred to as a symbol allocation control message. The first control message may indicate whether one or more symbols of an OFDM channel are allocated for an FMCW signal or an OFDM signal. 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 an OFDM signal and a second set of symbols for transmission or reception of an FMCW signal. The OFDM signal and the FMCW signal may be time-division multiplexed across the symbols of the OFDM channel. The first wireless device 605 may send the first control message to the second wireless device 610 dynamically or semi-persistently to indicate 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 send the symbol allocation control message based on the capabilities message from the second wireless device 610 (e.g., in response to the capabilities message from the second wireless device 610, after the capabilities message from the second wireless device 610).

[0178] At 625, the first wireless device 605 may send a second control message, which in some aspects herein may be referred to as an FMCW parameter control message. The second control message may indicate a set of FMCW parameters associated with a first FMCW signal to be sent by the second wireless device 610. The set of FMCW parameters may include the start frequency of the first FMCW signal, the bandwidth of the first FMCW, the 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 in Figure 3 In some examples, the slope may be based on the bandwidth of the first FMCW signal and the duration of the symbol via which the first FMCW signal will be sent.

[0179] As referenced in Figure 4More specifically, the second control message can be a DCI message, MAC-CE, RRC message, some other type of control signaling, or any combination thereof. The first wireless device 605 can send the second control message (e.g., an indication of FMCW parameters) dynamically or semi-persistently. In some examples, the first wireless device 605 can send one or more RRC messages, each RRC message can configure (e.g., pre-configure) a set of FMCW parameters, and the second control message can be a DCI message or MAC-CE signaling that indicates an index for one of the sets of FMCW signals to the second wireless device 610. Additionally or alternatively, the first wireless device 605 can send a single RRC message that configures multiple sets of FMCW parameters, and the second control message can be a DCI message or MAC-CE signaling that indicates an index for one of the sets of FMCW signals to the second wireless device 610.

[0180] At 630, the first wireless device 605 can send a third control message to the second wireless device 610. In some aspects herein, the third control message can be referred to as an FMCW transmission trigger. The FMCW transmission trigger can trigger the second wireless device 610 to send an FMCW signal. That is, the FMCW transmission trigger can include a request, instruction, or indication for triggering the second wireless device 610 to generate and send an FMCW signal for estimating the frequency-domain OFDM channel.

[0181] Although the symbol allocation control message, the FMCW parameter control message, and the FMCW transmission trigger (e.g., the first to third control messages) are shown as separate control messages, it should be understood that the first wireless device 605 may send any number of control messages to indicate any combination of the described symbol allocation, FMCW parameters, and FMCW transmission trigger. In some examples, the first wireless device 605 may send a single control message (e.g., a single DCI, MAC-CE, or RRC message) that indicates 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 send two control messages to indicate the symbol allocation for FMCW and the set of FMCW parameters, respectively. In some examples, the reception by the second wireless device 610 of the symbol allocation for FMCW, the set of FMCW parameters, or both may trigger the second wireless device 610 to send an FMCW signal for channel estimation (e.g., via the allocated symbols and using the indicated FMCW parameters). In some examples, any one or more of the first to third control messages may be sent by the first wireless device 605 based on a capability message from the second wireless device 610 indicating that the second wireless device 610 supports FMCW transmission (e.g., in response to a capability message from the second wireless device 610 indicating that the second wireless device 610 supports FMCW transmission, after a capability message from the second wireless device 610 indicating that the second wireless device 610 supports FMCW transmission).

[0182] At 635, the second wireless device 610 may generate a first FMCW signal for estimation of the 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, second, and third control messages. For example, the second wireless device 610 may generate the first FMCW signal based on the 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 a transmission capability message (e.g., in response to or after a transmission capability message), based on receiving any control message or any combination of the first to third control messages.

[0183] At 640, the second wireless device 610 may send the first FMCW signal to the first wireless device 605 via the OFDM channel. The first wireless device 605 may receive the first FMCW signal as an analog time-domain signal via the OFDM channel.

[0184] 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., as 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 start frequency, slope, and bandwidth as the first FMCW signal, as further described elsewhere herein (including with reference to Figure 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 an FMCW function configured to support improved OFDM channel estimation.

[0185] At 650, the first wireless device 605 may estimate the OFDM channel based on the first and second FMCW signals. To estimate the frequency-domain OFDM channel, in some examples, the first wireless device 605 may combine the first and second FMCW signals 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 505 may sample the combined FMCW signal in the time domain using a sampling rate based on one or more parameters of the OFDM channel, such as the sub-band frequency range or size of the OFDM channel (e.g., f subband ). In some examples, the first wireless device 605 may sample the combined FMCW signal using an ADC, as further described elsewhere herein (including with reference to Figure 3 ).

[0186] The first wireless device 605 may estimate the frequency-domain OFDM channel by estimating the respective values of the OFDM channel for each of a plurality of sub-bands in the frequency domain of the OFDM channel based on the sampling. For example, the sampling may produce a sampling sequence, where each value in the sampling sequence is associated with a respective sub-band of the OFDM channel. By adjusting the sampling rate used by the first wireless device 605 based on the sub-band frequency range (e.g., frequency estimation granularity), the first wireless device 605 may vary the number of sub-bands estimated (e.g., the first wireless device 605 may make the frequency-domain OFDM channel estimation have a greater or smaller granularity). The sampling rate used to sample the combined and filtered FMCW signal may be relatively low (e.g., less than the sampling rate used to estimate the OFDM channel based on an OFDM signal), which may reduce the processing complexity and power consumption at the device.

[0187] At 655, the first wireless device 605 and the second wireless device 610 may transmit OFDM signals via an OFDM channel based on an estimate of the frequency-domain OFDM channel. For example, the first wireless device 605 may send one or more subsequent data transmissions to the second wireless device 610 after estimating the frequency-domain OFDM channel. The subsequent data transmission may be an OFDM signal indicating the channel estimate or other information associated with the estimate of the frequency-domain OFDM channel. The first wireless device 605 and the second wireless device 610 may send and receive uplink data, downlink data, sidelink data, or any combination thereof, where the data may be transmitted via OFDM signals.

[0188] The FMCW-based frequency-domain OFDM channel estimation techniques described herein may thus provide the first wireless device 605 with the ability to reliably and accurately estimate 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 may improve throughput, communication reliability, and coordination between devices while maintaining or reducing processing complexity, latency, and power consumption.

[0189] Figure 7 Block diagram 700 illustrates a device 705 that supports using FMCW to estimate an OFDM channel, in accordance with one or more aspects of the present disclosure. Device 705 may be an example of aspects of UE 115 or network entity 105 as described herein. Device 705 may include a receiver 710, a transmitter 715, and a communication manager 720. Device 705 may also include a processor. Each of these components may communicate with one another (e.g., via one or more buses).

[0190] The receiver 710 may provide means for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to using FMCW to estimate an OFDM channel). The information may be passed to other components of device 705. The receiver 710 may utilize a single antenna or an array of multiple antennas.

[0191] The transmitter 715 may provide means for transmitting signals generated by other components of device 705. For example, the transmitter 715 may transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to using FMCW to estimate an OFDM channel). In some examples, the transmitter 715 may be co-located with the receiver 710 in a transceiver module. The transmitter 715 may utilize a single antenna or an array of multiple antennas.

[0192] The communication manager 720, the receiver 710, the transmitter 715, or various combinations thereof or various components thereof can be examples of units for performing various aspects of estimating an OFDM channel using FMCW as described herein. For example, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof can support methods for performing one or more of the functions described herein.

[0193] In some examples, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof can be implemented in hardware (e.g., in a communication management circuit). The hardware can 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 to or otherwise supporting units for performing the functions described in this disclosure. In some examples, a processor and a memory coupled to the processor can be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

[0194] Additionally or alternatively, in some examples, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof can be implemented with code executed by a processor (e.g., as communication management software or firmware). If implemented with code executed by a processor, the functions of the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof can 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., configured to or otherwise supporting units for performing the functions described in this disclosure).

[0195] In some examples, the communication manager 720 can be configured to perform various operations (e.g., receive, obtain, monitor, output, transmit) using the receiver 710, the transmitter 715, or both or otherwise in cooperation with the receiver 710, the transmitter 715, or both. For example, the communication manager 720 can receive information from the receiver 710, send information to the transmitter 715, or be integrated in combination with the receiver 710, the transmitter 715, or both to obtain information, output information, or perform various other operations as described herein.

[0196] According to examples as disclosed herein, communication manager 720 may support wireless communication at a first wireless device. For example, communication manager 720 may be configured to or otherwise support a unit for receiving a first FMCW signal via an OFDM channel. Communication manager 720 may be configured to or otherwise support a unit for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. Communication manager 720 may be configured to or otherwise support a unit for estimating the OFDM channel based on samples of the combined FMCW signals in the time domain, the combined FMCW signals including a combination of the first FMCW signal and the second FMCW signal.

[0197] Additionally or alternatively, according to examples as disclosed herein, communication manager 720 may support wireless communication at a second wireless device. For example, communication manager 720 may be configured to or otherwise support a unit for generating an FMCW signal for estimation of an OFDM channel by a first wireless device. Communication manager 720 may be configured to or otherwise support a unit for transmitting the FMCW signal via the OFDM channel. Communication manager 720 may be configured to or otherwise support a unit for communicating an OFDM signal with the first wireless device via the OFDM channel based on the estimation of the OFDM channel.

[0198] By including or configuring communication manager 720 according to examples as described herein, device 705 (e.g., control receiver 710, transmitter 715, communication manager 720, or a processor coupled to or otherwise associated with them) may support techniques for reducing processing, reducing power consumption, and more efficiently utilizing communication resources.

[0199] Figure 8 Block diagram 800 shows a device 805 that supports estimating an OFDM channel using FMCW according to one or more aspects of the present disclosure. Device 805 may be an example of aspects of device 705, UE 115, or network entity 105 as described herein. Device 805 may include a receiver 810, a transmitter 815, and a communication manager 820. Device 805 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0200] Receiver 810 may provide a unit for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to estimating an OFDM channel using FMCW). The information may be passed to other components of device 805. Receiver 810 may utilize a single antenna or an array of multiple antennas.

[0201] The transmitter 815 can provide a unit for transmitting signals generated by other components of the device 805. For example, the transmitter 815 can transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (such as control channels, data channels, information channels related to estimating OFDM channels using FMCW). In some examples, the transmitter 815 can be co-located with the receiver 810 in a transceiver module. The transmitter 815 can utilize a single antenna or an array of multiple antennas.

[0202] The device 805 or its various components can be examples of units for performing various aspects of estimating OFDM channels using FMCW as described herein. For example, the communication manager 820 can include the FMCW signal component 825, the FMCW signal generation component 830, the OFDM estimation component 835, the OFDM signal component 840, or any combination thereof. The communication manager 820 can be an example of aspects of the communication manager 720 as described herein. In some examples, the communication manager 820 or its various components can be configured to perform various operations (such as receive, obtain, monitor, output, transmit) using the receiver 810, the transmitter 815, or both, or otherwise cooperate with the receiver 810, the transmitter 815, or both. For example, the communication manager 820 can receive information from the receiver 810, send information to the transmitter 815, or be integrated with the receiver 810, the transmitter 815, or both in combination to obtain information, output information, or perform various other operations as described herein.

[0203] According to examples disclosed herein, the communication manager 820 can support wireless communication at a first wireless device. The FMCW signal component 825 can be configured to or otherwise support a unit for receiving a first FMCW signal via an OFDM channel. The FMCW signal generation component 830 can be configured to or otherwise support a unit for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The OFDM estimation component 835 can be configured to or otherwise support a unit for estimating an OFDM channel based on samples of the combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

[0204] Additionally or alternatively, according to an example as disclosed herein, the communication manager 820 may support wireless communication at a second wireless device. The FMCW signal generation component 830 may be configured to or otherwise support a unit for generating an FMCW signal for estimation of an OFDM channel by a first wireless device. The FMCW signal component 825 may be configured to or otherwise support a unit for transmitting the FMCW signal via the OFDM channel. The OFDM signal component 840 may be configured to or otherwise support a unit for communicating an OFDM signal with the first wireless device via the OFDM channel based on an estimation of the OFDM channel.

[0205] Figure 9 Block diagram 900 of a communication manager 920 supporting the use of FMCW to estimate an OFDM channel is shown in accordance with one or more aspects of the present disclosure. The communication manager 920 may be an example of aspects of the communication manager 720, the communication manager 820, or both as described herein. The communication manager 920 or its various components may be examples of units for performing various aspects of using FMCW to estimate an OFDM channel as described herein. For example, the communication 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 assignment component 960, an FMCW parameter component 965, a CSI component 970, an FMCW component 975, or any combination thereof. Each of these components may communicate directly or indirectly with each other (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 the protocol stack (e.g., between protocol layers of the protocol stack, within a device, component, or virtualized component associated with the network entity 105, between devices, components, or virtualized components associated with the network entity 105), or any combination thereof.

[0206] According to an example as disclosed herein, the communication manager 920 may support wireless communication at a first wireless device. The FMCW signal component 925 may be configured to or otherwise support a unit for receiving a first FMCW signal via the OFDM channel. The FMCW signal generation component 930 may be configured to or otherwise support a unit 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 to or otherwise support a unit for estimating the OFDM channel based on samples of a combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

[0207] In some examples, to support estimating the OFDM channel, the filtering component 945 may be configured to or otherwise support a unit for filtering the combined FMCW signal. In some examples, to support estimating the OFDM channel, the FMCW sampling component 950 may be configured to or otherwise support a unit for sampling the combined FMCW signal in the time domain using a sampling rate based on the sub-band frequency range of the OFDM channel after filtering, where the estimation includes: estimating the respective values of the OFDM channels of each sub-band in a set of multiple sub-bands in the frequency domain of the OFDM channel based on the sampling.

[0208] In some examples, the OFDM signal component 940 may be configured to or otherwise support a unit for receiving one or more OFDM signals time-division multiplexed with a first FMCW signal within the OFDM channel.

[0209] In some examples, the FMCW capability component 955 may be configured to or otherwise support a unit for sending a capability message indicating that a first wireless device is capable of using a time-domain FMCW signal to estimate the OFDM channel, where the first wireless device includes a UE. In some examples, the FMCW capability component 955 may be configured to or otherwise support a unit for receiving a capability message indicating that a second wireless device is capable of sending an FMCW signal for OFDM channel estimation, where the first wireless device includes a network entity.

[0210] In some examples, the symbol allocation component 960 may be configured to or otherwise support a unit for receiving a control message indicating whether one or more symbols of the OFDM channel are allocated for the FMCW signal, where the first FMCW signal is received within the symbol or symbols indicated as being allocated for the FMCW signal, and where the first wireless device includes a UE.

[0211] In some examples, the symbol allocation component 960 may be configured to or otherwise support a unit for sending a control message indicating whether one or more symbols of the OFDM channel are allocated for the FMCW signal or for the OFDM signal, where the first FMCW signal is received within the symbol or symbols allocated for the FMCW signal based on the control message, and where the first wireless device includes a network entity.

[0212] In some examples, the FMCW parameter component 965 can be configured to or otherwise support a unit for receiving a control message indicating a set of FMCW parameters, the set of FMCW parameters including the start frequency of a first FMCW signal, the bandwidth of the first FMCW signal, the slope of the first FMCW signal, or any combination thereof, wherein the slope is based on the bandwidth of the first FMCW signal and the duration of the symbol via which the first FMCW signal is received.

[0213] In some examples, the FMCW parameter component 965 can be configured to or otherwise support a unit for sending a control message indicating a set of FMCW parameters, the set of FMCW parameters including the start frequency of a first FMCW signal, the bandwidth of the first FMCW signal, the slope of the first FMCW signal, or any combination thereof, wherein the slope is based on the bandwidth of the first FMCW signal and the duration of the symbol via which the first FMCW signal is received, and wherein receiving the first FMCW signal is based on the set of FMCW parameters.

[0214] In some examples, the OFDM estimation component 935 can be configured to or otherwise support a unit for receiving a control message, the control message including a trigger for a first wireless device to perform OFDM channel estimation using an FMCW signal, wherein estimating the OFDM channel using the first FMCW signal and a second FMCW signal is based on the trigger, and wherein the first wireless device includes a UE.

[0215] In some examples, the CSI component 970 can be configured to or otherwise support a unit for receiving a control message, the control message including a trigger for a first wireless device to send a channel state information report based on a first FMCW signal. In some examples, the CSI component 970 can be configured to or otherwise support a unit for sending a channel state information report including a set of channel state information parameters based on receiving the trigger and estimating the OFDM channel.

[0216] In some examples, the FMCW signal component 925 can be configured to or otherwise support a unit for sending a control message, the control message including a trigger for a second wireless device to send a first FMCW signal. In some examples, the first wireless device includes a UE or a network entity.

[0217] Additionally or alternatively, according to the examples disclosed herein, the communication manager 920 may support wireless communication at a second wireless device. In some examples, the FMCW signal generation component 930 may be configured to or otherwise support a unit for generating an FMCW signal for use by a first wireless device to estimate an OFDM channel. In some examples, the FMCW signal component 925 may be configured to or otherwise support a unit for transmitting the FMCW signal via the OFDM channel. The OFDM signal component 940 may be configured to or otherwise support a unit for communicating an OFDM signal with the first wireless device via the OFDM channel based on an estimate of the OFDM channel.

[0218] In some examples, the OFDM signal component 940 may be configured to or otherwise support a unit for transmitting one or more OFDM signals time-division multiplexed with the FMCW signal within the OFDM channel.

[0219] In some examples, the FMCW capability component 955 may be configured to or otherwise support a unit 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 includes a UE.

[0220] In some examples, the FMCW capability component 955 may be configured to or otherwise support a unit for receiving a capability message indicating that the first wireless device is capable of using a time-domain FMCW signal to estimate the OFDM channel, where the second wireless device includes a network entity.

[0221] In some examples, the symbol allocation component 960 may be configured to or otherwise support a unit for receiving a control message indicating whether one or more symbols of the OFDM channel are allocated for the FMCW signal, where the FMCW signal is transmitted within the symbol or symbols of the one or more symbols allocated for the FMCW signal based on the control message, and where the second wireless device includes a UE.

[0222] In some examples, the symbol allocation component 960 may be configured to or otherwise support a unit for transmitting a control message indicating whether one or more symbols of the OFDM channel are allocated for the FMCW signal or for the OFDM signal, where the FMCW signal is transmitted within the symbol or symbols of the one or more symbols allocated for the FMCW signal, and where the second wireless device includes a network entity.

[0223] In some examples, the FMCW parameter component 965 may be configured to or otherwise support a unit for receiving a control message indicating a set of FMCW parameters associated with an FMCW signal, the set of FMCW parameters including the start frequency of the FMCW signal, the bandwidth of the FMCW signal, the 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 via which the FMCW signal is transmitted, and where the transmission of the FMCW signal is based on the set of FMCW parameters.

[0224] In some examples, the FMCW parameter component 965 may be configured to or otherwise support a unit for transmitting a control message indicating a set of FMCW parameters associated with an FMCW signal, the set of FMCW parameters including the start frequency of the FMCW signal, the bandwidth of the FMCW signal, the 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 via which the FMCW signal is transmitted, and where the estimation of the OFDM channel is based on the set of FMCW parameters.

[0225] In some examples, the OFDM estimation component 935 may be configured to or otherwise support a unit for transmitting a control message, the control message including a trigger for a first wireless device to perform OFDM channel estimation using an FMCW signal, where the estimation of the OFDM channel is based on the trigger, and where the second wireless device includes a network entity.

[0226] In some examples, the CSI component 970 may be configured to or otherwise support a unit for transmitting a control message, the control message including a trigger for a first wireless device to transmit a channel state information report based on an FMCW signal. In some examples, the CSI component 970 may be configured to or otherwise support a unit for receiving a channel state information report including a set of channel state information parameters at least partially based on the trigger.

[0227] In some examples, the FMCW component 975 may be configured to or otherwise support a unit for receiving a control message, the control message including a trigger for a second wireless device to transmit an FMCW signal, where the transmission of the FMCW signal is based on the trigger.

[0228] In some examples, the second wireless device includes a UE or a network entity.

[0229] Figure 10FIG. showing a system 1000 including a device 1005 that supports the use of FMCW to estimate an OFDM channel, in accordance with one or more aspects of the present disclosure. Device 1005 may be an example of or include components of device 705, device 805, or UE 115 as described herein. Device 1005 may communicate (e.g., wirelessly) with one or more network entities 105, one or more UEs 115, or any combination thereof. Device 1005 may include components for two-way voice and data communication, including components for sending and receiving communications, such as a communication 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 communicate electronically via one or more buses (e.g., bus 1045) or otherwise (e.g., operatively, communicatively, functionally, electronically, electrically) coupled.

[0230] The I / O controller 1010 may manage input and output signals for device 1005. The I / O controller 1010 may also manage peripheral devices not integrated into 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 or another known operating system. Additionally or alternatively, the I / O controller 1010 may represent a modem, keyboard, mouse, touch screen, or similar device or interact with the foregoing devices. In some cases, the I / O controller 1010 may be implemented as part of a processor (such as processor 1040). In some cases, a user may interact with device 1005 via the I / O controller 1010 or via hardware components controlled by the I / O controller 1010.

[0231] In some cases, device 1005 may include a single antenna 1025. However, in some other cases, device 1005 may have more than one antenna 1025 that are capable of simultaneously transmitting or receiving multiple wireless transmissions. Transceiver 1015 may communicate bidirectionally via one or more antennas 1025, wired or wireless links as described herein. For example, transceiver 1015 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. 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 one or more antennas 1025. Transceiver 1015 or transceiver 1015 and one or more antennas 1025 may be examples of transmitter 715, transmitter 815, receiver 710, receiver 810 or any combination thereof or components thereof as described herein.

[0232] Memory 1030 may include random access memory (RAM) and read only memory (ROM). Memory 1030 may store computer-readable, computer-executable code 1035 that includes instructions that, when executed by processor 1040, cause device 1005 to perform the various functions described herein. Code 1035 may be stored in a non-transitory computer-readable medium (such as system memory or another type of memory). In some cases, code 1035 may not be directly executable by processor 1040 but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, in addition, memory 1030 may also contain a basic input / output system (BIOS) that may control basic hardware or software operations, such as interactions with peripheral components or devices.

[0233] Processor 1040 may include intelligent hardware devices (e.g., general purpose processor, DSP, CPU, microcontroller, ASIC, FPGA, programmable logic device, discrete gate or transistor logic components, discrete hardware components or any combination thereof). In some cases, 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 processor 1040. Processor 1040 may be configured to execute computer-readable instructions stored in memory (e.g., memory 1030) to cause device 1005 to perform various functions (e.g., functions or tasks supporting the estimation of an OFDM channel using FMCW). For example, device 1005 or components of device 1005 may include processor 1040 and memory 1030 coupled to or coupled with processor 1040, where processor 1040 and memory 1030 are configured to perform the various functions described herein.

[0234] According to examples disclosed herein, communication manager 1020 may support wireless communication at a first wireless device. For example, communication manager 1020 may be configured to or otherwise support a unit for receiving a first FMCW signal via an OFDM channel. Communication manager 1020 may be configured to or otherwise support a unit for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. Communication manager 1020 may be configured to or otherwise support a unit for estimating an OFDM channel based on samples of a combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

[0235] Additionally or alternatively, according to examples disclosed herein, communication manager 1020 may support wireless communication at a second wireless device. For example, communication manager 1020 may be configured to or otherwise support a unit for generating an FMCW signal for estimation of an OFDM channel by a first wireless device. Communication manager 1020 may be configured to or otherwise support a unit for transmitting the FMCW signal via the OFDM channel. Communication manager 1020 may be configured to or otherwise support a unit for transmitting an OFDM signal via the OFDM channel to the first wireless device based on the estimation of the OFDM channel.

[0236] By including or configuring communication manager 1020 according to examples described herein, device 1005 may support techniques for improving communication reliability, reducing latency, improving the user experience associated with reduced processing, reducing power consumption, more efficiently utilizing communication resources, improving coordination between devices, and extending battery life.

[0237] In some examples, communication manager 1020 may be configured to perform various operations (e.g., receive, monitor, transmit) using transceiver 1015, one or more antennas 1025, or any combination thereof or in cooperation therewith. Although communication manager 1020 is shown as a separate component, in some examples, one or more functions described with reference to communication manager 1020 may be supported 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 aspects of estimating an OFDM channel using FMCW as described herein, or processor 1040 and memory 1030 may be otherwise configured to perform or support such operations.

[0238] Figure 11FIG. showing a system 1100 including a device 1105 that supports using FMCW to estimate an OFDM channel, in accordance with one or more aspects of the present disclosure. The device 1105 may be an example of or include components of the device 705, the device 805, or the network entity 105 as 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 communicating via one or more wired interfaces, via one or more wireless interfaces, or any combination thereof. The device 1105 may include components that support outputting and obtaining communications, such as a communication manager 1120, a transceiver 1110, an antenna 1115, a memory 1125, code 1130, and a processor 1135. These components may communicate electronically or otherwise be coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., bus 1140).

[0239] The transceiver 1110 can support two-way communication via a wired link, a wireless link, or both, as described herein. In some examples, the transceiver 1110 can include a wired transceiver and can communicate bidirectionally with another wired transceiver. Additionally or alternatively, in some examples, the transceiver 1110 can include a wireless transceiver and can communicate bidirectionally with another wireless transceiver. In some examples, the device 1105 can include one or more antennas 1115 capable of transmitting or receiving wireless transmissions (e.g., concurrently). The transceiver 1110 can also include a modem for modulating signals, providing the modulated signals for transmission (e.g., via one or more antennas 1115, via a wired transmitter), receiving the modulated signals (e.g., from one or more antennas 1115, from a wired receiver), and demodulating the signals. In some implementations, the transceiver 1110 can include one or more interfaces, such as one or more interfaces coupled to one or more antennas 1115 configured to support various receiving or obtaining operations, or one or more interfaces coupled to one or more antennas 1115 configured to support various transmitting or output operations, or a combination thereof. In some implementations, the transceiver 1110 can include one or more processors or memory components or be configured to be coupled thereto, the one or more processors or memory components operable to perform or support operations based on received or obtained information or signals, or 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., processor 1135, or memory 1125, or both) can be included in a chip or chip component installed in the device 1105. In some examples, the transceiver can be operable to support communication via one or more communication links (e.g., communication link 125, backhaul communication link 120, midhaul communication link 162, fronthaul communication link 168).

[0240] The memory 1125 can include RAM and ROM. The memory 1125 can store computer-readable, computer-executable code 1130 including instructions that, when executed by the processor 1135, cause the device 1105 to perform the various functions described herein. The code 1130 can be stored in 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 can cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, in addition, the memory 1125 can also contain BIOS, which can control basic hardware or software operations, such as interactions with peripheral components or devices.

[0241] The processor 1135 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, ASICs, CPUs, FPGAs, microcontrollers, programmable logic devices, 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 the estimation of an OFDM channel using FMCW). For example, the device 1105 or components of the device 1105 may include the processor 1135 and the memory 1125 coupled to the processor 1135, and the processor 1135 and the memory 1125 are configured to perform the various functions described herein. The 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 functions (e.g., by executing code 1130) to perform the functions of the device 1105. The processor 1135 may be any one or more suitable processors capable of executing scripts or instructions of one or more software programs stored in the device 1105 (such as within the memory 1125). In some implementations, the processor 1135 may be a component of a processing system. A processing system generally may refer to a system or series of machines or components that receive input and process the input to produce a set of outputs (which may be passed to other systems or components of, for example, the device 1105). For example, the processing system of the device 1105 may refer to a system including various other components or sub-components of the device 1105, such as the processor 1135, or the transceiver 1110, or the communication manager 1120, or a combination of other components or components of the device 1105. The processing system of the device 1105 may interface with other components of the device 1105 and may process information (such as input or signals) received from other components or output information to other components. For example, a chip or modem of the device 1105 may include a processing system and one or more interfaces to output information, or obtain information, or both. One or more interfaces may be implemented as or otherwise include a first interface configured to output information and a second interface configured to obtain information, or the same interface configured to output information and obtain information, and other implementations. In some implementations, one or more interfaces may refer to an interface between the processing system of a chip or modem and a transmitter such that the device 1105 can transmit information output from the chip or modem. Additionally or alternatively, in some implementations, one or more interfaces may refer to an interface between the processing system of a chip or modem and a receiver such that the device 1105 can obtain information or signal input, and the information can be passed to the processing system.One of ordinary skill in the art will readily recognize that the first interface may also obtain information or signal input, and the second interface may also output information or signal output.

[0242] In some examples, bus 1140 may support communication within a protocol layer of a protocol stack (e.g., within the protocol layer). In some examples, bus 1140 may support communication associated with a logical channel of a protocol stack (e.g., between protocol layers of the protocol stack), which may include communication performed within components of device 1105, or communication performed between different components of device 1105 that may be co-located or located at different locations (e.g., where device 1105 may refer to a system in which one or more of communication manager 1120, transceiver 1110, memory 1125, code 1130, and processor 1135 may be located in one of different components or divided between different components).

[0243] In some examples, communication manager 1120 may manage aspects of communication with core network 130 (e.g., via one or more wired or wireless backhaul links). For example, communication manager 1120 may manage the transmission of data communication for client devices (such as one or more UEs 115). In some examples, communication manager 1120 may manage communication with other network entities 105, and may include a controller or scheduler for cooperatively controlling communication with UEs 115 with other network entities 105. In some examples, communication manager 1120 may support the X2 interface within LTE / LTE-A wireless communication network technology to provide communication between network entities 105.

[0244] According to examples disclosed herein, communication manager 1120 may support wireless communication at a first wireless device. For example, communication manager 1120 may be configured or otherwise support a unit for receiving a first FMCW signal via an OFDM channel. Communication manager 1120 may be configured or otherwise support a unit for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. Communication manager 1120 may be configured or otherwise support a unit for estimating an OFDM channel based on samples of a combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal.

[0245] Additionally or alternatively, according to examples as disclosed herein, communication manager 1120 may support wireless communication at a second wireless device. For example, communication manager 1120 may be configured to or otherwise support a unit for generating an FMCW signal for estimation of an OFDM channel by a first wireless device. Communication manager 1120 may be configured to or otherwise support a unit for transmitting the FMCW signal via the OFDM channel. Communication manager 1120 may be configured to or otherwise support a unit for communicating an OFDM signal via the OFDM channel with the first wireless device based on the estimation of the OFDM channel.

[0246] By including or configuring communication manager 1120 according to examples as described herein, device 1105 may support techniques for improving communication reliability, reducing latency, improving the user experience associated with reduced processing, reducing power consumption, more efficiently utilizing communication resources, and improving coordination between devices.

[0247] In some examples, communication manager 1120 may be configured to perform various operations (e.g., receive, obtain, monitor, output, transmit) using transceiver 1110, one or more antennas 1115 (e.g., when applicable), or any combination thereof or in cooperation therewith. Although communication manager 1120 is shown as a separate component, in some examples, one or more functions described with reference to communication manager 1120 may be supported or performed 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 an OFDM channel using FMCW as described herein, or processor 1135 and memory 1125 may be otherwise configured to perform or support such operations.

[0248] Figure 12 A flowchart illustrating a method 1200 for supporting estimation of an OFDM channel using FMCW in accordance with one or more aspects of the present disclosure is shown. Operations of method 1200 may be implemented by a UE or network entity or components thereof as described herein. For example, operations of method 1200 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11 described. In some examples, the UE or network entity may execute a set of instructions to control functional units of the UE or network entity to perform the described functions. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functions.

[0249] At 1205, the method can include: receiving a first FMCW signal via an OFDM channel. The operation of 1205 can be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1205 can be performed by an FMCW signal component 925 as described with reference to Figure 9 described.

[0250] At 1210, the method can include: generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The operation of 1210 can be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1210 can be performed by an FMCW signal generation component 930 as described with reference to Figure 9 described.

[0251] At 1215, the method can include: estimating the OFDM channel based on samples of a combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal. The operation of 1215 can be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1215 can be performed by an OFDM estimation component 935 as described with reference to Figure 9 described.

[0252] Figure 13 FIG. shows a flowchart of a method 1300 that illustrates supporting the use of FMCW to estimate an OFDM channel according to one or more aspects of the present disclosure. The operations of method 1300 can be implemented by a UE or a network entity or its components as described herein. For example, the operations of method 1300 can be performed by a UE 115 or a network entity as described with reference to Figures 1 to 11 described. In some examples, the UE or the network entity can execute an instruction set to control functional units of the UE or the network entity to perform the described functions. Additionally or alternatively, the UE or the network entity can use dedicated hardware to perform aspects of the described functions.

[0253] At 1305, the method can include: receiving a first FMCW signal via an OFDM channel. The operation of 1305 can be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1305 can be performed by an FMCW signal component 925 as described with reference to Figure 9 described.

[0254] At 1310, the method can include: generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The operation of 1310 can be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1310 can be performed by an FMCW signal generation component 930 as described with reference to Figure 9 described.

[0255] At 1315, the method may include: filtering the combined FMCW signals in the time domain, where the combined FMCW signals include a combination of a first FMCW signal and a second FMCW signal. The operations at 1315 may be performed according to the examples disclosed herein. In some examples, aspects of the operations at 1315 may be performed by a filtering component 945 as described with reference to Figure 9 described.

[0256] At 1320, the method may include: after filtering, sampling the combined FMCW signals in the time domain using a sampling rate based on the sub-band frequency ranges of the OFDM channels. The operations at 1320 may be performed according to the examples disclosed herein. In some examples, aspects of the operations at 1320 may be performed by an FMCW sampling component 950 as described with reference to Figure 9 described.

[0257] At 1325, the method may include: estimating corresponding values of the OFDM channels for each sub-band in a set of multiple sub-bands in the frequency domain of the OFDM channels based on the sampling. The operations at 1325 may be performed according to the examples disclosed herein. In some examples, aspects of the operations at 1325 may be performed by an OFDM estimation component 935 as described with reference to Figure 9 described.

[0258] Figure 14 FIG. shows a flowchart of a method 1400 that illustrates support for using FMCW to estimate OFDM channels according to 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 as described herein. For example, the operations of method 1400 may be performed by a UE 115 or a network entity as described with reference to Figures 1 to 11 described. In some examples, the UE or the network entity may execute an instruction set to control functional units of the UE or the network entity to perform the described functions. Additionally or alternatively, the UE or the network entity may use dedicated hardware to perform aspects of the described functions.

[0259] At 1405, the method may include: receiving a first FMCW signal via an OFDM channel. The operations at 1405 may be performed according to the examples disclosed herein. In some examples, aspects of the operations at 1405 may be performed by an FMCW signal component 925 as described with reference to Figure 9 described.

[0260] At 1410, the method may include: receiving, within an OFDM channel, one or more OFDM signals time-division multiplexed with a first FMCW signal. The operation of 1410 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1410 may be performed by an OFDM signal component 940 as described with reference to Figure 9 .

[0261] At 1415, the method may include: generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal. The operation of 1415 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1415 may be performed by an FMCW signal generation component 930 as described with reference to Figure 9 .

[0262] At 1420, the method may include: estimating an OFDM channel based on samples of a combined FMCW signal in the time domain, the combined FMCW signal including a combination of the first FMCW signal and the second FMCW signal. The operation of 1420 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1420 may be performed by an OFDM estimation component 935 as described with reference to Figure 9 .

[0263] Figure 15 FIG. shows a flowchart of a method 1500 supporting the use of FMCW to estimate an OFDM channel 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 as described herein. For example, the operations of method 1500 may be performed by a UE 115 or a network entity as described with reference to Figures 1 to 11 . In some examples, the UE or network entity may execute an instruction set to control functional units of the UE or network entity to perform the described functions. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functions.

[0264] At 1505, the method may include: generating an FMCW signal for estimation of an OFDM channel by a first wireless device. The operation of 1505 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1505 may be performed by an FMCW signal generation component 930 as described with reference to Figure 9 .

[0265] At 1510, the method may include: transmitting the FMCW signal via the OFDM channel. The operation of 1510 may be performed according to the examples disclosed herein. In some examples, aspects of the operation of 1510 may be performed by as described with reference to Figure 9Execute with the described FMCW signal component 925.

[0266] At 1515, the method may include: transmitting an OFDM signal via an OFDM channel with a first wireless device based on an estimate of the OFDM channel. The operations of 1515 may be performed according to the examples disclosed herein. In some examples, aspects of the operations of 1515 may be performed by the OFDM signal component 940 as described with reference to Figure 9 Execute with the described OFDM signal component 940.

[0267] Figure 16 A flowchart illustrating a method 1600 that supports using FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure is shown. The operations of method 1600 may be implemented by a UE or a network entity or components thereof as described herein. For example, the operations of method 1600 may be performed by the UE 115 or a network entity as described with reference to Figures 1 to 11 Execute with the described UE 115 or network entity. In some examples, the UE or network entity may execute an instruction set to control the functional units of the UE or network entity to perform the described functions. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functions.

[0268] At 1605, the method may include: generating an FMCW signal for use by a first wireless device to estimate an OFDM channel. The operations of 1605 may be performed according to the examples disclosed herein. In some examples, aspects of the operations of 1605 may be performed by the FMCW signal generation component 930 as described with reference to Figure 9 Execute with the described FMCW signal generation component 930.

[0269] At 1610, the method may include: transmitting the FMCW signal via the OFDM channel. The operations of 1610 may be performed according to the examples disclosed herein. In some examples, aspects of the operations of 1610 may be performed by the FMCW signal component 925 as described with reference to Figure 9 Execute with the described FMCW signal component 925.

[0270] At 1615, the method may include: transmitting one or more OFDM signals time-division multiplexed with the FMCW signal within the OFDM channel. The operations of 1615 may be performed according to the examples disclosed herein. In some examples, aspects of the operations of 1615 may be performed by the OFDM signal component 940 as described with reference to Figure 9 Execute with the described OFDM signal component 940.

[0271] At 1620, the method may include: transmitting an OFDM signal via the OFDM channel with a first wireless device based on an estimate of the OFDM channel. The operations of 1620 may be performed according to the examples disclosed herein. In some examples, aspects of the operations of 1620 may be performed by the... as described with reference toFigure 9 Execute using the described OFDM signal component 940.

[0272] Figure 17 FIG. 1700 is a flow chart illustrating a method for supporting the use of FMCW to estimate an OFDM channel in accordance with one or more aspects of the present disclosure. Operations of method 1700 may be implemented by a UE or a network entity or components thereof as described herein. For example, operations of method 1700 may be performed by the UE 115 or network entity as described with reference to Figures 1 to 11 described. In some examples, the UE or network entity may execute an instruction set to control functional units of the UE or network entity to perform the described functions. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the described functions.

[0273] At 1705, the method may include: transmitting a capabilities message that indicates that a second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, where the second wireless device includes a UE. The operation of 1705 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operation of 1705 may be performed by the FMCW capabilities component 955 as described with reference to Figure 9 described.

[0274] At 1710, the method may include: generating an FMCW signal for estimation of an OFDM channel by a first wireless device. The operation of 1710 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operation of 1710 may be performed by the FMCW signal generation component 930 as described with reference to Figure 9 described.

[0275] At 1715, the method may include: transmitting the FMCW signal via the OFDM channel. The operation of 1715 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operation of 1715 may be performed by the FMCW signal component 925 as described with reference to Figure 9 described.

[0276] At 1720, the method may include: transmitting an OFDM signal via the OFDM channel to the first wireless device based on an estimate of the OFDM channel. The operation of 1720 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operation of 1720 may be performed by the OFDM signal component 940 as described with reference to Figure 9 described.

[0277] An overview of aspects of the present disclosure is provided below:

[0278] Aspect 1: A method for wireless communication at a first wireless device, comprising: 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 the OFDM channel based at least in part on samples of the combined FMCW signals in the time domain, the combined FMCW signals including a combination of the first FMCW signal and the second FMCW signal.

[0279] Aspect 2: The method according to aspect 1, wherein estimating the OFDM channel comprises: filtering the combined FMCW signals; and after the filtering, sampling the combined FMCW signals in the time domain using a sampling rate based at least in part on a sub-band frequency range of the OFDM channel, wherein the estimating comprises: estimating respective values of the OFDM channel for each of a plurality of sub-bands in the frequency domain of the OFDM channel based at least in part on the sampling.

[0280] Aspect 3: The method according to any one of aspects 1 to 2, further comprising: receiving one or more OFDM signals time-division multiplexed with the first FMCW signal within the OFDM channel.

[0281] Aspect 4: The method according to any one of aspects 1 to 3, further comprising: transmitting a capability message indicating that the first wireless device is capable of using a time-domain FMCW signal to estimate the OFDM channel, wherein the first wireless device comprises a UE.

[0282] Aspect 5: The method according to any one of aspects 1 to 3, further comprising: receiving a capability message indicating that a second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, wherein the first wireless device comprises a network entity.

[0283] Aspect 6: The method according to any one of aspects 1 to 4, further comprising: receiving a control message indicating whether one or more symbols of the OFDM channel are allocated for an FMCW signal, wherein the first FMCW signal is received within a symbol indicated as being allocated for the FMCW signal in a set of the one or more symbols, and wherein the first wireless device comprises a UE.

[0284] Aspect 7: The method according to any one of Aspects 1 to 3 and 5 further includes: sending a control message indicating whether one or more symbols of the OFDM channel are allocated for the FMCW signal or for the OFDM signal, wherein the first FMCW signal is received within symbols of the one or more symbol sets that are at least partially allocated for the FMCW signal based on the control message, and wherein the first wireless device includes a network entity.

[0285] Aspect 8: The method according to any one of Aspects 1 to 4 and 6 further includes: receiving a control message indicating a set of FMCW parameters, the set of FMCW parameters including a start 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 at least partially based on the bandwidth of the first FMCW signal and the duration of the symbol via which the first FMCW signal is received.

[0286] Aspect 9: The method according to any one of Aspects 1 to 3, 5 and 7 further includes: sending a control message indicating a set of FMCW parameters, the set of FMCW parameters including a start 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 at least partially based on the bandwidth of the first FMCW signal and the duration of the symbol via which the first FMCW signal is received, and wherein receiving the first FMCW signal is at least partially based on the set of FMCW parameters.

[0287] Aspect 10: The method according to any one of Aspects 1 to 4, 6 and 8 further includes: receiving a control message including a trigger for the first wireless device to perform OFDM channel estimation using the FMCW signal, wherein estimating the OFDM channel using the first FMCW signal and the second FMCW signal is at least partially based on the trigger, and wherein the first wireless device includes a UE.

[0288] Aspect 11: The method according to any one of Aspects 1 to 4, 6, 8 and 10 further includes: receiving a control message including a trigger for the first wireless device to send a CSI report at least partially based on the first FMCW signal; and sending the CSI report including a set of CSI parameters at least partially based on receiving the trigger and estimating the OFDM channel.

[0289] Aspect 12: The method according to any one of Aspects 1 to 3, 5, 7, and 9 further includes: sending a control message, the control message including a trigger for the second wireless device to send the first FMCW signal.

[0290] Aspect 13: The method according to any one of Aspects 1 to 12, wherein the first wireless device includes a UE or a network entity.

[0291] Aspect 14: A method for wireless communication at a second wireless device, including: generating an FMCW signal for estimation of an OFDM channel by a first wireless device; sending the FMCW signal via the OFDM channel; and transmitting an OFDM signal via the OFDM channel with the first wireless device at least partially based on the estimation of the OFDM channel.

[0292] Aspect 15: The method according to Aspect 14 further includes: sending one or more OFDM signals time-division multiplexed with the FMCW signal within the OFDM channel.

[0293] Aspect 16: The method according to any one of Aspects 14 to 15 further includes: sending a capability message, the capability message indicating that the second wireless device is capable of sending an FMCW signal for OFDM channel estimation, wherein the second wireless device includes a UE.

[0294] Aspect 17: The method according to any one of Aspects 14 to 15 further includes: receiving a capability message, the capability message indicating that the first wireless device is capable of using a time-domain FMCW signal to estimate the OFDM channel, wherein the second wireless device includes a network entity.

[0295] Aspect 18: The method according to any one of Aspects 14 to 16 further includes: receiving a control message, the control message indicating whether one or more symbols of the OFDM channel are allocated for the FMCW signal, wherein the FMCW signal is sent within symbols of the set of one or more symbols that are at least partially allocated for the FMCW signal based on the control message, and wherein the second wireless device includes a UE.

[0296] Aspect 19: The method according to any one of Aspects 14, 15, and 17 further includes: sending a control message, the control message indicating whether one or more symbols of the OFDM channel are allocated for the FMCW signal or for the OFDM signal, wherein the FMCW signal is sent within symbols of the one or more symbols that are allocated for the FMCW signal, and wherein the second wireless device includes a network entity.

[0297] Aspect 20: The method according to any one of aspects 14, 16, and 18 further includes: receiving a control message indicating a set of FMCW parameters associated with the FMCW signal, the set of FMCW parameters including a start 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 at least partially based on the bandwidth of the FMCW signal and a duration of a symbol via which the FMCW signal is transmitted, and wherein transmitting the FMCW signal is at least partially based on the set of FMCW parameters.

[0298] Aspect 21: The method according to any one of aspects 14, 15, 17, and 19 further includes: transmitting a control message indicating a set of FMCW parameters associated with the FMCW signal, the set of FMCW parameters including a start 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 at least partially based on the bandwidth of the FMCW signal and a duration of a symbol via which the FMCW signal is transmitted, and wherein the estimation of the OFDM channel is at least partially based on the set of FMCW parameters.

[0299] Aspect 22: The method according to any one of aspects 14, 15, 17, 19, and 21 further includes: transmitting a control message including a trigger for the first wireless device to perform OFDM channel estimation using an FMCW signal, wherein the estimation of the OFDM channel is at least partially based on the trigger, and wherein the second wireless device includes a network entity.

[0300] Aspect 23: The method according to any one of aspects 14, 15, 17, 19, 21, and 22 further includes: transmitting a control message including a trigger for the first wireless device to transmit a CSI report at least partially based on the FMCW signal; and receiving the CSI report including a set of CSI parameters at least partially based on the trigger.

[0301] Aspect 24: The method according to any one of aspects 14, 16, 18, and 20 further includes: receiving a control message including a trigger for the second wireless device to transmit the FMCW signal, wherein transmitting the FMCW signal is at least partially based on the trigger.

[0302] Aspect 25: The method according to any one of aspects 14 to 24, wherein the second wireless device includes a UE or a network entity.

[0303] Aspect 26: An apparatus for wireless communication, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to any one of Aspects 1 to 13.

[0304] Aspect 27: An apparatus for wireless communication at a first wireless device, comprising at least one unit for performing the method according to any one of Aspects 1 to 13.

[0305] Aspect 28: A non-transitory computer-readable medium storing code for wireless communication at a first wireless device, the code comprising instructions executable by a processor to perform the method according to any one of Aspects 1 to 13.

[0306] Aspect 29: An apparatus for wireless communication, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to any one of Aspects 14 to 25.

[0307] Aspect 30: An apparatus for wireless communication at a second wireless device, comprising at least one unit for performing the method according to any one of Aspects 14 to 25.

[0308] Aspect 31: A non-transitory computer-readable medium storing code for wireless communication at a second wireless device, the code comprising instructions executable by a processor to perform the method according to any one of Aspects 14 to 25.

[0309] It should be noted that the methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise modified, and other implementations are possible. Additionally, aspects from two or more methods may be combined.

[0310] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for purposes of illustration, and the terms LTE, LTE-A, LTE-A Pro, or NR may be used in much of the description, the techniques described herein apply beyond the scope of LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may apply 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.

[0311] The information and signals described herein can be represented using any of a variety of different technologies and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0312] The various illustrative blocks and components described in connection with the present disclosure can be implemented or performed using a general-purpose processor, DSP, ASIC, CPU, 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. The general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. The 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 combination with a DSP core, or any other such configuration).

[0313] The functions described herein can be implemented using hardware, software executed by a processor, firmware, or any combination thereof. If implemented using software executed by a processor, the functions can be stored as one or more instructions or code on a computer-readable medium or transmitted using the same. Other examples and implementations are within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described herein can be implemented using software, hardware, firmware, hardwiring, or any combination of these items executed by a processor. The features implementing the functions can also be physically located at various positions, including being distributed such that portions of the functions are implemented at different physical locations.

[0314] Computer-readable media includes both non-transitory computer storage media and communication media, where communication media includes any medium that facilitates transfer of a computer program from one location to another. The non-transitory storage media can be any available media that can be accessed by a general purpose computer or a special purpose computer. By way of example, and not limitation, non-transitory computer-readable media can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc read only memory (CD-ROM) or other optical disc 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 units in the form of instructions or data structures and that can be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. Additionally, any connection is properly termed a computer-readable media. For example, if software is transmitted using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable media. As used herein, disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc. A disk can magnetically reproduce data, while a disc can optically reproduce data using lasers. Combinations of the above are also included within the scope of computer-readable media.

[0315] As used herein (including in the claims), the "or" as used in a list of items (e.g., a list of items that ends with a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such that a list of at least one of A, B, or C, for example, means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Additionally, as used herein, the phrase "based on" should not be construed as a reference to a closed set of conditions. For example, an example step described as "based on condition A" can 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" should be interpreted in the same manner as the phrase "at least partially based on".

[0316] The term "determine" or "determining" includes a variety of actions, and thus, "determine" can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, and the like. Additionally, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Additionally, "determine" can include parsing, obtaining, selecting, choosing, establishing, and other such like actions.

[0317] In the drawings, like components or features may have the same reference numerals. Additionally, various components of the same type may be distinguished by following the reference numeral with a dash and a second numeral, which is used to differentiate among like components. If only the first reference numeral is used in the specification, the description applies to any one of the like components having the same first reference numeral, regardless of the second or other subsequent reference numerals.

[0318] The description set forth herein in connection with the drawings describes example configurations, and does not represent all examples that may be implemented or within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration" and not "preferred" or "advantageous over other examples." For the purpose of providing an understanding of the described technology, the detailed description includes specific details. However, the technology 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.

[0319] This description is provided to enable a person skilled in the art to make or use the present disclosure. Various modifications to the present 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 present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but is accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a first wireless device, comprising: Receiving a first frequency-modulated continuous waveform signal via 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; And Estimating the orthogonal frequency division multiplexing channel based at least in part on samples of the combined frequency-modulated continuous waveform signal in the time domain, the combined frequency-modulated continuous waveform signal including a combination of the first frequency-modulated continuous waveform signal and the second frequency-modulated continuous waveform signal.

2. The method according to claim 1, wherein, Estimating the orthogonal frequency division multiplexing channel includes: Filtering the combined frequency-modulated continuous waveform signal; and After the filtering, sampling the combined frequency-modulated continuous waveform signal in the time domain using a sampling rate based at least in part on a sub-band frequency range of the orthogonal frequency division multiplexing channel, wherein the estimating includes: estimating corresponding values of the orthogonal frequency division multiplexing channel for each of a plurality of sub-bands in the frequency domain of the orthogonal frequency division multiplexing channel based at least in part on the sampling.

3. The method according to claim 1, further comprising: Receiving one or more orthogonal frequency division multiplexing signals time-division multiplexed with the first frequency-modulated continuous waveform signal within the orthogonal frequency division multiplexing channel.

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

5. The method according to claim 1, further comprising: Receiving a capability message indicating that a second wireless device is capable of sending a frequency-modulated continuous waveform signal for orthogonal frequency division multiplexing channel estimation, wherein the first wireless device includes a network entity.

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

7. The method according to claim 1, further comprising: Sending a control message indicating whether one or more symbols of the orthogonal frequency division multiplexing channel are allocated for a frequency-modulated continuous waveform signal or for an orthogonal frequency division multiplexing signal, wherein the first frequency-modulated continuous waveform signal is received within the symbol or symbols allocated for the frequency-modulated continuous waveform signal based at least in part on the control message, and wherein the first wireless device includes a network entity.

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

9. The method according to claim 1, further comprising: Sending a control message indicating the set of frequency-modulated continuous waveform parameters, the set of frequency-modulated continuous waveform parameters including the start frequency of the first frequency-modulated continuous waveform signal, the bandwidth of the first frequency-modulated continuous waveform signal, the slope of the first frequency-modulated continuous waveform signal, or any combination thereof, wherein the slope is at least partially based on the bandwidth of the first frequency-modulated continuous waveform signal and the duration of the symbol via which the first frequency-modulated continuous waveform signal is received, and wherein receiving the first frequency-modulated continuous waveform signal is at least partially based on the set of frequency-modulated continuous waveform parameters.

10. The method according to claim 1, further comprising: Receiving a control message, the 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, wherein estimating the orthogonal frequency division multiplexing channel using the first frequency-modulated continuous waveform signal and the second frequency-modulated continuous waveform signal is at least partially based on the trigger, and wherein the first wireless device includes a user equipment (UE).

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

12. The method according to claim 1, further comprising: Sending a control message, the control message including a trigger for a second wireless device to send the first frequency-modulated continuous waveform signal.

13. The method according to claim 1, wherein The first wireless device includes a user equipment (UE) or a network entity.

14. A method for wireless communication at 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 waveform signal via the orthogonal frequency division multiplexing channel; And Transmitting an orthogonal frequency division multiplexing signal with the first wireless device via the orthogonal frequency division multiplexing channel at least partially based on the estimation of the orthogonal frequency division multiplexing channel.

15. The method according to claim 14, further comprising: Transmitting one or more orthogonal frequency division multiplexing signals time-division multiplexed with the frequency-modulated continuous waveform signal within the orthogonal frequency division multiplexing channel.

16. The method according to claim 14, further comprising: Send a capability message, the capability message indicating that the second wireless device is capable of sending a frequency-modulated continuous waveform signal for orthogonal frequency-division multiplexing channel estimation, wherein the second wireless device includes a user equipment (UE).

17. The method according to claim 14, further comprising: Receive a capability message, the capability message indicating that the first wireless device is capable of using a time-domain frequency-modulated continuous waveform signal to estimate the orthogonal frequency-division multiplexing channel, wherein the second wireless device includes a network entity.

18. The method according to claim 14, further comprising: Receive a control message, the control message indicating whether one or more symbols of the orthogonal frequency-division multiplexing channel are allocated for a frequency-modulated continuous waveform signal, wherein the frequency-modulated continuous waveform signal is sent within at least some of the one or more symbols that are allocated for the frequency-modulated continuous waveform signal based at least in part on the control message, and wherein the second wireless device includes a user equipment (UE).

19. The method according to claim 14, further comprising: Send a control message, the control message indicating whether one or more symbols of the orthogonal frequency-division multiplexing channel are allocated for a frequency-modulated continuous waveform signal or for an orthogonal frequency-division multiplexing signal, wherein the frequency-modulated continuous waveform signal is sent within the symbols that are allocated for the frequency-modulated continuous waveform signal, and wherein the second wireless device includes a network entity.

20. The method according to claim 14, further comprising: Receive 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, wherein the slope is based at least in part on the bandwidth of the frequency-modulated continuous waveform signal and a duration of the symbol via which the frequency-modulated continuous waveform signal is sent, and wherein sending the frequency-modulated continuous waveform signal is based at least in part on the set of frequency-modulated continuous waveform parameters.

21. The method according to claim 14, further comprising: Send 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, wherein the slope is based at least in part on the bandwidth of the frequency-modulated continuous waveform signal and a duration of the symbol via which the frequency-modulated continuous waveform signal is sent, and wherein the estimation of the orthogonal frequency-division multiplexing channel is based at least in part on the set of frequency-modulated continuous waveform parameters.

22. The method according to claim 14, further comprising: Send a control message, the 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, wherein the estimation of the orthogonal frequency division multiplexing channel is at least partially based on the trigger, and wherein the second wireless device includes a network entity.

23. The method according to claim 14, further comprising: Send a control message, the control message including a trigger for the first wireless device to send a channel state information report that is at least partially based on the frequency modulated continuous waveform signal; And Receive the channel state information report including a set of channel state information parameters at least partially based on the trigger.

24. The method according to claim 14, further comprising: Receive a control message, the control message including a trigger for the second wireless device to send the frequency modulated continuous waveform signal, wherein sending the frequency modulated continuous waveform signal is at least partially based on the trigger.

25. The method according to claim 14, wherein The second wireless device includes a user equipment (UE) or a network entity.

26. An apparatus for wireless communication, comprising: A processor; A memory coupled to the processor; And Instructions stored in the memory and executable by the processor to cause the apparatus to perform the following operations: Receive a first frequency modulated continuous waveform signal via an orthogonal frequency division multiplexing channel; Generate a second frequency modulated continuous waveform signal at least partially based on a set of frequency modulated continuous waveform parameters associated with the first frequency modulated continuous waveform signal; And Estimate the orthogonal frequency division multiplexing channel at least partially based on samples of the combined frequency modulated continuous waveform signal in the time domain, the combined frequency modulated continuous waveform signal including a combination of the first frequency modulated continuous waveform signal and the second frequency modulated continuous waveform signal.

27. The apparatus according to claim 26, wherein, The instructions for estimating the orthogonal frequency division multiplexing channel are executable by the processor to cause the apparatus to perform the following operations: Filter the combined frequency modulated continuous waveform signal; And After the filtering, sample the combined frequency modulated continuous waveform signal in the time domain using a sampling rate that is at least partially based on a sub-band frequency range of the orthogonal frequency division multiplexing channel, wherein the estimation includes: estimating corresponding values of the orthogonal frequency division multiplexing channel for each of a plurality of sub-bands in the frequency domain of the orthogonal frequency division multiplexing channel at least partially based on the sampling.

28. The apparatus according to claim 26, wherein, The instructions can further be executable by the processor to cause the apparatus to perform the following operations: Receive one or more orthogonal frequency division multiplexing signals time-division multiplexed with the first frequency modulated continuous waveform signal within the orthogonal frequency division multiplexing channel.

29. An apparatus for wireless communication, comprising: A processor; A memory coupled to the processor; And Instructions stored in the memory and executable by the processor to cause the apparatus to perform the following operations: Generate a frequency modulated continuous waveform signal for estimation of an orthogonal frequency division multiplexing channel by a first wireless device; Send the frequency modulated continuous waveform signal via the orthogonal frequency division multiplexing channel; And Transmit an orthogonal frequency division multiplexing signal via the orthogonal frequency division multiplexing channel based at least in part on the estimation of the orthogonal frequency division multiplexing channel with the first wireless device.

30. The apparatus according to claim 29, wherein, The instructions may also be executed by the processor to cause the device to perform the following operations: Transmit one or more orthogonal frequency division multiplexing signals time-division multiplexed with the frequency modulated continuous waveform signal within the orthogonal frequency division multiplexing channel.

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