Cyclic shift-based frequency-modulated continuous waveform chirp as a reference signal for multi-port channel estimation

Abstract

A device for wireless communication can be configured to generate a first frequency-modulated continuous waveform (FMCW) signal, generate a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal, and cause a transmitter to transmit the first FMCW signal and the second FMCW signal via an orthogonal frequency division multiplexing (OFDM) spectrum.

Description

Technical Field

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

Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content, including voice, video, packet data, messaging, and broadcast. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth-generation (4G) systems such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), or LTE-A Pro systems, and fifth-generation (5G) systems, sometimes 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 multiple access communication system may include one or more base stations, each of which supports wireless communication with a communication device that may be known as user equipment (UE).

[0003] In some systems, a receiving device, such as a UE, network entity, or both, may estimate the 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 to digital form, and convert the digital OFDM signal to a frequency domain signal. The receiving device may then perform OFDM channel estimation in the frequency domain based on the frequency domain signal. [Overview of the project]

[0004] According to one embodiment of the present disclosure, a device for wireless communication includes a memory and one or more processors coupled to the memory and mounted in a circuit, configured to generate a first frequency-modulated continuous waveform (FMCW) signal, a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal, and to cause a transmitter to transmit the first FMCW signal and the second FMCW signal via an orthogonal frequency division multiplexing (OFDM) spectrum.

[0005] According to one embodiment of the present disclosure, the device for wireless communication includes a memory and one or more processors coupled to the memory and implemented in a circuit, configured to receive a first frequency-modulated continuous waveform (FMCW) signal via an orthogonal frequency division multiplexing (OFDM) channel, receive a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal via the OFDM spectrum, determine the cyclic offset, estimate the OFDM spectrum of a first port based on the first FMCW signal, and estimate the OFDM spectrum of a second port based on the second FMCW signal and the cyclic offset.

[0006] According to one embodiment of the present disclosure, a wireless communication method includes receiving a first frequency-modulated continuous waveform (FMCW) signal via an orthogonal frequency division multiplexing (OFDM) channel; receiving a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal via an OFDM spectrum; determining the cyclic offset; estimating the OFDM spectrum of a first port based on the first FMCW signal; and estimating the OFDM spectrum of a second port based on the second FMCW signal and the cyclic offset.

[0007] Details of one or more examples are described in the accompanying drawings and the following description. Other features, purposes, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawing]

[0008] [Figure 1] An example of a wireless communication system that supports the estimation of orthogonal frequency division multiplexing (OFDM) channels using frequency-modulated continuous waveforms (FMCWs) is shown according to one or more aspects of the present disclosure. [Figure 2] One embodiment of an OFDM multiport channel estimation scheme that supports OFDM channel estimation using FMCW, according to one or more aspects of the present disclosure, is shown. [Figure 3A] One embodiment of an OFDM multiport channel estimation scheme that supports OFDM channel estimation using FMCW, according to one or more aspects of the present disclosure, is shown. [Figure 3B] This figure shows the FMCW waveform. [Figure 3C] An embodiment of a cyclic offset that may be used in accordance with the techniques of this disclosure is shown. [Figure 4] An example of a wireless communication system that supports estimating an OFDM channel using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 5]One embodiment of a process flow supporting the estimation of OFDM channels using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 6] An example of a process flow supporting the estimation of OFDM channels using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 7] A block diagram of a device that supports estimating OFDM channels using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 8] A block diagram of a device that supports estimating OFDM channels using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 9] A block diagram of a communications manager supporting the estimation of an OFDM channel using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 10] A diagram of a system including a UE that supports estimating OFDM channels using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 11] A diagram of a system including a network entity that supports estimating OFDM channels using FMCW, according to one or more aspects of this disclosure, is shown. [Figure 12] A flowchart illustrating a process that supports estimating OFDM channels using FMCW according to one or more aspects of this disclosure is shown. [Figure 13] A flowchart illustrating a process that supports estimating OFDM channels using FMCW according to one or more aspects of this disclosure is shown. [Figure 14] A flowchart illustrating a process that supports estimating OFDM channels using FMCW according to one or more aspects of this disclosure is shown. [Figure 15] A flowchart illustrating a process that supports estimating OFDM channels using FMCW according to one or more aspects of this disclosure is shown. [Figure 16]A flowchart illustrating a process that supports estimating OFDM channels using FMCW according to one or more aspects of this disclosure is shown. [Figure 17] A flowchart illustrating a process that supports estimating OFDM channels using FMCW according to one or more aspects of this disclosure is shown. [Figure 18] A flowchart illustrating a process supporting multiport channel estimation according to one or more aspects of this disclosure is shown. [Figure 19] A flowchart illustrating a process supporting multiport channel estimation according to one or more aspects of this disclosure is shown. [Modes for carrying out the invention]

[0009] In some systems, a wireless device may estimate an orthogonal frequency division multiplexing (OFDM) channel based on one or more received signals to improve the reliability and throughput of transmission and reception by the wireless device. The wireless device may, in some cases, receive OFDM signals via OFDM channels. 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 can then perform a fast Fourier transform (FFT) on the time-domain digital signal to convert it into one or more frequency-domain signals. The wireless device can then use the frequency-domain signal to estimate the OFDM channel in the frequency domain. In some examples, the sampling rate of the ADC in the wireless device may be relatively high to accurately convert the analog OFDM signal into digital format. Additionally or alternatively, performing an FFT to convert a time-domain signal to a frequency-domain signal can be relatively complex.

[0010] The techniques, systems, and devices described herein provide improved OFDM multiport channel estimation using frequency-modulated continuous waveform (FMCW) signals, and more specifically, multiport channel estimation using FMCW chirps. A transmitting device may transmit a first FMCW signal for channel estimation over an OFDM channel. A receiving device may receive the first FMCW signal and generate a second (e.g., local) FMCW signal using a set of FMCW parameters associated with the first FMCW signal. The receiving device may combine the first and second FMCW signals and filter the combined signal (e.g., using a low-pass filter (LPF) or some other type of filter). The receiving device may estimate a frequency-domain OFDM channel by sampling the combined FMCW signal using a relatively low sampling rate. The sampling rate used by the receiving device may be based on one or more parameters of the OFDM channel, such as the bandwidth or subband frequency size of the OFDM channel.

[0011] In some examples, transmitting and receiving devices may exchange signaling to facilitate OFDM channel estimation using FMCW signals. For example, one of the devices (e.g., a user device (UE)) may send a capability message to indicate that the device supports FMCW for channel estimation or supports FMCW transmission. In some embodiments, one or both devices may send one or more control messages that assign symbols in an OFDM channel (e.g., an OFDM resource grid) for FMCW transmission, indicate FMCW parameters, trigger the transmission of FMCW signals, trigger channel estimation using FMCW signals, or any combination thereof. In some examples, the signaling exchanged between devices may be based on the type of device. The transmitting and receiving devices may each be a UE, a network entity, some other type of device, or any combination thereof.

[0012] Therefore, the techniques described may support the estimation of frequency-domain OFDM channels, or more generally OFDM spectra, based on FMCW signals, which may be referred to as FMCW-based OFDM channel estimation in some aspects of this specification. The sampling rate applied by the receiving device to estimate frequency-domain OFDM channels using the FMCW-based OFDM channel estimation technique may be lower than the sampling rate used by the receiving device to estimate frequency-domain OFDM channels based on OFDM signals (e.g., channel state information reference signals (CSI-RSs), sounding reference signals (SRSs), demodulation reference signals (DMRSs), or any combination thereof). Additionally or alternatively, the receiving device may estimate frequency-domain OFDM channels in the time domain using time-domain signal processing based on the FMCW signal (e.g., the receiving device may refrain from performing an FFT), which can reduce complexity and power consumption compared to OFDM-based estimation techniques to which an FFT is applied.

[0013] Exemplary FMCW waveforms generated by analog voltage-controlled oscillators (VCOs) occupy the entire bandwidth (BW) and therefore prevent the multiplexing of multiple reference signal ports in frequency division multiplexing (FDM), as supported by newer radio (NR) standards where multiple CSI-RS ports are allocated using different resource elements (REs). To support multi-port FMCW-based OFDM channel estimation, various techniques have been developed, including time-division multiplexing-based techniques and partial time-overlap techniques. However, as will be discussed in more detail below, both these time-division multiplexing-based techniques and partial time-overlap techniques potentially increase the chirp gradient compared to single-port transmission, and a higher chirp gradient requires a higher sampling rate and therefore more complex and expensive equipment to process.

[0014] As will be described in more detail below, this disclosure describes a technique for generating a first FMCW signal and a second FMCW signal having a cyclic offset relative to the first FMCW signal. Thus, by using a cyclic shift-based multiport FMCW chirp as a reference signal for channel estimation, as described herein, multiport channel estimation can be performed with the same chirp gradient as in the case of a single-port reference signal.

[0015] Therefore, compared to other OFDM-based multiport CSI-RS port transmissions, the FMCW-based solution of this disclosure allows the receiver (e.g., UE) to apply lower sampling rates, thus reducing receiver complexity by eliminating the need for a high-rate ADC. Furthermore, compared to existing multiport solutions such as the TDM-based and partial time overlap-based solutions described above, the cyclic shift-based multiport technique described herein can reduce the sampling rate (while maintaining the same chirp gradient as a single-port FMCW chirp), thereby further reducing receiver complexity.

[0016] The aspects of this disclosure are first described in the context of wireless communication systems. Additional aspects are described with reference to OFDM multiport channel estimation schemes and process flows. The aspects of this disclosure are further illustrated and described with reference to apparatus diagrams, system diagrams and flow diagrams relating to estimating OFDM channels using FMCW.

[0017] Figure 1 shows one embodiment of a wireless communication system 100 that supports estimating an OFDM channel using FMCW, according to one or more aspects of the present disclosure. The wireless communication system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some embodiments, the wireless communication system 100 may be a network operating according to a Long-Term Evolution (LTE) network, an LTE Advanced (LTE-A) network, an LTE-A Pro network, an NR network, or other systems and radio technologies, including future systems and radio technologies not expressly mentioned herein.

[0018] The network entity 105 can be distributed across a geographical area to form a wireless communication system 100 and may include devices of different forms or with different capabilities. In various embodiments, the network entity 105 may be referred to as a network element, mobility element, radio access network (RAN) node, or network equipment, among many technical terms. In some embodiments, the network entity 105 and UE 115 can communicate wirelessly via one or more communication links 125 (e.g., radio frequency (RF) access links). For example, the network entity 105 can support a coverage area 110 (e.g., a geographical coverage area) on which the UE 115 and the network entity 105 can establish one or more communication links 125. The coverage area 110 can be an embodiment of a geographical area on which the network entity 105 and UE 115 can support signal communication according to one or more radio access technologies (RATs).

[0019] The UE115 can be distributed across the entire coverage area 110 of the wireless communication system 100, and each UE115 can be fixed, mobile, or both at different times. The UE115 can be different forms of devices or devices with different capabilities. Several exemplary UE115 are shown in Figure 1. The UE115 described herein may support communication with various types of devices, such as other UE115 or network entities 105, as shown in Figure 1.

[0020] As described herein, a node of the wireless communication system 100, which may be referred to as a network node or wireless node, can 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, a computing system, one or more components, or another preferred processing entity configured to perform any of the techniques described herein. For example, a node can be a UE 115. In another embodiment, a node can also be a network entity 105. In another embodiment, a first node can be configured to communicate with a second node or a third node. In one aspect of this embodiment, the first node can be a UE 115, the second node can be a network entity 105, and the third node can be a UE 115. In another aspect of this embodiment, the first node can be a UE 115, the second node can be a network entity 105, and the third node can be a network entity 105. In yet another embodiment of this embodiment, the first node, the second node, and the third node may differ from those of this embodiment. Similarly, references to UE115, network entity 105, apparatus, devices, computing systems, etc. may include disclosure that UE115, network entity 105, apparatus, devices, computing systems, etc. are nodes. For example, a disclosure that UE115 is configured to receive information from network entity 105 also discloses that the first node is configured to receive information from the second node.

[0021] In some embodiments, network entities 105 can communicate with the core network 130, communicate with each other, or communicate with both. For example, network entities 105 can 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 embodiments, network entities 105 can communicate with each other via the backhaul communication links 120 (e.g., according to X2, Xn, or other interface protocols) either directly (e.g., directly between network entities 105) or indirectly (e.g., via the core network 130). In some embodiments, network entities 105 can communicate with each other via a midhaul communication link 162 (e.g., according to a midhaul interface protocol), or via a fronthaul communication link 168 (e.g., according to a fronthaul interface protocol), or via any combination thereof. The backhaul communication link 120, the midhaul communication link 162, or the fronthaul communication link 168 may be one or more wired links (e.g., electrical links, fiber optic links), one or more wireless links (e.g., wireless links, wireless optical links), or may include such links, in various embodiments or combinations thereof. The UE 115 can communicate with the core network 130 via the communication link 155.

[0022] One or more of the network entities 105 described herein may include a base station 140 (e.g., base transceiver station, radio base station, NR base station, access point, radio transceiver, node B, enode B (eNodeB, eNB), next-generation node B or giganode B (both sometimes referred to as gNB), 5G NB, next-generation eNB (ng-eNB), home node B, home enode B, or other preferred terminology), or may be referred to as base station 140. In some embodiments, the network entity 105 (e.g., base station 140) can be implemented in an aggregated (e.g., monolithic, standalone) base station architecture, which can be configured to utilize a protocol stack that is physically or logically integrated within a single network entity 105 (e.g., a single RAN node such as base station 140).

[0023] In some embodiments, the network entity 105 can be implemented in a decoupled architecture (e.g., a decoupled base station architecture, a decoupled RAN architecture) that can be configured to utilize a protocol stack that is 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 supported by the O-RAN Alliance), or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN)). For example, network entity 105 may include one or more of the following: central unit (CU) 160, distributed unit (DU) 165, radio unit (RU) 170, RAN Intelligent Controller (RIC) 175 (e.g., near-real-time RIC, near-RT-RIC, non-real-time RIC), service management and orchestration (SMO) 180 system, or any combination thereof. RU 170 may also be referred to as a radio head, smart radio head, remote radio head (RRH), remote radio unit (RRU), or transmission reception point (TRP). In a separated RAN architecture, one or more components of network entity 105 may be co-located, or one or more components of network entity 105 may be located in distributed locations (e.g., separate physical locations).In some embodiments, one or more network entities 105 of a separate RAN architecture can be implemented as virtual units (e.g., virtual CUs (VCUs), virtual DUs (VDUs), virtual RUs (VRUs)).

[0024] The functional division between CU160, DU165, and RU170 is flexible, and different functionalities can be supported depending on which function (e.g., network layer function, protocol layer function, baseband function, RF function, and any combination thereof) is performed in CU160, DU165, or RU170. For example, a functional division of the protocol stack may be adopted between CU160 and DU165, so that CU160 can support one or more layers of the protocol stack, and DU165 can support one or more different layers of the protocol stack. In some embodiments, CU160 can host higher protocol layer (e.g., layer 3 (L3), layer 2 (L2)) functionality and signaling (e.g., Radio Resource Control (RRC), service data adaptation protocol (SDAP), packet data convergence protocol (PDCP)). A CU160 can connect to one or more DU165s or RU170s, each of which can host lower protocol layers such as Layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, each of which can be controlled at least partially by the CU160. Alternatively, a functional partition of the protocol stack may be employed between the DU165 and RU170, allowing the DU165 to support one or more layers of the protocol stack, and the RU170 to support one or more different layers of the protocol stack. The DU165 can support one or more different cells (e.g., via one or more RU170s).In some cases, the functional division between CU160 and DU165, or between DU165 and RU170, can be within the protocol layer (for example, some functions related to the protocol layer can be performed by one of CU160, DU165, or RU170, while other functions of the protocol layer can be performed by a different one of CU160, DU165, or RU170). CU160 can be further functionally divided into CU control plane (CU-CP) functions and CU user plane (CU-UP) functions. CU160 can be connected to one or more DU165s via midhaul communication links 162 (e.g., F1, F1-c, F1-u), and DU165s can be connected to one or more RU170s via fronthaul communication links 168 (e.g., open fronthaul (FH) interfaces). In some embodiments, a midhaul communication link 162 or a fronthaul communication link 168 can be implemented according to an interface (e.g., a channel) between layers of the protocol stack, supported by a corresponding network entity 105 communicating over such a communication link.

[0025] In a wireless communication system (e.g., wireless communication system 100), the infrastructure and spectral resources for radio access can provide an IAB network architecture (e.g., to a core network 130) by supporting wireless backhaul link capabilities to complement wired backhaul connections. 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 may be referred to as donor entities or IAB donors. One or more DU 165 or one or more RU 170 can be partially controlled by one or more CU 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 supported access links and backhaul links (e.g., backhaul communication link 120). IAB node 104 may include an IAB mobile termination (IAB-MT) controlled (e.g., scheduled) by the DU165 of the coupled IAB donor. The IAB-MT may include a separate set of antennas for relaying communications with UE115, or it may share the same antennas of IAB node 104 (e.g., RU170) used for access to IAB node 104 via DU165 (e.g., a virtual IAB-MT (referred to as vIAB-MT)). In some embodiments, IAB node 104 may include a DU165 that supports communication links with additional entities (e.g., IAB node 104, UE115) in the relay chain or relay configuration of the access network (e.g., downstream).In such cases, one or more components of the isolated RAN architecture (for example, one or more IAB nodes 104, or components of IAB nodes 104) can be configured to operate in accordance with the techniques described herein.

[0026] For example, an access network (AN) or RAN may include communication between an access node (e.g., an IAB donor), an IAB node 104, and one or more UEs 115. The IAB donor can facilitate the connection between the core network 130 and the AN (e.g., via a wired or wireless connection to the core network 130). That is, an IAB donor may refer to a RAN node 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., also a RU 170), in which case the CU 160 can communicate with the core network 130 via an interface (e.g., a backhaul link). The IAB donor and IAB node 104 can communicate via the F1 interface according to a protocol that defines signaling messages (e.g., the F1 AP protocol). As an addition or alternative, a CU160 can communicate with the core network via an interface that may be an example of a backhaul link, and can communicate with other CU160s (e.g., CU160s associated with an alternative IAB donor) via an Xn-C interface that may also be an example of a backhaul link.

[0027] IAB node 104 may refer to a RAN node that provides IAB functionality (e.g., access to UE 115, wireless self-backhaul capability). DU 165 may function as a distributed scheduling node directed to child nodes associated with IAB node 104, and IAB-MT may function as a scheduled node directed to a parent node associated with IAB node 104. That is, an IAB donor may be referred to as a parent node that communicates with one or more child nodes (e.g., an IAB donor can relay transmissions about the UE through one or more other IAB nodes 104). Additionally or alternatively, IAB node 104 may also be referred to as a parent or child node to other IAB nodes 104, depending on the relay chain or relay configuration of the AN. Therefore, the IAB-MT entity of IAB node 104 can provide a Uu interface for child IAB node 104 to receive signaling from parent IAB node 104, and the DU interface (e.g., DU165) can provide a Uu interface for parent IAB node 104 to signal to child IAB node 104 or UE115.

[0028] For example, IAB node 104 may be referred to as a parent node that supports communication with child IAB nodes, or as a child IAB node associated with an IAB donor, or both. An IAB donor may include a CU 160 with a wired or wireless connection (e.g., a backhaul communication link 120) to the core network 130 and may function as a parent node to IAB node 104. For example, the DU 165 of the IAB donor may relay transmissions to UE 115 via IAB node 104, or directly signal transmissions to UE 115, or both. The CU 160 of the IAB donor can signal the establishment of a communication link to IAB node 104 via the F1 interface, and IAB node 104 can schedule transmissions (e.g., transmissions to UE 115 relayed from the IAB donor) via the DU 165. In other words, data can be relayed to and from IAB node 104 via signaling through the NR Uu interface to the MT of IAB node 104. Communication with IAB node 104 can be scheduled by the DU165 of the IAB donor, and communication with IAB node 104 can also be scheduled by the DU165 of IAB node 104.

[0029] In the case of the techniques described herein applied in the context of a non-aggregated RAN architecture, one or more components of the non-aggregated RAN architecture may be configured to support the estimation of OFDM channels using FMCW as described herein. For example, some operations described as being performed by UE115 or network entity 105 (e.g., base station 140) may, in addition or alternatively, be performed by one or more components of a separate RAN architecture (e.g., IAB node 104, DU165, CU160, RU170, RIC175, SMO180).

[0030] UE115 may include, or may be referred to as, a mobile device, wireless device, remote device, handheld device, or subscriber device, or any other preferred term; “device” may also be referred to as, among many examples, a unit, station, terminal, or client. UE115 may also include, or may be referred to as, a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some embodiments, UE115 may include, or may be referred to as, a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine-type communications (MTC) device, among many examples, which can be implemented in a variety of items, such as home appliances, vehicles, or meters.

[0031] The UE115 described herein may be capable of communicating with various types of devices, including other UE115s that can sometimes function as repeaters, as well as network entities 105 and network equipment, including, among other examples, macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, as shown in Figure 1.

[0032] UE115 and network entity 105 can communicate wirelessly with each other over one or more communication links 125 (e.g., access links) using resources associated with one or more carriers. The term “carrier” may refer to a set of RF spectral resources having a defined physical layer structure for supporting communication links 125. For example, a carrier used with respect to communication link 125 may include a portion of the RF spectral band (e.g., a bandwidth part (BWP)) operating according to one or more physical layer channels with respect to a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquired signaling (e.g., synchronization signals, system information), control signaling that coordinates the operation with respect to the carrier, user data, or other signaling. Wireless communication system 100 can support communication with UE115 using carrier aggregation or multi-carrier operation. UE115 may consist of multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation can be used with both frequency division duplexing (FDD) component carriers and time division duplexing (TDD) component carriers. Communication between network entity 105 and other devices may refer to communication between those devices and any part of network entity 105 (e.g., entity, sub-entity). For example, when referring to network entity 105, the terms “transmitting,” “receiving,” or “communicating” may refer to any part of network entity 105 in the RAN (e.g., base station 140, CU160, DU165, RU170) communicating with another device (e.g., directly or via one or more other network entities 105).

[0033] In some examples, such as carrier aggregation configurations, a carrier may also have acquisition or control signaling to coordinate its operation with other carriers. A carrier can be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute RF channel number (EARFCN)) and can be identified according to a channel raster for detection by the UE115. A carrier can operate in standalone mode, in which case the UE115 can perform the initial acquisition and connection via that carrier, or a carrier can operate in non-standalone mode, in which case the connection is fixed using different carriers (e.g., the same radio access technology or different radio access technologies).

[0034] The communication link 125 shown in the wireless communication system 100 may include, among many transmission configurations, a downlink transmission from the network entity 105 to the UE 115 (e.g., a forward link transmission), an uplink transmission from the UE 115 to the network entity 105 (e.g., a reverse link transmission), or both. The carrier may carry downlink communication or uplink communication (e.g., in FDD mode), or may be configured to carry both downlink and uplink communication (e.g., in TDD mode).

[0035] A carrier may be associated with a specific bandwidth in the RF spectrum, and in some examples, the carrier bandwidth may be referred to as the carrier or the “system bandwidth” of the wireless communication system 100. For example, the carrier bandwidth may be one of a set of bandwidths (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)) with respect to the carrier of a particular radio access technology. Devices of the wireless communication system 100 (e.g., network entity 105, UE115, or both) may have a hardware configuration that supports communication using a specific carrier bandwidth, or may be configurable to support communication using one of the carrier bandwidths in a set of carrier bandwidths. In some examples, the wireless communication system 100 may include network entity 105 or UE115 that support simultaneous communication using carriers associated with multiple carrier bandwidths. In some examples, each serviced UE115 may be configured to operate using a portion (e.g., subband, BWP) or all of the carrier bandwidth.

[0036] The signal waveform transmitted on the carrier may consist of multiple subcarriers (using multi-carrier modulation (MCM) techniques such as OFDM or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In systems employing MCM technology, a resource element may refer to the resources of one symbol period (e.g., duration of one modulation symbol) and one subcarrier, in which case the symbol period and subcarrier spacing may be inversely proportional. The amount of bits carried by each resource element may depend on the modulation scheme (e.g., modulation order, modulation coding rate, or both) so that a relatively large number of resource elements (e.g., within the transmission duration) and a relatively high-order modulation scheme can accommodate a relatively high communication rate. Wireless communication resources may refer to a combination of RF spectral resources, temporal resources, and spatial resources (e.g., spatial layers, beams), and the use of multiple spatial resources can improve the data rate or data integrity for communication with the UE115.

[0037] One or more numerologies may be supported for a carrier, and the numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier can be divided into one or more BWPs having the same or different numerologies. In some embodiments, UE115 can consist of multiple BWPs. In some embodiments, a single BWP relating to a carrier can be activated at a given time, and communication relating to UE115 can be restricted to one or more active BWPs.

[0038] The time interval relating to network entity 105 or UE115 is, for example, T s =1 / ((Δf max ·N f )) This can refer to a sampling period of seconds, which can be expressed as a multiple of the basic time unit, in which case Δf maxThis may represent the supported subcarrier intervals, N f This may represent the supported Discrete Fourier Transform (DFT) size. The time interval of the 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., in the range of 0 to 1023).

[0039] Each frame may contain multiple subframes or slots that are sequentially numbered, and each subframe or slot may have the same duration. In some examples, a frame can be divided into subframes (e.g., in the time domain), and each subframe may be further divided into a certain number of slots. Alternatively, each frame may contain a variable number of slots, the number of slots may depend on the subcarrier interval. Each slot may contain a certain number of symbol periods (e.g., depending on the length of the cyclic prefix added to the beginning of each symbol period). In some wireless communication systems 100, a slot may be further divided into a number of minislots associated with one or more symbols. Each symbol period, excluding the cyclic prefix, may be divided into one or more (e.g., N) f The sampling period can be associated with the number of symbols. The duration of the symbol period may depend on the subcarrier interval or the frequency band of operation.

[0040] A subframe, slot, minislot, or symbol can be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some embodiments, the TTI duration (e.g., the amount of symbol duration within the TTI) can be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 can be dynamically selected (e.g., in bursts of shortened TTIs, sTTIs).

[0041] With respect to carrier-based communications, physical channels can be multiplexed according to various techniques. For example, one or more of the following can be used to multiplex physical control channels and physical data channels with respect to signaling over the downlink carrier: time division multiplexing (TDM), frequency division multiplexing (FDM), or hybrid TDM-FDM. A control domain (e.g., a control resource set, CORESET) relating to a physical control channel can be defined by a set of symbol periods and can be extended over the system bandwidth or a subset of the system bandwidth of that carrier. One or more control domains (e.g., CORESETs) can be configured with respect to a set of UE115s. For example, one or more of the UE115s can monitor or explore control domains with respect to control information according to one or more search space sets, each of which may contain one or more control channel candidates at one or more aggregation levels, configured in a cascaded manner. The aggregation level for control channel candidates may refer to the amount of control channel resources (e.g., control channel elements, CCEs) associated with encoded information for a control information format with a given payload size. The search space set may include a common search space set configured to send control information to multiple UE115s, and a UE-specific search space set for sending control information to a specific UE115.

[0042] Network entity 105 can provide communication coverage through one or more cells, such as macrocells, small cells, hotspots, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used in relation to communication with network entity 105 (e.g., using a carrier), and may be associated with an identifier for distinguishing adjacent cells (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), etc.). In some examples, a cell may also refer to a coverage area 110 or a portion of coverage area 110 (e.g., a sector) on which a logical communication entity operates. Such cells may range from smaller areas (e.g., structures, subsets of structures) to larger areas, depending on various factors, such as the capabilities of network entity 105. For example, a cell may be, among many examples, a building, a subset of a building, or external space between or overlapping with coverage area 110.

[0043] Macrocells typically cover relatively large geographical areas (e.g., a radius of several kilometers) and may allow unrestricted access by UE115s subscribed to the services of the network provider supporting the macrocell. Small cells can be associated with lower-power network entities 105 (e.g., lower-power base stations 140) compared to macrocells, and small cells can operate using the same or different (e.g., unlicensed, unauthorized) frequency bands as macrocells. Small cells can provide unrestricted access to UE115s subscribed to the network provider's services, or they can provide restricted access to UE115s associated with the small cell (e.g., UE115s within a closed subscriber group (CSG), or UE115s associated with users in a home or office). A network entity 105 can support one or more cells and can also support communication through one or more of those cells using one or more component carriers.

[0044] In some embodiments, a carrier can support multiple cells, and different cells can be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that can provide access to different types of devices.

[0045] In some embodiments, network entities 105 (e.g., base stations 140, RU 170) can be mobile and therefore can provide communication coverage for a moving coverage area 110. In some embodiments, different coverage areas 110 associated with different technologies may overlap, but these different coverage areas 110 can be supported by the same network entity 105. In some other embodiments, overlapping coverage areas 110 associated with different technologies can also be supported by different network entities 105. The wireless communication system 100 may include, for example, a heterogeneous network in which different types of network entities 105 provide coverage for various coverage areas 110 using the same or different radio access technologies.

[0046] The wireless communication system 100 can support synchronous or asynchronous operation. In synchronous operation, network entities 105 (e.g., base stations 140) may have similar frame timings, and transmissions from different network entities 105 may be approximately synchronized in time. In asynchronous operation, network entities 105 may have different frame timings, and transmissions from different network entities 105 may, in some cases, not be synchronized in time. The techniques described herein can be used for either synchronous or asynchronous operation.

[0047] Some UE115s, such as MTC devices or IoT devices, can be low-cost or low-complexity devices that can provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technology that enables devices to communicate with each other or with a network entity 105 (e.g., base station 140) without human intervention. In some embodiments, M2M communication or MTC may include communication from a device that incorporates sensors or meters for measuring or capturing information, relaying such information to a central server or application program that uses the information, or presenting the information to a human interacting with the application program. Some UE115s can be designed to collect information or to enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, vehicle management and tracking, remote security sensing, physical access control, and transaction-based business billing.

[0048] Some UE115s can be configured to employ power-saving operating modes, such as half-duplex communication (e.g., a mode that supports one-way communication via transmit or receive, but does not support transmit and receive simultaneously). In some embodiments, half-duplex communication can be performed at a reduced peak rate. Other power-saving techniques for the UE115 include entering a power-saving deep sleep mode when not actively communicating, operating using a limited bandwidth (e.g., according to narrowband communication), or a combination of these techniques. For example, some UE115s can be configured to operate using narrowband protocol types associated with a defined portion or range (e.g., a set of subcarriers or resource blocks, RBs) within, within, or outside the carrier's protected band.

[0049] The wireless communication system 100 can be configured to support ultra-reliable low-latency communications, low-latency communications, or various combinations thereof. For example, the wireless communication system 100 can be configured to support ultra-reliable low-latency communications (URLLC). The UE 115 can be designed to support ultra-reliable, low-latency, or critical functions. Ultra-reliable communications may include private or group communications and may be supported by one or more services such as push-to-talk, video, or data. Support for ultra-reliable and low-latency functions may include service prioritization, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency may be used interchangeably in this specification.

[0050] In some embodiments, a UE 115 can be configured to support direct communication with other UEs 115 via a device-to-device (D2D) communication link 135 (for example, according to a peer-to-peer (P2P) protocol, a D2D protocol, or a sidelink protocol). In some embodiments, one or more UEs 115 in a group performing D2D communication may reside within the coverage area 110 of a network entity 105 (e.g., base station 140, RU 170), and the modes of such D2D communication may be configured (e.g., scheduled) by the network entity 105. In some embodiments, one or more UEs 115 in such a group may reside outside the coverage area 110 of the network entity 105, or may be unable to receive or not configured to receive transmissions from the network entity 105. In some examples, a group of UE115s communicating via D2D communication can support a one-to-many (1:M) system, where each UE115 transmits to each of the other UE115s in the group. In some embodiments, a network entity 105 can facilitate the scheduling of resources related to D2D communication. In some other embodiments, D2D communication can be performed between UE115s without the involvement of the network entity 105.

[0051] In some systems, the D2D communication link 135 may be an example of a communication channel between vehicles (e.g., UE115), such as a side-link communication channel. In some examples, vehicles may communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or any combination thereof. Vehicles may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to the V2X system. In some examples, the V2X system may communicate with roadside infrastructure such as roadside units, or with a network via one or more network nodes (e.g., network entity 105, base station 140, RU170) using vehicle-to-network (V2N), or both.

[0052] 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 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) that manages access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), or a user plane function (UPF)) that routes packets or interconnects to external networks. The control plane entity can manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management, for UE 115 serviced by a network entity 105 (e.g., base station 140) associated with the core network 130. User IP packets can be forwarded via a user plane entity capable of providing IP address assignment and other functions. The user plane entity can connect to IP services 150 relating to one or more network operators. IP services 150 may include access to the Internet, one or more intranets, IP Multimedia Subsystems (IMS), or packet-switched streaming services.

[0053] The wireless communication system 100 can operate using one or more frequency bands, which can range from 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the 300 MHz to 3 GHz range is known as the ultra-high frequency (UHF) range or decimeter band, as its wavelengths range from approximately 1 decimeter to 1 meter. UHF waves may be blocked or redirected by buildings and environmental features, sometimes referred to as clusters, but these waves can penetrate structures well enough for macrocells to serve UE115 located indoors. Communication using UHF waves can be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers) compared to communication using lower frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0054] The wireless communication system 100 may also operate using the super high frequency (SHF) region, which may range from 3 GHz to 30 GHz and is also known as the centimeter band, or using the extremely high frequency (EHF) region of the spectrum (e.g., 30 GHz to 300 GHz) and is 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 the network entity 105 (e.g., base station 140, RU 170), although the EHF antennas of each device may be smaller and more closely spaced than UHF antennas. In some examples, such techniques may facilitate the use of antenna arrays within the device. However, propagation of EHF transmissions may be subject to greater attenuation than SHF or UHF transmissions and may be over shorter distances. The techniques disclosed herein may be employed across transmissions using one or more different frequency domains, and the specified use of bands across these frequency domains may vary by country or regulatory body.

[0055] The wireless communication system 100 can utilize both licensed and unlicensed RF spectrum bands. For example, the wireless communication system 100 can employ NR technologies that use unlicensed bands such as License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or the 5GHz industrial, scientific, and medical (ISM) band. While operating using unlicensed RF spectrum bands, devices such as network entities 105 and UE115 can employ carrier sensing for collision detection and avoidance. In some embodiments, operation using unlicensed bands may be based on a carrier aggregation configuration (e.g., LAA) that works in conjunction with component carriers operating using licensed bands. Operation using unlicensed spectrum may include, among many examples, downlink transmission, uplink transmission, P2P transmission, or D2D transmission.

[0056] A network entity 105 (e.g., base station 140, RU170) or UE115 may be equipped with multiple antennas that can be used to employ technologies such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of the network entity 105 or UE115 may be located in one or more antenna arrays or antenna panels that support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located in an antenna assembly such as an antenna tower. In some embodiments, the antennas or antenna arrays associated with the network entity 105 may be located in diverse 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 can use to support beamforming for communication with the UE115. Similarly, the UE115 may include one or more antenna arrays that can support various MIMO or beamforming operations. As an addition or alternative, the antenna panel may support RF beamforming for signals transmitted through the antenna port.

[0057] Network entities 105 or UE115 may use MIMO communication to leverage multipath signal propagation and improve spectral efficiency by transmitting or receiving multiple signals through different spatial layers. Such techniques may be referred to as spatial multiplexing. Multiple signals can be transmitted by a transmitting device, for example, through different antennas or different combinations of antennas. Similarly, multiple signals can be received by a receiving device, for example, through different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and can carry information associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers can be associated with different antenna ports used 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 multiple-user MIMO (MU-MIMO), where multiple spatial layers are transmitted to multiple devices.

[0058] Beamforming, sometimes referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that can be used in a transmitting or receiving device (e.g., network entity 105, UE115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming can be achieved by combining signals communicated through the antenna elements of an antenna array such that some signals propagating along a particular orientation relative to the antenna array undergo constructive interference, while other signals undergo destructive interference. The modulation of signals communicated through antenna elements may include the transmitting or receiving device applying amplitude offset, phase offset, or both to the signals carried through the antenna elements associated with that device. The modulation associated with each antenna element can be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the antenna array of the transmitting or receiving device, or to some other orientation).

[0059] The network entity 105 or UE 115 can use beam sweeping techniques as part of its beamforming operation. For example, the 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 the UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) can be transmitted multiple times by the network entity 105 along different directions. For example, the network entity 105 can transmit signals according to different beamforming weight sets associated with different transmission directions. Transmissions along different beam directions can be used to identify the beam direction for subsequent transmission or reception by the network entity 105 (e.g., by a transmitting device such as the network entity 105, or by a receiving device such as the UE 115).

[0060] Some signals, such as data signals associated with a specific receiving device, can be transmitted by a transmitting device (e.g., transmitting network entity 105, transmitting UE 115) along a single beam direction (e.g., the direction associated with the receiving device, such as receiving network entity 105 or receiving UE 115). In some examples, the beam direction associated with transmission along a single beam direction may be determined based on signals transmitted along one or more beam directions. For example, UE 115 may receive one or more signals transmitted by network entity 105 along different directions and report to network entity 105 an indication of the signal received by UE 115 that has the highest signal quality, or at least an acceptable signal quality.

[0061] In some examples, transmission by a device (e.g., by network entity 105 or UE115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or beamforming to generate a composite beam for transmission (e.g., from network entity 105 to UE115). UE115 may report feedback indicating precoding weights for one or more beam directions, which may correspond to a configured set of beams across the system bandwidth or one or more subbands. Network entity 105 may transmit a reference signal (e.g., cell-specific reference signal, CRS, CSI-RS) that can be precoded or amplified. UE115 may provide feedback on beam selection, which can be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination type codebook, a port selection type codebook). While these techniques are described with reference to signals transmitted by a network entity 105 (e.g., base station 140, RU170) along one or more directions, UE115 may employ similar techniques for transmitting signals multiple times along different directions (e.g., to identify beam directions for subsequent transmission or reception by UE115) or for transmitting signals along a single direction (e.g., to transmit data to a receiving device).

[0062] A receiving device (e.g., UE115) can perform receiving operations according to multiple receiving configurations (e.g., directional listening) when receiving various signals from another receiving device (e.g., network entity 105), such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device can perform receiving according to multiple receiving directions by receiving through different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different sets of receive beamforming weights (e.g., different directional listening weights) applied to signals received by multiple antenna elements of an antenna array, or by processing received signals according to different sets of receive beamforming weights applied to signals received by multiple antenna elements of an antenna array, any of which may be referred to as “listening” according to different receiving configurations or receiving directions. In some examples, a receiving device may use a single receiving configuration to receive along a single beam direction (e.g., when receiving data signals). A single receiving configuration can be matched along a beam direction determined based on listening according to different receiving configuration directions (for example, the 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).

[0063] The wireless communication system 100 can be a packet-based network operating according to a layered protocol stack. In the user plane, communication at the bearer or PDCP layer can be IP-based. To communicate over logical channels, the RLC layer can perform packet segmentation and reassembly. The MAC layer can perform priority processing and multiplexing of logical channels to transport channels. The MAC layer may also implement error detection techniques, error correction techniques, or both to support retransmission to improve link efficiency. In the control plane, the RRC layer can provide establishment, configuration, and maintenance of RRC connections between the UE 115 and the network entity 105 or core network 130 supporting the wireless bearer for user plane data. The PHY layer can map transport channels to physical channels.

[0064] UE115 and network entity 105 can support data retransmission to increase the likelihood of successful data reception. Hybrid Automatic Repeat Request (HARQ) feedback is one technique to increase the likelihood of correct data reception over a communication link (e.g., communication link 125, D2D communication link 135). HARQ may 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 under poor radio conditions (e.g., low signal-to-noise conditions). In some examples, devices may support same-slot HARQ feedback, in which case the device may provide HARQ feedback in a particular slot for data received via previous symbols in that slot. In some other embodiments, the device may provide HARQ feedback in subsequent slots or according to some other time interval.

[0065] Waveforms and multiple access designs used for wireless communications can be configured to support a relatively wide variety of use cases, including mobile broadband, metaverse, large-scale Internet of Things (IoT), sidelinks, large-scale spectrum aggregation or duplexing, UE coordination, other use cases, or any combination thereof. In some examples, waveforms and multiple access designs can support a relatively wide variety of technologies, including full-duplex technology, radio frequency sensing, positioning, physical layer security, other technologies, or any combination thereof. As an addition or alternative, waveforms and multiple access designs can be supported across multiple frequency ranges (e.g., mmW and above) as use cases and technologies expand. In some examples, waveforms and multiple access designs can be configured to support relatively large amounts of connectivity and relatively high cell capacity (e.g., waveforms and multiple access designs can provide relatively efficient support for channel access for a relatively large number of users).

[0066] One or more waveforms used for wireless communication may be based on multiple design metrics. These design metrics may include, for example, spectral efficiency, energy efficiency (e.g., power amplifier efficiency and processing power efficiency in the transmitting and receiving devices, respectively), waveform processing complexity and latency, radio frequency interference (e.g., error vector magnitude, EVM), spectral confinement by the power amplifier model (e.g., in-band and out-of-band radiation), and support for relatively efficient multi-user or MIMO multiple access. One or more waveforms may be designed to support one or more channel conditions, such as fading (e.g., time variation or inter-symbol interference, ISI), phase noise, power amplifier nonlinearity, or any combination thereof. In some examples, one or more waveforms may be designed based on advances in digital pre-distortion (DPD) and digital post-distortion (DPoD) techniques, spectral confinement for full duplex, joint sensing and common (JSAC) use cases, or any combination thereof.

[0067] 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 the wireless communication system 100 may support the FMCW-based OFDM multiport channel estimation techniques described herein. For example, a transmitting device (e.g., UE 115 or network entity 105) may transmit a first FMCW signal over an OFDM channel. A receiving device (e.g., UE 115 or network entity 105 communicating with the transmitting device) may receive the first FMCW signal. The receiving device may generate a second FMCW signal (e.g., a local FMCW signal) based on one or more sets of FMCW parameters associated with the first FMCW signal. The set of one or more FMCW parameters may include the starting frequency of the first FMCW signal, the bandwidth of the first FMCW signal, the slope of the first FMCW signal, or any combination thereof. The receiving device may combine the first FMCW signal and the second FMCW signal and filter the combined FMCW signal (for example, using a low-pass filter (LPF)). The receiving device may sample the combined FMCW signal using a sampling rate that may be based on one or more parameters associated with the OFDM channel. The receiving device may use its samples 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.

[0068] Figure 2 shows one embodiment of an OFDM multiport channel estimation scheme 200 that supports estimating an OFDM channel using FMCW, according to one or more aspects of the present disclosure. In some embodiments, the OFDM multiport channel estimation scheme 200 may implement an embodiment of the wireless communication system 100 described with reference to Figure 1. In this embodiment, a transmitting device 205 (e.g., a UE, base station, RU, DU, CU, IAB node, or any other device) and a receiving device 210 (e.g., a UE, base station, RU, DU, CU, IAB node, or any other device) can exchange OFDM signals over a wireless channel 235 which may be an OFDM channel. The receiving device 210 can estimate the wireless channel 235 using frequency domain signal processing.

[0069] The transmitting device 205 and the receiving device 210 can establish a connection for wireless communication via wireless channel 235. The transmitting device 205 can generate an OFDM signal for transmission to the receiving device 210 via wireless channel 235. To generate the OFDM signal, the transmitting device 205 can identify data scheduled for transmission to the receiving device 210. The data is a set of frequency domain signals 215 (e.g., {X(0), X(1), ... X(N) c -1)}) may be included or converted to it. The transmitting device 205 can perform an inverse fast Fourier transform (IFFT) 220 on the frequency domain signal 215 to convert the frequency domain signal 215 into a time domain signal (e.g., X(m)).

[0070] The transmitting device 205 can perform cyclic prefix addition 225 to a time-domain signal. For example, the transmitting device 205 may add a cyclic prefix to a time-domain signal to generate an OFDM signal. The transmitting device 205 can then use a digital-to-analog converter (DAC) 230 to convert the time-domain signal from a digital to an analog signal. In some examples, the transmitting device 205 may convert the real and imaginary parts of a digital time-domain signal separately to the analog domain. The transmitting device 205 can transmit the analog time-domain OFDM signal to the receiving device 210 via a wireless channel 235.

[0071] The receiving device 210 receives an analog time-domain OFDM signal and can convert the received signal to the digital domain using the ADC 240 in the receiving device 210. In some examples, the receiving device 210 may convert the real and imaginary parts of the analog signal to the digital domain separately. After using the ADC 240, the receiving device 210 may perform cyclic prefix removal 245 to remove one or more cyclic prefixes from the time-domain digital signal. After removing the cyclic prefixes, the receiving device 210 may perform an FFT 250 on the digital time-domain signal. The FFT 250 can convert the time-domain signal to the frequency domain; that is, the FFT 250 can create a set of frequency-domain signals 255.

[0072] The receiving device 210 can estimate a frequency-domain OFDM channel (e.g., the frequency domain of the wireless channel 235) using the set of frequency-domain signals 255 created by the FFT 250. In some examples, as described with reference to FIG. 2, for estimating the frequency-domain OFDM channel based on the OFDM signal, the ADC 240 in the receiving device 210 can be a relatively high-rate ADC 240. That is, the sampling rate of the ADC 240 can be relatively high to accurately convert the analog OFDM signal to a digital OFDM signal.

[0073] An exemplary sampling rate of the ADC 240 that can be used for different configured subcarrier spacing (SCS) values is shown in Table 1.

[0074]

Table 1

[0075] The sampling rate can be defined in units of megasamples per second (Msps). The sampling rate can be calculated based on the SCS value and each FFT size and can be associated with each quantity of subcarriers (e.g., in terms of the quantity 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., 15 KHz * × 2048 = 30.72 MHz).

[0076] In some cases, performing the FFT250 by the receiving device 210 may be associated with relatively high processing and complexity. Additionally or alternatively, the ADC240 in the receiving device 210 may be a relatively high-rate ADC240. The sampling rates used to convert the received analog signal to digital format, such as those shown in Table 1, may be relatively high in order for the receiving device 210 to accurately convert the OFDM signal and then perform the FFT250.

[0077] The techniques, systems, and devices described herein provide a transmitting device 205 and a receiving device 210 for exchanging FMCW signals over a wireless channel 235. The FMCW signal may be configured for channel estimation of an OFDM channel, which can support a reduction in processing complexity at the receiver. For example, the FMCW signal may be sampled at a reduced sampling rate compared to the OFDM signal and used to estimate a frequency-domain OFDM channel using time-domain signal processing, which can reduce complexity compared to using the OFDM signal to estimate the OFDM channel, so that the receiving device 210 can refrain from performing an FFT 250. FMCW-based channel estimation techniques are described in further detail elsewhere in this specification, including with reference to Figures 3A–6.

[0078] Figure 3A shows one embodiment of an OFDM multiport channel estimation scheme 300 that supports estimating an OFDM channel using FMCW, according to one or more aspects of the present disclosure. In some embodiments, the OFDM multiport channel estimation scheme 300 may implement an embodiment of the wireless communication system 100 described with reference to Figure 1. In this embodiment, a transmitting device 305 (e.g., a UE, base station, RU, DU, CU, IAB node, or any other device) and a receiving device 310 (e.g., a UE, base station, RU, DU, CU, IAB node, or any other device) can exchange FMCW signals over an OFDM channel 315. The FMCW signals may be used to facilitate channel estimation of a frequency domain OFDM channel by the receiving device 310.

[0079] The transmitting device 305 and the receiving device 310 can establish a connection for wireless communication via the OFDM channel 315. The devices may be the UE 115, the network entity 105, other devices, or any combination thereof. In some embodiments, the devices may exchange one or more capability messages, control messages, or both to initiate the FMCW-based OFDM multiport channel estimation procedure described herein. Such signaling may be described in further detail elsewhere in this specification, including by reference to Figures 4–6.

[0080] After the FMCW-based OFDM multiport channel estimation procedure is initiated, the transmitting device 305 may generate an FMCW signal 320 (e.g., a first FMCW signal). In some embodiments, the transmitting device 305 may generate the FMCW signal 320 in the analog domain using a VCO 345. The transmitting device 305 may transmit the FMCW signal 320 over the OFDM channel 315 using at least one antenna element in the transmitting device 305. The analog domain FMCW signal 320 generated and transmitted by the transmitting device 305 is x RF,Tx It can be expressed by (t), as shown in Equation 1.

[0081]

number

[0082] As shown in Equation 1, the FMCW signal 320 can be a time-domain signal (e.g., a function of time (t)). In the example of Equation 1, f c can represent the starting frequency 390 of the FMCW signal 320, S can represent the slope 385 of the FMCW signal 320, φ Tx This may represent the phase of the transmitting device 305.

[0083] As shown in Figure 3A, the FMCW signal 320 may be associated with a waveform signal transmitted through 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 may contain one or more resource blocks 375 in the frequency domain. In some examples, each resource block 375 may contain a set of resource elements in the frequency domain. The OFDM channel 315 may contain multiple symbols 380 in the time domain. The duration or length of each symbol 380 may correspond to the length of the OFDM symbol, or the length of the OFDM symbol and the duration of its respective cyclic prefix, or the partial length of the OFDM symbol, or the partial length of the OFDM symbol and the duration of its respective cyclic prefix, or any other length longer than the length of the OFDM symbol and the length of the OFDM symbol and the duration of its cyclic prefix, or any other symbol duration, or any combination thereof. The FMCW signal 320 can spread to frequencies between the starting frequency 390 and the sum of the starting frequency 390 and the bandwidth 370 (for example, {f c ,f c The gradient 385 of the FMCW signal 320 may correspond to the quotient of the bandwidth 370 and the duration of the symbol 380 to which the FMCW signal 320 is transmitted, as shown by Equation 2.

[0084]

number

[0085]

number

[0086] The radio frequency FMCW signal 325 received by the receiving device 310 via OFDM channel 315 in response to the FMCW signal 320 transmitted by the transmitting device 305 is y RF,Rx It can be expressed by (t), as shown in equation 3.

[0087]

number

[0088] In the example of Equation 3, P may represent the number of channel delay paths associated with the OFDM channel 315 (e.g., the number of multipaths), and τ p This can represent a given channel delay with index p. That is, the received FMCW signal 325 can be sampled over various channel delays (e.g., p = 0 to P-1). p can represent the conditions of the OFDM channel 315, and n(t) can represent the channel noise. In some examples, the channel noise may be associated with a relatively small value with respect to the other values ​​that define the radio frequency FMCW signal 325 received by the receiving device 310 in Equation 3.

[0089] As described herein, the receiving device 310 can generate an FMCW signal 330 in the receiving device. The FMCW signal 330 generated in the receiving device 310 may be called a second FMCW signal or local FMCW signal. The receiving device 310 can generate an FMCW signal 330 in the analog domain using the VCO 355 in the receiving device 310. The receiving device 310 can generate an FMCW signal 330 simultaneously with or after receiving an FMCW signal 325. The FMCW signal 330 generated by the receiving device 310 is x RF,Rx It can be expressed by (t), as shown in equation 4.

[0090]

number

[0091] As shown in Equation 4, the receiving device 310 can generate an FMCW signal 320 based on a set of FMCW parameters associated with the FMCW signal 330 transmitted by the transmitting device 305. The set of FMCW parameters is, for example, the starting frequency 390(f c ), gradient 385(S) of the FMCW signal 320, initial phase of the transmitting device (e.g., φ Tx ), or any combination thereof. That is, the FMCW signal 330 generated by the receiving device 310 may have the same start frequency 390 and gradient 385 as the FMCW signal 320 generated by the transmitting device 305. In the example of Equation 4, φ Rx φ may represent the phase of the receiving device 310. In some examples, the phase of the receiving device may be the same as the phase of the transmitting device (for example, φ Tx =φ RxIn some examples, the transmitting device 305 may transmit a control message indicating a set of FMCW parameters for the generation of the FMCW signal 330 by the receiving device 310. Additionally or alternatively, the receiving device 310 may transmit a control message indicating a set of FMCW parameters for the generation of the FMCW signal 320 by the transmitting device 305 and for the generation of the FMCW signal 330 by the receiving device 310, including by referring to Figures 4 to 6.

[0092] The FMCW signal 320 transmitted by the transmitting device 305 and the FMCW signal 330 generated by the receiving device 310 may have similar FMCW structures. For example, both signals may be broadband signals (e.g., spread across the entire bandwidth 370 of the OFDM channel 315), spread across the duration of the symbol 380 in the OFDM channel 315, associated with the starting frequency 390, and associated with the gradient 385. In some examples, the FMCW signal 320 transmitted by the transmitting device 305 may be a real signal. For example, the FMCW signal 320 may contain a single stream (e.g., a cosine stream as shown in Equation 1). The FMCW signal 330 generated by the receiving device 310 may contain 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 may be designed for channel estimation. In some examples, the receiving device 310 may be configured to generate an FMCW signal 330 for channel estimation, or the receiving device 310 may receive a control message indicating the function of generating an FMCW signal 330 for channel estimation.

[0093] After generating the FMCW signal 330 configured for channel estimation, the receiving device 310 generates the synthesized FMCW signal 335 (e.g., y mixed(t)) can be generated. To generate the combined FMCW signal 335, the receiving device 310 can use the mixer 350 to combine the FMCW signal 325 received in the receiving device 310 with the locally generated FMCW signal 330. The mixer 350 may represent an example of one or more components (e.g., hardware, software, or both) of the receiving device 310 configured to combine two or more time-domain FMCW signals. In some examples, combining may involve multiplying the FMCW signals (e.g., y mixed (t=y RF,Rx (t)x RF,Rx (t)).

[0094] The receiving device 310 can filter the combined FMCW signal 335 using the LPF 360 in the receiving device 310. The LPF 360 filters the combined and filtered FMCW signal 340 (for example, y mixed,LPF (t)) can be generated. LPF360 may represent an example of a component of the receiving device 310 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 synthesized and filtered FMCW signal 340 can be represented by Equation 5.

[0095]

number

[0096] Equation 5 can be simplified according to Equation 6.

[0097]

number

[0098] In some examples, β p The second exponential function in can represent a channel estimation error that may be ignored to further simplify Equation 6. For example, β p Half of the second exponential function (for example,

[0099]

number

[0100]

number

[0101]

number

[0102] After synthesizing and filtering the FMCW signals, the receiving device 310 may perform frequency-domain OFDM multiport channel estimation using time-domain signal processing based on sampling of the synthesized and filtered FMCW signals 340. The receiving device 310 can use the ADC 365 to sample the synthesized and filtered FMCW signals 340 in the time domain. The sampling rate used to sample the synthesized and filtered FMCW signals 340 may be based on one or more parameters associated with the OFDM channel 315. For example, the sampling rate may be based on the frequency range of one or more subbands in the OFDM channel 315 (e.g., sampling rate

[0103]

number

[0104]

number

[0105] Sampling by the receiving device 310 as part of OFDM multiport channel estimation is performed in sampling sequence D Rx (k) can be generated, which may represent a set of values ​​associated with the OFDM channel estimation. The sampling sequence is f subband It may have a granularity of D Rx Each value of (k) may represent an example of an estimate for each frequency subband of OFDM channel 315. Sampling sequence D Rx (k) is shown by equation 7.

[0106]

number

[0107] In the example of Equation 7, F s k may represent the sampling rate used by the receiving device 310 to estimate the OFDM channel 315. K may represent the total number of subbands in the OFDM channel 315, which may also correspond to the total number of samples in the sampling sequence. Thus, each value of k may represent the index of each subband out of the total number of subbands. In one example, the subband frequency range f of the OFDM channel 315. subband If is equal to one resource element, the sampling sequence may include each sample or estimate of each resource element in the OFDM channel 315 (e.g., per comb). In some examples, the subband frequency range f subband This can be a set of two or more resource elements, a resource block, or any other granularity such as some other frequency range.

[0108] As a result, the receiving device 310 uses time-domain signal processing to perform f based on the FMCW signal 325 received by the receiving device 310 and the FMCW signal 330 generated by the receiving device 310. subbandThe frequency-domain OFDM channel 315 can be estimated at this granularity. The FMCW-based OFDM multiport channel estimation technique described may be performed by the receiving device 310 in the time domain using time-domain signal processing. That is, when the receiving device 310 estimates the frequency-domain OFDM channel 315 using the FMCW signal, it can refrain from applying an FFT or other frequency transformation. By performing OFDM multiport channel estimation in the time domain, the receiving device 310 can reduce processing complexity, latency, and power consumption compared to other OFDM multiport 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 may estimate the frequency-domain OFDM channel 315 using both broadband and narrowband radio frequency processing. For example, the FMCW signal 325 received by the receiving device 310 may be a broadband signal at radio frequency, and the FMCW signal 340, synthesized and filtered after the LPF 360, may be a narrowband signal for baseband processing.

[0109] The sampling rate used by the receiving device 310 to estimate the frequency domain OFDM channel 315 using the FMCW signal may be relatively low. The sampling rates described herein are based on the gradient 385 and frequency granularity f of the FMCW signal. subband This can be based on the following. For example, the sampling rate is

[0110]

number

[0111]

number

[0112] As shown by Equation 8, the ratio of the sampling rate of the FMCW-based OFDM channel estimation technique to that of the OFDM-based OFDM channel estimation technique can be relatively low. That is, the sampling rate of the FMCW-based OFDM channel estimation technique can be relatively low compared to that of the OFDM-based OFDM channel estimation technique. For example, 273 out of a bandwidth of 370 * There are 12 resource elements (for example, N RE =273*12), if each subband contains a single resource element (for example, k subband =1), the ratio can be equal to 0.8. That is, in such cases, the FMCW-based OFDM channel estimation technique can produce an ADC sampling gain of about 20 percent. In some embodiments, such as in a scenario where the receiving device (e.g., UE115) reports channel state information (CSI) or a precoding matrix indicator (PMI), the maximum number of subbands that can be reported via CSI or PMI reporting (e.g., N3) can be 37, so the subband size is at least

[0113]

number

[0114] Table 2 includes a comparison of exemplary sampling rates for achieving accurate estimation of frequency-domain OFDM channels 315 using the FMCW-based OFDM channel estimation technique described herein, with exemplary sampling rates for achieving accurate estimation of frequency-domain OFDM channels 315 using other OFDM channel estimation techniques in the frequency domain, as described with reference to Figure 2. The exemplary sampling rates shown in Table 2 represent exemplary sampling rates that may be used by the receiving device 310 to accurately estimate OFDM channels 315 at a granularity of four resource blocks 375 when the channel bandwidth 370 is 50 MHz.

[0115] [Table 2]

[0116] As shown in Table 2, the FMCW-based channel estimation techniques described herein can reduce the sampling rate by a relatively large amount compared to OFDM-based channel estimation. For example, when the channel bandwidth 370 is 50 MHz and an FMCW signal is used, the sampling rate used by the receiving device 310 to estimate the OFDM channel 315 at a granularity of four resource blocks 375 may be about 1.69 percent of the sampling rate that could be used by the receiving device 310 if OFDM-based channel estimation were performed in the same scenario.

[0117] The FMCW-based OFDM channel estimation described herein can reliably estimate frequency-domain OFDM channels 315 using a reduced sampling rate. For example, the accuracy of the FMCW-based OFDM channel estimation technique may be relatively similar to that of an OFDM-based OFDM channel estimation technique that uses a frequency-domain reference signal across a range of packet delay protocols, SCS values, and bandwidths, when compared to benchmark values. In other words, the described technique can maintain or improve the accuracy and reliability of frequency-domain OFDM channel estimation while reducing processing and power consumption.

[0118] Figure 3B shows the FMCW waveform. As seen in the example in Figure 3B, the bandwidth (BW) is equal to the starting frequency f. c It contains multiple resource blocks (RBs) starting with (only the first RB304 is labeled). Each resource block contains several REs (only one RE306 is labeled). The FMCW waveform 302 with gradient S has symbol length T sym It extends across the entire bandwidth BW. In contrast to Figure 3A, the FMCW waveform 302 starts after a period corresponding to the cyclic prefix (CP) length. The FMCW waveform 302 can be time-division multiplexed (TDM) with the OFDM waveform so that the OFDM waveform starts after the FMCW waveform. The FMCW waveform 302 has a frequency of f c f c This can also be called a chirp signal that linearly ramps up to +BW. Although not shown in Figure 3B, multiple chirps can exist within a single symbol length.

[0119] The transmitting device 305 may utilize an FMCW chirp with a cyclic shift as a reference signal. To transmit a new port other than the port with the basic chirp, the transmitting device 305 may maintain the BW and shift the FMCW chirp to the right (e.g., defer). The left duration of the chirp may then be blank. The transmitting device 305 may then fill the blank using the cyclic shifted FMCW chirp. Thus, the cyclic shifted FMCW waveform may be as follows:

[0120]

number

[0121]

number

[0122]

number

[0123]

number

[0124]

number

[0125]

number

[0126]

number

[0127]

number

[0128]

number

[0129]

number

[0130]

number

[0131]

number

[0132]

number

[0133]

number

[0134]

number

[0135] Using the techniques described above, the transmitting device 305 may be configured to generate and transmit a cyclically shifted FMCW-based multiport reference signal. The transmitting device 305 may simultaneously transmit multiple ports of an FMCW-based reference signal (e.g., CSI-RS, SRS) using a different cyclically shifted FMCW waveform for each port, as follows:

[0136]

number

[0137]

number

[0138] To overcome multipath propagation, the transmitting device 305 adds a CP before the FMCW chirps on multiple ports by copying the chirp tail portion into the header. The length of the CP determines the maximum path delay.

[0139]

number

[0140] The receiving device 310 can perform multi-port channel estimation. To perform multi-port channel estimation, the receiving device 310 may perform sampling in the time domain for channel estimation of port 0, as follows:

[0141]

number

[0142] For channel estimation of port 0, the receiving device 310 then uses the cutoff frequency SΔ0 to determine {z n A digital domain LPF can be performed on} and the channel can be estimated in the same way as the single-port FMCW described above. For channel estimation of port i>0, the receiving device 310,

[0143]

number

[0144]

number

[0145] The receiving device 310 is,

[0146]

number

[0147]

number

[0148] Next, we will describe the method of calculating the sampling rate for cyclic shift-based FMCW. The cyclic shift-based multiport FMCW chirp described above has the same chirp gradient as the single port FMCW chirp described above. For channel estimation per subband, the sampling rate

[0149]

number

[0150] Also, as mentioned above, in the case of multi-port isolation,

[0151]

number

[0152] These two formulas can be combined as follows:

[0153]

number

[0154] Large BW subband Or a large path delay is f s,separation >f s,single If it brings about f s,cyclic >f s,single Conversely, the smaller BW subband Or a small path delay is f s,separation <f s,singleIf it brings about f s,cyclic =f s,single For example, if BW = 100MHz, then BW will be used for 2000 subbands. subband =50kHz, therefore,

[0155]

number

[0156]

number

[0157] BW subband Alternatively, by increasing the path delay, f s,cyclic >f s,single And so, BW subband Alternatively, by reducing the path delay, f s,cyclic =f s,single This is the result.

[0158] Figure 4 shows one embodiment of a wireless communication system 400 that supports estimating an OFDM channel using FMCW according to one or more aspects of the present disclosure. The wireless communication system 400 may implement, or can be implemented by, embodiments of the wireless communication system 100 or OFDM channel estimation scheme 300 described with reference to Figures 1 and 3. For example, the wireless communication system 400 may include network entities 105-a and UE115-a that may represent embodiments of the network entities 105 and UE115 described with reference to Figures 1 to 3. Network entity 105-a may communicate with UE115-a within a geographical coverage area 110-a via uplink communication link 410 and downlink communication link 415. In this example, network entity 105-a may transmit an FMCW signal 430 to UE115-a for use in estimating an OFDM channel.

[0159] Network entities 105-a and UE115-a may represent examples of transmitting and receiving devices. 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 embodiment shown in Figure 4, network entity 105-a may be a transmitting device and UE115-a may be a receiving device, and these may represent embodiments of the transmitting device 305 and receiving device 310 described with reference to Figure 3A. In the example shown in Figure 4, network entity 105-a is shown as a transmitting device, but it should be understood that in some examples, UE115-a may be a transmitting device and transmit the FMCW signal 430 to network entity 105-a, as will be described in more detail elsewhere in this specification, including with reference to Figure 6.

[0160] UE115-a may establish a connection with network entity 105-a for wireless communication via uplink communication link 410 and downlink communication link 415. After establishing the connection, UE115-a may send a capability message 420 to network entity 105-a via uplink communication link 410. The capability message 420 may indicate that UE115-a is capable of receiving FMCW signals 430. The capability message 420 may be an uplink control information (UCI) message, a medium access control-control element (MAC-CE) message, or some other type of uplink signaling. In some examples, UE115-a may send multiple capability messages 420 dynamically or semi-permanently.

[0161] Network entity 105-a receives capability message 420 and may determine that UE 115-a has received FMCW signal 430 and is capable of performing OFDM channel estimation based on FMCW signal 430. This allows network entity 105-a to decide to initiate the FMCW-based OFDM channel estimation procedure. To facilitate the FMCW-based OFDM channel estimation procedure, network entity 105-a may send one or more control messages 425 to UE 115-a via the downlink communication link 415. One or more control messages 425 may include, for example, symbol assignment information, FMCW parameter information, channel estimation triggers, or any combination thereof.

[0162] In some examples, the first control message 425 may indicate whether each symbol in the set of symbols in the OFDM channel is assigned for the FMCW signal 430 or for the OFDM signal 435. The FMCW signal 430 and the OFDM signal 435 may be multiplexed in the time domain across the symbols of the OFDM channel, and the first control message 425 may indicate which symbols are assigned for which type of signaling. The second control message 425 may indicate a set 445 of one or more FMCW parameters that the network entity 105-a intends to use to transmit the FMCW signal 430. The set 445 of FMCW parameters may include the bandwidth of the FMCW signal 430, the start frequency of the FMCW signal 430, the slope of the FMCW signal 430, the initial phase of the FMCW signal 430, and the cyclic offset of the FMCW signal 430, or any combination thereof, as will be described in more detail elsewhere in this specification, including by reference to Figure 3A. In some examples, network entity 105-a may send an RRC configuration to UE115-a after establishing communication with UE115-a, and the RRC configuration may consist of one or more sets 445 of FMCW parameters. In such cases, a second control message 425 may be configured to indicate (e.g., via a pointer) the index of one of the configured sets 445 of FMCW parameters.

[0163] In some examples, a 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 FMCW signal 430. In some examples, network entity 105-a may send a single control message including 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, another type of downlink message, 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 (e.g., in response to or after) receiving a capability message 420 from UE 115-a. In other words, based on the fact that UE115-a indicates that UE115-a is capable of receiving the FMCW signal 430, network entity 105-a can send a control message 425 to facilitate the FMCW-based OFDM channel estimation procedure.

[0164] The network entity 105-a may then transmit a first FMCW signal 430 to UE 115-a via the downlink communication link 415. The network entity 105-a may transmit the first FMCW signal 430 based on (for example, using and in accordance with) a set of FMCW parameters 445 indicated via at least one of the one or more control messages 425. The first FMCW signal 430 may be transmitted via an OFDM channel and may be configured to assist UE 115-a in estimating the frequency domain OFDM channel.

[0165] The UE115-a can receive a first FMCW signal 430 via an OFDM channel, and can generate a second FMCW signal (e.g., a local FMCW signal). The UE115-a can estimate the OFDM channel based on a sample of the synthesized FMCW signal, which includes a combination of the first FMCW signal 430 and the second FMCW signal. The sampling rate used by the UE115-a to sample the synthesized FMCW signal and estimate the frequency-domain OFDM channel can be relatively low, as will be described in more detail elsewhere in this specification, including by referring to Figure 3A.

[0166] In some examples, UE115-a may transmit a report such as a CSI report 440 that provides information associated with the OFDM channel estimation based on the FMCW signal. Network entity 105-a may transmit a control message 425 that includes a trigger or request for UE115-a to transmit the CSI report 440, and UE115-a may, based on the trigger, generate the CSI report 440 and transmit it over the uplink communication link 410. Network entity 105-a and UE115-a may adjust one or more parameters for subsequent communication based on the channel estimation, which may improve the throughput and reliability of subsequent communication between network entity 105-a and UE115-a.

[0167] In the example in Figure 4, the network entity 105-a is shown as the transmitting device, but it should be understood that in some examples, the UE 115-a could be the transmitting device. For example, the UE 115-a can transmit a 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 a frequency domain OFDM channel based on the first FMCW signal 430 and time domain samples of the local FMCW signal. In such a case, the capability message 420 transmitted by the UE 115-a may indicate that the UE 115-a is capable of transmitting the FMCW signal 430. The control message 425 transmitted by the network entity 105-a may include symbol assignment information, a set of FMCW parameters 445, and a trigger for the UE 115-a to transmit the first FMCW signal 430 (e.g., via the uplink communication link 410). UE115-a can transmit a first FMCW signal 430 via a symbol assigned for FMCW, based on the set of FMCW parameters 445 shown and a trigger.

[0168] This allows devices in the wireless communication system 400 to exchange FMCW signals 430 configured for frequency-domain OFDM channel estimation using time-domain signal processing (e.g., without performing FFT) and a relatively low sampling rate. Network entity 105-a may decide to send one or more control messages or other signaling to facilitate FMCW-based OFDM channel estimation, based on the ability of UE 115-a to either transmit or receive FMCW signals 430. Examples of signaling that may be exchanged between transmitting and receiving devices are described in further detail elsewhere in this specification, including by reference to Figures 5 and 6.

[0169] Figure 5 shows one embodiment of a process flow 500 that supports OFDM channel estimation using FMCW according to one or more aspects of the present disclosure. The process flow 500 may implement, or can be implemented by, a form of wireless communication systems 100 and 400 or 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 may represent a form of the corresponding device described with reference to Figures 1 to 4. In this example, the first wireless device 505 may represent an example of UE 115, and the second wireless device 510 may represent an example of network entity 105. In some examples, the devices may swap signaling to support FMCW-based OFDM channel estimation.

[0170] In the following description of process flow 500, the operations between the first wireless device 505 and the second wireless device 510 may be performed in a different order or at different times. Some operations may also be omitted from process flow 500, or other operations may be added. Although the first wireless device 505 and the second wireless device 510 are shown performing the operations of process flow 500, some aspects of some operations may also be performed by one or more other wireless devices.

[0171] In 515, the first wireless device 505 may transmit a capability message to the second wireless device 510. The capability message may indicate whether the first wireless device 505 is capable of receiving FMCW signals (e.g., FMCW receiving capability). In some examples, the capability message may indicate whether the first wireless device 505 is capable of estimating frequency-domain OFDM channels based on FMCW signals.

[0172] In 520, the second wireless device 510 may transmit a first control message, which may be referred to as a symbol assignment control message in some embodiments of this specification. The first control message may indicate whether one or more symbols of an OFDM channel are assigned for an FMCW signal or for an OFDM signal. For example, the first control message may include a bitmap or one or more indices configured to assign a first set of symbols for transmitting and receiving OFDM signals and a second set of symbols for transmitting and receiving FMCW signals. OFDM and FMCW signals may be time-division multiplexed across the symbols of the OFDM channel. The second wireless device 510 may transmit the first control message to the first wireless device 505 dynamically or semi-permanently to indicate the symbol assignment 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.

[0173] In 525, the second wireless device 510 may transmit a second control message, which in some embodiments of this specification may be referred to as an FMCW parameter control message. The second control message may indicate a set of FMCW parameters associated with the FMCW signal to be transmitted by the second wireless device 510. The set of FMCW parameters may include the start frequency of the FMCW signal, the bandwidth of the FMCW signal, the chirp gradient of the FMCW signal, or any combination thereof (e.g., {f c}, {BW}, {S}). The starting frequency, bandwidth, and slope may represent examples of the corresponding parameters described with reference to Figure 3A. In some embodiments, the slope may be based on the bandwidth of the FMCW signal and the duration of the symbol on which the FMCW signal will be transmitted. The FMCW parameter control message indicates that the CSI-RS type will be cyclically shifted based on the FMCW chirp, an indication of the cyclic offset (single or multiple), the length of the CP, multiple (N) portIt may further include a CSI-RS resource with a different offset Δ i It is associated with this.

[0174] As will be further illustrated with reference to Figure 4, the second control message may be a DCI message, MAC-CE, RRC message, some other type of control signaling, or any combination thereof. The second wireless device 510 may transmit the second control message (e.g., an instruction for FMCW parameters) dynamically or semi-permanently. In some examples, the second wireless device 510 may transmit one or more RRC messages, each constituting (e.g., pre-configured) a set of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling indicating to the first wireless device 505 an index for one of the sets of FMCW signals. As an addition or alternative, the second wireless device 510 may transmit a single RRC message constituting multiple sets of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling indicating to the first wireless device 505 an index for one of the sets of FMCW signals.

[0175] In 530, the second wireless device 510 may transmit a third control message to the first wireless device 505. The third control message may be referred to as a channel estimation trigger in some embodiments of this specification. The channel estimation trigger may trigger the first wireless device 505 to perform channel estimation by FMCW. That is, the channel estimation trigger may include a request, command, or instruction to trigger the first wireless device 505 to begin monitoring the FMCW signal for use in estimating a frequency domain OFDM channel.

[0176] Although the symbol assignment control message, FMCW parameter control message, and 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 transmit 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 transmit a single control message (e.g., a single DCI, MAC-CE, or RRC message) indicating each of the symbol assignment, FMCW parameter set, and channel estimation trigger for the FMCW. In addition or alternatively, the second wireless device 510 may transmit two control messages, respectively, to indicate the symbol assignment and FMCW parameter set for the FMCW. In some examples, reception by the first wireless device 505 of the symbol assignment, FMCW parameter set, or both may trigger the first wireless device 505 to perform OFDM channel estimation using the FMCW signal.

[0177] In 535, the second wireless device 510 may generate FMCW signals having multiple cyclic shifts for the estimation of the OFDM channel by the first wireless device 505. For example, the second wireless device 510 may generate a first FMCW signal and a second FMCW signal having a cyclic offset relative to the first FMCW signal. The first and second FMCW signals may overlap in the time domain but not in the delay domain. The cyclic offset may be, for example, greater than or equal to the OFDM channel, or more generally, the maximum channel delay of the OFDM spectrum, and less than the duration of a symbol in the OFDM spectrum. The header portion of the second chirp of the second FMCW signal may include a copy of the tail portion of the first chirp of the first FMCW signal. In some embodiments, the second wireless device 510 may also generate third and fourth, or any other number of FMCW signals, each having a corresponding cyclic offset. The cyclic offsets can be equal; for example, the cyclic offset of the third FMCW signal relative to the first FMCW signal is twice the cyclic offset of the second FMCW signal relative to the first FMCW signal, the cyclic offset of the fourth FMCW signal relative to the first FMCW signal is three times the cyclic offset of the second FMCW signal relative to the first FMCW signal, and so on.

[0178] In some embodiments, the FMCW signal may be generated or configured to support frequency-domain OFDM channel estimation. The second wireless device 510 may generate the FMCW signal as a time-domain signal. The second wireless device 510 may generate the FMCW signal based on some or all of the information carried via the first control message, the second control message, and the third control message. For example, the second wireless device 510 may generate an FMCW signal with multiple cyclic shifts based on a set of FMCW parameters indicated via the second control message. In some embodiments, the second wireless device 510 may generate the FMCW signal based on receiving a capability message from the first wireless device 505 (e.g., in accordance with or after), based on transmitting any of the first to third control messages, or any combination thereof.

[0179] In 540, the second wireless device 510 may transmit an FMCW signal to the first wireless device 505 via an OFDM channel through a transmitter. The first wireless device 505 may receive the FMCW signal as an analog time-domain signal via an OFDM channel.

[0180] In 545, the first wireless device 505 may generate or receive an FMCW control signal. The first wireless device 505 may generate an FMCW control signal based on a set of FMCW parameters associated with an FMCW signal (for example, indicated via an FMCW parameter control message in 525). For example, the first wireless device 505 may generate or process an FMCW control signal based on the same start frequency, gradient, and bandwidth as the FMCW signal, as described in more detail elsewhere in this specification, including with reference to Figure 3A. The generation of a control 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, a control FMCW signal may be generated based on an FMCW function configured to support improved OFDM channel estimation.

[0181] In 550, the first wireless device 505 may estimate the OFDM channel based on the first FMCW signal, the second FMCW signal, and the FMCW control signal. The first wireless device 505 may, for example, receive an FMCW signal via the OFDM spectrum, which includes the first FMCW signal and the second FMCW signal having a cyclic offset, determine the cyclic offset, and estimate the OFDM channel, or more generally the OFDM spectrum, for the first port based on the first FMCW signal and for the second port based on the second FMCW signal and the cyclic offset.

[0182] To estimate the frequency domain OFDM channel, the first wireless device 505 may, in some embodiments, synthesize the FMCW signal and the FMCW control signal to generate a synthesized FMCW signal. The first wireless device 505 may filter the synthesized FMCW signal (e.g., using an LPF). After filtering, the first wireless device 505 may determine the subband frequency range of the OFDM channel (e.g., f subbandThe synthesized FMCW signal can be sampled in the time domain using a sampling rate based on one or more parameters of the OFDM channel, such as ). In some embodiments, the first wireless device 505 may sample the synthesized FMCW signal using an ADC, as will be described in more detail elsewhere in this specification, including with reference to Figure 3A.

[0183] To estimate the OFDM spectrum of a first port, the first wireless device 505 may be configured to filter the synthesized FMCW signal, and after filtering, to sample the synthesized FMCW signal in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum, and to estimate the OFDM spectrum, one or more processors may be further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, at least partially based on the sampling. To estimate the OFDM spectrum of the second port, the first wireless device 505 may be configured to determine a cutoff frequency based on a cyclic offset, filter the synthesized FMCW signal based on the cutoff frequency, and after filtering, sample the synthesized FMCW signal in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum, and to estimate the OFDM spectrum, one or more processors may be further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, at least partially based on sampling.

[0184] The first wireless device 505 can estimate frequency-domain OFDM channels by estimating the respective values ​​of the OFDM channel for each subband of multiple subbands in the frequency domain of the OFDM channel based on sampling. For example, sampling can create a sampling sequence, where each value in the sampling sequence is associated with each subband of the OFDM channel. By adjusting the sampling rate used by the first wireless device 505 based on the subband frequency range (e.g., frequency estimation granularity), the first wireless device 505 can change the number of subbands estimated (e.g., the first wireless device 505 can make the frequency-domain OFDM channel estimation finer or coarser in granularity). The sampling rate used to sample the synthesized and filtered FMCW signal may be relatively low (e.g., lower than the sampling rate used to estimate the OFDM channel based on the OFDM signal), which can reduce the processing complexity and power consumption in the device.

[0185] In 555, in some examples, the second wireless device 510 may transmit a control message containing a trigger (e.g., a request) that causes the first wireless device 505 to transmit a CSI report or any other report indicating an OFDM channel estimation. The first wireless device 505 may generate a CSI report based on a CSI report trigger and an OFDM channel estimation based on an FMCW signal. In 560, the first wireless device 505 may transmit a CSI report to the second wireless device 510.

[0186] In 565, the second wireless device 510 and the first wireless device 505 can communicate OFDM signals over an OFDM channel based on the estimation of the frequency domain OFDM channel. For example, the second wireless device 510 and the first wireless device 505 can transmit and receive uplink data, downlink data, sidelink data, or any combination thereof, and the data can be transmitted over an OFDM signal. Thus, the FMCW-based frequency domain OFDM channel estimation technique described herein can provide the first wireless device 505 with reliable and accurate estimation of the frequency domain OFDM channel using time domain signal processing and a relatively low sampling rate. By estimating the OFDM channel based on the FMCW signal, the first wireless device 505 can improve throughput, communication reliability, and inter-device coordination while maintaining or reducing processing complexity, latency, and power consumption.

[0187] Figure 6 shows one embodiment of a process flow 600 that supports OFDM channel estimation using FMCW according to one or more aspects of the present disclosure. Process flow 600 may implement, or can be implemented by, aspects of wireless communication systems 100 and 400 or OFDM channel estimation scheme 300. For example, process flow 600 shows communication between a first wireless device 605 and a second wireless device 610, which may represent aspects of the corresponding devices described with reference to Figures 1 to 5. In this example, the first wireless device 605 may represent an example of network entity 105, and the second wireless device 610 may represent an example of UE 115. The devices may exchange signaling to support FMCW-based OFDM channel estimation.

[0188] In the following description of 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 omitted from process flow 600, or other operations may be added. Although the first wireless device 605 and the second wireless device 610 are shown performing the operations of process flow 600, some aspects of some operations may also be performed by one or more other wireless devices.

[0189] In 615, the second wireless device 610 may transmit a capability message to the first wireless device 605. The capability message may indicate whether the second wireless device 610 is capable of transmitting an FMCW signal (e.g., FMCW transmission capability). In some examples, the capability message may indicate whether the second wireless device 610 is capable of transmitting an FMCW signal configured for frequency domain OFDM channel estimation.

[0190] In 620, the first wireless device 605 may transmit a first control message, which may be referred to as a symbol assignment control message in some embodiments of this specification. The first control message may indicate whether one or more symbols of an OFDM channel are assigned for an FMCW signal or for an OFDM signal. For example, the first control message may include a bitmap or one or more indices configured to assign a first set of symbols for transmitting and receiving OFDM signals and a second set of symbols for transmitting and receiving FMCW signals. OFDM and FMCW signals may be time-division multiplexed across the symbols of the OFDM channel. The first wireless device 605 may dynamically or semi-permanently transmit the first control message to the second wireless device 610 to indicate the symbol assignment 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 a symbol assignment control message based on (for example, in response to) a capability message from the second wireless device 610.

[0191] In 625, the first wireless device 605 may transmit a second control message, which in some embodiments of this specification may be referred to as an FMCW parameter control message. The second control message may indicate a set of FMCW parameters associated with an FMCW signal to be transmitted by the second wireless device 610. The set of FMCW parameters may include the start frequency of the FMCW signal, the bandwidth of the FMCW signal, the chirp gradient of the FMCW signal, or any combination thereof (e.g., {f c}(, {BW}, {S}). The start frequency, bandwidth, and slope may represent examples of the corresponding parameters described with reference to FIG. 3A. In some embodiments, the slope may be based on the bandwidth of the FMCW signal and the duration of the symbol for which the FMCW signal is to be transmitted. The FMCW parameter control message may include an indication that the SRS type is cyclically shifted based on an FMCW chirp, an indication of the cyclic offset(s), the length of the CP, and an SRS resource including a plurality (N port number) of ports, each port being associated with a different offset Δ i .

[0192] As will be described in more detail with reference to FIG. 4, the second control message may be a DCI message, a MAC-CE, an RRC message, some other type of control signaling, or any combination thereof. The first wireless device 605 may transmit the second control message (e.g., an indication of FMCW parameters) dynamically or semi-persistently. In some examples, the first wireless device 605 may transmit one or more RRC messages each configured (e.g., pre-configured) with a set of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling indicating an index to one of the set of FMCW signals to the second wireless device 610. Additionally or alternatively, the first wireless device 605 may transmit a single RRC message configuring a plurality of sets of FMCW parameters, and the second control message may be a DCI message or MAC-CE signaling indicating an index to one of the set of FMCW signals to the second wireless device 610.

[0193] At 630, the first wireless device 605 may send a third control message to the second wireless device 610. The third control message may be referred to as an FMCW transmission trigger in some aspects of this specification. The FMCW transmission trigger may trigger the second wireless device 610 to transmit an FMCW signal. That is, the FMCW transmission trigger may include a request, instruction, or indication for triggering the second wireless device 610 to generate and transmit an FMCW signal for estimating a frequency domain OFDM channel.

[0194] Although the symbol assignment control message, FMCW parameter control message, and FMCW transmit 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 transmit any number of control messages to indicate any combination of the described symbol assignment, FMCW parameters, and FMCW transmit trigger. In some examples, the first wireless device 605 may transmit a single control message (e.g., a single DCI, MAC-CE, or RRC message) indicating each of the symbol assignment, FMCW parameter set, and FMCW transmit trigger for the FMCW. In addition or alternatively, the first wireless device 605 may transmit two control messages, respectively, to indicate the symbol assignment and FMCW parameter set for the FMCW. In some examples, the reception of a symbol assignment for FMCW, a set of FMCW parameters, or both by the second wireless device 610 may trigger the second wireless device 610 to transmit an FMCW signal for channel estimation (e.g., using the indicated FMCW parameters via the assigned symbol). In some examples, one or more of the first to third control messages may be transmitted by the first wireless device 605 based on (e.g., in response to, and thereafter) a capability message from the second wireless device 610 indicating that the second wireless device 610 supports FMCW transmission.

[0195] In 635, the second wireless device 610 may generate FMCW signals having multiple cyclic shifts for the estimation of the OFDM channel by the first wireless device 605. For example, the second wireless device 510 may generate a first FMCW signal and a second FMCW signal having a cyclic offset relative to the first FMCW signal. The first and second FMCW signals may overlap in the time domain, and the cyclic offset may be, for example, greater than or equal to the OFDM channel, or more generally, the maximum channel delay of the OFDM spectrum, and less than the duration of a symbol in the OFDM spectrum. The header portion of the second chirp of the second FMCW signal may include a copy of the tail portion of the first chirp of the first FMCW signal. In some embodiments, the second wireless device 510 may also generate third and fourth, or any other number of FMCW signals, each having a corresponding cyclic offset. The cyclic offsets can be equal; for example, the cyclic offset of the third FMCW signal relative to the first FMCW signal is twice the cyclic offset of the second FMCW signal relative to the first FMCW signal, the cyclic offset of the fourth FMCW signal relative to the first FMCW signal is three times the cyclic offset of the second FMCW signal relative to the first FMCW signal, and so on.

[0196] In some embodiments, the FMCW signal may be generated or configured to support frequency-domain OFDM channel estimation. The second wireless device 610 may generate the FMCW signal as a time-domain signal. The second wireless device 610 may generate the FMCW signal based on some or all of the information carried via the first control message, the second control message, and the third control message. For example, the second wireless device 610 may generate the FMCW signal based on a set of FMCW parameters received via the second control message. In some embodiments, the second wireless device 610 may generate the FMCW signal based on transmitting a capability message (e.g., accordingly or thereafter), based on receiving any of the first to third control messages, or any combination thereof.

[0197] In 640, the second wireless device 610 may transmit an FMCW signal to the first wireless device 605 via an OFDM channel through a transmitter. The first wireless device 605 may receive the FMCW signal as an analog time-domain signal via an OFDM channel.

[0198] In 645, the first wireless device 605 may generate or receive an FMCW control signal. The first wireless device 605 may generate an FMCW control signal based on a set of FMCW parameters associated with an FMCW signal (for example, indicated via an FMCW parameter control message in 625). For example, the first wireless device 605 may generate or process an FMCW control signal based on the same start frequency, gradient, and bandwidth as the FMCW control signal, as described in more detail elsewhere in this specification, including with reference to Figure 3A. The generation of an FMCW control 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, an FMCW control signal may be generated based on an FMCW function configured to support improved OFDM channel estimation.

[0199] In 650, the first wireless device 605 may estimate the OFDM channel based on the first FMCW signal, the second FMCW signal, and the FMCW control signal. The first wireless device 505 may, for example, receive an FMCW signal via the OFDM spectrum, which includes the first FMCW signal and the second FMCW signal having a cyclic offset, determine the cyclic offset, and estimate the OFDM channel, or more generally the OFDM spectrum, for the first port based on the first FMCW signal and for the second port based on the second FMCW signal and the cyclic offset.

[0200]

number

[0201]

number

[0202] To estimate the OFDM spectrum of a first port, the first wireless device 605 may be configured to filter the synthesized FMCW signal, and after filtering, to sample the synthesized FMCW signal in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum, and to estimate the OFDM spectrum, one or more processors may be further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, at least partially based on the sampling. To estimate the OFDM spectrum of the second port, the first wireless device 605 may be configured to determine a cutoff frequency based on a cyclic offset, filter the synthesized FMCW signal based on the cutoff frequency, and after filtering, sample the synthesized FMCW signal in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum, and to estimate the OFDM spectrum, one or more processors may be further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, at least partially based on sampling.

[0203] The first wireless device 605 can estimate frequency-domain OFDM channels by estimating the respective values ​​of the OFDM channel for each subband of multiple subbands in the frequency domain of the OFDM channel based on sampling. For example, sampling can create a sampling sequence, where each value in the sampling sequence is associated with each subband of the OFDM channel. By adjusting the sampling rate used by the first wireless device 605 based on the subband frequency range (e.g., frequency estimation granularity), the first wireless device 605 can change the number of subbands estimated (e.g., the first wireless device 605 can make the frequency-domain OFDM channel estimation finer or coarser in granularity). The sampling rate used to sample the synthesized and filtered FMCW signal may be relatively low (e.g., lower than the sampling rate used to estimate the OFDM channel based on the OFDM signal), which can reduce the processing complexity and power consumption in the device.

[0204] In 655, the first wireless device 605 and the second wireless device 610 may communicate OFDM signals over an OFDM channel based on the estimation of a frequency domain OFDM channel. For example, the first wireless device 605 may, after estimating a frequency domain OFDM channel, transmit one or more follow-up data transmissions to the second wireless device 610. The follow-up data transmissions may be OFDM signals indicating other information associated with the channel estimation or the estimation of a frequency domain OFDM channel. The first wireless device 605 and the second wireless device 610 may transmit and receive uplink data, downlink data, sidelink data, or any combination thereof, and the data may be transmitted over OFDM signals.

[0205] Therefore, the FMCW-based frequency-domain OFDM channel estimation technique described herein can provide the first wireless device 605 with the ability to reliably and accurately estimate frequency-domain OFDM channels using time-domain signal processing and relatively low sampling rates. By estimating OFDM channels based on FMCW signals, the first wireless device 605 can improve throughput, communication reliability, and inter-device coordination while maintaining or reducing processing complexity, latency, and power consumption.

[0206] Figure 7 shows a block diagram 700 of a device 705 supporting multiport channel estimation according to one or more embodiments of the present disclosure. Device 705 may be an embodiment of an embodiment of a UE 115 or network entity 105 as described herein. Device 705 may include a receiver 710, a transmitter 715, and a communications manager 720. Device 705 may also include a processor. Each of these components can communicate with one another (for example, via one or more buses).

[0207] 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 channel, data channel, information channel related to estimating the OFDM channel using FMCW). The information may be passed to other components of device 705. The receiver 710 may utilize a single antenna or a set of multiple antennas.

[0208] 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 associated with various information channels (e.g., control channels, data channels, information channels related to estimating OFDM channels using FMCW), user data, control information, or any combination thereof. In some embodiments, the transmitter 715 may be co-located with the receiver 710 within the transceiver module. The transmitter 715 may utilize a single antenna or a set of multiple antennas.

[0209] The communication manager 720, receiver 710, transmitter 715, or various combinations thereof or various components thereof may be examples of means for carrying out various aspects of estimating an OFDM channel using FMCW as described herein. For example, the communication manager 720, receiver 710, transmitter 715, or various combinations thereof or components thereof may support a process that performs one or more of the functions described herein.

[0210] In some embodiments, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuit). The hardware may include a processor, a digital signal processor (DSP), a central processing unit (CPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a microcontroller, discrete gates or transistor logic, discrete hardware components, or any combination thereof configured as means for performing, or supporting the performance of, the functions described in this disclosure. In some embodiments, a processor and memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by executing instructions stored in the memory by the processor).

[0211] Additionally or alternatively, in some embodiments, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communication management software or firmware). When implemented in code executed by a processor, the functions of the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be performed by a general-purpose processor, DSP, CPU, ASIC, FPGA, microcontroller, or any combination of these programmable logic devices or other programmable logic devices configured as means for performing, or otherwise supporting the performance of, the functions described in this disclosure.

[0212] In some embodiments, the communications manager 720 may be configured to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting) using or in other ways in cooperation with the receiver 710, the transmitter 715, or both. For example, the communications manager 720 may receive information from the receiver 710 and transmit information to the transmitter 715, or, in combination with the receiver 710, the transmitter 715, or both, acquire information, output information, or perform various other operations as described herein.

[0213] The communication manager 720 may support wireless communication in a first wireless device according to embodiments disclosed herein. For example, the communication manager 720 may be configured as a means for receiving a first FMCW signal via an OFDM channel, or may otherwise support such means. The communication manager 720 may be configured as a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, or may otherwise support such means. The communication manager 720 may be configured as a means for estimating an OFDM channel in the time domain based on a sample of a synthesized FMCW signal, including a synthesis of the first FMCW signal and the second FMCW signal, or may otherwise support such means.

[0214] In addition or alternatively, the communication manager 720 may support wireless communication in a second wireless device according to embodiments disclosed herein. For example, the communication manager 720 may be configured as a means for generating an FMCW signal for the estimation of an OFDM channel by the first wireless device, or may otherwise support such means. The communication manager 720 may be configured as a means for transmitting an FMCW signal over an OFDM channel, or may otherwise support such means. The communication manager 720 may be configured as a means for communicating an OFDM signal over an OFDM channel with the first wireless device based on the estimation of an OFDM channel, or may otherwise support such means.

[0215] By including or configuring the communications manager 720 in accordance with the embodiments described herein, the device 705 (e.g., a processor controlling the receiver 710, transmitter 715, communications manager 720, or a combination thereof, or otherwise coupled thereto) can support techniques for reducing processing load, reducing power consumption, and more efficient use of communications resources.

[0216] Figure 8 shows a block diagram 800 of a device 805 supporting multiport channel estimation according to one or more embodiments of the present disclosure. Device 805 may be an embodiment of an embodiment of device 705, UE 115, or network entity 105 as described herein. Device 805 may include a receiver 810, a transmitter 815, and a communications manager 820. Device 805 may also include a processor. Each of these components can communicate with one another (for example, via one or more buses).

[0217] Receiver 810 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 channel, data channel, information channel related to estimating the OFDM channel using FMCW). The information may be passed to other components of device 805. Receiver 810 may utilize a single antenna or a set of multiple antennas.

[0218] Transmitter 815 may provide means for transmitting signals generated by other components of device 805. For example, transmitter 815 may transmit information such as packets associated with various information channels (e.g., control channel, data channel, information channel related to estimating the OFDM channel using FMCW), user data, control information, or any combination thereof. In some embodiments, transmitter 815 may be co-located with receiver 810 within the transceiver module. Transmitter 815 may utilize a single antenna or a set of antennas.

[0219] Device 805 or its various components may be examples of means for carrying out various embodiments of estimating an OFDM channel using the FMCW described herein. For example, the communication manager 820 may include an FMCW signaling component 825, an FMCW signal generating component 830, an OFDM estimation component 835, an OFDM signaling component 840, or any combination thereof. The communication manager 820 may be an embodiment of an embodiment of the communication manager 720 as described herein. In some embodiments, the communication manager 820 or its various components may be configured to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting) using or in other ways in cooperation with the receiver 810, the transmitter 815, or both. For example, the communication manager 820 may receive information from the receiver 810 and transmit information to the transmitter 815, or be integrated with the receiver 810, the transmitter 815, or both to acquire information, output information, or perform various other operations as described herein.

[0220] The communication manager 820 may support wireless communication in the first wireless device according to embodiments disclosed herein. The FMCW signaling component 825 may be configured as a means for receiving a first FMCW signal via an OFDM channel, or may otherwise support such means. The FMCW signaling component 830 may be configured as a means for generating a second FMCW signal based on a set of FMCW parameters associated with a first FMCW signal, or may otherwise support such means. The OFDM estimation component 835 may be configured as a means for estimating an OFDM channel in the time domain based on a sample of a synthesized FMCW signal, including a synthesis of the first FMCW signal and the second FMCW signal, or may otherwise support such means.

[0221] In addition or alternatively, the communication manager 820 may support wireless communication in a second wireless device according to embodiments disclosed herein. The FMCW signal generation component 830 is configured as a means for generating an FMCW signal for the estimation of an OFDM channel by the first wireless device, or may otherwise support such means. The FMCW signal component 825 is configured as a means for transmitting an FMCW signal over an OFDM channel, or may otherwise support such means. The OFDM signal component 840 may be configured as a means for communicating an OFDM signal over an OFDM channel with the first wireless device based on the estimation of an OFDM channel, or may otherwise support such means.

[0222] Figure 9 shows a block diagram 900 of a communications manager 920 supporting multiport channel estimation according to one or more aspects of the present disclosure. The communications manager 920 may be an embodiment of communications manager 720, communications manager 820, or both, as described herein. The communications manager 920 or its various components may be examples of means for carrying out various aspects of estimating OFDM channels using FMCW as described herein. For example, the communications manager 920 may include an FMCW signaling component 925, an FMCW signaling component 930, an OFDM estimation component 935, an OFDM signaling 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 with one another directly or indirectly (for example, via one or more buses), which may include communication within the protocol layer of the protocol stack, communication associated with the logical channels of the protocol stack (for example, between protocol layers of the protocol stack, within devices, components, or virtualization components associated with network entity 105, between devices, components, or virtualization components associated with network entity 105), or any combination thereof.

[0223] The communication manager 920 may support wireless communication in the first wireless device according to embodiments disclosed herein. The FMCW signaling component 925 is configured as a means for receiving a first FMCW signal via an OFDM channel, or may otherwise support such means. The FMCW signaling component 930 is configured as a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, or may otherwise support such means. The OFDM estimation component 935 is configured as a means for estimating an OFDM channel in the time domain based on a sample of a synthesized FMCW signal, including a synthesis of the first FMCW signal and the second FMCW signal, or may otherwise support such means.

[0224] In some examples, to support the estimation of OFDM channels, the filtering component 945 is configured as a means for filtering the synthesized FMCW signal, or may otherwise support such a means. In some examples, to support the estimation of OFDM channels, the FMCW sampling component 950 is configured as a means for sampling the synthesized FMCW signal in the time domain after filtering, using a sampling rate based on the subband frequency range of the OFDM channels, or may otherwise support such a means, and the estimation includes estimating the respective values ​​of the OFDM channels for each subband of a set of multiple subbands in the frequency domain of the OFDM channels, based on the sampling.

[0225] In some examples, the OFDM signaling component 940 is configured as a means for receiving one or more OFDM signals time-division multiplexed with a first FMCW signal within an OFDM channel, or may otherwise support such means.

[0226] In some examples, the FMCW capability component 955 is configured as a means for transmitting a capability message indicating that a first wireless device is capable of estimating an OFDM channel using a time-domain FMCW signal, or may otherwise support such means, and the first wireless device includes a UE. In some examples, the FMCW capability component 955 is configured as a means for receiving a capability message indicating that a second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, or may otherwise support such means, and the first wireless device includes a network entity.

[0227] In some examples, the symbol assignment component 960 is configured as a means for receiving a control message indicating whether one or more symbols of an OFDM channel are assigned for an FMCW signal, or may otherwise support such means, the first FMCW signal is received in one of the one or more symbols indicated as assigned for the FMCW signal, and the first wireless device includes a UE.

[0228] In some examples, the symbol assignment component 960 is configured, or otherwise may support, means for sending a control message indicating whether one or more symbols of an OFDM channel are assigned for an FMCW signal, or for an OFDM signal, the first FMCW signal is received in one of the symbols of the one or more symbols assigned for the FMCW signal based on the control message, and the first wireless device includes a network entity.

[0229] In some examples, the FMCW parameter component 965 is configured as a means for receiving, or otherwise supporting, a control message indicating a set of FMCW parameters including the start frequency of a first FMCW signal, the bandwidth of a first FMCW signal, the slope of a first FMCW signal, or any combination thereof, where the slope is based on the bandwidth of the first FMCW signal and the duration of the symbol in which the first FMCW signal is received.

[0230] In some examples, the FMCW parameter component 965 is configured as a means for transmitting a control message indicating a set of FMCW parameters, including the start frequency of a first FMCW signal, the bandwidth of a first FMCW signal, the slope of a first FMCW signal, or any combination thereof, or otherwise may support such means, where the slope is based on the bandwidth of the first FMCW signal and the duration of the symbol in which the first FMCW signal is received, and receiving the first FMCW signal is based on the set of FMCW parameters.

[0231] In some examples, the OFDM estimation component 935 is configured as a means for receiving a control message containing a trigger for a first wireless device to perform OFDM channel estimation using an FMCW signal, or may otherwise support such means, and the estimation of the OFDM channel using a first FMCW signal and a second FMCW signal is triggered, and the first wireless device includes a UE.

[0232] In some examples, the CSI component 970 is configured as a means for receiving a control message including a trigger for a first wireless device to transmit a channel status information report based on a first FMCW signal, or may otherwise support such a means. In some examples, the CSI component 970 is configured as a means for transmitting a channel status information report including a set of channel status information parameters, based on receiving a trigger and estimating an OFDM channel, or may otherwise support such a means.

[0233] In some examples, the FMCW signaling component 925 is configured as a means for transmitting a control message that includes a trigger for a second wireless device to transmit a first FMCW signal, or may otherwise support such means. In some examples, the first wireless device includes a UE or network entity.

[0234] In addition or alternatively, the communication manager 920 may support wireless communication in a second wireless device according to embodiments disclosed herein. In some examples, the FMCW signal generation component 930 is configured as a means for generating an FMCW signal for the estimation of an OFDM channel by the first wireless device, or may otherwise support such means. In some examples, the FMCW signal component 925 is configured as a means for transmitting an FMCW signal over an OFDM channel, or may otherwise support such means. The OFDM signal component 940 is configured as a means for communicating an OFDM signal over an OFDM channel with the first wireless device based on the estimation of an OFDM channel, or may otherwise support such means.

[0235] In some examples, the OFDM signaling component 940 is configured as a means for transmitting one or more OFDM signals time-division multiplexed with an FMCW signal within an OFDM channel, or may otherwise support such means.

[0236] In some examples, the FMCW capability component 955 is configured as a means for transmitting a capability message indicating that a second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, or may otherwise support such means, and the second wireless device includes a UE.

[0237] In some examples, the FMCW capability component 955 is configured as a means for receiving a capability message indicating that a first wireless device is capable of estimating an OFDM channel using a time-domain FMCW signal, or may otherwise support such means, and the second wireless device includes a network entity.

[0238] In some examples, the symbol assignment component 960 is configured as a means for receiving a control message indicating whether one or more symbols of an OFDM channel are assigned for an FMCW signal, or may otherwise support such means, the FMCW signal is transmitted within one of the one or more symbols assigned for the FMCW signal based on the control message, and the second wireless device includes a UE.

[0239] In some examples, the symbol assignment component 960 is configured, or otherwise may support, means for sending a control message indicating whether one or more symbols of an OFDM channel are assigned for an FMCW signal, or for an OFDM signal, the FMCW signal is transmitted within one of the symbols of the one or more symbols assigned for the FMCW signal, and the second wireless device includes a network entity.

[0240] In some examples, the FMCW parameter component 965 is configured as a means for receiving, or otherwise may support, a means for receiving, a control message indicating a set of FMCW parameters associated with an FMCW signal, which includes the start frequency of the FMCW signal, the bandwidth of the FMCW signal, the gradient of the FMCW signal, or any combination thereof, and transmitting the FMCW signal is based on the set of FMCW parameters, with the gradient being based on the bandwidth of the FMCW signal and the duration of the symbol on which the FMCW signal is transmitted.

[0241] In some examples, the FMCW parameter component 965 is configured as a means for transmitting a control message indicating a set of FMCW parameters associated with an FMCW signal, which includes the start frequency of the FMCW signal, the bandwidth of the FMCW signal, the gradient of the FMCW signal, or any combination thereof, or otherwise may support such means, the gradient being based on the bandwidth of the FMCW signal and the duration of the symbol on which the FMCW signal is transmitted, and the estimation of the OFDM channel being based on the set of FMCW parameters.

[0242] In some examples, the OFDM estimation component 935 is configured as a means for sending a control message containing a trigger for a first wireless device to perform OFDM channel estimation using an FMCW signal, or may otherwise support such means, and the OFDM channel estimation is based on the trigger, and the second wireless device includes a network entity.

[0243] In some examples, the CSI component 970 is configured as a means for transmitting a control message including a trigger for a first wireless device to transmit a channel status information report based on an FMCW signal, or may otherwise support such a means. In some examples, the CSI component 970 is configured as a means for receiving a channel status information report including a set of channel status information parameters, at least in part on the trigger, or may otherwise support such a means.

[0244] In some examples, the FMCW component 975 is configured as a means for receiving a control message containing a trigger for a second wireless device to transmit an FMCW signal, or may otherwise support such means, and the transmission of the FMCW signal is trigger-based.

[0245] In some examples, the second wireless device includes a UE or network entity.

[0246] Figure 10 shows a diagram of a system 1000 including a device 1005 that supports estimating an OFDM channel using FMCW, according to one or more aspects of the present disclosure. Device 1005 may be an embodiment of device 705, device 805, or UE 115, or may include components thereof, as described herein. Device 1005 may communicate (for example, wirelessly) with one or more network entities 105, one or more UE 115, or any combination thereof. Device 1005 may include components for bidirectional voice and data communication, including components for sending and receiving communications, such as a communications manager 1020, an input / output (I / O) controller 1010, a transceiver 1015, an antenna 1025, a memory 1030, a code 1035, and a processor 1040. These components can communicate electronically or otherwise be coupled (e.g., operably, communicatively, functionally, electronically, electrically) via one or more buses (e.g., bus 1045).

[0247] The I / O controller 1010 can manage input and output signals related to device 1005. The I / O controller 1010 can also manage peripherals not integrated into device 1005. In some cases, the I / O controller 1010 may represent physical connections or ports to external peripherals. In some cases, the I / O controller 1010 may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another known operating system. Additionally or alternatively, the I / O controller 1010 may represent, or interact with, a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 1010 may be implemented as part of a processor, such as processor 1040. In some cases, the user may interact with device 1005 via the I / O controller 1010 or via hardware components controlled by the I / O controller 1010.

[0248] In some cases, device 1005 may include a single antenna 1025. However, in some other cases, device 1005 may have two or more antennas 1025 that can simultaneously transmit or receive multiple wireless transmissions. Transceiver 1015 may communicate bidirectionally via one or more antennas 1025, a wired link, or a wireless link, as described herein. For example, transceiver 1015 may represent a wireless transceiver and communicate bidirectionally with another wireless transceiver. Transceiver 1015 may also include a modem for modulating packets, providing those modulated packets to one or more antennas 1025 for transmission, and demodulating packets received from those one or more antennas 1025. The transceiver 1015, or the transceiver 1015 and one or more antennas 1025, may be a transmitter 715, a transmitter 815, a receiver 710, a receiver 810, or any combination thereof, or an embodiment of their components, as described herein.

[0249] Memory 1030 may include random access memory (RAM) and read-only memory (ROM). Memory 1030 may store computer-readable computer-executable code 1035, which, when executed by processor 1040, causes device 1005 to perform various functions described herein. Code 1035 may be stored in a non-temporary 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 (for example, when compiled and executed) may cause the computer to perform the functions described herein. In some cases, memory 1030 may include a basic I / O system (BIOS) that can control basic hardware or software operations, such as interactions with peripheral components or peripheral devices.

[0250] The processor 1040 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, individual gate or transistor logic components, individual hardware components, or any combination thereof). In some cases, the processor 1040 may be configured to operate a memory array using a memory controller. In some other cases, a memory controller may be incorporated within the processor 1040. The 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 that support estimating OFDM channels using FMCW). For example, device 1005 or components of device 1005 may include the processor 1040 and memory 1030 coupled to the processor 1040, and the processor 1040 and memory 1030 are configured to perform various functions described herein.

[0251] The communication manager 1020 may support wireless communication in a first wireless device according to embodiments disclosed herein. For example, the communication manager 1020 may be configured as a means for receiving a first FMCW signal via an OFDM channel, or may otherwise support such a means. The communication manager 1020 may be configured as a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, or may otherwise support such a means. The communication manager 1020 may be configured as a means for estimating an OFDM channel in the time domain based on a sample of a synthesized FMCW signal, including a synthesis of the first FMCW signal and the second FMCW signal, or may otherwise support such a means.

[0252] In addition or alternatively, the communication manager 1020 may support wireless communication in a second wireless device according to embodiments disclosed herein. For example, the communication manager 1020 may be configured as a means for generating an FMCW signal for the estimation of an OFDM channel by the first wireless device, or may otherwise support such a means. The communication manager 1020 may be configured as a means for transmitting an FMCW signal over an OFDM channel, or may otherwise support such a means. The communication manager 1020 may be configured as a means for communicating an OFDM signal over an OFDM channel to the first wireless device based on the estimation of an OFDM channel, or may otherwise support such a means.

[0253] By including or configuring the communication manager 1020 in accordance with the examples described herein, device 1005 may support techniques for improving communication reliability, reducing latency, improving user experience related to reduced processing, reducing power consumption, more efficient use of communication resources, improved coordination between devices, and longer battery life.

[0254] In some embodiments, the communications manager 1020 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or in cooperation with the transceiver 1015, one or more antennas 1025, or any combination thereof. Although the communications manager 1020 is shown as a separate component, in some embodiments, one or more functions described with reference to the communications manager 1020 may be supported or performed by the processor 1040, memory 1030, code 1035, or any combination thereof. For example, code 1035 may include instructions executable by the processor 1040 to cause device 1005 to perform various aspects of estimating an OFDM channel using the FMCW described herein, or the processor 1040 and memory 1030 may be configured to perform or support such operations in a different manner.

[0255] Figure 11 shows a diagram of a system 1100 including a device 1105 that supports estimating an OFDM channel using FMCW, according to one or more aspects of the present disclosure. Device 1105 may be an embodiment of device 705, device 805, or network entity 105 as described herein, or may include components thereof. Device 1105 may communicate with one or more network entities 105, one or more UEs 115, or any combination thereof, which may include communication via one or more wired interfaces, communication via one or more wireless interfaces, or any combination thereof. Device 1105 may include components that support outputting and acquiring communications, such as a communications manager 1120, a transceiver 1110, an antenna 1115, a memory 1125, a code 1130, and a processor 1135. These components can communicate electronically via one or more buses (e.g., bus 1140) or be coupled in other ways (e.g., operably, communicatively, functionally, electronically, electrically).

[0256] The transceiver 1110 may support bidirectional communication via a wired link, a wireless link, or both, as described herein. In some embodiments, the transceiver 1110 may include a wired transceiver and be able to communicate bidirectionally with another wired transceiver. Additionally or alternatively, in some embodiments, the transceiver 1110 may include a wireless transceiver and be able to communicate bidirectionally with another wireless transceiver. In some embodiments, the device 1105 may include one or more antennas 1115 that may be able to transmit or receive wireless transmissions (e.g., simultaneously). The transceiver 1110 may also include a modem for modulating a signal, providing to transmit the modulated signal (e.g., by one or more antennas 1115, by a wired transmitter), receiving the modulated signal (e.g., from one or more antennas 1115, from a wired receiver), and demodulating the signal. In some implementations, the transceiver 1110 may include one or more interfaces, such as one or more interfaces coupled with one or more antennas 1115 configured to support various receiving or acquiring operations, or one or more interfaces coupled with one or more antennas 1115 configured to support various transmitting or output operations, or a combination thereof. In some implementations, the transceiver 1110 may include, or be configured to be coupled with, one or more processors or memory components capable of performing or supporting operations based on received or acquired information or signals, or generating 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) may be included in a chip or chip assembly installed in device 1105.In some examples, the transceiver may be capable of operating to support communication over one or more communication links (e.g., communication link 125, backhaul communication link 120, midhaul communication link 162, fronthaul communication link 168).

[0257] Memory 1125 may include RAM and ROM. Memory 1125 may store computer-readable computer-executable code 1130, which, when executed by processor 1135, includes instructions that cause device 1105 to perform various functions described herein. Code 1130 may be stored in a non-temporary computer-readable medium, such as system memory or another type of memory. In some cases, code 1130 may not be directly executable by processor 1135, but (for example, when compiled and executed) may cause the computer to perform the functions described herein. In some cases, memory 1125 may include a BIOS that can control basic hardware or software operations, such as interactions with peripheral components or peripheral devices.

[0258] The processor 1135 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, ASICs, CPUs, FPGAs, microcontrollers, programmable logic devices, individual gate or transistor logic, individual 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, a memory controller may be incorporated within the processor 1135. The processor 1135 may be configured to execute computer-readable instructions stored in memory (e.g., memory 1125) to cause device 1105 to perform various functions (e.g., functions or tasks that support estimating OFDM channels using FMCW). For example, device 1105 or components of device 1105 may include the processor 1135 and memory 1125 coupled to the processor 1135, and the processor 1135 and memory 1125 are configured to perform various functions described herein. Processor 1135 may be an embodiment of a cloud computing platform (e.g., one or more physical nodes and supporting software such as an operating system, virtual machines, or container instances) that can host functions to perform the functions of device 1105 (e.g., by executing code 1130). Processor 1135 may be any one or more suitable processors capable of executing scripts or instructions of one or more software programs stored in device 1105 (e.g., in memory 1125). In some implementations, processor 1135 may be a component of a processing system. A processing system may generally refer to a system or set of machines or components that receive inputs, process those inputs, and produce a set of outputs (e.g., which may be passed to other systems or components of device 1105).For example, the processing system of device 1105 may refer to a system that includes various other components or sub-components of device 1105, such as the processor 1135, or the transceiver 1110, or the communication manager 1120, or other components or combinations of components of device 1105. The processing system of device 1105 may interface with other components of device 1105, process information (such as inputs or signals) received from other components, or output information to other components. For example, the chip or modem of device 1105 may include the processing system and one or more interfaces for outputting information, or for acquiring information, or both. One or more interfaces may be implemented, in particular in some implementations, as a first interface configured to output information and a second interface configured to acquire information, or as the same interface configured to output and acquire information, or otherwise include them. In some implementations, one or more interfaces may refer to an interface between the processing system of the chip or modem and a transmitter, as a result, device 1105 may transmit information output from the chip or modem. As an addition or alternative, in some implementations, one or more interfaces may refer to an interface between the chip or modem's processing system and the receiver, and as a result, device 1105 may acquire information or signal inputs, which may be passed to the processing system. Those skilled in the art will readily recognize that the first interface may also acquire information or signal inputs, and the second interface may also output information or signal outputs.

[0259] In some embodiments, bus 1140 may support (e.g., internal) communications of the protocol layer of the protocol stack. In some embodiments, bus 1140 may support communications associated with logical channels of the protocol stack (e.g., between protocol layers of the protocol stack), which may include communications performed within a component of device 1105 or between different components of device 1105 that may be located side-by-side or in different locations (for example, device 1105 may refer to a system in which one or more of the communications manager 1120, transceiver 1110, memory 1125, code 1130, and processor 1135 may be located in one of the different components or divided into different components).

[0260] In some embodiments, the communications manager 1120 may manage the manner of communication with the core network 130 (e.g., via one or more wired or wireless backhaul links). For example, the communications manager 1120 may manage the transfer of data communications for client devices, such as one or more UEs 115. In some embodiments, the communications manager 1120 may manage communication with other network entities 105 and may include a controller or scheduler for coordinating with other network entities 105 to control communication with the UEs 115. In some embodiments, the communications manager 1120 may support an X2 interface within LTE / LTE-A wireless communications network technology to provide communication between network entities 105.

[0261] The communication manager 1120 may support wireless communication in a first wireless device according to examples disclosed herein. For example, the communication manager 1120 may be configured as a means for receiving a first FMCW signal via an OFDM channel, or otherwise may support such means. The communication manager 1120 may be configured as a means for generating a second FMCW signal based on a set of FMCW parameters associated with the first FMCW signal, or otherwise may support such means. The communication manager 1120 may be configured as a means for estimating an OFDM channel in the time domain based on a sample of a synthesized FMCW signal, including a synthesis of the first FMCW signal and the second FMCW signal, or otherwise may support such means.

[0262] In addition or alternatively, the communication manager 1120 may support wireless communication in a second wireless device in accordance with the examples disclosed herein. For example, the communication manager 1120 may be configured as a means for generating an FMCW signal for the estimation of an OFDM channel by the first wireless device, or otherwise support such means. The communication manager 1120 may be configured as a means for transmitting an FMCW signal over an OFDM channel, or otherwise support such means. The communication manager 1120 may be configured as a means for communicating an OFDM signal over an OFDM channel to the first wireless device based on the estimation of an OFDM channel, or otherwise support such means.

[0263] By including or configuring the communication manager 1120 according to the embodiments described herein, device 1105 may support techniques for improving communication reliability, reducing latency, improving the user experience in terms of reduced processing load, reducing power consumption, more efficient use of communication resources, and improving coordination between devices.

[0264] In some embodiments, the communications manager 1120 may be configured to perform various operations (e.g., receiving, acquiring, monitoring, outputting, transmitting) using or in other ways with the transceiver 1110, one or more antennas 1115 (e.g., where applicable), or any combination thereof. Although the communications manager 1120 is shown as a separate component, in some embodiments, one or more functions described with reference to the communications manager 1120 may be supported or performed by the transceiver 1110, the processor 1135, the memory 1125, the code 1130, or any combination thereof. For example, the code 1130 may include instructions executable by the processor 1135 to cause the device 1105 to perform various aspects of estimating an OFDM channel using the FMCW described herein, or the processor 1135 and the memory 1125 may be configured to perform or support such operations in a different manner.

[0265] Figure 12 shows a flowchart illustrating a process 1200 that supports estimating OFDM channels using FMCW according to one or more embodiments of the present disclosure. In the case of multi-port channel estimation, process 1200 may be performed for all ports, and the signals for all ports are redundant. The operation of process 1200 may be performed by a UE or network entity or its components as described herein. For example, the operation of process 1200 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may perform embodiments of the functions described using dedicated hardware.

[0266] In 1205, the process may include receiving a first FMCW signal via an OFDM channel. The operation of 1205 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1205 may be performed by an FMCW signaling component 925, as described with reference to Figure 9.

[0267] In 1210, the process may include generating a second FMCW signal based on a set of FMCW parameters associated with a first FMCW signal. The operation of 1210 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1210 may be performed by an FMCW signal generation component 930, as described with reference to Figure 9.

[0268] In 1215, the process may include estimating an OFDM channel based on a sample of a synthesized FMCW signal, which includes the synthesis of a first FMCW signal and a second FMCW signal in the time domain. The operation of 1215 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1215 may be performed by an OFDM estimation component 935, as described with reference to Figure 9.

[0269] Figure 13 shows a flowchart illustrating a process 1300 that supports estimating OFDM channels using FMCW according to one or more embodiments of the present disclosure. In the case of multi-port channel estimation, process 1300 may be performed for all ports, and the signals for all ports are redundant. The operation of process 1300 may be performed by a UE or network entity or its components as described herein. For example, the operation of process 1300 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may perform embodiments of the functions described using dedicated hardware.

[0270] In 1305, the process may include receiving a first FMCW signal via an OFDM channel. The operation of 1305 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1305 may be performed by an FMCW signaling component 925, as described with reference to Figure 9.

[0271] In 1310, the process may include generating a second FMCW signal based on a set of FMCW parameters associated with a first FMCW signal. The operation of 1310 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1310 may be performed by an FMCW signal generation component 930, as described with reference to Figure 9.

[0272] In 1315, the process may include filtering a synthesized FMCW signal, which includes the synthesis of a first FMCW signal and a second FMCW signal, in the time domain. The operation of 1315 may be carried out according to embodiments such as those disclosed herein. In some examples, the operation of 1315 may be carried out by a filtering component 945 described with reference to Figure 9.

[0273] In 1320, the process may include sampling the synthesized FMCW signal in the time domain after filtering, using a sampling rate based on the subband frequency range of the OFDM channel. The operation of 1320 may be performed according to embodiments such as those disclosed herein. In some examples, the operation of 1320 may be carried out by an FMCW sampling component 950 described with reference to Figure 9.

[0274] In 1325, the process may include estimating the respective values ​​of the OFDM channel for each subband of a set of multiple subbands in the frequency domain of the OFDM channel, based on sampling. The operation of 1325 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1325 may be performed by the OFDM estimation component 935 described with reference to Figure 9.

[0275] Figure 14 shows a flowchart illustrating a process 1400 that supports estimating OFDM channels using FMCW according to one or more embodiments of the present disclosure. In the case of multi-port channel estimation, process 1400 may be performed for all ports, and the signals for all ports are redundant. The operation of process 1400 may be performed by a UE or network entity or its components as described herein. For example, the operation of process 1400 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may perform embodiments of the functions described using dedicated hardware.

[0276] In 1405, the process may include receiving a first FMCW signal via an OFDM channel. The operation of 1405 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1405 may be performed by an FMCW signaling component 925, as described with reference to Figure 9.

[0277] In 1410, the process may include receiving one or more OFDM signals time-division multiplexed with a first FMCW signal within an OFDM channel. Operation of 1410 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1410 may be performed by an OFDM signaling component 940 described with reference to Figure 9.

[0278] In 1415, the process may include generating a second FMCW signal based on a set of FMCW parameters associated with a first FMCW signal. The operation of 1415 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1415 may be performed by an FMCW signal generation component 930 described with reference to Figure 9.

[0279] In 1420, the process may include estimating an OFDM channel based on a sample of a synthesized FMCW signal, which includes the synthesis of a first FMCW signal and a second FMCW signal, in the time domain. The operation of 1420 may be performed according to embodiments such as those disclosed herein. In some examples, the operation of 1420 may be carried out by an OFDM estimation component 935 described with reference to Figure 9.

[0280] Figure 15 shows a flowchart illustrating a process 1500 that supports estimating OFDM channels using FMCW according to one or more embodiments of the present disclosure. In the case of multi-port channel estimation, process 1500 may be performed for all ports, and the signals for all ports are redundant. The operation of process 1500 may be performed by a UE or network entity or its components as described herein. For example, the operation of process 1500 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may perform embodiments of the functions described using dedicated hardware.

[0281] In 1505, the process may include generating an FMCW signal for estimation of the OFDM channel by the first wireless device. The operation of 1505 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1505 may be performed by an FMCW signal generation component 930 described with reference to Figure 9.

[0282] In 1510, the process may include transmitting an FMCW signal via an OFDM channel. The operation of 1510 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1510 may be performed by an FMCW signaling component 925, as described with reference to Figure 9.

[0283] In 1515, the process may include communicating an OFDM signal to a first wireless device via an OFDM channel, based on the estimation of the OFDM channel. The operation of 1515 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1515 may be performed by an OFDM signaling component 940, as described with reference to Figure 9.

[0284] Figure 16 shows a flowchart illustrating a process 1600 that supports estimating OFDM channels using FMCW according to one or more embodiments of this disclosure. In the case of multi-port channel estimation, process 1600 may be performed for all ports, and the signals for all ports are redundant. The operation of process 1600 may be performed by a UE or network entity or its components as described herein. For example, the operation of process 1600 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may perform embodiments of the functions described using dedicated hardware.

[0285] In 1605, the process may include generating an FMCW signal for estimation of the OFDM channel by the first wireless device. The operation of 1605 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1605 may be performed by an FMCW signal generation component 930, as described with reference to Figure 9.

[0286] In 1610, the process may include transmitting an FMCW signal via an OFDM channel. The operation of 1610 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1610 may be performed by an FMCW signaling component 925, as described with reference to Figure 9.

[0287] In 1615, the process may include transmitting one or more OFDM signals time-division multiplexed with an FMCW signal within an OFDM channel. The operation of 1615 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1615 may be performed by an OFDM signaling component 940 described with reference to Figure 9.

[0288] In 1620, the process may include communicating an OFDM signal to a first wireless device via an OFDM channel, based on the estimation of the OFDM channel. The operation of 1620 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1620 may be performed by an OFDM signaling component 940, as described with reference to Figure 9.

[0289] Figure 17 shows a flowchart illustrating a process 1700 that supports estimating OFDM channels using FMCW according to one or more embodiments of the present disclosure. In the case of multi-port channel estimation, process 1700 may be performed for all ports, and the signals for all ports are redundant. The operation of process 1700 may be performed by a UE or network entity or its components as described herein. For example, the operation of process 1700 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions to control functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may perform embodiments of the functions described using dedicated hardware.

[0290] In 1705, the process may include sending a capability message indicating that a second wireless device is capable of transmitting an FMCW signal for OFDM channel estimation, the second wireless device including a UE. The operation of 1705 may be performed according to embodiments such as those disclosed herein. In some examples, the operation of 1705 may be carried out by an FMCW capability component 955 described with reference to Figure 9.

[0291] In 1710, the process may include generating an FMCW signal for estimation of the OFDM channel by the first wireless device. The operation of 1710 may be carried out according to embodiments such as those disclosed herein. In some examples, the operation of 1710 may be carried out by an FMCW signal generation component 930 described with reference to Figure 9.

[0292] In 1715, the process may include transmitting an FMCW signal via an OFDM channel. The operation of 1715 may be performed according to embodiments such as those disclosed herein. In some embodiments, the operation of 1715 may be performed by an FMCW signaling component 925 described with reference to Figure 9.

[0293] In 1720, the process may include communicating an OFDM signal to a first wireless device via an OFDM channel, based on the estimation of the OFDM channel. The operation of 1720 may be performed according to embodiments such as those disclosed herein. In some examples, the operation of 1720 may be carried out by an OFDM signaling component 940 described with reference to Figure 9.

[0294] Figure 18 shows a flowchart illustrating a process 1800 supporting multiport channel estimation according to one or more embodiments of the present disclosure. The operation of process 1800 may be performed by a UE or network entity or its components as described herein. For example, the operation of process 1800 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions for controlling functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may perform embodiments of the functions described using dedicated hardware.

[0295] In 1805, the process includes generating a first FMCW signal. In 1810, the process includes generating a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal. The cyclic offset may be, for example, greater than or equal to the maximum channel delay of the OFDM spectrum and less than the symbol duration of the OFDM spectrum. In 1815, the process includes causing a transmitter to transmit the first FMCW signal and the second FMCW signal over an OFDM channel.

[0296] Figure 19 shows a flowchart illustrating a process 1900 supporting multiport channel estimation according to one or more aspects of the present disclosure. The operation of process 1900 may be performed by a UE or network entity or its components as described herein. The operation of process 1800 may be performed, for example, by a first device communicating with a second device running process 1900. For example, the operation of process 1900 may be performed by a UE 115 or network entity as described with reference to Figures 1 to 11. In some embodiments, the UE or network entity may execute a set of instructions for controlling functional elements of the UE or network entity to perform the functions described. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform aspects of the functions described.

[0297] In step 1905, the process includes receiving a first FMCW signal via an OFDM spectrum. In step 1910, the process includes receiving a second FMCW waveform signal via an OFDM spectrum having a cyclic offset relative to the first FMCW signal. In some embodiments, the process may also include receiving additional FMCW signals, each having its own cyclic offset relative to the first FMCW signal.

[0298] In step 1915, the process includes determining the cyclic offset. An indication that the second FMCW signal includes the cyclic offset, as well as an indication of the cyclic offset itself, may be included in the FMCW parameter control message, for example, along with other FMCW parameters. Examples of other parameters include the bandwidth of the OFDM spectrum, the chirp gradient, or any other such parameter.

[0299] In step 1920, the process includes estimating the OFDM spectrum of a first port based on a first FMCW signal. To estimate the OFDM spectrum of a first port, a device (e.g., a network entity or UE) receives an FMCW parameter control message containing a set of FMCW parameters associated with a first FMCW signal and a second FMCW signal, and may estimate the OFDM spectrum of a first port based at least partially on a sample of the synthesized FMCW signal in the time domain. The combined FMCW signal includes at least the combination of an FMCW control signal and a first FMCW signal. The FMCW control signal is generated based on a set of FMCW parameters. To estimate the OFDM spectrum, the device may filter the synthesized FMCW signal and, after filtering, sample the synthesized FMCW signal in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum. To estimate the OFDM spectrum, one or more processors are further configured to estimate the respective values ​​of the OFDM spectrum for each subband of multiple subbands in the frequency domain of the OFDM spectrum, at least partially based on the sampling.

[0300] In step 1925, the process includes estimating the OFDM spectrum of the second port based on the second FMCW signal and the cyclic offset. To estimate the OFDM spectrum of the second port, the device receives an FMCW parameter control message containing a set of FMCW parameters associated with the first and second FMCW signals, and may estimate the OFDM spectrum of the second port based at least partially on a sample of the synthesized FMCW signal in the time domain. The combined FMCW signal includes at least the combination of the FMCW control signal and the second FMCW signal. The FMCW control signal is generated based on the set of FMCW parameters. To estimate the OFDM spectrum of the second port, the device determines a cutoff frequency based on a cyclic offset, filters the synthesized FMCW signal based on the cutoff frequency, samples the synthesized FMCW signal in the time domain after filtering using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum, and to estimate the OFDM spectrum, one or more processors are further configured to estimate the respective values ​​of the OFDM spectrum for each subband of multiple subbands in the frequency domain of the OFDM spectrum, at least partially based on sampling.

[0301] The following numbered clauses illustrate one or more aspects of the devices and techniques described herein.

[0302] Clause 1: A device for wireless communication comprising a memory and one or more processors coupled to the memory and mounted in a circuit, configured to generate a first frequency-modulated continuous waveform (FMCW) signal, a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal, and to cause a transmitter to transmit the first FMCW signal and the second FMCW signal via an orthogonal frequency division multiplexing (OFDM) spectrum.

[0303] Clause 2: The apparatus described in Clause 1, wherein the cyclic offset is greater than or equal to the maximum channel delay of the OFDM spectrum and less than the duration of a symbol in the OFDM spectrum.

[0304] Clause 3: The apparatus according to Clause 1 or 2, wherein the header portion of the second chirp of the second FMCW signal includes a copy of the tail portion of the first chirp of the first FMCW signal.

[0305] Clause 4: The apparatus according to any one of Clauses 1 to 3, wherein one or more processors are further configured to generate FMCW parameter control messages, the FMCW parameter control messages comprising a set of FMCW parameters associated with a first FMCW signal and a second FMCW signal.

[0306] Clause 5: The apparatus according to any one of Clauses 1 to 3, wherein one or more processors are further configured to process a received FMCW signal, which includes a set of FMCW parameters associated with the received FMCW signal, and to estimate an OFDM spectrum in the time domain, on at least in part to a sample of a synthesized FMCW signal, which includes a synthesis of the received FMCW signal and a second FMCW signal; to estimate the OFDM spectrum, one or more processors are further configured to determine a cutoff frequency based on a cyclic offset, filter the synthesized FMCW signal based on the cutoff frequency, and after filtering, sample the synthesized FMCW signal in the time domain using a sampling rate at least in part to a subband frequency range of the OFDM spectrum; and to estimate the OFDM spectrum, one or more processors are further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, on at least in part to the sampling.

[0307] Clause 6: The apparatus described in Clause 5, wherein the set of FMCW parameters includes the bandwidth and chirp gradient of the OFDM spectrum.

[0308] Clause 7: The apparatus according to any one of Clauses 1 to 6, further configured to cause a transmitter to transmit the third FMCW signal and the fourth FMCW signal via the OFDM spectrum, wherein one or more processors generate a third FMCW signal having a second cyclic offset relative to a first FMCW signal, and a fourth FMCW signal having a third cyclic offset relative to the first FMCW signal, wherein the cyclic offset, the second cyclic offset, and the third cyclic offset are all different, and the apparatus is further configured to cause a transmitter to transmit the third FMCW signal and the fourth FMCW signal.

[0309] Clause 8: The apparatus described in Clause 7, wherein the second cyclic offset is twice the cyclic offset and the third cyclic offset is three times the cyclic offset.

[0310] Clause 9: The apparatus described in Clause 7, wherein the difference between the cyclic offset and the second cyclic offset is different from the difference between the second cyclic offset and the third cyclic offset.

[0311] Clause 10: The apparatus described in any one of Clauses 1 to 9, wherein the first FMCW signal and the second FMCW signal overlap in the time domain but do not overlap in the delay domain.

[0312] Clause 11: The device is any device described in any one of Clauses 1 to 10, including a base station.

[0313] Clause 12: The apparatus is any apparatus described in any one of Clauses 1 to 10, including user equipment devices.

[0314] Clause 13: Apparatus for wireless communication comprising: memory; and one or more processors coupled to the memory and mounted in a circuit, configured to receive a first frequency-modulated continuous waveform (FMCW) signal via an orthogonal frequency division multiplexing (OFDM) spectrum; receive a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal via the OFDM spectrum; determine the cyclic offset; estimate the OFDM spectrum of a first port based on the first FMCW signal; and estimate the OFDM spectrum of a second port based on the second FMCW signal and the cyclic offset.

[0315] Clause 14: The apparatus described in Clause 13, wherein the cyclic offset is greater than or equal to the maximum channel delay of the OFDM spectrum and less than the duration of a symbol in the OFDM spectrum.

[0316] Clause 15: The apparatus described in Clause 13 or 14, wherein the header portion of the second chirp of the second FMCW signal includes a copy of the tail portion of the first chirp of the first FMCW signal.

[0317] Clause 16: The apparatus according to any one of Clauses 13 to 15, wherein one or more processors are further configured to process an FMCW parameter control message including a set of FMCW parameters associated with a first FMCW signal and a second FMCW signal, and to estimate the OFDM spectrum of a first port on at least in part on a sample of a synthesized FMCW signal including a synthesis of an FMCW control signal generated based on the set of FMCW parameters and the first FMCW signal in the time domain, in order to estimate the OFDM spectrum, one or more processors are further configured to filter the synthesized FMCW signal, and after filtering, to sample the synthesized FMCW signal in the time domain using a sampling rate at least in part on the subband frequency range of the OFDM spectrum, and to estimate the OFDM spectrum, one or more processors are further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum on at least in part on the sampling.

[0318] Clause 17: The apparatus according to any one of Clauses 13 to 15, wherein one or more processors are further configured to process an FMCW parameter control message including a set of FMCW parameters associated with a first FMCW signal and a second FMCW signal, and to estimate the OFDM spectrum of a second port on at least in part on a sample of a synthesized FMCW signal including a synthesis of an FMCW control signal generated based on the set of FMCW parameters and the second FMCW signal in the time domain, in order to estimate the OFDM spectrum, one or more processors are further configured to determine a cutoff frequency based on a cyclic offset, filter the synthesized FMCW signal based on the cutoff frequency, and after filtering, sample the synthesized FMCW signal in the time domain using a sampling rate at least in part on a subband frequency range of the OFDM spectrum, and to estimate the OFDM spectrum, one or more processors are further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum on at least in part on the sampling.

[0319] Clause 18: The apparatus described in Clause 17, which includes a set of FMCW parameters for the bandwidth and chirp gradient of the OFDM spectrum.

[0320] Clause 19: The apparatus described in Clause 17 or 18, wherein the set of FMCW parameters includes an instruction that the second FMCW signal includes a cyclic offset.

[0321] Clause 20: An apparatus as described in any one of Clauses 17 to 19, in which the set of FMCW parameters includes instructions for cyclic offset.

[0322] Clause 21: The apparatus according to any one of Clauses 13 to 20, wherein one or more processors are further configured to receive a third FMCW signal having a second cyclic offset with respect to a first FMCW signal, receive a fourth FMCW signal having a third cyclic offset with respect to the first FMCW signal, wherein the cyclic offset, second cyclic offset, and third cyclic offset are all different, estimate the OFDM spectrum of a third port based on the third FMCW signal and the second cyclic offset, and estimate the OFDM spectrum of a fourth port based on the fourth FMCW signal and the third cyclic offset.

[0323] Clause 22: The apparatus described in any one of Clauses 13 to 221, wherein the second cyclic offset is twice the cyclic offset and the third cyclic offset is three times the cyclic offset.

[0324] Clause 23: The apparatus described in any one of Clauses 13 to 21, wherein the difference between the cyclic offset and the second cyclic offset is different from the difference between the second cyclic offset and the third cyclic offset.

[0325] Clause 24: The apparatus described in any one of Clauses 13 to 23, wherein the first FMCW signal and the second FMCW signal overlap in the time domain but do not overlap in the delay domain.

[0326] Clause 25: The device is a device described in any one of Clauses 13 to 24, including a base station.

[0327] Clause 26: The apparatus is any apparatus described in any one of Clauses 13 to 24, including user equipment devices.

[0328] Clause 27: A method of wireless communication comprising: receiving a first frequency-modulated continuous waveform (FMCW) signal via an orthogonal frequency division multiplexing (OFDM) spectrum; receiving a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal via an OFDM spectrum; determining the cyclic offset; estimating the OFDM spectrum of a first port based on the first FMCW signal; and estimating the OFDM spectrum of a second port based on the second FMCW signal and the cyclic offset.

[0329] Clause 28: The method according to Clause 27, wherein the cyclic offset is greater than or equal to the maximum channel delay of the OFDM spectrum and less than the duration of the symbol in the OFDM spectrum.

[0330] Clause 29: The method according to Clause 27 or 28, wherein the header portion of the second chirp of the second FMCW signal includes a copy of the tail portion of the first chirp of the first FMCW signal.

[0331] Clause 30: The method according to any one of Clauses 27 to 29, further comprising processing an FMCW parameter control message including a set of FMCW parameters associated with a first FMCW signal and a second FMCW signal, and estimating the OFDM spectrum of a first port on at least in part on a sample of a synthesized FMCW signal including a synthesis of an FMCW control signal generated based on the set of FMCW parameters and the first FMCW signal in the time domain, wherein to estimate the OFDM spectrum, one or more processors are further configured to filter the synthesized FMCW signal, and after filtering, to sample the synthesized FMCW signal in the time domain using a sampling rate at least in part on the subband frequency range of the OFDM spectrum, and the estimation includes estimating the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum on at least in part on the sampling.

[0332] Clause 31: The method according to any one of Clauses 27 to 29, further comprising processing an FMCW parameter control message including a set of FMCW parameters associated with a first FMCW signal and a second FMCW signal, and estimating the OFDM spectrum of a second port on at least in part on a sample of a synthesized FMCW signal including the synthesis of an FMCW control signal generated based on the set of FMCW parameters and the second FMCW signal in the time domain, wherein to estimate the OFDM spectrum, one or more processors are further configured to determine a cutoff frequency based on a cyclic offset, filter the synthesized FMCW signal based on the cutoff frequency, and after filtering, sample the synthesized FMCW signal in the time domain using a sampling rate at least in part on the subband frequency range of the OFDM spectrum, and estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum on at least in part on the sampling.

[0333] Clause 32: The method according to Clause 31, wherein the set of FMCW parameters includes the bandwidth and chirp gradient of the OFDM spectrum.

[0334] Clause 33: The method according to Clause 31 or 32, wherein the set of FMCW parameters includes an instruction that the second FMCW signal includes a cyclic offset.

[0335] Clause 34: The set of FMCW parameters as described in any one of Clauses 31 to 33, including the indication of a cyclic offset.

[0336] Clause 35: The method according to any one of Clauses 27 to 34, further comprising: receiving a third FMCW signal having a second cyclic offset with respect to a first FMCW signal; receiving a fourth FMCW signal having a third cyclic offset with respect to the first FMCW signal, wherein the cyclic offset, second cyclic offset, and third cyclic offset are all different; estimating the OFDM spectrum of a third port based on the third FMCW signal and the second cyclic offset; and estimating the OFDM spectrum of a fourth port based on the fourth FMCW signal and the third cyclic offset.

[0337] Clause 36: The method according to Clause 35, wherein the second cyclic offset is twice the cyclic offset and the third cyclic offset is three times the cyclic offset.

[0338] Clause 37: The method according to Clause 35 or 36, wherein the difference between the cyclic offset and the second cyclic offset is different from the difference between the second cyclic offset and the third cyclic offset.

[0339] Clause 38: The method according to any one of Clauses 27 to 37, wherein the first FMCW signal and the second FMCW signal overlap in the time domain but do not overlap in the delay domain.

[0340] The processes described herein illustrate possible implementations, and it should be noted that the operations and steps may be reconfigured or otherwise modified, and other implementations are possible. Furthermore, two or more aspects of these processes may be combined.

[0341] While various embodiments of LTE, LTE-A, LTE-A Pro, or NR systems may be described for illustrative purposes, and the terms LTE, LTE-A, LTE-A Pro, or NR may be used in most of the descriptions, the technologies described herein are applicable beyond the scope of LTE, LTE-A, LTE-A Pro, or NR networks. For example, the technologies described may be applicable to a variety of other wireless communication systems, such as Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and wireless technologies not expressly mentioned herein.

[0342] The information and signals described herein can be represented using any of a wide variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips, which may be referred to throughout this description, can be represented by voltage, electric current, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination thereof.

[0343] Various exemplary blocks and components described in connection with the disclosure herein can be implemented or run using general-purpose processors, DSPs, ASICs, CPUs, FPGAs or other programmable logic devices, individual gate or transistor logic, individual hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, a processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working with a DSP core, or any other such configuration).

[0344] The functions described herein can be implemented using hardware, software executed by a processor, firmware, or any combination thereof. When implemented using software executed by a processor, these functions can be stored as instructions or code on one or more computer-readable media, or transmitted using such media. Other embodiments and implementations are within the scope of this disclosure and the accompanying claims. For example, due to the nature of the software, the functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. The features implementing these functions can also be physically arranged in various locations, including being distributed so that parts of the function are implemented in different physical locations.

[0345] Computer-readable media include both non-temporary computer storage media and communication media, including any media that facilitate the transfer of computer programs from one location to another. Non-temporary storage media can be any available media accessible by a general-purpose computer or a dedicated computer. Examples, but not limited to, of non-temporary computer-readable media include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage, magnetic disc storage or other magnetic storage devices, or any other non-temporary media that can be used to transport or store desired program code means in the form of instructions or data structures, and that can be accessed by a general-purpose computer or a dedicated computer, or a general-purpose processor or a dedicated processor. Furthermore, any connection is appropriately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then those coaxial cables, fiber optic cables, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of computer-readable media. Disks and discs, as used herein, include CDs (discs), laserdiscs (discs), optical discs (discs), digital versatile discs (DVDs), floppy disks (discs), and Blu-ray discs (discs). A disk can reproduce data magnetically, and a disc can reproduce data optically using a laser. Combinations of the above are also included within the scope of computer-readable media.

[0346] Where used herein, including in the claims, “or” in an enumeration of items (for example, an enumeration of items followed by phrases such as “at least one of the following” or “one or more of the following”) means an inclusive enumeration, such as the enumeration of at least one of A, B, or C meaning A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Where used herein, the phrase “based on” should not be interpreted as referring to a closed set of conditions. For example, an exemplary step described as “based on condition A” may be based on both condition A and condition B without departing from the scope of this disclosure. In other words, where used herein, the phrase “based on” should be interpreted in the same way as the phrase “at least partially based on.”

[0347] The term "determine" or "determine" encompasses a wide range of actions, and therefore "determine" may include calculating, calculating, processing, deriving, investigating, searching (such as by searching a table, database, or other data structure), clarifying, etc. "Determine" may also include receiving (e.g., receiving information), accessing (e.g., accessing data stored in memory), etc. Furthermore, "determine" may also include resolving, acquiring, selecting, choosing, establishing, and other similar actions.

[0348] In the attached figures, similar components or features may have the same reference label. Furthermore, various components of the same type may be distinguished by adding a dash and a second label to distinguish similar components after the reference label. Where only the first reference marking is used herein, the description is applicable to any of the similar components having the same first reference marking, regardless of the second reference marking or any other subsequent reference markings.

[0349] The descriptions provided herein in relation to the accompanying drawings are illustrative and do not represent all embodiments that are implementable or within the scope of the claims. The term “exemplary” as used herein means “serving as an example, illustration, or representation,” and does not mean “preferred” or “advantageous over other embodiments.” “Modes for carrying out the invention” include specific details intended to provide an understanding of the described art. However, these arts can be practiced without these specific details. In some cases, well-known structures and devices are shown in block diagram form to avoid obscuring the concept of the described embodiments.

[0350] The descriptions herein are provided to enable those skilled in the art to construct or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the scope of the disclosure. Therefore, the disclosure is not limited to the embodiments and designs described herein, but should be given the broadest scope that is consistent with the principles and novel features disclosed herein.

Claims

1. A device for wireless communication, Memory and Coupled to the memory and implemented in the circuit, A first frequency-modulated continuous waveform (FMCW) signal is generated, A second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal is generated. The transmitter is made to transmit the first FMCW signal and the second FMCW signal via orthogonal frequency division multiplexing (OFDM) spectrum. One or more processors configured as such, A device equipped with the following features.

2. The apparatus according to claim 1, wherein the cyclic offset is greater than or equal to the maximum channel delay of the OFDM spectrum and less than the duration of the symbol of the OFDM spectrum.

3. The apparatus according to claim 1, wherein the header portion of the second chirp of the second FMCW signal includes a copy of the tail portion of the first chirp of the first FMCW signal.

4. The aforementioned one or more processors Further configured to generate an FMCW parameter control message, wherein the FMCW parameter control message includes a set of FMCW parameters associated with the first FMCW signal and the second FMCW signal. The apparatus according to claim 1.

5. The apparatus according to claim 1, wherein the set of FMCW parameters includes an instruction for the cyclic offset.

6. The apparatus according to claim 5, wherein the set of FMCW parameters includes the bandwidth and chirp gradient of the OFDM spectrum.

7. The aforementioned one or more processors A third FMCW signal having a second cyclic offset with respect to the first FMCW signal is generated. A fourth FMCW signal is generated having a third cyclic offset relative to the first FMCW signal, wherein the cyclic offset, the second cyclic offset, and the third cyclic offset are all different. The transmitter is instructed to transmit the third FMCW signal and the fourth FMCW signal via the OFDM spectrum. It is further structured in such a way. The apparatus according to claim 1.

8. The apparatus according to claim 7, wherein the second cyclic offset is twice the cyclic offset, and the third cyclic offset is three times the cyclic offset.

9. The apparatus according to claim 7, wherein the difference between the cyclic offset and the second cyclic offset is different from the difference between the second cyclic offset and the third cyclic offset.

10. The apparatus according to claim 1, wherein the first FMCW signal and the second FMCW signal overlap in the time domain but do not overlap in the delay domain.

11. The apparatus according to claim 1, wherein the apparatus includes a base station.

12. The apparatus according to claim 1, wherein the apparatus includes a user equipment device.

13. A device for wireless communication, Memory and Coupled to the memory and implemented in the circuit, A first frequency-modulated continuous waveform (FMCW) signal is received via an orthogonal frequency-division multiplexing (OFDM) spectrum. A second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal is received via the OFDM spectrum. Determine the aforementioned cyclic offset, Based on the first FMCW signal, the OFDM spectrum of the first port is estimated. The OFDM spectrum of the second port is estimated based on the second FMCW signal and the cyclic offset. One or more processors configured as such, A device equipped with the following features.

14. The apparatus according to claim 13, wherein the cyclic offset is greater than or equal to the maximum channel delay of the OFDM spectrum and less than the duration of a symbol in the OFDM spectrum.

15. The apparatus according to claim 13, wherein the header portion of the second chirp of the second FMCW signal includes a copy of the tail portion of the first chirp of the first FMCW signal.

16. The aforementioned one or more processors Processing an FMCW parameter control message that includes a set of FMCW parameters associated with the first FMCW signal and the second FMCW signal, In the time domain, the OFDM spectrum of the first port is estimated based at least partially on a sample of a synthesized FMCW signal, which includes the synthesis of an FMCW control signal generated based on the set of FMCW parameters and the first FMCW signal. It is further configured in this way, In order to estimate the OFDM spectrum, one or more processors, The synthesized FMCW signal is filtered, After the filtering, the synthesized FMCW signal is sampled in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum. It is further configured in this way, To estimate the OFDM spectrum, one or more processors are further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, at least partially based on the sampling. The apparatus according to claim 13.

17. The aforementioned one or more processors Processing an FMCW parameter control message that includes a set of FMCW parameters associated with the first FMCW signal and the second FMCW signal, In the time domain, the OFDM spectrum of the second port is estimated based at least partially on a sample of the synthesized FMCW signal, which includes the synthesis of the FMCW control signal generated based on the set of FMCW parameters and the second FMCW signal. It is further configured in this way, In order to estimate the OFDM spectrum, one or more processors, The cutoff frequency is determined based on the cyclic offset, The synthesized FMCW signal is filtered based on the aforementioned cutoff frequency. After the filtering, the synthesized FMCW signal is sampled in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum. It is further configured in this way, To estimate the OFDM spectrum, one or more processors are further configured to estimate the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, at least partially based on the sampling. The apparatus according to claim 13.

18. The apparatus according to claim 17, wherein the set of FMCW parameters includes the bandwidth and chirp gradient of the OFDM spectrum.

19. The apparatus according to claim 17, wherein the set of FMCW parameters includes an instruction that the second FMCW signal includes the cyclic offset.

20. The apparatus according to claim 17, wherein the set of FMCW parameters includes the instruction for the cyclic offset.

21. The aforementioned one or more processors A third FMCW signal having a second cyclic offset with respect to the first FMCW signal is received. A fourth FMCW signal is received which has a third cyclic offset relative to the first FMCW signal, wherein the cyclic offset, the second cyclic offset, and the third cyclic offset are all different. Based on the third FMCW signal and the second cyclic offset, the OFDM spectrum of the third port is estimated. The OFDM spectrum of the fourth port is estimated based on the fourth FMCW signal and the third cyclic offset. It is further structured in such a way. The apparatus according to claim 13.

22. The apparatus according to claim 21, wherein the second cyclic offset is twice the cyclic offset, and the third cyclic offset is three times the cyclic offset.

23. The apparatus according to claim 21, wherein the difference between the cyclic offset and the second cyclic offset is different from the difference between the second cyclic offset and the third cyclic offset.

24. The apparatus according to claim 13, wherein the first FMCW signal and the second FMCW signal overlap in the time domain but do not overlap in the delay domain.

25. The apparatus according to claim 13, wherein the apparatus includes a base station.

26. The apparatus according to claim 13, wherein the apparatus includes a user equipment device.

27. A method of wireless communication, Receiving a first frequency-modulated continuous waveform (FMCW) signal via an orthogonal frequency-division multiplexing (OFDM) spectrum, Receiving a second FMCW waveform signal having a cyclic offset with respect to the first FMCW signal via the OFDM spectrum, Determining the cyclic offset, Estimating the OFDM spectrum of the first port based on the first FMCW signal, Estimating the OFDM spectrum of the second port based on the second FMCW signal and the cyclic offset, Methods that include...

28. The method according to claim 27, wherein the cyclic offset is greater than or equal to the maximum channel delay of the OFDM spectrum and less than the duration of the symbol of the OFDM spectrum.

29. The method according to claim 27, wherein the header portion of the second chirp of the second FMCW signal includes a copy of the tail portion of the first chirp of the first FMCW signal.

30. Processing an FMCW parameter control message that includes a set of FMCW parameters associated with the first FMCW signal and the second FMCW signal, In the time domain, the OFDM spectrum of the first port is estimated based at least partially on a sample of a synthesized FMCW signal, which includes the synthesis of an FMCW control signal generated based on the set of FMCW parameters and the first FMCW signal. Furthermore, the estimation of the OFDM spectrum is The synthesized FMCW signal is filtered, After the filtering, the synthesized FMCW signal is sampled in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum. This includes, and the estimation involves estimating the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, based at least partially on the sampling. The method according to claim 27.

31. Processing an FMCW parameter control message that includes a set of FMCW parameters associated with the first FMCW signal and the second FMCW signal, In the time domain, the OFDM spectrum of the second port is estimated based at least partially on a sample of a synthesized FMCW signal, which includes the synthesis of an FMCW control signal generated based on the set of FMCW parameters and the second FMCW signal. Furthermore, the estimation of the OFDM spectrum is The cutoff frequency is determined based on the aforementioned cyclic offset, The synthesized FMCW signal is filtered based on the aforementioned cutoff frequency, After the filtering, the synthesized FMCW signal is sampled in the time domain using a sampling rate that is at least partially based on the subband frequency range of the OFDM spectrum. This includes, and the estimation involves estimating the respective values ​​of the OFDM spectrum for each subband of a plurality of subbands in the frequency domain of the OFDM spectrum, based at least partially on the sampling. The method according to claim 27.

32. The method according to claim 31, wherein the set of FMCW parameters includes the bandwidth and chirp gradient of the OFDM spectrum.

33. The method according to claim 31, wherein the set of FMCW parameters includes an instruction that the second FMCW signal includes the cyclic offset.

34. The method according to claim 31, wherein the set of FMCW parameters includes an instruction for the cyclic offset.

35. Receiving a third FMCW signal having a second cyclic offset with respect to the first FMCW signal, Receiving a fourth FMCW signal having a third cyclic offset relative to the first FMCW signal, wherein the cyclic offset, the second cyclic offset, and the third cyclic offset are all different, Estimating the OFDM spectrum of the third port based on the third FMCW signal and the second cyclic offset, Estimating the OFDM spectrum of the fourth port based on the fourth FMCW signal and the third cyclic offset, The method according to claim 27, further comprising:

36. The method according to claim 35, wherein the second cyclic offset is twice the cyclic offset, and the third cyclic offset is three times the cyclic offset.

37. The method according to claim 35, wherein the difference between the cyclic offset and the second cyclic offset is different from the difference between the second cyclic offset and the third cyclic offset.

38. The method according to claim 27, wherein the first FMCW signal and the second FMCW signal overlap in the time domain but do not overlap in the delay domain.

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