Slot format for reference radar signal and at least one target radar signal between base stations

Abstract

In one aspect, a radar controller determines a radar slot format, the radar time slot format configures transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; and transmitting an indication of the radar slot format to the first base station and the second base station. The first base station transmits the reference radar signal and the at least one target radar signal according to the radar slot format, and the second base station receives the reference radar signal and the at least one target radar signal according to the radar slot format.

Description

[0001] This application is a divisional application of an application with the application date of August 31, 2021, application number 202180066964.4 (international application number PCT / US2021 / 048376), and name “Time slot format for a reference radar signal and at least one target radar signal between base stations”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims the benefit of U.S. Provisional Application No. 63 / 088,096, filed on October 6, 2020, entitled “SLOT FORMAT FOR REFERENCE RADAR SIGNAL AND AT LEAST ONE TARGET RADAR SIGNAL BETWEEN BASE STATIONS,” and U.S. Non-Provisional Application No. 17 / 461,397, filed on August 30, 2021, entitled “SLOT FORMAT FOR REFERENCE RADAR SIGNAL AND AT LEAST ONE TARGET RADAR SIGNAL BETWEEN BASE STATIONS,” both of which are assigned to the assignee of this application and are expressly incorporated herein by reference in their entirety.

[0004] Public background

[0005] 1. Public Domain

[0006] Aspects of the present disclosure relate generally to wireless communications and, more particularly, to a time slot format for a reference radar signal and at least one target radar signal between base stations.

[0007] 2. Description of Related Technologies

[0008] Wireless communication systems have evolved over several generations, including first-generation analog wireless telephone service (1G), second-generation (2G) digital wireless telephone service (including transitional 2.5G and 2.75G networks), third-generation (3G) high-speed data wireless service with Internet capabilities, and fourth-generation (4G) services (e.g., Long Term Evolution (LTE) or WiMax). Currently, there are many different types of wireless communication systems in use, including cellular and personal communications service (PCS) systems. Examples of known cellular systems include the cellular analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile Communications (GSM), and the like.

[0009] The fifth generation (5G) wireless standard, known as New Radio (NR), calls for higher data transmission speeds, a greater number of connections, and better coverage, among other improvements. According to the Next Generation Mobile Networks Alliance, the 5G standard is designed to provide data rates of tens of megabits per second to each of tens of thousands of users, and 1 gigabit per second to dozens of employees on an office floor. Hundreds of thousands of simultaneous connections should be supported to support large sensor deployments. Therefore, the spectral efficiency of 5G mobile communications should be significantly improved compared to the current 4G standard. In addition, signaling efficiency should be improved and latency should be significantly reduced compared to current standards.

[0010] 5G enables the use of mmW RF signals for wireless communication between network nodes (such as base stations, user equipment (UE), vehicles, factory automation machines, etc.). However, mmW RF signals can also be used for other purposes. For example, mmW RF signals can be used in weapons systems (e.g., as short-range fire control radars in tanks and aircraft), security screening systems (e.g., in scanners that detect weapons and other dangerous items carried under clothing), medicine (e.g., treating diseases by altering cell growth), etc.

[0011] Overview

[0012] The following is a simplified summary of one or more aspects disclosed herein. Thus, the following summary should not be considered an exhaustive overview of all contemplated aspects, nor should it be considered to identify key or critical elements related to all contemplated aspects or to delineate the scope associated with any particular aspect. Accordingly, the sole purpose of the following summary is to present certain concepts related to one or more aspects of the mechanisms disclosed herein in a simplified form prior to the detailed description given below.

[0013] In one aspect, a method of operating a radar controller includes determining a radar slot format that configures transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; and transmitting an indication of the radar slot format to the first base station and the second base station.

[0014] In one aspect, a method of operating a first base station includes: receiving a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from the first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; transmitting the reference radar signal over the first link from the first base station to the second base station on the first symbol; and transmitting the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0015] In one aspect, a method of operating a second base station includes: receiving a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from a first base station to the second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; receiving the reference radar signal over the first link from the first base station to the second base station on the first symbol; and receiving the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0016] In one aspect, a radar controller includes: a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: determine a radar slot format that configures transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; and transmit an indication of the radar slot format to the first base station and the second base station via the at least one transceiver.

[0017] Other objects and advantages associated with the aspects disclosed herein will be apparent to those skilled in the art based on the drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are presented to aid in describing examples of one or more aspects of the disclosed subject matter and are provided solely for the purpose of illustrating the examples and not limiting thereof:

[0019] Figure 1 An example wireless communication system is illustrated in accordance with aspects of the present disclosure.

[0020] Figure 2A and Figure 2B Example wireless network structures are illustrated in accordance with various aspects of the present disclosure.

[0021] Figures 3A to 3C is a simplified block diagram of several sample aspects of components that may be employed in a wireless communication node and configured to support communications as taught herein.

[0022] Figure 4A and 4B is a diagram illustrating examples of frame structures and channels within these frame structures in accordance with aspects of the present disclosure.

[0023] Figure 5A An example monostatic radar system is illustrated.

[0024] Figure 5B An example bistatic radar system is illustrated.

[0025] Figure 5C is an example graph illustrating radio frequency (RF) channel response over time.

[0026] Figure 6 An example single-target beam management use case for bistatic RF sensing is illustrated.

[0027] Figure 7 An example multi-target beam management use case for bistatic RF sensing is illustrated.

[0028] Figure 8A An example scanning phase employing bistatic radio frequency sensing is illustrated.

[0029] Figure 8B An example tracking phase employing bistatic radio frequency sensing is illustrated.

[0030] Figure 9 is a simplified diagram showing the basic operation of a bistatic radar system.

[0031] Figure 10 The implementation of a bistatic radar system in a wireless communication system according to an embodiment of the present disclosure is explained.

[0032] Figure 11 is a block diagram of a wireless communication system that may include a radar controller according to an embodiment of the present disclosure.

[0033] Figure 12 An example of a radar configuration parameter list provided by a radar server to a TX base station and an RX base station for a bistatic or multistatic radar measurement session according to an embodiment of the present disclosure is shown.

[0034] Figure 13 An example of a TX / RX timing sub-list according to various embodiments of the present disclosure is shown.

[0035] Figure 14 An example of a Doppler sublist according to various embodiments of the present disclosure is shown.

[0036] Figure 15 An exemplary communication process according to aspects of the present disclosure is illustrated.

[0037] Figure 16 Exemplary wireless communication processes according to aspects of the present disclosure are illustrated.

[0038] Figure 17 Exemplary wireless communication processes according to aspects of the present disclosure are illustrated.

[0039] Figure 18A A radar slot format according to the first aspect of the present disclosure is explained.

[0040] Figure 18B A radar slot format according to the second aspect of the present disclosure is explained. Detailed description

[0041] Various aspects of the present disclosure are provided below in the description and related drawings of various examples provided for illustrative purposes. Alternative aspects may be designed without departing from the scope of the present disclosure. In addition, well-known elements in the present disclosure will not be described in detail or will be omitted to avoid obscuring the relevant details of the present disclosure.

[0042] The words "exemplary" and / or "example" are used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" and / or "example" is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term "aspects of the disclosure" does not require that all aspects of the disclosure include the discussed feature, advantage, or mode of operation.

[0043] Those skilled in the art will appreciate that the information and signals described below may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the following description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof, depending in part on the specific application, in part on the desired design, in part on the corresponding technology, etc.

[0044] In addition, many aspects are described in terms of sequences of actions performed by, for example, elements of a computing device. It will be appreciated that the various actions described herein can be performed by dedicated circuits (e.g., application specific integrated circuits (ASICs)), by program instructions being executed by one or more processors, or by a combination of the two. In addition, the sequences of actions described herein may be considered to be fully embodied within any form of non-transient computer-readable storage medium having stored therein a corresponding set of computer instructions that, upon execution, will cause or instruct an associated processor of a device to perform the functionality described herein. Thus, various aspects of the present disclosure may be embodied in several different forms, all of which have been contemplated as falling within the scope of the claimed subject matter. In addition, for each aspect described herein, the corresponding form of any such aspect may be described herein as, for example, "logic configured to perform the described actions."

[0045] As used herein, the terms "user equipment" (UE) and "base station" (BS) are not intended to be specific to or otherwise limited to any particular radio access technology (RAT), unless otherwise specified. In general, a UE can be any wireless communication device (e.g., a mobile phone, router, tablet, laptop, tracking device, wearable device (e.g., smart watch, glasses, augmented reality (AR) / virtual reality (VR) headset, etc.), vehicle (e.g., car, motorcycle, bicycle, etc.), Internet of Things (IoT) device, etc.) used by a user to communicate on a wireless communication network. A UE can be mobile or can be stationary (e.g., at certain times) and can communicate with a radio access network (RAN). As used herein, the term "UE" can be interchangeably referred to as an "access terminal" or "AT," "client device," "wireless device," "subscriber device," "subscriber terminal," "subscriber station," "user terminal" or UT, "mobile device," "mobile terminal," "mobile station," or variations thereof. In general, a UE can communicate with a core network via the RAN, and through the core network, the UE can connect to external networks (such as the Internet) and other UEs. Of course, other mechanisms for connecting to the core network and / or the Internet are also possible for the UE, such as through a wired access network, a wireless local area network (WLAN) network (eg, based on IEEE 802.11, etc.), and the like.

[0046] A base station may operate according to one of several RATs to communicate with UEs, depending on the network in which it is deployed, and may be referred to interchangeably as an access point (AP), network node, Node B, evolved Node B (eNB), next-generation eNB (ng-eNB), new radio (NR) Node B (also referred to as gNB or gNodeB), etc. A base station may primarily be used to support wireless access by UEs, including supporting data, voice, and / or signaling connections for the supported UEs. In some systems, a base station may provide pure edge node signaling functionality, while in other systems, a base station may provide additional control and / or network management functionality. The communication link by which a UE may send signals to a base station is referred to as an uplink (UL) channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). The communication link by which a base station may send signals to a UE is referred to as a downlink (DL) or forward link channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc.). As used herein, the term traffic channel (TCH) may refer to either an uplink / reverse traffic channel or a downlink / forward traffic channel.

[0047] The term "base station" may refer to a single physical transmit receive point (TRP) or may refer to multiple physical TRPs that may or may not be co-located. For example, where the term "base station" refers to a single physical TRP, the physical TRP may be the base station antenna corresponding to the cell (or several cell sectors) of the base station. Where the term "base station" refers to multiple co-located physical TRPs, the physical TRP may be the antenna array of the base station (e.g., as in a multiple-input multiple-output (MIMO) system or where the base station employs beamforming). Where the term "base station" refers to multiple non-co-located physical TRPs, the physical TRP may be a distributed antenna system (DAS) (a network of spatially separated antennas connected to a common source via a transmission medium) or a remote radio head (RRH) (a remote base station connected to a serving base station). Alternatively, the non-co-located physical TRPs may be a serving base station that receives measurement reports from a UE and a neighbor base station whose reference RF signal (or simply "reference signal") the UE is measuring. Since a TRP is the point from which a base station transmits and receives wireless signals, as used herein, references to transmissions from or receptions at a base station should be understood as references to the specific TRP of that base station.

[0048] In some implementations that support UE positioning, a base station may not support wireless access for the UE (e.g., may not support data, voice, and / or signaling connections for the UE), but may instead transmit a reference signal to the UE to be measured by the UE and / or may receive and measure signals transmitted by the UE. Such a base station may be referred to as a positioning tower (e.g., when transmitting signals to the UE) and / or as a position measurement unit (e.g., when receiving and measuring signals from the UE).

[0049] An "RF signal" comprises an electromagnetic wave of a given frequency that transmits information through the space between a transmitter and a receiver. As used herein, a transmitter may transmit a single "RF signal" or multiple "RF signals" to a receiver. However, due to the propagation characteristics of each RF signal through a multipath channel, the receiver may receive multiple "RF signals" corresponding to each transmitted RF signal. The same RF signal transmitted over different paths between a transmitter and a receiver may be referred to as a "multipath" RF signal. As used herein, an RF signal may also be referred to as a "wireless signal" or simply a "signal," where the context clearly indicates whether the term "signal" refers to a wireless signal or an RF signal.

[0050] Reference Figure 1 , an example wireless communication network 100 is shown. The wireless communication system 100 (which may also be referred to as a wireless wide area network (WWAN)) may include various base stations 102 and various UEs 104. The base stations 102 may include macrocell base stations (high-power cellular base stations) and / or small cell base stations (low-power cellular base stations). In one aspect, the macrocell base stations may include eNBs and / or ng-eNBs (where the wireless communication system 100 corresponds to an LTE network), or gNBs (where the wireless communication system 100 corresponds to an NR network), or a combination of both, and the small cell base stations may include femtocells, picocells, microcells, and the like.

[0051] Each base station 102 may collectively form a RAN and interface with a core network 170 (e.g., an evolved packet core (EPC) or a 5G core (5GC)) via backhaul links 122, and connect to one or more location servers 172 (which may be part of the core network 170 or external to the core network 170) via the core network 170. Among other functions, the base stations 102 may also perform functions related to one or more of communicating user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of alert messages. The base stations 102 may communicate with each other directly or indirectly (e.g., via the EPC / 5GC) via backhaul links 134 (which may be wired or wireless).

[0052] Base stations 102 may communicate wirelessly with UEs 104. Each base station 102 may provide communication coverage for a respective geographic coverage area 110. In one aspect, one or more cells may be supported by base station 102 in each geographic coverage area 110. A "cell" is a logical communication entity used to communicate with a base station (e.g., on a certain frequency resource, referred to as a carrier frequency, component carrier, carrier, frequency band, etc.) and may be associated with an identifier (e.g., a physical cell identifier (PCI), a virtual cell identifier (VCI), a cell global identifier (CGI)) to distinguish between cells operating on the same or different carrier frequencies. In some cases, different cells may be configured according to different protocol types (e.g., machine type communication (MTC), narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB), or other) that may provide access to different types of UEs. Because a cell is supported by a specific base station, the term "cell" may refer to either or both the logical communication entity and the base station supporting the logical communication entity, depending on the context. Additionally, because a TRP is typically the physical transmission point of a cell, the terms "cell" and "TRP" may be used interchangeably. In some cases, the term "cell" may also refer to a geographic coverage area (e.g., a sector) of a base station, in the sense that a carrier frequency may be detected and used for communications within a portion of geographic coverage area 110.

[0053] Although the geographic coverage areas 110 of adjacent macrocell base stations 102 may partially overlap (e.g., in a handover region), some geographic coverage areas 110 may be substantially overlapped by a larger geographic coverage area 110. For example, a small cell base station 102' may have a geographic coverage area 110' that substantially overlaps with the geographic coverage areas 110 of one or more macrocell base stations 102. A network that includes both small cell and macrocell base stations may be referred to as a heterogeneous network. A heterogeneous network may also include a home eNB (HeNB), which may provide service to a restricted group known as a closed subscriber group (CSG).

[0054] The communication link 120 between the base station 102 and the UE 104 may include uplink (also known as reverse link) transmissions from the UE 104 to the base station 102 and / or downlink (also known as forward link) transmissions from the base station 102 to the UE 104. The communication link 120 may utilize MIMO antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link 120 may utilize one or more carrier frequencies. The allocation of carriers may be asymmetric with respect to the downlink and uplink (e.g., more or fewer carriers may be allocated to the downlink than to the uplink).

[0055] The wireless communication system 100 may further include a wireless local area network (WLAN) access point (AP) 150 in communication with a WLAN station (STA) 152 in an unlicensed spectrum (e.g., 5 GHz) via a communication link 154. When communicating in the unlicensed spectrum, the WLAN STA 152 and / or the WLAN AP 150 may perform a clear channel assessment (CCA) or listen-before-talk (LBT) procedure to determine whether a channel is available before communicating.

[0056] Small cell base station 102' can operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, small cell base station 102' can employ LTE or NR technology and use the same 5 GHz unlicensed spectrum used by WLAN AP 150. Small cell base station 102' employing LTE / 5G in the unlicensed spectrum can improve coverage and / or increase capacity of the access network. NR in the unlicensed spectrum can be referred to as NR-U. LTE in the unlicensed spectrum can be referred to as LTE-U, Licensed Assisted Access (LAA), or MulteFire.

[0057] The wireless communication system 100 may further include a millimeter wave (mmW) base station 180 that can operate in mmW and / or near-mmW frequencies to communicate with a UE 182. Extremely high frequencies (EHF) are part of the RF spectrum within the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 mm and 10 mm. Radio waves in this frequency band may be referred to as millimeter waves. Near-mmW frequencies extend down to 3 GHz with a wavelength of 100 mm. Super high frequency (SHF) frequency bands extend between 3 GHz and 30 GHz and are also referred to as centimeter waves. Communications using mmW / near-mmW radio frequency bands have high path loss and a relatively short range. The mmW base station 180 and the UE 182 may utilize beamforming (transmit and / or receive) on the mmW communication link 184 to compensate for the extremely high path loss and short range. Furthermore, it will be appreciated that, in alternative configurations, one or more base stations 102 may also transmit using mmW or near-mmW frequencies and beamforming. Accordingly, it will be appreciated that the foregoing explanation is merely an example, and should not be construed as limiting the various aspects disclosed herein.

[0058] Transmit beamforming is a technique for focusing an RF signal in a specific direction. Conventionally, when a network node (e.g., a base station) broadcasts an RF signal, it broadcasts the signal in all directions (omnidirectionally). Using transmit beamforming, the network node determines where a given target device (e.g., a UE) is located (relative to the transmitting network node) and projects a stronger downlink RF signal in that specific direction, thereby providing the receiving device with a faster (in terms of data rate) and stronger RF signal. In order to change the directionality of the RF signal when transmitting, the network node can control the phase and relative amplitude of the RF signal at each of the one or more transmitters that are broadcasting the RF signal. For example, the network node can use an antenna array (referred to as a "phased array" or "antenna array") that generates a beam of RF waves that can be "steered" in different directions without actually moving the antennas. Specifically, the RF currents from the transmitters are fed to the individual antennas in the correct phase relationship so that the radio waves from the separate antennas add together in the desired direction to increase radiation, and cancel out in the undesired direction to suppress radiation.

[0059] The transmit beams can be quasi-co-located, which means that they appear to the receiver (e.g., UE) to have the same parameters, regardless of whether the transmit antennas of the network nodes themselves are physically co-located. In NR, there are four types of quasi-co-located (QCL) relationships. Specifically, a given type of QCL relationship means that certain parameters about the second reference RF signal on the second beam can be derived from information about the source reference RF signal on the source beam. Thus, if the source reference RF signal is QCL type A, the receiver can use the source reference RF signal to estimate the Doppler shift, Doppler spread, average delay, and delay spread of the second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL type B, the receiver can use the source reference RF signal to estimate the Doppler shift and Doppler spread of the second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL type C, the receiver can use the source reference RF signal to estimate the Doppler shift and average delay of the second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL type D, the receiver may use the source reference RF signal to estimate spatial reception parameters of a second reference RF signal transmitted on the same channel.

[0060] In receive beamforming, a receiver uses a receive beam to amplify the RF signal detected on a given channel. For example, the receiver may increase the gain setting of the antenna array and / or adjust the phase setting of the antenna array in a particular direction to amplify (e.g., increase the gain level of) the RF signal received from that direction. Thus, when a receiver is said to be beamforming in a certain direction, it means that the beam gain in that direction is high relative to the beam gain along other directions, or the beam gain in that direction is the highest compared to the beam gain in that direction for all other receive beams available to the receiver. This results in a stronger received signal strength (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal to interference and noise ratio (SINR), etc.) for the RF signal received from that direction.

[0061] The receive beams may be spatially correlated. The spatial relationship means that the parameters of the transmit beam for the second reference signal may be derived from information about the receive beam of the first reference signal. For example, a UE may receive one or more reference downlink reference signals (e.g., positioning reference signal (PRS), tracking reference signal (TRS), phase tracking reference signal (PTRS), cell-specific reference signal (CRS), channel state information reference signal (CSI-RS), primary synchronization signal (PSS), secondary synchronization signal (SSS), synchronization signal block (SSB), etc.) from a base station using a specific receive beam. The UE may then form a transmit beam based on the parameters of the receive beam for sending one or more uplink reference signals (e.g., uplink positioning reference signal (UL-PRS), sounding reference signal (SRS), demodulation reference signal (DMRS), PTRS, etc.) to the base station.

[0062] Note that depending on the entity forming the "downlink" beam, the beam can be a transmit beam or a receive beam. For example, if the base station is forming a downlink beam to transmit a reference signal to the UE, the downlink beam is a transmit beam. However, if the UE is forming a downlink beam, the downlink beam is a receive beam for receiving downlink reference signals. Similarly, depending on the entity forming the "uplink" beam, the beam can be a transmit beam or a receive beam. For example, if the base station is forming an uplink beam, the uplink beam is an uplink receive beam, while if the UE is forming an uplink beam, the uplink beam is an uplink transmit beam.

[0063] In 5G, the spectrum in which wireless nodes (e.g., base stations 102 / 180, UEs 104 / 182) operate is divided into multiple frequency ranges: FR1 (from 450 to 6000 MHz), FR2 (from 24250 to 52600 MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). In a multi-carrier system (such as 5G), one of the carrier frequencies is referred to as the "primary carrier" or "anchor carrier" or "primary serving cell" or "PCell," and the remaining carrier frequencies are referred to as "secondary carriers" or "secondary serving cells" or "SCells." In carrier aggregation, the anchor carrier is the carrier operating on the primary frequency (e.g., FR1) utilized by the UE 104 / 182 and on the cell in which the UE 104 / 182 performs an initial radio resource control (RRC) connection establishment procedure or initiates an RRC connection re-establishment procedure. The primary carrier carries all common control channels as well as UE-specific control channels and can be a carrier in a licensed frequency (however, this is not always the case). A secondary carrier is a carrier operating on a second frequency (e.g., FR2) that can be configured once an RRC connection is established between the UE 104 and the anchor carrier and can be used to provide additional radio resources. In some cases, the secondary carrier can be a carrier in an unlicensed frequency. The secondary carrier may contain only necessary signaling information and signals; for example, UE-specific signaling information and signals may not be present in the secondary carrier because both the primary uplink and downlink carriers are typically UE-specific. This means that different UEs 104 / 182 in a cell can have different downlink primary carriers. The same is true for the uplink primary carrier. The network can change the primary carrier for any UE 104 / 182 at any time. This is done, for example, to balance the load on the different carriers. Since a "serving cell" (whether PCell or SCell) corresponds to a carrier frequency / component carrier that a base station is using for communication, the terms "cell", "serving cell", "component carrier", "carrier frequency", etc. may be used interchangeably.

[0064] For example, still referring to Figure 1 One of the frequencies utilized by the macrocell base station 102 may be an anchor carrier (or "PCell"), and the other frequencies utilized by the macrocell base station 102 and / or the mmW base station 180 may be secondary carriers ("Scells"). Simultaneous transmission and / or reception of multiple carriers enables the UE 104 / 182 to significantly increase its data transmission and / or reception rate. For example, two 20 MHz aggregated carriers in a multi-carrier system would theoretically result in a two-fold increase in data rate (i.e., 40 MHz) compared to the data rate achieved by a single 20 MHz carrier.

[0065] The wireless communication system 100 may further include a UE 164 that may communicate with the macrocell base station 102 over the communication link 120 and / or with the mmW base station 180 over the mmW communication link 184. For example, the macrocell base station 102 may support a PCell and one or more SCells for the UE 164, and the mmW base station 180 may support one or more SCells for the UE 164.

[0066] The wireless communication system 100 may further include one or more UEs (such as UE 190) that are indirectly connected to one or more communication networks via one or more device-to-device (D2D) or peer-to-peer (P2P) links (referred to as “side links”). Figure 1 In the example shown in FIG1 , UE 190 has a D2D P2P link 192 with a UE 104 connected to a base station 102 (e.g., UE 190 can indirectly obtain cellular connectivity therefrom), and a D2D P2P link 194 with a WLAN STA 152 connected to a WLAN AP 150 (e.g., UE 190 can indirectly obtain WLAN-based Internet connectivity therefrom). In one example, the D2D P2P links 192 and 194 can use any well-known D2D RAT (such as LTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth etc.) to support.

[0067] Reference Figure 2A , illustrates an example wireless network architecture 200. For example, 5GC 210 (also known as Next Generation Core (NGC)) can be functionally considered to include control plane functions 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and user plane functions 212 (e.g., UE gateway functions, access to data networks, IP routing, etc.), which operate in conjunction to form the core network. User plane interface (NG-U) 213 and control plane interface (NG-C) 215 connect gNB 222 to 5GC 210, specifically to control plane functions 214 and user plane functions 212. In additional configurations, ng-eNB 224 can also connect to 5GC 210 via NG-C 215 to control plane functions 214 and NG-U 213 to user plane functions 212. Furthermore, ng-eNB 224 can communicate directly with gNB 222 via backhaul connection 223. In some configurations, the new RAN 220 may have only one or more gNBs 222, while other configurations include both one or more ng-eNBs 224 and one or more gNBs 222. The gNB 222 or the ng-eNB 224 may communicate with the UE 204 (e.g., Figure 1204). Another optional aspect may include a location server 230 that can be in communication with the 5GC 210 to provide location assistance for the UE 204. The location servers 230 can be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively can each correspond to a single server. The location servers 230 can be configured to support one or more location services for the UE 204, which can be connected to the location server 230 via the core network, the 5GC 210, and / or via the Internet (not illustrated). In addition, the location server 230 can be integrated into a component of the core network, or alternatively can be external to the core network.

[0068] Reference Figure 2B , illustrates another example wireless network architecture 250. For example, the 5GC 260 can be functionally considered to include control plane functions (provided by the access and mobility management function (AMF) 264) and user plane functions (provided by the user plane function (UPF) 262), which operate in conjunction to form the core network (i.e., the 5GC 260). A user plane interface 263 and a control plane interface 265 connect the ng-eNB 224 to the 5GC 260, and in particular to the UPF 262 and AMF 264, respectively. In additional configurations, the gNB 222 can also connect to the 5GC 260 via a control plane interface 265 to the AMF 264 and a user plane interface 263 to the UPF 262. Furthermore, the ng-eNB 224 can communicate directly with the gNB 222 via a backhaul connection 223, with or without direct gNB connectivity to the 5GC 260. In some configurations, the new RAN 220 may have only one or more gNBs 222, while other configurations include both one or more ng-eNBs 224 and one or more gNBs 222. The gNB 222 or the ng-eNB 224 may communicate with the UE 204 (e.g., Figure 1 The base stations of the new RAN 220 communicate with the AMF 264 via the N2 interface and with the UPF 262 via the N3 interface.

[0069] The functions of the AMF 264 include registration management, connection management, reachability management, mobility management, lawful interception, transmission of session management (SM) messages between the UE 204 and the session management function (SMF) 266, a transparent proxy service for routing SM messages, access authentication and access authorization, transmission of short message service (SMS) messages between the UE 204 and the short message service function (SMSF) (not shown), and security anchor functionality (SEAF). The AMF 264 also interacts with the authentication server function (AUSF) (not shown) and the UE 204 and receives intermediate keys established as a result of the UE 204 authentication process. In the case of authentication based on the UMTS (Universal Mobile Telecommunications System) Subscriber Identity Module (USIM), the AMF 264 retrieves security material from the AUSF. The functions of the AMF 264 also include security context management (SCM). The SCM receives keys from the SEAF, which are used by the SCM to derive keys that vary depending on the access network. The functionality of the AMF 264 also includes: location service management for regulatory services, transmission of location service messages between the UE 204 and the Location Management Function (LMF) 270 (which acts as the location server 230), transmission of location service messages between the new RAN 220 and the LMF 270, allocation of EPS bearer identifiers for interworking with the Evolved Packet System (EPS), and notification of mobility events for the UE 204. In addition, the AMF 264 also supports functionality for non-3GPP access networks.

[0070] The functions of the UPF 262 include: serving as an anchor point for intra-RAT / inter-RAT mobility (when applicable), serving as an external protocol data unit (PDU) session point for interconnection to a data network (not shown), providing packet routing and forwarding, packet inspection, user plane policy rule enforcement (e.g., gating, redirection, traffic steering), lawful interception (user plane collection), traffic usage reporting, quality of service (QoS) handling for the user plane (e.g., uplink / downlink rate enforcement, reflective QoS marking in the downlink), uplink traffic verification (service data flow (SDF) to QoS flow mapping), transport level packet marking in the uplink and downlink, downlink packet buffering and downlink data notification triggering, and sending and forwarding one or more "end markers" to the source RAN node. The UPF 262 may also support the transmission of location service messages on the user plane between the UE 204 and a location server (such as a secure user plane location (SUPL) location platform (SLP) 272).

[0071] The functions of the SMF 266 include session management, UE Internet Protocol (IP) address allocation and management, selection and control of user plane functions, traffic steering configuration for routing traffic to the correct destination at the UPF 262, partial control of policy enforcement and QoS, and downlink data notification. The interface that the SMF 266 uses to communicate with the AMF 264 is called the N11 interface.

[0072] Another optional aspect may include an LMF 270 that can be in communication with the 5GC 260 to provide location assistance for the UE 204. The LMF 270 can be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively, each can correspond to a single server. The LMF 270 can be configured to support one or more location services for the UE 204, which can connect to the LMF 270 via the core network, the 5GC 260, and / or via the Internet (not illustrated). The SLP 272 may support similar functionality to the LMF 270, but while the LMF 270 may communicate with the AMF 264, the new RAN 220, and the UE 204 on the control plane (e.g., using interfaces and protocols intended to convey signaling messages rather than voice or data), the SLP 272 may communicate with the UE 204 and external clients (e.g., using protocols intended to carry voice and / or data, such as Transmission Control Protocol (TCP) and / or IP) on the user plane. Figure 2B Communicate with the

[0073] In one aspect, the LMF 270 and / or SLP 272 may be integrated into a base station, such as a gNB 222 and / or ng-eNB 224. When integrated into the gNB 222 and / or ng-eNB 224, the LMF 270 and / or SLP 272 may be referred to as a "location management component" or "LMC." However, as used herein, references to the LMF 270 and SLP 272 include both the case where the LMF 270 and SLP 272 are components of a core network (e.g., 5GC 260) and the case where the LMF 270 and SLP 272 are components of a base station.

[0074] Reference Figure 3A 、 3B3C illustrate several example components (represented by corresponding blocks) that may be incorporated into a UE 302 (which may correspond to any UE described herein), a base station 304 (which may correspond to any base station described herein), and a network entity 306 (which may correspond to or embody any network function described herein, including location server 230 and LMF 270) to support file transfer operations. It will be appreciated that these components may be implemented in different types of devices (e.g., in an ASIC, in a system-on-chip (SoC), etc.) in different implementations. The illustrated components may also be incorporated into other devices in a communication system. For example, other devices in the system may include components similar to those described to provide similar functionality. Furthermore, a given device may include one or more of these components. For example, a device may include multiple transceiver components that enable the device to operate on multiple carriers and / or communicate via different technologies.

[0075] UE 302 and base station 304 each include a wireless wide area network (WWAN) transceiver 310 and 350, respectively, configured to communicate via one or more wireless communication networks (not shown) (such as NR networks, LTE networks, GSM networks, etc.). WWAN transceivers 310 and 350, respectively, can be connected to one or more antennas 316 and 356, respectively, for communicating with other network nodes (such as other UEs, access points, base stations (e.g., eNBs, gNBs), etc.) over a wireless communication medium of interest (e.g., a set of time / frequency resources in a specific spectrum) via at least one designated RAT (e.g., NR, LTE, GSM, etc.). WWAN transceivers 310 and 350, respectively, can be configured in various ways according to the designated RAT to transmit and encode signals 318 and 358 (e.g., messages, indications, information, etc.), and conversely, to receive and decode signals 318 and 358 (e.g., messages, indications, information, pilots, etc.). Specifically, transceivers 310 and 350 include one or more transmitters 314 and 354, respectively, for transmitting and encoding signals 318 and 358, respectively, and one or more receivers 312 and 352, respectively, for receiving and decoding signals 318 and 358, respectively.

[0076] In at least some cases, the UE 302 and the base station 304 also include wireless local area network (WLAN) transceivers 320 and 360, respectively. The WLAN transceivers 320 and 360 can be connected to one or more antennas 326 and 366, respectively, for communicating via at least one designated RAT (e.g., WiFi, LTE-D, Bluetooth ) to communicate with other network nodes (such as other UEs, access points, base stations, etc.) over the wireless communication medium of interest. WLAN transceivers 320 and 360 can be configured in various ways according to a designated RAT to transmit and encode signals 328 and 368 (e.g., messages, indications, information, etc.), and conversely, to receive and decode signals 328 and 368 (e.g., messages, indications, information, pilots, etc.). Specifically, transceivers 320 and 360 include one or more transmitters 324 and 364, respectively, to transmit and encode signals 328 and 368, respectively, and one or more receivers 322 and 362, respectively, to receive and decode signals 328 and 368, respectively.

[0077] The transceiver circuitry, including at least one transmitter and at least one receiver, may comprise an integrated device (e.g., the transmitter circuitry and the receiver circuitry implemented as a single communication device) in some implementations, may comprise separate transmitter devices and separate receiver devices in some implementations, or may be implemented in other ways in other implementations. In one aspect, the transmitter may comprise or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array, which permit the respective device to perform transmit "beamforming," as described herein. Similarly, the receiver may comprise or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array, which permit the respective device to perform receive beamforming, as described herein. In one aspect, the transmitter and receiver may share the same multiple antennas (e.g., antennas 316, 326, 356, 366), such that the respective device can only receive or transmit at a given time, but not both simultaneously. The wireless communication equipment of UE 302 and / or base station 304 (eg, one or both of transceivers 310 and 320 and / or one or both of transceivers 350 and 360) may also include a network listening module (NLM) or the like for performing various measurements.

[0078] In at least some cases, UE 302 and base station 304 also include satellite positioning system (SPS) receivers 330 and 370. SPS receivers 330 and 370 can be connected to one or more antennas 336 and 376, respectively, for receiving SPS signals 338 and 378, respectively, such as Global Positioning System (GPS) signals, Global Navigation Satellite System (GLONASS) signals, Galileo signals, BeiDou signals, Indian Regional Navigation Satellite System (NAVIC), Quasi-Zenith Satellite System (QZSS), etc. SPS receivers 330 and 370 can include any suitable hardware and / or software for receiving and processing SPS signals 338 and 378, respectively. SPS receivers 330 and 370 request information and operations from other systems as appropriate and perform the necessary calculations to determine the location of UE 302 and base station 304 using measurements obtained by any suitable SPS algorithm.

[0079] The base station 304 and the network entity 306 each include at least one network interface 380 and 390 for communicating with other network entities. For example, the network interfaces 380 and 390 (e.g., one or more network access ports) can be configured to communicate with one or more network entities via a wired-based backhaul connection or a wireless backhaul connection. In some aspects, the network interfaces 380 and 390 can be implemented as transceivers configured to support wired-based signal communication or wireless signal communication. The communication can involve, for example, sending and receiving messages, parameters, and / or other types of information.

[0080] UE 302, base station 304, and network entity 306 also include other components that can be used in conjunction with the operations disclosed herein. UE 302 includes processor circuitry that implements a processing system 332 for providing, for example, functionality related to RF sensing, and for providing other processing functionality. Base station 304 includes a processing system 384 for providing, for example, functionality related to RF sensing, as disclosed herein, and for providing other processing functionality. Network entity 306 includes a processing system 394 for providing, for example, functionality related to RF sensing, as disclosed herein, and for providing other processing functionality. In one aspect, processing systems 332, 384, and 394 may include, for example, one or more general-purpose processors, multi-core processors, ASICs, digital signal processors (DSPs), field programmable gate arrays (FPGAs), or other programmable logic devices or processing circuitry.

[0081] UE 302, base station 304, and network entity 306 include memory circuitry that implements memory components 340, 386, and 396, respectively (e.g., each including a memory device), for maintaining information (e.g., information indicating reserved resources, thresholds, parameters, etc.). In some cases, UE 302, base station 304, and network entity 306 may include radar components 342, 388, and 398, respectively. Radar components 342, 388, and 398, respectively, may be hardware circuits that are part of or coupled to processing systems 332, 384, and 394, respectively, that, when executed, enable UE 302, base station 304, and network entity 306 to perform the functionality described herein. In other aspects, radar components 342, 388, and 398 may be external to processing systems 332, 384, and 394 (e.g., part of a modem processing system, integrated with another processing system, etc.). Alternatively, radar components 342, 388, and 398 may be memory modules stored in memory components 340, 386, and 396, respectively (e.g., Figures 3A-3C ), which, when executed by the processing systems 332, 384, and 394 (or a modem processing system, another processing system, etc.), cause the UE 302, base station 304, and network entity 306 to perform the functionality described herein.

[0082] The UE 302 may include one or more sensors 344 coupled to the processing system 332 to provide movement and / or orientation information that is independent of motion data derived from signals received by the WWAN transceiver 310, the WLAN transceiver 320, and / or the SPS receiver 330. By way of example, the sensors 344 may include an accelerometer (e.g., a microelectromechanical system (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometric altimeter), and / or any other type of motion detection sensor. Furthermore, the sensors 344 may include multiple different types of devices and combine their outputs to provide motion information. For example, the sensor(s) 344 may use a combination of a multi-axis accelerometer and an orientation sensor to provide the ability to calculate a position in a 2D and / or 3D coordinate system.

[0083] In addition, the UE 302 includes a user interface 346 for providing indications to the user (e.g., audible and / or visual indications) and / or for receiving user input (e.g., when the user actuates a sensing device such as a keypad, touch screen, microphone, etc.). Although not shown, the base station 304 and the network entity 306 may also include a user interface.

[0084] Referring to the processing system 384 in more detail, in the downlink, IP packets from the network entity 306 may be provided to the processing system 384. The processing system 384 may implement functionality for the RRC layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, and the Medium Access Control (MAC) layer. The processing system 384 may provide RRC layer functionality associated with system information (e.g., Master Information Block (MIB), System Information Block (SIB)) broadcast, RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-RAT mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer packet data units (PDUs), error correction through automatic repeat request (ARQ), concatenation, segmentation and reassembly of RLC service data units (SDUs), resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, scheduling information reporting, error correction, priority handling, and logical channel prioritization.

[0085] Transmitter 354 and receiver 352 may implement Layer 1 functionality associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) coding / decoding of the transport channel, interleaving, rate matching, mapping onto the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. Transmitter 354 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to orthogonal frequency division multiplexing (OFDM) subcarriers, multiplexed with reference signals (e.g., pilots) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time-domain OFDM symbol stream. The OFDM symbol stream is spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator may be used to determine the coding and modulation schemes and for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback transmitted by the UE 302. Each spatial stream may then be provided to one or more different antennas 356. The transmitter 354 may modulate an RF carrier with the corresponding spatial stream for transmission.

[0086] At UE 302, receiver 312 receives a signal via its corresponding antenna 316. Receiver 312 recovers the information modulated onto the RF carrier and provides the information to processing system 332. Transmitter 314 and receiver 312 implement Layer 1 functionality associated with various signal processing functions. Receiver 312 may perform spatial processing on the information to recover any spatial streams destined for UE 302. If multiple spatial streams are destined for UE 302, they may be combined by receiver 312 into a single OFDM symbol stream. Receiver 312 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the signal constellation point most likely transmitted by base station 304. These soft decisions may be based on channel estimates calculated by a channel estimator. These soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by the base station 304. These data and control signals are then provided to the processing system 332 that implements layer 3 and layer 2 functionality.

[0087] In the uplink, the processing system 332 provides demultiplexing between transport channels and logical channels, packet reassembly, code decoding, header decompression, and control signal processing to recover IP packets from the core network. The processing system 332 is also responsible for error detection.

[0088] Similar to the functionality described in conjunction with downlink transmissions performed by the base station 304, the processing system 332 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through hybrid automatic repeat request (HARQ), priority handling, and logical channel prioritization.

[0089] Channel estimates derived by a channel estimator from a reference signal or feedback transmitted by base station 304 may be used by transmitter 314 to select appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by transmitter 314 may be provided to different antennas 316. Transmitter 314 may modulate an RF carrier with the corresponding spatial stream for transmission.

[0090] The uplink transmission is processed at the base station 304 in a manner similar to that described in conjunction with the receiver functionality at the UE 302. The receiver 352 receives the signal through its respective antenna 356. The receiver 352 recovers the information modulated onto the RF carrier and provides the information to the processing system 384.

[0091] In the uplink, processing system 384 provides demultiplexing between transport and logical channels, packet reassembly, code decoding, header decompression, and control signal processing to recover IP packets from UE 302. IP packets from processing system 384 can be provided to the core network. Processing system 384 is also responsible for error detection.

[0092] For convenience, UE 302, base station 304 and / or network entity 306 may be configured to Figures 3A-3C 1 and 2. The diagram in FIG. 1 is shown as including various components that can be configured according to the various examples described herein. However, it will be appreciated that the illustrated blocks can have different functionality in different designs.

[0093] The various components of the UE 302, base station 304, and network entity 306 may communicate with one another over data buses 334, 382, ​​and 392, respectively. Figures 3A-3C The components of can be implemented in various ways. In some implementations, Figures 3A-3CThe components of the present invention may be implemented in one or more circuits (e.g., such as one or more processors and / or one or more ASICs (which may include one or more processors)). Here, each circuit may use and / or include at least one memory component for storing information or executable code used by the circuit to provide this functionality. For example, some or all of the functionality represented by blocks 310 to 346 may be implemented by the processor and memory components of the UE 302 (e.g., by executing appropriate code and / or by appropriately configuring the processor components). Similarly, some or all of the functionality represented by blocks 350 to 388 may be implemented by the processor and memory components of the base station 304 (e.g., by executing appropriate code and / or by appropriately configuring the processor components). Furthermore, some or all of the functionality represented by blocks 390 to 398 may be implemented by the processor and memory components of the network entity 306 (e.g., by executing appropriate code and / or by appropriately configuring the processor components). For simplicity, various operations, actions, and / or functions are described herein as being performed “by a UE,” “by a base station,” “by a positioning entity,” etc. However, as will be appreciated, such operations, actions, and / or functions may actually be performed by specific components or combinations of components of the UE, base station, positioning entity, etc., such as the processing systems 332, 384, 394, the transceivers 310, 320, 350, and 360, the memory components 340, 386, and 396, the radar components 342, 388, and 398, etc.

[0094] Figure 4A is a diagram 400 illustrating an example of a DL frame structure in accordance with aspects of the present disclosure. Figure 4B is a diagram 430 illustrating an example of channels within a DL frame structure in accordance with aspects of the present disclosure. Other wireless communication technologies may have different frame structures and / or different channels.

[0095] LTE, and in some cases NR, utilizes OFDM on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. However, unlike LTE, NR also has the option of using OFDM on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also often referred to as tones, bins, etc. Each subcarrier can be modulated with data. Generally speaking, modulation symbols are sent in the frequency domain for OFDM and in the time domain for SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the subcarrier spacing can be 15 kHz, and the minimum resource allocation (resource block) can be 12 subcarriers (or 180 kHz). Therefore, for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), the nominal FFT size can be equal to 128, 256, 512, 1024, or 2048, respectively. The system bandwidth may be further divided into subbands. For example, a subband may cover 1.08 MHz (ie, 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, respectively.

[0096] LTE supports a single set of parameters (subcarrier spacing, symbol length, etc.). In contrast, NR can support multiple parameter designs. For example, subcarrier spacing of 15kHz, 30kHz, 60kHz, 120kHz, and 204kHz or larger may be available.

[0097] Table 1 provided below lists some of the various parameters used for different NR parameter sets.

[0098]

[0099] Table 1

[0100] exist Figure 4A and 4B In the example of , a parameter design of 15 kHz is used. Therefore, in the time domain, a frame (e.g., 10 ms) is divided into 10 equally sized subframes, each 1 ms, and each subframe includes one time slot. Figure 4A and 4B , time is represented horizontally (eg, on the X-axis), where time increases from left to right, and frequency is represented vertically (eg, on the Y-axis), where frequency increases (or decreases) from bottom to top.

[0101] A resource grid may be used to represent a time slot, each of which includes one or more time-concurrent resource blocks (RBs) (also known as physical RBs (PRBs)) in the frequency domain. The resource grid is further divided into a plurality of resource elements (REs). An RE may correspond to one symbol length in the time domain and one subcarrier in the frequency domain. Figure 4A and 4B In the parameter design of [1], for a normal cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols in the time domain (OFDM symbols for DL ​​and SC-FDMA symbols for UL), for a total of 84 REs. For an extended cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

[0102] like Figure 4A As explained in [1], some REs carry DL reference (pilot) signals (DL-RS) for channel estimation at the UE. DL-RS may include a demodulation reference signal (DMRS) and a channel state information reference signal (CSI-RS), with exemplary locations at Figure 4A are marked with an "R".

[0103] Figure 4B An example of various channels within a DL subframe of an explanation frame. The physical downlink control channel (PDCCH) carries DL control information (DCI) within one or more control channel elements (CCEs), each CCE comprising 9 RE groups (REGs), each REG comprising 4 consecutive REs in an OFDM symbol. DCI carries information about UL resource allocations (persistent and non-persistent) and a description of DL data transmitted to the UE. Multiple (e.g., up to 8) DCIs can be configured in the PDCCH, and these DCIs can have one of a variety of formats. For example, there are different DCI formats for UL scheduling, for non-MIMO DL scheduling, for MIMO DL scheduling, and for UL power control.

[0104] The primary synchronization signal (PSS) is used by the UE to determine the subframe / symbol timing and the physical layer identity. The secondary synchronization signal (SSS) is used by the UE to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the PCI. Based on the PCI, the UE can determine the location of the aforementioned DL-RS. The physical broadcast channel (PBCH) carrying the MIB can be logically grouped with the PSS and SSS to form an SSB (also known as SS / PBCH). The MIB provides the number of RBs in the DL system bandwidth, and the system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information that is not transmitted through the PBCH (such as system information blocks (SIBs)), and paging messages. In some cases, in Figure 4A The DL RS illustrated in may be a Positioning Reference Signal (PRS).

[0105] Wireless communication signals (e.g., RF signals configured to carry OFDM symbols) transmitted between a UE and a base station can be reused for environmental sensing (also known as "RF sensing" or "radar"). The use of wireless communication signals for environmental sensing can be viewed as a consumer-grade radar with advanced detection capabilities that are particularly capable of contactless / deviceless interaction with devices / systems. The wireless communication signals can be cellular communication signals, such as LTE or NR signals, WLAN signals, etc. As a specific example, the wireless communication signals can be OFDM waveforms used in LTE and NR. High-frequency communication signals (such as mmW RF signals) are particularly advantageous for use as radar signals because the higher frequencies at least provide more accurate spacing (distance) detection.

[0106] Generally speaking, there are different types of radars, specifically monostatic and bistatic. Figure 5A and 5B Two of these various types of radar are explained. Specifically, Figure 5A is a diagram 500 illustrating a monostatic radar scenario, and Figure 5B is a diagram 530 illustrating a bistatic radar scenario. Figure 5A In , the base station 502 may be configured for full duplex operation and thus the transmitter (Tx) and receiver (Rx) are co-located. For example, a transmitted radio signal 506 may reflect off a target object (e.g., a building 504) and the receiver on the base station 502 is configured to receive and measure the reflected beam 508. This is a typical use case for traditional or conventional radar. In Figure 5B, the base station 505 may be configured as a transmitter (Tx) and the UE 532 may be configured as a receiver (Rx). In this example, the transmitter and the receiver are not co-located, i.e., they are separate. The base station 505 may be configured to transmit a beam, such as an omnidirectional downlink RF signal 506, which may be received by the UE 532. A portion of the RF signal 506 may be reflected or refracted by the building 504, and the UE 532 may receive the reflected signal 534. This is a typical use case for RF sensing based on wireless communication (e.g., WiFi-based, LTE-based, NR-based). Note that although Figure 5B The use of downlink RF signal 506 as the RF sensing signal is illustrated, but uplink RF signal can also be used as the RF sensing signal. In the downlink scenario, as shown, the transmitter is the base station 505 and the receiver is the UE 532, while in the uplink scenario, the transmitter is the UE and the receiver is the base station.

[0107] For more details, refer to Figure 5B , the base station 505 transmits an RF sensing signal (e.g., a PRS) to the UE 532, but some of the RF sensing signal reflects off a target object, such as a building 504. The UE 532 can measure the ToA of the RF signal 506 received directly from the base station and the ToA of the reflected signal 534 reflected from the target object (e.g., the building 504).

[0108] The base station 505 can be configured to transmit a single RF signal 506 or multiple RF signals to a receiver (e.g., a UE 532). However, due to the propagation characteristics of each RF signal through a multipath channel, the UE 532 may receive multiple RF signals corresponding to each transmitted RF signal. Each path can be associated with a cluster of one or more channel taps. Generally speaking, the time at which the receiver detects the first cluster of channel taps is considered the ToA of the RF signal on a line-of-sight (LOS) path (i.e., the shortest path between the transmitter and the receiver). Subsequent clusters of channel taps are considered to have reflected off objects between the transmitter and the receiver and, therefore, have followed a non-LOS (NLOS) path between the transmitter and the receiver.

[0109] Therefore, return to the reference Figure 5B , RF signal 506 follows a LOS path between base station 505 and UE 532, and reflected signal 534 represents an RF sensing signal that follows a NLOS path between base station 505 and UE 532 due to reflection off building 504 (or another target object). Base station 505 may have transmitted multiple RF sensing signals ( Figure 5B(not shown in the figure), some of the multiple RF sensing signals follow LOS paths, while other of the multiple RF sensing signals follow NLOS paths. Alternatively, the base station 505 may have transmitted a single RF sensing signal in a sufficiently wide beam, wherein a portion of the RF sensing signal follows the LOS path and a portion of the RF sensing signal follows the NLOS path.

[0110] Based on the difference between the ToA of the LOS path, the ToA of the NLOS path, and the speed of light, UE 532 can determine the distance to building 504. Furthermore, if UE 532 is capable of receiving beamforming, UE 532 can determine the general direction to building 504 as the direction of reflected signal 534, which is the received RF sensing signal following the NLOS path. UE 532 can then optionally report this information to the transmitting base station 505, an application server associated with the core network, an external client, a third-party application, or some other entity. Alternatively, UE 532 can report the ToA measurement to base station 505 or other entity, and base station 505 can determine the distance to the target object and, optionally, the direction to the target object.

[0111] Note that if the RF sensing signal is an uplink RF signal transmitted by the UE 532 to the base station 505, the base station 505 will perform object detection based on the uplink RF signal, just as the UE 532 does based on the downlink RF signal.

[0112] Reference Figure 5C , an example graph 550 showing the RF channel response at a receiver (e.g., any of the UEs or base stations described herein) as a function of time is shown. Figure 5C In the example of FIG, a receiver receives multiple (four) clusters of channel taps. Each channel tap represents the multipath followed by the RF signal between the transmitter (e.g., any of the UEs or base stations described herein) and the receiver. That is, the channel taps represent the arrival of the RF signal on the multipath. Each cluster of channel taps indicates that the corresponding multipath follows substantially the same path. Different clusters may exist due to the RF signals being transmitted on different transmit beams (and therefore at different angles), or due to the propagation characteristics of the RF signal (e.g., potentially following very different paths due to reflections), or both.

[0113] exist Figure 5CUnder the illustrated channel, the receiver receives a first cluster of two RF signals on the channel taps at time T1, a second cluster of five RF signals on the channel taps at time T2, a third cluster of five RF signals on the channel taps at time T3, and a fourth cluster of four RF signals on the channel taps at time T4. Figure 5C In the example of , because the first RF signal cluster arrives first at time T1, it is assumed to be the LOS data stream (ie, the data stream that arrives on the LOS or shortest path) and may correspond to Figure 5B The third cluster at time T3 consists of the strongest RF signal and may correspond to Figure 5B NLOS path (e.g., reflected signal 534) as illustrated in FIG. Figure 5C Clusters of two to five channel taps are illustrated, but as will be appreciated, the clusters may have more or fewer channel taps than the illustrated number of channel taps.

[0114] Reference Figure 6 , illustrates an example single-target beam management use case 600 for bistatic RF sensing. Use case 600 includes a base station 602 (such as a 5G NRgNB) configured to transmit multiple beamformed signals along different azimuths and / or elevations, and a UE 610 configured to utilize receive beamforming to improve signal gain based on angle of arrival. Base station 602 can be configured to generate N different reference beams and various azimuths, elevations, and / or beamwidths. In one example, the beams transmitted by base station 602 can be based on SS blocks, CSI-RS, TRS, or PRS resource sets. Other sensing and tracking reference signals can also be used. UE 610 can be configured to utilize phase shifters and other software and hardware techniques to generate receive beams, such as a first receive beam 612, a second receive beam 614, and a third receive beam 616. UE 610 can also be configured to utilize beamforming for the transmit beams. Base station 602 may transmit a first reference signal 604 in the direction of a target object (such as building 504). First reference signal 604 may be reflected, and UE 610 may receive reflected signal 606 using a first receive beam 612. Reflected signal 606 represents the NLOS path of first reference signal 604 to UE 610. Base station 602 also transmits a second reference signal 608 on a second beam. In one example, second reference signal 608 may be quasi-co-located (in QCL) with first reference signal 604. UE 610 receives second reference signal 608 using a second receive beam 614. Second reference signal 608 is the LOS path to UE 610.

[0115] In operation, the UE 610 may be configured to report the channel response for each of the first reference signal and the second reference signal 604, 608 to the base station 602 or another serving cell, and the base station 602 may be configured to manage the transmit beam and receive beam pairs for object sensing. For example, the base station 602 may be configured to provide the UE 610 with transmit and receive beam identification information to track an object, such as a building 504. The beam identification information may be a transmission configuration indicator (TCI) sent in a DCI message that includes various configurations, such as the QCL relationship between the transmit beam and the receive beam.

[0116] Reference Figure 7 , and further reference Figure 6 , shows an example multi-target use case 700 for bistatic radio frequency sensing. Use case 700 is extended by including a second target Figure 6 6. A single target use case 600 is shown. By way of example and not limitation, the second target may be a second building 704. The number and nature of targets may vary based on the environment and the radio sensing application. In use case 700, base station 602 transmits a third reference signal 702 that is reflected by second building 704, and the resulting reflected signal 708 is detected by second receive beam 614 of UE 610. UE 610 may report a channel response for third reference signal 702 with an indication that the measurement was obtained using second receive beam 614. Base station 602 is configured to manage a beam pair associated with the second target (i.e., third reference signal 702 and second receive beam 614). Additional targets and corresponding beam pairs may also be managed by base station 602. Base station 602 may be configured to track one or more of the targets and, therefore, may provide corresponding beam pair information to UE 610 as the QCL / TCI of the respective targets.

[0117] Reference Figure 8A, an example scanning phase 800 with bistatic RF sensing is shown. Base station 802 is an example of base station 304 and is configured to transmit multiple beamformed reference signals at varying azimuths, elevations, and / or beamwidths. The reference signals may be SS blocks, CSI-RS, TRS, PRS, or sensing scanning reference signals (SSRS) configured for RF sensing applications. UE 810 is an example of UE 302 and may be configured to perform receive beam scanning along different azimuths, elevations, and / or beamwidths relative to the orientation of UE 810. In operation, base station 802 may transmit one or more of the reference signals in a sequential order (i.e., beam sweeping), and UE 810 may be configured to perform beam sweeping through different receive beams. Scanning phase 800 may be used to initially detect potential objects to be tracked via RF sensing. For example, a first reference signal 804 may be reflected by a first object 820a, and the first reflected reference signal 804a may be detected by UE 810. UE 810 may cycle through different receive beams, such as a first receive beam 812, a second receive beam 814, and a third receive beam 816. Figure 8A , first reflected reference signal 804a may be received using first receive beam 812. UE 810 may also detect second reference signal 805 using a LOS path with second receive beam 814. Beam sweeping on base station 802 may generate third reference signal 806 that is reflected on second object 820b, and third reflected reference signal 806a is received by UE 810 on third receive beam 816.

[0118] In one embodiment, the UE 810 may be configured to detect a target based on the RSRP of the received signal. For example, the UE 810 may report that the RSRP values ​​associated with the first reference signal 804 and the third reference signal 806 are above a threshold. The threshold may be a fixed value, or the threshold may be scaled based on the RSRP of the LOS signal (such as the second reference signal 805). The UE 810 is configured to report one or more channel measurements (e.g., RSRP, RSRQ, SINR) associated with the received reference signal to the base station 802 or other network node. The measurements obtained during the scanning phase 800 may be used in the subsequent tracking phase.

[0119] Reference Figure 8B , and further reference Figure 8A , shows an example tracking phase 850 employing bistatic radio frequency sensing. Figure 8AIn an example, the base station 802 (or another network node in the communication system 100) may determine to track one or more objects detected in the scanning phase 800. For example, the base station 802 may choose to track the first object 820a and will send beam configuration information to the UE 810 to enable the UE 810 to track the first object 820a. The beam configuration information may include reference signal information and receive beam configuration information for the UE 810. The base station 802 may use a sensing tracking reference signal (STRS) based on the first reference signal 804 to track or improve measurements associated with the first object. In one example, the STRS may be quasi-co-located with the corresponding SSRS (i.e., the first reference signal 804). SS blocks, CSI-RS, TRS, and PRS may be used as STRS. Other reference signals may also be developed and used as STRS. The beam configuration information sent to the UE 810 may be sent via RRC, a media access control control element (MAC-CE), DCI, or other signaling protocols. Upon receiving the beam configuration information, the UE 810 may detect the first object 820a, for example, using the first receive beam 812 with STRS.

[0120] The base station 802 may be configured to track multiple targets based on the number of reference signals that the base station 802 may generate. In one embodiment, the base station 802 may be configured to track one object for each reference signal. For example, the base station 802 may track the second object 820b by generating a second STRS based on the third reference signal 806. The beam configuration information sent to the UE 810 may include beam parameters for the second STRS and corresponding receive beam information (e.g., the third receive beam 816) provided by the UE 810 during the scanning phase 800. Thus, the UE 810 may be configured to track both the first object 820a and the second object 820b. Up to the number of reference signals generated by the base station 802 may be tracked.

[0121] Figure 9 9 is a simplified diagram illustrating the basic operation of a bistatic radar system 900. Transmitter 902 and receiver 904 are used to transmit and receive radar signals to sense a target 906. While a bistatic radar example is shown, the same operating principles can be applied to multistatic radars that utilize more than two transmitters / receivers. For example, a multistatic radar may utilize one transmitter and two receivers. In another example, a multistatic radar may utilize two transmitters and one receiver. A larger number of transmitters and / or receivers is also possible.

[0122] In bistatic radar system 900, transmitter 902 sends a transmit signal 908, which travels a distance RT to a target 906. Transmitted signal 908 reflects from target 906 and becomes an echo signal 910, which travels a distance RR to receiver 904. The primary function served by bistatic radar system 900 is to sense the range, or distance RR, from target 906 to receiver 904. The system primarily does this by sensing the distance RR traveled by transmit signal 908 and echo signal 910. sum The amount of time it takes to determine the range RR, the total distance R sum is the sum of RT and RR:

[0123] R sum = R T + R R (Formula 1)

[0124] Total distance R sum An ellipsoid (also called an iso-range contour) is defined, with its foci located at the positions of the transmitter 902 and the receiver 904, respectively. The ellipsoid represents the distance R sum All possible locations of target 906 in the case of . The radar system 900 is able to measure the distance R sum For example, if perfect timing synchronization between the transmitter 902 and the receiver 904 can be assumed, then the time duration T between the moment the transmitter 902 sends the transmit signal 908 and the moment the receiver 904 receives the echo signal 910 is simply measured. sum It will be easy. sum Multiplying by the speed of the signal through free space (e.g., approximately c = 3*908 m / s) yields R sum Thus, the ellipsoids of all possible positions of target 906 can be calculated by measuring the “time of flight” T of the bistatic radar signal. sum Obtain.

[0125] According to some embodiments, the distance R sum The measurements may be made without tight time synchronization between the transmitter 902 and the receiver 904. In one embodiment, a line of sight (LOS) signal 912 may be sent from the transmitter 902 to the receiver 904. That is, while the transmitter 902 is sending the transmit signal 908 toward the target 906, the transmitter 902 may also be sending the LOS signal 912 toward the receiver 904. According to a specific embodiment, the transmit signal 908 may correspond to a main lobe of a transmit antenna beam pattern transmitted from the transmitter 902, while the LOS signal 912 corresponds to a side lobe of the same transmit antenna beam pattern transmitted from the transmitter 902.

[0126] Receiver 904 receives both echo signal 910 and LOS signal 912 and can use the reception timing of these two signals to measure the total distance Rsum using the following expression:

[0127]

[0128] Here, TRx_echo is the reception time of the echo signal 910. TRxLOS is the reception time of the LOS signal 912. As mentioned, c = 3*108 m / s is the speed of a signal through free space. L is the distance between the transmitter 902 and the receiver 904. Once Rsum is found, it can be used to calculate the target range RR (i.e., the distance between the target 906 and the receiver 904) using the following formula:

[0129]

[0130] The bistatic radar system 900 can also be used to determine the angle of arrival (AoA) θ at which the return signal 910 is received by the receiver 904. R This can be done in various ways. One way is to estimate θ by using an antenna array at the receiver 904. R The antenna array (which includes multiple antenna elements) can operate as a programmable directional antenna capable of sensing the angle at which the signal is received. Thus, the receiver 904 can use the antenna array to sense the arrival angle of the return signal 910. R Another approach involves multilateration. Multilateration involves determining the intersection of two or more curves or surfaces that represent the possible locations of a target. For example, Figure 9 The bistatic radar system 900 shown in FIG. 1 can define a first ellipsoidal surface representing the possible locations of target 906, as previously described. A second bistatic radar system with a differently positioned transmitter and / or receiver can define a second, different ellipsoidal surface also representing the possible locations of target 906. The intersection of the first and second ellipsoidal surfaces can reduce the possible locations of target 906. In three-dimensional space, four such ellipsoidal surfaces would generally be required to reduce the possible locations to a single point, thereby identifying the location of target 906. In two-dimensional space (e.g., assuming all transmitters, receivers, and targets are confined to objects on the ground), three such ellipsoidal surfaces would generally be required (for two-dimensional space, the ellipsoidal surfaces are reduced to elliptical curves) to reduce the possible locations to a single point, thereby identifying the location of target 906. Multilateration can also be achieved in a similar manner using a multistatic radar system rather than multiple bistatic radar systems.

[0131] Additionally, bistatic radar system 900 can be used to determine the Doppler frequency associated with target 906. From the perspective of receiver 904, this Doppler frequency represents the relative velocity of target 906—that is, the speed at which target 906 is approaching / moving away from receiver 904. For a stationary transmitter 902 and a stationary receiver 904, the Doppler frequency of target 906 can be calculated as:

[0132]

[0133] Here, f D is the Doppler frequency, v is the velocity of target 906 relative to the fixed reference frame defined by the stationary transmitter 902 and receiver 904. β is the angle formed between the transmitted signal 908 and the return signal 910 at target 906. δ is the angle between the velocity vector v and the central ray (half angle) defined within angle β.

[0134] exist Figure 9 In

[0065] , a fixed reference frame is defined with respect to a stationary transmitter 902 and a stationary receiver 904. Specifically, a baseline of length L may be drawn between the transmitter 902 and the receiver 904. The baseline may extend beyond the transmitter 902 and the receiver 904. One or more normals may be drawn perpendicular to the baseline. The launch angle θ may be defined relative to a normal drawn from the location of the launch angle 902. T The reception angle θ may be defined relative to a normal line drawn from the position of the receiver 904. R , which is referred to above as the angle of arrival.

[0135] As previously mentioned, the bistatic radar system 900 can be operated to sense targets in two or three dimensions. In the case of three dimensions, additional degrees of freedom are introduced. However, the same basic principles apply and similar calculations can be performed.

[0136] Figure 10 The implementation of a bistatic radar system 900 in a wireless communication system according to an embodiment of the present disclosure is illustrated. The wireless communication system may include Figure 10. The wireless communication system 1000 shown in . The wireless communication system 1000 may include numerous transmit receive points (TRPs) that provide transmission and / or reception of signals in conjunction with other devices. Examples of TRPs within the wireless communication system 1000 include base stations 1002 and 1004, which are used to provide wireless communication for user equipment (UE) (such as nearby vehicles, wireless phones, wearable devices, personal access points, and a large number of other types of user devices that require wireless data communication). For example, base stations 1002 and 1004 can be configured to support data communication with the UE device by transmitting / receiving data codewords to / from the UE device. Resources within the wireless communication system 1000 (such as base stations 1002 and 1004) can thus be used to serve "dual missions" to support not only wireless communication operations, but also bi-base and / or multi-base radar operations. The wireless communication system 900 can be a cellular communication system.

[0137] For example, base station 1002 and base station 1004 may be used as Figure 9 902 and receiver 904 of bistatic radar system 900 are shown in FIG. Base station 1002 may transmit a transmit signal 1008, which reflects from target 906 and becomes an echo signal 1010 received by base station 1004. Base station 1004 may also receive a line of sight (LOS) signal 1012 from base station 1002.

[0138] By receiving both the LOS signal 1012 and the echo signal 1010, the RX base station 1004 can measure a value associated with the time difference between the receive times TRx_echo and TRxLOS associated with receiving the LOS signal 1012 and the echo signal 1010, respectively. For example, the RX base station 1004 can cross-correlate the received LOS signal 1012 with the received echo signal 1010 (such as by mixing the two signals in analog or digital form) to obtain a value representing the time difference (TRx_echo-TRxLOS). This time difference can be used to find the total distance Rsum. The total distance Rsum can then be used to define an ellipsoid, which, along with other information, can be used to calculate the total distance using the previously described information. Figure 9 One or more of the techniques discussed herein are used to determine the target range RR, angle of arrival (AoA) θ associated with target 1006. R and / or Doppler frequency.

[0139] Here, target 906 may be, but is not necessarily, a UE being supported by wireless communication system 1000. In some instances, target 906 may be a UE configured to transmit and receive wireless signals carrying voice, text, and / or wireless data using a base station of wireless communication system 1000. In other instances, target 906 may simply be a remote object that is within the bistatic radar range of base station 1002 and base station 1004 but is otherwise unrelated to the wireless communication functionality of system 1000.

[0140] exist Figure 10 In the bistatic example shown in FIG, the transmitter is referred to as TX base station 1002 and the receiver is referred to as RX base station 1004. More generally, TX base station 1002 may be referred to as a TX TRP and RX base station 1004 may be referred to as an RX TRP. Here, "TX" and "RX" refer only to the fact that base station 1002 is used to transmit radar transmit signals 1008 and base station 1004 is used to receive radar return signals 1010. The terms "TX" and "RX" in this context do not limit the operation of base stations 1002 and 1004 to serve other functions, for example, for other bistatic or multistatic radar operations (beyond Figure 9 1000) or as a base station for transmitting and receiving data communications in normal operation of the wireless communication system 1000. Figure 10 A simple bistatic radar system is described, but a multistatic radar system can also be implemented in a similar manner within a wireless communication system. Figure 10 A simple example in two-dimensional space is explained, but the same operations can be extended to three-dimensional space.

[0141] Implementing a bistatic or multistatic radar system within a wireless communication system according to various embodiments of the present disclosure can yield numerous benefits. One particular benefit is the flexible utilization of bandwidth allocated for wireless communication. An example of a wireless communication system 1000 is a cellular communication system. For example, according to one embodiment, the wireless communication system 1000 may comply with the "5G" standard introduced in Release 15 of the Third Generation Partnership Project (3GPP) specifications. Bistatic and multistatic radar signals can be transmitted using the increasing bandwidth allocated to current and future wireless communication systems (including 5G and beyond 5G). Thus, radio frequency (RF) sensing (e.g., radar) can be implemented by utilizing available wireless RF spectrum resources. For example, one or more of the transmit signal 1008, the return signal 1010, and / or the LOS signal 1012 may occupy bandwidth within a portion of the radio frequency (RF) spectrum allocated to the wireless communication system 1000 for data communication. Another example of a wireless communication system 1000 is a Long Term Evolution (LTE) wireless communication system. Other examples of wireless communication system 1000 include wireless local area networks (WLANs), wireless wide area networks (WWANs), small cell-based wireless communication systems, millimeter wave-based (mmwave-based) communication systems, and other types of communication systems including TRPs.

[0142] Furthermore, the inherent benefits of bistatic and multistatic radar systems can be realized through the existing widespread network of transmitters and receivers in the form of appropriately located wireless base stations. Compared to monostatic radar systems, bistatic or multistatic radar systems mitigate self-interference by having physically separate transmitter and receiver equipment. Wireless base stations such as Figure 10 1002 and 1004) already exist and cover a wide geographic area where users, vehicles, and other objects of interest are likely to be present. Such wireless base stations are well dispersed and, as a result, provide the opportunity to select appropriately located base stations to serve as transmitters and receivers for bistatic and multistatic radar operations.

[0143] A significant challenge that arises in the development of bistatic or multistatic radar systems is the coordination between transmitter(s) and receiver(s). Various techniques for addressing such coordination issues are presented through embodiments of the present disclosure, as discussed in the following sections.

[0144] According to certain embodiments, a "radar controller" may be implemented to support the operation of one or more bistatic and / or multistatic radar systems implemented within a wireless communication system. Here, a "radar controller" may be implemented as a combination of hardware and / or software resources residing within the wireless communication network. Thus, a radar controller may be defined as a functional block, facility, or node that, for example, configures and / or controls parameters relied upon by the TX and RX base stations participating in bistatic and / or multistatic radar operations.

[0145] Figure 11 FIG1 is a block diagram of a wireless communication system 1100 that may include a radar controller according to one embodiment of the present disclosure. Wireless communication system 1100 includes a core network (CN) 1102, a radio access network (RAN) 1104, and one or more user equipment (UE) 1106. In one embodiment, a radar controller 1108 may be implemented within CN 1102. CN 1102 provides system 1100 with connectivity to the Internet and application services. CN 1102 may be implemented using various computing resources, including memory and one or more processors that execute an operating system and execute applications including programmed instructions. In a specific embodiment, radar controller 1108 may be implemented within the computing resources of CN 1102.

[0146] In another embodiment, radar controller 1110 may be implemented within RAN 1104. For example, RAN 1104 may include base stations 1002-1004. Each of base stations 1002-1004 may include transmitter and receiver hardware, such as antennas, antenna elements, cables, physical tower structures, modems, encoders / decoders, networking equipment, computing resources, and other components. The computing resources associated with each base station may include memory and one or more processors that execute an operating system and execute applications including programmed instructions. In a specific embodiment, radar controller 1110 may be implemented within the computing resources of one or more of base stations 1002-1004.

[0147] Radar controller 1108 (or 1110) can be implemented in a radio access network (RAN), a core network (CN) 1102, or elsewhere in a wireless communication system (e.g., cellular communication system 1100). Radar controller 1108 (or 1110) need not be a dedicated server. For example, radar controller 1108 (or 1110) can be a general-purpose server, a positioning server, an assisted driving server, a tracker server, or another server providing different functionality. Furthermore, radar controller 1108 (or 1110) can (but is not necessarily) be operated or owned by a network operator. Radar controller 1108 (or 1110) can be a network-independent server (e.g., a third-party server).

[0148] Regardless of where implemented, the radar controller 1108 (or 1110) can be communicatively coupled to a transmit reception point (TRP) within the RAN 1104, such as base stations 1002 and 1004, via one or more interfaces. The one or more interfaces may include a point-to-point interface. An example of such a point-to-point interface is an interface that implements an Internet Protocol (IP) communication protocol over a wired network (e.g., a "backhaul" network).

[0149] In some embodiments, the wireless communication system 1100 may comply with the "5G" standard. In such a case, the CN 1102 may be a 5G core node (5G CN), the RAN 1104 may be a 3GPP next-generation radio access network (NG RAN), and each of the base stations 1002 and 1004 may be a "gNodeB" or "gNB."

[0150] Figure 12 An example of a radar configuration parameter list 1200 provided by radar controller 1108 (or 1110) to TX base station 1002 and RX base station 1004 for a bistatic or multistatic radar measurement session is shown in accordance with an embodiment of the present disclosure. Here, a radar measurement session may include one or more radar signal transmissions / receptions associated with obtaining range, Doppler, or angle estimates about a target. An example of such a radar measurement session may be a "chirp" sequence of a frequency modulated continuous wave (FMCW) radar signal transmitted by the TX base station and a corresponding echo "chirp" sequence of the FMCW radar signal received by the RX base station.

[0151] like Figure 12 As shown in FIG, radar configuration parameter list 1200 may include several entries, which may include values ​​for parameters such as radar session ID, TX base station ID, RX base station ID, TX / RX timing parameters, Doppler parameters, radar waveform type, radar signal center frequency, radar signal bandwidth (BW), radar period, radar repetition factor, and linear frequency modulation (LFM) frequency slope. These parameters are given for illustrative purposes, and the entries in the configuration parameter list of any given radar system implemented within a wireless communication system may vary. Figure 12 The example shown in .

[0152] Refer again Figure 12 The radar session ID identifies a specific radar measurement session. The TX base station ID identifies a specific base station in the wireless communication system as the transmitter of the radar transmission signal. The RX base station ID identifies a specific base station in the wireless communication system as the receiver of the radar echo signal reflected from the target. Figure 12 The example shown in assumes a basic bistatic radar measurement session using one transmitter and one receiver. Additional transmitter and / or receiver IDs may be included for a multistatic radar measurement session. The TX / RX timing parameters may contain multiple entries and include sublists (described in more detail in a later section). Links or pointers to the sublists may be provided. Similarly, the Doppler parameters may contain multiple entries and include sublists (for which links or pointers may be provided). The radar waveform type specifies the waveform type to be used. Different tuple values ​​may correspond to different waveform types. By way of example only, the following values ​​and corresponding waveforms may be provided:

[0153] “0” = FMCW

[0154] "1" = Positioning Reference Signal (PRS)

[0155] "2" = Single Sideband (SSB)

[0156] "3" = Tracking Reference Signal (TRS)

[0157] "4" = Demodulation Reference Signal (DMRS)

[0158] "5" = Channel State Information Reference Signal (CSI-RS).

[0159] A variety of waveforms can be selected. Some waveforms (such as FMCW) can be specifically associated with radar system operations. However, other waveforms (such as PRS, SSB, TRS, DMRS, and CSI-RS) can be associated with wireless system operations. Thus, according to various embodiments of the present disclosure, waveforms that already exist in wireless communication systems can be opportunistically used as radar signal waveforms.

[0160] Radar controller 1108 (or 1110) may specify one or more parameters associated with the selected reference signal. A reference signal may be defined by selecting a waveform type, such as those listed above. Additionally, a reference signal may be defined by specifying one or more other attributes. For example, radar configuration parameter list 1200 or other configuration parameters may be used to specify such attributes. Figure 12 , radar signal center frequency specifies the center frequency of the radar transmit signal. For example only, Figure 12 , a center frequency of 79 GHz is shown. Thus, the center frequency in this example falls within the spectrum allocated for wireless communication system 1000 (e.g., within the 5G spectrum (which ranges from 300 MHz to 100 GHz)). The center frequency of the radar return signal may exhibit a Doppler shift away from the radar center frequency. Such Doppler shifts are discussed in more detail in later sections. The radar signal bandwidth (BW) specifies the bandwidth of the transmitted radar signal. By way of example only, Figure 12 The bandwidth is shown as 2 GHz. The radar return signal is expected to have the same bandwidth. The radar repetition factor specifies the number of times the radar waveform can repeat in a specified radar session (e.g., in radar session 12345678). In this example, the waveform repeats 10 times. The LFM frequency slope specifies the slope, or rate of change, of the frequency of the linear frequency modulated (LFM) radar waveform. Here, the slope is 100 MHz / microsecond. One type of LFM waveform is the previously mentioned FMCW waveform.

[0161] In short, Figure 12The radar session specified in [ 110 ] may utilize an FMCW waveform that forms a "chirp" that repeats 10 times for a total duration of 200 microseconds. Each chirp may have a duration of 20 microseconds, during which the center frequency of the continuous wave (CW) signal increases linearly from 79 GHz to 81 GHz at a rate of 100 MHz / microsecond. Even though the CW signal has a very narrow bandwidth, the effective bandwidth for the entire sweep of the FMCW signal is 2 GHz. These and other characteristics of the reference signal (in this case, the FMCW reference signal) may be specified as one or more parameters provided by radar controller 1108 (or 1110).

[0162] Various embodiments of the present disclosure can utilize wireless communication system 1000 to estimate certain physical properties in a radar system. For example, the distance L between TX base station 1002 and RX base station 1004 is an important number that may be useful in calculating target range RR and other values. The resources available within wireless communication system 1000 may provide different ways to determine L. One possibility is to use the known locations of TX base station 1002 and RX base station 1004. Such location information may be available in an almanac of collected physical descriptions available for all base stations within wireless communication system 1000. Another possibility is to use GNSS (e.g., GPS) reports from base stations such as TX base station 1002 and RX base station 1004. Typically, GNSS reports include the location of the base stations. Using the accurate longitude and latitude information available for the base station locations, the distance L between TX base station 1002 and RX base station 1004 can be calculated. Yet another possibility is to use inter-base station positioning signals to obtain a position fix for TX base station 1002 and RX base station 1004. For example, positioning signals, such as positioning reference signals (PRS), may be transmitted and received between base stations according to positioning techniques adapted for the new radio / 5G standard. Such inter-base station positioning signals may be used to determine a positioning fix for the TX base station 1002 and the RX base station 1004, and the distance L between them may be determined accordingly.

[0163] Figure 13 An example of a TX / RX timing sub-list 1300 according to various embodiments of the present disclosure is shown. In one embodiment, the TX / RX timing sub-list 1300 may simply be incorporated as an additional entry in the radar configuration parameter list 1200. In another embodiment, the TX / RX timing sub-list 1300 may be a separate but linked sub-list.

[0164] The timing parameters specified in the TX / RX timing sub-list 1300 rely on a certain degree of timing synchronization between the TX base station 1002 and the RX base station 1004. Such TX / RX timing synchronization is important for a number of reasons. If the RX base station 1004 begins "listening" at just the right time (i.e., upon the arrival of (or shortly before the arrival of) the first expected signal (which may be the LOS signal 1012 or the echo signal 1010), the performance of the radar system can be greatly improved. If the RX base station 1004 begins listening too early, the system may prematurely turn on equipment such as the intermediate frequency (IF) receiving hardware, wasting power and computing resources and increasing the radar system's false alarm probability. If the RX base station 1004 begins listening too late, the system may miss receiving the LOS signal 1012 or the echo signal 1010. If a certain degree of timing synchronization can be achieved between the TX base station 1002 and the RX base station 1004, then knowing when the transmit signal 1008 is sent from the TX base station 1002, calculations can be performed to predict the arrival time of the LOS signal 1012 or the echo signal 1010 at the RX base station 1004 (with a certain acceptable degree of uncertainty). In this way, the RX base station 1004 can be controlled to start "listening" at just the right time to reduce unnecessary waste of power and computing resources and minimize false alarms, while ensuring that the LOS signal 1012 and the echo signal 1010 are not missed.

[0165] Various aspects of the present disclosure advantageously utilize the wireless communication system 1000 to meet such radar TX / RX timing synchronization requirements. For example, the wireless communication system 1000 may include a 5G system (e.g., system 1100) that guarantees that the timing synchronization error between any two base stations does not exceed a certain amount of time. By way of example only, the 5G system may utilize orthogonal frequency division multiplexing (OFDM) signals for data communication and may ensure that the timing synchronization error between any two base stations does not exceed the duration of the cyclic prefix (CP) of the OFDM signal. The CP is a guard band in time that separates consecutive data symbols and provides protection against inter-symbol interference (ISI). For a 60kHz subcarrier channel, the CP duration may be, for example, 1.69 microseconds. Thus, the wireless communication system 1000 in this scenario can ensure that the timing error between any two base stations will not exceed 1.69 microseconds. With such timing synchronization guarantees, radar controller 1108 (or 1110 ) may be able to more effectively control the timing regarding when TX base station 1002 sends transmit signal 1008 and when RX base station 204 begins listening for LOS signal 1012 and return signal 1010 .

[0166] Refer back to Figure 13TX / RX timing sub-list 1300 may include the radar session ID (discussed previously), TX transmission time, expected reception time, and expected reception time uncertainty. Radar controller 1108 (or 1110) may provide all or relevant portions of TX / RX timing sub-list 1300 to TX base station 1002 and RX base station 1004. For example, radar controller 1108 (or 1110) may provide TX base station 1002 with a TX transmission time, which in this example is specified as 20,000.00 microseconds. In response, TX base station 1002 begins transmitting transmit signal 1008 at time 20,000.00 microseconds. By way of example only, the value "20,000.00 microseconds" may correspond to the time elapsed since the last "tick" of a periodic reference event / signal used to synchronize timing across entities within wireless communication network 1000 (e.g., all base stations and other equipment).

[0167] Radar controller 1108 (or 1110) may also provide RX base station 1002 with an expected reception time, which in this example is specified as 20133.33 microseconds. Radar controller 1108 (or 1110) may be able to calculate the expected reception time in different ways. In one embodiment, the expected reception time may be estimated by assuming that LOS signal 1012 is likely to arrive at the RX base station before return signal 1010 (which is a valid assumption in many cases). Given this assumption, the expected reception time may be estimated as the TX transmission time plus the amount of time it is expected to take for LOS signal 1012 to traverse distance L:

[0168] Expected Receive Time = L / c + TX Transmission Time (Equation 5)

[0169] Radar controller 1108 (or 1110) may also provide an expected reception time uncertainty, which in this example is specified as a pair of values: [upper bound, lower bound]. The lower bound may simply be the negative of the network synchronization error. By way of example only, the network synchronization error may be 1.69 microseconds. The upper bound may include two components. The first component of the upper bound may correspond to the signal propagation time associated with the maximum possible distance at which a detectable target may be located. In one embodiment, such a maximum distance, L_Max, may be specified as part of the link budget. Thus, the first component of the upper bound may be expressed as L_Max / c=L / c. The second component of the upper bound may simply be the positive of the network synchronization error, which in this example is specified as 1.69 microseconds. Accordingly, the expected reception time uncertainty may be expressed as:

[0170] Expected Receive Time Uncertainty

[0171] =[lower bound,upper bound]([upper bound,lower bound])

[0172] = [-network syn uncertainty (network synchronization uncertainty), L_max / cL / c + network synerror (network synchronization error)] (Equation 6)

[0173] There may also be flexibility in the manner in which these and other configuration parameters are specified and communicated. For example, to specify an upper bound on the expected reception time uncertainty, it may be sufficient for radar controller 1108 (or 1110) to simply send the value "L_max / c + network synchronization error" to RX base station 1004 (particularly if the term L / c is known locally at RX base station 1004).

[0174] In response, RX base station 1004 may begin “listening” (i.e., begin sensing for LOS signal 1012 and echo signal 1010) within a time window specified by:

[0175] Expected Receive Time + Expected Receive Time Uncertainty

[0176] =Expected Receive Time + [lower bound, upper bound]

[0177] = [Lc + TX Transmission Time (TX transmission time) - network syn uncertainty (network synchronization uncertainty),

[0178] L_max / c + TX Transmission Time + Network Syn Error (Equation 7)

[0179] The TX / RX timing parameters for a bistatic radar session (involving one TX base station and one RX base station) are described above. In practice, many such bistatic radar sessions (as well as multistatic radar sessions) can be specified in a similar manner. For each unique path L (i.e., a unique TX and RX station pair), radar controller 1108 (or 1110) can specify a different set of TX / RX timing parameters. In a simple multistatic scenario with one transmitter and multiple receivers, each unique pair can share a common TX base station but have a different RX base station. In such a scenario, a single TX transmission time can be specified, along with multiple sets of expected receive times and expected receive time uncertainties.

[0180] Figure 14 An example of a Doppler sublist 1400 according to various embodiments of the present disclosure is shown. In one embodiment, the Doppler sublist 1400 may simply be incorporated as an additional entry in the radar configuration parameter list 1200. In another embodiment, the Doppler sublist 1400 may be a separate but linked sublist.

[0181] The Doppler sub-list 1400 is primarily used to estimate Doppler shift and Doppler spread for the benefit of the RX base station 1004. Figure 14 As shown in FIG, Doppler sublist 1400 may include the radar session ID (discussed previously), the expected Doppler shift value, and the expected Doppler spread value. Radar controller 1108 (or 1110) typically provides these frequency-domain parameters to improve the performance of RX base station 1004. Target 906 may be moving rapidly, which may introduce a large Doppler shift and / or Doppler spread. By providing Doppler sublist 1400, radar controller 1108 (or 1110) can dynamically configure the "expected Doppler shift" and "expected Doppler spread" assumed by RX base station 1004.

[0182] For example, in acquisition mode, the Doppler sub-list 1400 may specify larger values ​​for expected Doppler shift and expected Doppler spread. This allows the RX base station 1004 to receive signals over a wider range of Doppler frequencies, thereby improving detection rates. For example only, Figure 14 It is shown that the expected Doppler shift value is specified as 80,000 meters / second and the expected Doppler spread is specified as 10,000 meters / second.

[0183] In contrast, in tracking mode, Doppler sublist 1400 may specify finer and narrower values. These values ​​may be based on a history of measurements already taken. A finer set of Doppler parameters may be focused on a specific target. An instance of Doppler sublist 1400 may be specified for each target being tracked. Thus, a particular RX base station 1004 may receive multiple Doppler sublists 1400 corresponding to multiple targets.

[0184] Figure 12 、 13 The specific parameters shown in Figures 1 and 14 are described for illustrative purposes. Depending on the implementation, some parameters may be deleted or added, and different parameters may be specified simultaneously. Nevertheless, according to various embodiments of the present disclosure, the configuration parameters for the TX base station(s) and / or RX base station(s) in a bistatic or multistatic radar system may be provided by a radar controller within an entity located in a wireless communication network, such as a core network (CN) or a radio access network (RAN).

[0185] The time interval between the reception of the LOS signal transmitted by Tx and the reception of the target echo can be used to measure the distance and R sum Therefore, small-scale synchronization errors between Tx / Rx do not introduce estimation errors. In a classical radar system, the same / shared transmitted radar signal propagates through the channel. The Rx then estimates the ToA difference between the LOS path and the echo path.

[0186] In some cases, using the same radar reference signal to estimate ToA in both the LOS and target return paths is suboptimal for various reasons. First, a single wide-angle beam can be applied to the radar Tx waveform, which reduces the system's coverage (e.g., a more focused beam can provide more coverage but may not travel along both the LOS and return paths). Second, digital beamforming can achieve two concurrent beams: one for the LOS direction and one for the transmitter-target direction. However, this increases the number of Tx antennas at the gNB for concurrent transmission along both paths (two beams), doubling the antenna cost. Third, maintaining two concurrent beams is also possible for mmWave systems using analog beamforming. However, this requires at least two antenna panels per sector (i.e., one for the LOS beam and one for the transmitter-target direction), doubling the antenna panel cost.

[0187] Thus, one or more aspects of the present disclosure relate to a radar slot format that configures the transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by the transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol. In some designs, the corresponding radar signals can be offset in time and transmitted in a time division multiplexing (TDM) manner using the same hardware (e.g., antenna or antenna panel). Such aspects can provide various technical advantages, such as cost savings on the transmitter side, increased tracking coverage through the use of narrower beam(s), and the like.

[0188] Figure 15 An exemplary communication process 1500 according to aspects of the present disclosure is illustrated. In one aspect, process 1500 can be performed by a radar controller, which, as mentioned above, can be integrated with a RAN component (such as BS 304) or a core network component or an external server (such as network entity 306). In some designs, the radar controller can be integrated with the first or second base station as described above, in which case any data exchange between the radar controller and the respective base station would correspond to internal data transmission rather than conveying signal(s) across the network.

[0189] At 1510, a radar controller (e.g., processing system 380 or 394, radar component 388 or 389, etc.) determines a radar slot format that configures transmission of a reference radar signal via a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal via at least one second link from the first base station to the second base station on at least one second symbol. For example, in the case of TDM operation, the respective radar signals may be offset from each other in the radar slot format by a number of symbols based on the amount of time required for the first base station to perform RF switching for the respective TDM transmissions. In some designs, the first link corresponds to a LOS link from the first base station to the second base station, and the at least one second link corresponds to at least one NLOS link from the first base station to the second base station. In some designs, the reference radar signal is transmitted on the LOS link via a default beam (e.g., a desired beam may be identified earlier and subsequently set as the default beam), and the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined set of beams (e.g., due to target mobility).

[0190] At 1520, the radar controller (e.g., data bus 382, ​​network interface(s) 380 or 390, etc.) transmits an indication of the radar slot format to the first and second base stations. In some designs, the reference radar signal may have a much longer periodicity than the target radar signal (e.g., because the Tx gNB and Rx gNB have static locations such that the propagation delay between the Tx gNB and Rx gNB is substantially constant except for clock drift). In this case, the radar slot format described with respect to 1510-1520 is used when the reference radar signal is used in conjunction with the target radar signal(s), while other slots may include only the target radar signal(s) and therefore do not use the radar slot format described with respect to 1510-1520.

[0191] Figure 16An exemplary communication process 1600 is illustrated in accordance with aspects of the present disclosure. In one aspect, process 1600 may be performed by a first base station, such as BS 304. For example, regarding Figure 16 The first base station described may correspond to the above Figure 15 In some designs, the radar controller may be integrated with the first base station as described above, in which case any data exchange between the radar controller and the first base station would correspond to internal data transmission rather than communicating signal(s) across the network.

[0192] At 1610, a first base station (e.g., network interface(s) 380, data bus 382, ​​etc.) receives a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from the first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol. For example, the radar slot format may be as described above with respect to Figure 15 The configuration described in 1510.

[0193] For example, a first base station (e.g., transmitter 354 or 364, etc.) transmits the reference radar signal over the first link from the first base station to the second base station on the first symbol at 1620. In some designs, the reference radar signal is transmitted over the LOS link via a default beam (e.g., an ideal beam may be identified earlier and subsequently set as the default beam).

[0194] At 1630, a first base station (e.g., transmitter 354 or 364, etc.) transmits the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol. In some designs, the at least one target radar signal is transmitted over the at least one NLOS link via a dynamically determined beam set (e.g., due to target mobility). In some designs, the at least one target radar signal may include multiple target radar signals targeting the same or different targets. In the case of different targets, R may be determined for each target relative to the same reference radar signal. sum .

[0195] Figure 17 An exemplary communication process 1700 is illustrated in accordance with aspects of the present disclosure. In one aspect, process 1700 may be performed by a second base station, such as BS 304. For example, Figure 17 The second base station described may correspond to the above Figure 15In some designs, the radar controller may be integrated with the second base station as described above, in which case any data exchange between the radar controller and the second base station would correspond to internal data transmission rather than communicating signal(s) across the network.

[0196] At 1710, a second base station (e.g., network interface(s) 380, data bus 382, ​​etc.) receives a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from the first base station to the second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol. For example, the radar slot format may be as described above with respect to Figure 15 The configuration described in 1510.

[0197] At 1720, a second base station (e.g., receiver 352 or 362, etc.) receives the reference radar signal over the first link from the first base station to the second base station on the first symbol. In some designs, the reference radar signal is received over the LOS link via a default beam (e.g., a desired beam may be identified earlier and subsequently set as the default beam).

[0198] At 1730, a second base station (e.g., receiver 352 or 362, etc.) receives the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol. In some designs, the at least one target radar signal is received over the at least one NLOS link via a dynamically determined beam set (e.g., due to target mobility). In some designs, the at least one target radar signal may include multiple target radar signals targeting the same or different targets. In the case of different targets, R may be determined for each target relative to the same reference radar signal. sum .

[0199] Reference Figure 15-17 In some designs, a radar slot format may be defined at the slot level, where different radar signals have different transmission properties (e.g., beams, durations, etc.) despite sharing the same slot. In other designs, a radar slot format may be defined at the symbol level, where different radar signals have different transmission properties (e.g., beams, durations, etc.) despite sharing the same symbol or symbol group. Thus, radar slot formats may be associated with different granularities of scheduling relative to corresponding radar signals within corresponding slots.

[0200] Reference Figure 15-17In some designs, the transmission properties of the reference radar signal can be different from the transmission properties of the target reference signal(s). For example, the duration of one instance of the reference radar signal can be smaller than the duration of each instance of the target radar signal (e.g., the path loss along the LOS path is smaller, so fewer or zero repetitions of the reference radar signal may be required along the LOS path).

[0201] Reference Figure 15-17 In some designs, the radar slot format can explicitly specify the first symbol for the reference radar signal. For example, the radar slot format can specify which symbol is used for the reference radar waveform transmission. In another example, the radar slot format can place the reference radar signal before the target radar signal(s), with a corresponding time difference "delta" between the corresponding radar signals. In this case, at least one second symbol can be specified via at least one offset relative to the first symbol.

[0202] Reference Figure 15-17 In some designs, the radar slot format can explicitly designate at least one target radar signal as being associated with a reference radar signal. Alternatively, at least one target radar signal can be implicitly associated with a reference radar signal. For example, any target radar signal can be implicitly associated with the most recent reference radar signal preceding the corresponding target radar signal (or, in other words, preceding the next indicated reference radar signal that has not yet arrived).

[0203] Reference Figure 15-17 As described above, the radar controller can signal the "expected reception time" and "expected reception time uncertainty" to the second base station to guide its time window for radar waveform reception. For operation via TDM beams, in some designs, the radar controller may only need to signal the "expected reception time" and "expected reception time uncertainty" for the radar reference signal to the second base station (i.e., rather than the "expected reception time" and "expected reception time uncertainty" for the target radar signal(s). In this case, the Rx time of the target radar waveform can be derived based on the "expected reception time" and "expected reception time uncertainty" for the radar reference signal and the radar slot format. The Rx gNB can be directed to receive the target radar signal(s) in the time window "expected reception time + expected reception time uncertainty," for example:

[0204] [L / c+T1-network syn error (network synchronization error), L_max / c+T1+delta_max (increment_maximum) + network syn error]

[0205] Expression 1

[0206] Where T1 is the transmission time of the reference radar signal, L / c is the time of the baseline LOS propagation time, delta_max can be derived based on the link budget, and the network synchronization (synchronization) error limit can be defined by the operator of the carrier network or can be predefined according to relevant standards. In Expression 1, delta_max represents the time difference between the reference radar signal and the last (i.e., most recently transmitted) target radar reference signal associated with the reference radar signal.

[0207] Reference Figure 15-17 In some designs, in principle, there is a time domain proximity between the reference radar signal and the set of target radar signals. In some designs, this time domain proximity can be quantified based on the timing drift rate of the first base station (or Tx gNB). The higher the timing drift rate, the closer the time domain proximity between the reference radar signal and the target radar reference signal(s).

[0208] Reference Figure 15-17 In some designs, the first base station may transmit an indication of a time domain drift associated with the first base station to the radar controller. In some designs, the reference radar signal is scheduled in response to the time domain drift indication. For example, the reference radar signal may be scheduled periodically, in response to detecting a time domain drift exceeding a certain threshold, or some combination thereof (e.g., periodically, but with reduced periodicity or aperiodic reference radar signal operation when the time drift exceeds the threshold). Thus, in some designs, the periodicity of the reference radar signal may be configured based on the time domain drift indication. In a specific example, if the time domain drift indication indicates a time domain drift of approximately x ns within y time slots (assuming that a drift of x ns still meets the sensing accuracy requirement), the radar controller may configure the reference radar signal every y time slots.

[0209] Reference Figure 15-17 In some designs, the radar reference waveform may be transmitted periodically to compensate for the timing drift problem at the first base station as mentioned above. In one example, the Rx time difference between each target radar signal and the reference radar signal is used to estimate the range and R sum The timing drift at the first base station (or Tx gNB) may cause the estimated distance and R sum Inaccurate.

[0210] Reference Figure 15-17In some designs, the first base station and / or the radar controller may further transmit a time domain drift indication to the second base station. For example, the radar controller may signal the time domain drift of the first base station to the second base station (or Rx gNB) to enhance detection / estimation performance. For example, to achieve low Doppler estimation, the target radar signal may span a long time duration, and if the drift rate is high (e.g., above a certain threshold), the Tx timing drift effect may not be negligible. As mentioned above, in some designs, the first base station may send a time domain drift indication to the radar controller, so that the first base station or the radar controller may send the time domain drift indication to the second base station.

[0211] Figure 18A The radar slot format 1800A according to the first aspect of the present disclosure is illustrated. Figure 18A In , a symbol for transmission of a reference radar signal is represented as "R", and a symbol for transmission of a target radar signal is represented as "T". Figure 18A In , a 1:1 radar slot format is used, whereby a single symbol (Symbol 1) is allocated to the reference radar signal and a single symbol (Symbol 4) is allocated to the target radar signal.

[0212] Figure 18B The radar slot format 1800B according to the second aspect of the present disclosure is illustrated. Figure 18B In , a symbol for transmission of a reference radar signal is represented as "R", and a symbol for transmission of a target radar signal is represented as "T". Figure 18B In FIG, a 1:N radar slot format is used, whereby a single symbol (symbol 1) is assigned to the reference radar signal, and multiple symbols (symbols 5, 7, and 9) are assigned to three respective target radar signals. In this example, R can be calculated for each of these target radar signals relative to the reference radar signal. sum three times (e.g., redundantly associated with the same target, or with respect to different targets).

[0213] In the above detailed description, it can be seen that different features are grouped together in each example. This disclosure should not be understood as an intention that the example clauses have more features than the features explicitly mentioned in each clause. On the contrary, various aspects of the present disclosure may include less than all the features of the disclosed individual example clauses. Therefore, the attached clauses should be considered to be incorporated into this description, wherein each clause itself may be a separate example. Although each dependent clause can be cited in each clause in a specific combination with one of the other clauses, the (all) aspects of the dependent clause are not limited to this specific combination. It will be appreciated that other example clauses may also include a combination of the dependent clause (all) aspects with the subject matter of any other dependent clause or independent clause or a combination of any feature with other dependent and independent clauses. The various aspects disclosed herein explicitly include these combinations, unless explicitly expressed or can be easily inferred that it is not intended to be a specific combination (for example, contradictory aspects, such as defining an element as an insulator and a conductor at the same time). In addition, it is also intended that the various aspects of the clause can be included in any other independent clause, even if the clause is not directly subordinate to the independent clause.

[0214] Implementation examples are described in the following numbered clauses:

[0215] Clause 1. A method of operating a radar controller, comprising: determining a radar slot format that configures transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; and transmitting an indication of the radar slot format to the first base station and the second base station.

[0216] Clause 2. The method of Clause 1, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0217] Clause 3. A method as described in any of clauses 1 to 2, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0218] Clause 4. The method of clause 3, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0219] Clause 5. The method of any one of clauses 1 to 4, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0220] Clause 6. The method of clause 5, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0221] Clause 7. The method of any one of clauses 1 to 6, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0222] Clause 8. The method of any one of clauses 1 to 7, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0223] Clause 9. The method of any one of clauses 1 to 8, further comprising: transmitting to the second base station an expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal.

[0224] Clause 10. The method of any of clauses 1 to 9, further comprising: receiving, at the radar controller from the first base station, an indication of a time domain drift associated with the first base station.

[0225] Clause 11. The method of clause 10, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0226] Clause 12. The method of clause 11, wherein the periodicity of the reference radar signal is configured based on the time domain drift indication.

[0227] Clause 13. The method of any one of clauses 10 to 12, further comprising: transmitting the time domain drift indication to the second base station.

[0228] Clause 14. A method of operating a first base station, comprising: receiving a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from the first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; transmitting the reference radar signal over the first link from the first base station to the second base station on the first symbol; and transmitting the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0229] Clause 15: The method of clause 14, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0230] Clause 16: A method as described in any of clauses 14 to 15, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0231] Clause 17: The method of clause 16, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0232] Clause 18: The method of any of clauses 14 to 17, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0233] Clause 19: The method of clause 18, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0234] Clause 20: The method of any of clauses 18 to 19, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0235] Clause 21: The method of any of clauses 14 to 20, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0236] Clause 22: The method of any one of clauses 14 to 21, further comprising: determining a time domain drift associated with the first base station.

[0237] Clause 23: The method of clause 22, further comprising: transmitting an indication of the time domain drift to the radar controller.

[0238] Clause 24: The method of clause 23, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0239] Clause 25: The method of clause 24, wherein the periodicity of the reference radar signal is configured based on the time domain drift indication.

[0240] Clause 26: The method of any one of clauses 22 to 25, further comprising: transmitting an indication of the time domain drift to the second base station.

[0241] Clause 27: A method of operating a second base station, comprising: receiving a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from a first base station to the second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; receiving the reference radar signal over the first link from the first base station to the second base station on the first symbol; and receiving the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0242] Clause 28: The method of clause 27, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDMed).

[0243] Clause 29: A method as described in any of clauses 27 to 28, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0244] Clause 30: The method of clause 29, wherein the reference radar signal is received on the LOS link via a default beam, and wherein the at least one target radar signal is received on the at least one NLOS link via a dynamically determined beam set.

[0245] Clause 31: The method of any of clauses 27 to 30, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0246] Clause 32: The method of clause 31, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0247] Clause 33: The method of any of clauses 27 to 32, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0248] Clause 34: The method of any one of clauses 27 to 33, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0249] Clause 35: The method of any one of clauses 27 to 34, further comprising: receiving from the radar controller an expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal.

[0250] Clause 36: The method of any of clauses 27 to 35, further comprising: receiving an indication of a time domain drift associated with the first base station from the first base station or the radar controller.

[0251] Clause 37: The method of clause 36, wherein the temporal drift indication indicates that the temporal drift is below a time threshold.

[0252] Clause 38: The method of clause 37, further comprising: performing a low-Doppler estimation of the at least one target radar signal without taking into account the time-domain drift indication.

[0253] Clause 39: The method of any one of clauses 36 to 38, wherein the temporal drift indication indicates that the temporal drift is equal to or greater than a time threshold.

[0254] Clause 40: The method of clause 39, further comprising: performing a low-Doppler estimation of the at least one target radar signal based on the time-domain drift indication.

[0255] Clause 41: A radar controller comprising: a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: determine a radar slot format that configures transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; and transmit an indication of the radar slot format to the first base station and the second base station via the at least one transceiver.

[0256] Clause 42: The radar controller of clause 41, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0257] Clause 43: A radar controller as described in any of clauses 41 to 42, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0258] Clause 44: The radar controller of clause 43, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0259] Clause 45: The radar controller of any of clauses 41 to 44, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0260] Clause 46: The radar controller of clause 45, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0261] Clause 47: The radar controller of any of clauses 41 to 46, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0262] Clause 48: The radar controller of any of clauses 41 to 47, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0263] Clause 49: The radar controller of any one of clauses 41 to 48, wherein the at least one processor is further configured to: transmit, via the at least one transceiver, to the second base station an expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal.

[0264] Clause 50: The radar controller of any of clauses 41 to 49, wherein the at least one processor is further configured to: receive at the radar controller from the first base station via the at least one transceiver an indication of a time domain drift associated with the first base station.

[0265] Clause 51: The radar controller of clause 50, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0266] Clause 52: The radar controller of clause 51, wherein the periodicity of the reference radar signal is configured based on the time domain drift indication.

[0267] Clause 53: The radar controller of any of clauses 50 to 52, wherein the at least one processor is further configured to: transmit the time domain drift indication to the second base station via the at least one transceiver.

[0268] Clause 54: A first base station comprising: a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: receive a radar slot format from a radar controller via the at least one transceiver, the radar slot format configuring transmission of a reference radar signal over a first link from the first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; transmit, via the at least one transceiver, the reference radar signal over the first link from the first base station to the second base station on the first symbol; and transmit, via the at least one transceiver, the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0269] Clause 55: The first base station of clause 54, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0270] Clause 56: A first base station as in any of clauses 54 to 55, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0271] Clause 57: The first base station of clause 56, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0272] Clause 58: The first base station of any of clauses 54 to 57, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0273] Clause 59: The first base station of clause 58, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0274] Clause 60: The first base station of any of clauses 58 to 59, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0275] Clause 61: The first base station of any of clauses 54 to 60, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0276] Clause 62: The first base station of any of clauses 54 to 61, wherein the at least one processor is further configured to: determine a time domain drift associated with the first base station.

[0277] Clause 63: The first base station of clause 62, wherein the at least one processor is further configured to: transmit an indication of the time domain drift to the radar controller via the at least one transceiver.

[0278] Clause 64: The first base station of clause 63, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0279] Clause 65: The first base station of clause 64, wherein the periodicity of the reference radar signal is configured based on the time domain drift indication.

[0280] Clause 66: The first base station of any of clauses 62 to 65, wherein the at least one processor is further configured to: transmit an indication of the time domain drift to the second base station via the at least one transceiver.

[0281] Clause 67: A second base station comprising: a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to: receive a radar slot format from a radar controller via the at least one transceiver, the radar slot format configuring transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; receive the reference radar signal via the at least one transceiver over the first link from the first base station to the second base station on the first symbol; and receive the at least one target radar signal via the at least one transceiver over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0282] Clause 68: The second base station of clause 67, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0283] Clause 69: A second base station as in any of clauses 67 to 68, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0284] Clause 70: The second base station of clause 69, wherein the reference radar signal is received on the LOS link via a default beam, and wherein the at least one target radar signal is received on the at least one NLOS link via a dynamically determined beam set.

[0285] Clause 71: The second base station of any of clauses 67 to 70, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0286] Clause 72: The second base station of clause 71, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0287] Clause 73: The second base station of any of clauses 67 to 72, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0288] Clause 74: The second base station of any of clauses 67 to 73, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0289] Clause 75: The second base station of any one of clauses 67 to 74, wherein the at least one processor is further configured to: receive an expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal from the radar controller via the at least one transceiver.

[0290] Clause 76: The second base station of any of clauses 67 to 75, wherein the at least one processor is further configured to: receive an indication of a time domain drift associated with the first base station from the first base station or the radar controller via the at least one transceiver.

[0291] Clause 77: The second base station of clause 76, wherein the time domain drift indication indicates that the time domain drift is below a time threshold.

[0292] Clause 78: The second base station of clause 77, wherein the at least one processor is further configured to: perform a low Doppler estimation of the at least one target radar signal without taking into account the time domain drift indication.

[0293] Clause 79: The second base station of any one of clauses 76 to 78, wherein the time domain drift indication indicates that the time domain drift is equal to or greater than a time threshold.

[0294] Clause 80: The second base station of clause 79, wherein the at least one processor is further configured to: perform a low-Doppler estimation of the at least one target radar signal based on the time domain drift indication.

[0295] Clause 81: A radar controller comprising: means for determining a radar slot format, the radar slot format being configured to transmit a reference radar signal on a first symbol via a first link from a first base station to a second base station, followed by transmission of at least one target radar signal on at least one second symbol via at least one second link from the first base station to the second base station; and means for transmitting an indication of the radar slot format to the first base station and the second base station.

[0296] Clause 82: The radar controller of clause 81, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0297] Clause 83: A radar controller as described in any of clauses 81 to 82, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0298] Clause 84: The radar controller of clause 83, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0299] Clause 85: The radar controller of any of clauses 81 to 84, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0300] Clause 86: The radar controller of clause 85, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0301] Clause 87: The radar controller of any of clauses 81 to 86, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0302] Clause 88: The radar controller of any one of clauses 81 to 87, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0303] Clause 89: The radar controller of any of clauses 81 to 88, further comprising: means for transmitting the expected reception time associated with the reference radar signal and the expected reception time uncertainty associated with the reference radar signal to the second base station.

[0304] Clause 90: The radar controller of any of clauses 81 to 89, further comprising: means for receiving, at the radar controller, from the first base station, an indication of a time domain drift associated with the first base station.

[0305] Clause 91: The radar controller of clause 90, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0306] Clause 92: The radar controller of clause 91, wherein the periodicity of the reference radar signal is configured based on the time domain drift indication.

[0307] Clause 93: The radar controller of any one of clauses 90 to 92, further comprising: means for transmitting the time domain drift indication to the second base station.

[0308] Item 94: A first base station comprising: means for receiving a radar slot format from a radar controller, the radar slot format configured for transmission of a reference radar signal on a first symbol via a first link from the first base station to a second base station, followed by transmission of at least one target radar signal on at least one second symbol via at least one second link from the first base station to the second base station; means for transmitting the reference radar signal on the first symbol via the first link from the first base station to the second base station; and means for transmitting the at least one target radar signal on the at least one second symbol via the at least one second link from the first base station to the second base station.

[0309] Clause 95: The first base station of clause 94, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0310] Clause 96: A first base station as described in any of clauses 94 to 95, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0311] Clause 97: The first base station of clause 96, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0312] Clause 98: The first base station of any of clauses 94 to 97, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0313] Clause 99: The first base station of clause 98, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0314] Clause 100: The first base station of any of clauses 98 to 99, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0315] Clause 101: The first base station of any of clauses 94 to 100, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0316] Clause 102: The first base station of any one of clauses 94 to 101, further comprising: means for determining a time domain drift associated with the first base station.

[0317] Clause 103: The first base station of clause 102, further comprising: means for transmitting an indication of the time domain drift to the radar controller.

[0318] Clause 104: The first base station of clause 103, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0319] Clause 105: The first base station of clause 104, wherein the periodicity of the reference radar signal is configured based on the time domain drift indication.

[0320] Clause 106: The first base station of any of clauses 102 to 105, further comprising: means for transmitting an indication of the time domain drift to the second base station.

[0321] Item 107: A second base station comprising: means for receiving a radar slot format from a radar controller, the radar slot format configured to transmit a reference radar signal on a first symbol via a first link from a first base station to the second base station, followed by transmission of at least one target radar signal on at least one second symbol via at least one second link from the first base station to the second base station; means for receiving the reference radar signal on the first symbol via the first link from the first base station to the second base station; and means for receiving the at least one target radar signal on the at least one second symbol via the at least one second link from the first base station to the second base station.

[0322] Clause 108: The second base station of clause 107, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM).

[0323] Clause 109: A second base station as described in any of clauses 107 to 108, wherein the first link corresponds to a line of sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0324] Clause 110: The second base station of clause 109, wherein the reference radar signal is received on the LOS link via a default beam, and wherein the at least one target radar signal is received on the at least one NLOS link via a dynamically determined beam set.

[0325] Clause 111: The second base station of any of clauses 107 to 110, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0326] Clause 112: The second base station of clause 111, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0327] Clause 113: The second base station of any of clauses 107 to 112, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0328] Clause 114: The second base station of any of clauses 107 to 113, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on a most recent reference radar signal before the reference radar signal corresponds to the at least one target radar signal.

[0329] Clause 115: The second base station of any of clauses 107 to 114, further comprising: means for receiving from the radar controller an expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal.

[0330] Clause 116: The second base station of any of clauses 107 to 115, further comprising: means for receiving an indication of a time domain drift associated with the first base station from the first base station or the radar controller.

[0331] Clause 117: The second base station of clause 116, wherein the time domain drift indication indicates that the time domain drift is below a time threshold.

[0332] Clause 118: The second base station of clause 117, further comprising: means for performing a low-Doppler estimation of the at least one target radar signal without taking into account the time domain drift indication.

[0333] Clause 119: The second base station of any one of clauses 116 to 118, wherein the time domain drift indication indicates that the time domain drift is equal to or greater than a time threshold.

[0334] Clause 120: The second base station of clause 119, further comprising: means for performing a low-Doppler estimation of the at least one target radar signal based on the time domain drift indication.

[0335] Clause 121: A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a radar controller, cause the radar controller to: determine a radar slot format that configures transmission of a reference radar signal over a first link from a first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; and transmit an indication of the radar slot format to the first base station and the second base station.

[0336] Clause 122: The non-transitory computer-readable medium of clause 121, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDMed).

[0337] Clause 123: A non-transitory computer-readable medium as in any of clauses 121 to 122, wherein the first link corresponds to a line-of-sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0338] Clause 124: The non-transitory computer-readable medium of clause 123, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0339] Clause 125: The non-transitory computer-readable medium of any of clauses 121 to 124, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0340] Clause 126: The non-transitory computer-readable medium of clause 125, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0341] Clause 127: The non-transitory computer-readable medium of any of clauses 121 to 126, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0342] Clause 128: The non-transitory computer-readable medium of any of clauses 121 to 127, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on the reference radar signal corresponding to a most recent reference radar signal before the at least one target radar signal.

[0343] Clause 129: The non-transitory computer-readable medium of any of clauses 121 to 128, further comprising instructions that, when executed by the radar controller, further cause the radar controller to: transmit to the second base station an expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal.

[0344] Clause 130: The non-transitory computer-readable medium of any of clauses 121 to 129, further comprising instructions that, when executed by the radar controller, further cause the radar controller to: receive at the radar controller from the first base station an indication of a time domain drift associated with the first base station.

[0345] Clause 131: The non-transitory computer-readable medium of clause 130, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0346] Clause 132: The non-transitory computer-readable medium of clause 131, wherein the periodicity of the reference radar signal is configured based on the time-domain drift indication.

[0347] Clause 133: The non-transitory computer-readable medium of any of clauses 130 to 132, further comprising instructions that, when executed by the radar controller, further cause the radar controller to: transmit the time domain drift indication to the second base station.

[0348] Clause 134: A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a first base station, cause the first base station to: receive a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from the first base station to a second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; transmit the reference radar signal over the first link from the first base station to the second base station on the first symbol; and transmit the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0349] Clause 135: The non-transitory computer-readable medium of clause 134, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDMed).

[0350] Clause 136: A non-transitory computer-readable medium as in any of clauses 134 to 135, wherein the first link corresponds to a line-of-sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0351] Clause 137: The non-transitory computer-readable medium of clause 136, wherein the reference radar signal is transmitted on the LOS link via a default beam, and wherein the at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

[0352] Clause 138: The non-transitory computer-readable medium of any of clauses 134 to 137, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0353] Clause 139: The non-transitory computer-readable medium of clause 138, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0354] Clause 140: The non-transitory computer-readable medium of any of clauses 138 to 139, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0355] Clause 141: The non-transitory computer-readable medium of any of clauses 134 to 140, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on the reference radar signal corresponding to a most recent reference radar signal before the at least one target radar signal.

[0356] Clause 142: The non-transitory computer-readable medium of any of clauses 134 to 141, further comprising instructions that, when executed by the first base station, further cause the first base station to: determine a time domain drift associated with the first base station.

[0357] Clause 143: The non-transitory computer-readable medium of clause 142, further comprising instructions that, when executed by the first base station, further cause the first base station to: transmit an indication of the time domain drift to the radar controller.

[0358] Clause 144: The non-transitory computer-readable medium of clause 143, wherein the reference radar signal is scheduled in response to the time domain drift indication.

[0359] Clause 145: The non-transitory computer-readable medium of clause 144, wherein the periodicity of the reference radar signal is configured based on the time-domain drift indication.

[0360] Clause 146: The non-transitory computer-readable medium of any of clauses 142 to 145, further comprising instructions that, when executed by the first base station, further cause the first base station to: transmit an indication of the time domain drift to the second base station.

[0361] Clause 147: A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a second base station, cause the second base station to: receive a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from the first base station to the second base station on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first base station to the second base station on at least one second symbol; receive the reference radar signal over the first link from the first base station to the second base station on the first symbol; and receive the at least one target radar signal over the at least one second link from the first base station to the second base station on the at least one second symbol.

[0362] Clause 148: The non-transitory computer-readable medium of clause 147, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDMed).

[0363] Clause 149: A non-transitory computer-readable medium as in any of clauses 147 to 148, wherein the first link corresponds to a line-of-sight (LOS) link from the first base station to the second base station, and wherein the at least one second link corresponds to at least one non-LOS (NLOS) link from the first base station to the second base station.

[0364] Clause 150: The non-transitory computer-readable medium of clause 149, wherein the reference radar signal is received on the LOS link via a default beam, and wherein the at least one target radar signal is received on the at least one NLOS link via a dynamically determined beam set.

[0365] Clause 151: The non-transitory computer-readable medium of any of clauses 147 to 150, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

[0366] Clause 152: The non-transitory computer-readable medium of clause 151, wherein the at least one second symbol is specified via at least one offset relative to the first symbol.

[0367] Clause 153: The non-transitory computer-readable medium of any of clauses 147 to 152, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal.

[0368] Clause 154: The non-transitory computer-readable medium of any of clauses 147 to 153, wherein the at least one target radar signal is implicitly associated with the reference radar signal based on the reference radar signal corresponding to a most recent reference radar signal before the at least one target radar signal.

[0369] Clause 155: The non-transitory computer-readable medium of any of clauses 147 to 154, further comprising instructions that, when executed by the second base station, further cause the second base station to perform the following operations: receive from the radar controller an expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal.

[0370] Clause 156: The non-transitory computer-readable medium of any of clauses 147 to 155, further comprising instructions that, when executed by the second base station, further cause the second base station to: receive an indication of a time domain drift associated with the first base station from the first base station or the radar controller.

[0371] Clause 157: The non-transitory computer-readable medium of clause 156, wherein the temporal drift indication indicates that the temporal drift is below a time threshold.

[0372] Clause 158: The non-transitory computer-readable medium of clause 157, further comprising instructions that, when executed by the second base station, further cause the second base station to: perform a low-Doppler estimation of the at least one target radar signal without taking into account the time-domain drift indication.

[0373] Clause 159: The non-transitory computer-readable medium of any of clauses 156 to 158, wherein the temporal drift indication indicates that the temporal drift is equal to or greater than a time threshold.

[0374] Clause 160: The non-transitory computer-readable medium of clause 159, further comprising instructions that, when executed by the second base station, further cause the second base station to: perform a low-Doppler estimation of the at least one target radar signal based on the time-domain drift indication.

[0375] Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0376] In addition, those skilled in the art will appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the aspects disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. A skilled person may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as causing a departure from the scope of this disclosure.

[0377] The various illustrative logical blocks, modules, and circuits described in conjunction with the various aspects disclosed herein may be implemented or executed with a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0378] The methods, sequences and / or algorithms described in conjunction with the various aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read and write information from / to the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., UE). In an alternative, the processor and storage medium may reside in the user terminal as discrete components.

[0379] In one or more exemplary aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, each function may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one location to another. A storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Similarly, any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks typically reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0380] While the foregoing disclosure shows illustrative aspects of the present disclosure, it should be noted that various changes and modifications may be made therein without departing from the scope of the present disclosure as defined by the appended claims. The functions, steps, and / or actions of the method claims according to the various aspects of the present disclosure described herein do not have to be performed in any particular order. Furthermore, although elements of the present disclosure may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

Claims

1. A method of operating a radar controller, comprising: determining a radar slot format that configures transmission of a reference radar signal over a first link from a first wireless network component to a second wireless network component on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first wireless network component to the second wireless network component on at least one second symbol; as well as transmitting an indication of the radar slot format to the first wireless network component and the second wireless network component, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM), and The reference radar signal and the at least one target radar signal are associated with a radio frequency (RF) sensing procedure of at least one target object separate from the second wireless network component.

2. The method according to claim 1, wherein the first link corresponds to a line-of-sight (LOS) link from the first wireless network component to the second wireless network component, and The at least one second link corresponds to at least one non-line-of-sight (NLOS) link from the first wireless network component to the second wireless network component.

3. The method according to claim 2, wherein the reference radar signal is transmitted on the LOS link via a default beam, and The at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

4. The method of claim 1, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

5. The method according to claim 4, wherein: The at least one second symbol is specified via at least one offset relative to the first symbol.

6. The method according to claim 1, wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal, or The at least one target radar signal is implicitly associated with the reference radar signal based on the reference radar signal corresponding to a most recent reference radar signal before the at least one target radar signal.

7. The method of claim 1, further comprising: An expected time of receipt associated with the reference radar signal and an expected time of receipt uncertainty associated with the reference radar signal are communicated to the second wireless network component.

8. The method of claim 1, further comprising: An indication of a time domain drift associated with the first wireless network component is received at the radar controller from the first wireless network component.

9. The method of claim 8, wherein: The reference radar signal is scheduled in response to the time domain drift indication.

10. The method of claim 9, wherein: The periodicity of the reference radar signal is configured based on the time domain drift indication.

11. The method of claim 8, further comprising: A time domain drift indication is transmitted to the second wireless network component.

12. A method of operating a first wireless network component, comprising: receiving a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from the first wireless network component to a second wireless network component on a first symbol followed by transmission of at least one target radar signal over at least one second link from the first wireless network component to the second wireless network component on at least one second symbol; transmitting the reference radar signal over the first link from the first wireless network component to the second wireless network component on the first symbol; as well as transmitting the at least one target radar signal over the at least one second link from the first wireless network component to the second wireless network component over the at least one second symbol, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM), and The reference radar signal and the at least one target radar signal are associated with a radio frequency (RF) sensing procedure of at least one target object separate from the second wireless network component.

13. The method according to claim 12, wherein the first link corresponds to a line-of-sight (LOS) link from the first wireless network component to the second wireless network component, and The at least one second link corresponds to at least one non-line-of-sight (NLOS) link from the first wireless network component to the second wireless network component.

14. The method according to claim 13, wherein the reference radar signal is transmitted on the LOS link via a default beam, and The at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

15. The method according to claim 12, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal, The at least one target radar signal is implicitly associated with the reference radar signal based on the reference radar signal corresponding to a most recent reference radar signal before the at least one target radar signal.

16. The method of claim 12, further comprising: A time domain drift associated with the first wireless network component is determined.

17. The method of claim 16, further comprising: An indication of the time domain drift is transmitted to the radar controller.

18. The method of claim 17, wherein: The reference radar signal is scheduled in response to the time domain drift indication.

19. A method of operating a second wireless network component, comprising: receiving a radar slot format from a radar controller, the radar slot format configuring transmission of a reference radar signal over a first link from a first wireless network component to a second wireless network component on a first symbol followed by transmission of at least one target radar signal over at least one second link from the first wireless network component to the second wireless network component on at least one second symbol; receiving the reference radar signal over the first link from the first wireless network component to the second wireless network component over the first symbol; as well as receiving the at least one target radar signal over the at least one second link from the first wireless network component to the second wireless network component over the at least one second symbol, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM), and The reference radar signal and the at least one target radar signal are associated with a radio frequency (RF) sensing procedure of at least one target object separate from the second wireless network component.

20. The method of claim 19, wherein the first link corresponds to a line-of-sight (LOS) link from the first wireless network component to the second wireless network component, and The at least one second link corresponds to at least one non-line-of-sight (NLOS) link from the first wireless network component to the second wireless network component.

21. The method of claim 20, wherein the reference radar signal is transmitted on the LOS link via a default beam, and The at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

22. The method of claim 19, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal, or wherein the radar slot format explicitly designates the at least one target radar signal as being associated with the reference radar signal, or The at least one target radar signal is implicitly associated with the reference radar signal based on the reference radar signal corresponding to a most recent reference radar signal before the at least one target radar signal.

23. The method of claim 19, further comprising: An expected reception time associated with the reference radar signal and an expected reception time uncertainty associated with the reference radar signal are received from the radar controller.

24. The method of claim 19, further comprising: An indication of a time domain drift associated with the first wireless network component is received from the first wireless network component or the radar controller.

25. The method of claim 24, wherein: The time domain drift indication indicates that the time domain drift is below a time threshold.

26. The method of claim 24, wherein: The time domain drift indication indicates that the time domain drift is equal to or greater than a time threshold.

27. A radar controller comprising: one or more memories; one or more transceivers; as well as one or more processors communicatively coupled to the one or more memories and the one or more transceivers, the one or more processors being configured, individually or in combination, to: determining a radar slot format that configures transmission of a reference radar signal over a first link from a first wireless network component to a second wireless network component on a first symbol, followed by transmission of at least one target radar signal over at least one second link from the first wireless network component to the second wireless network component on at least one second symbol; as well as transmitting, via the at least one transceiver, to the first wireless network component and the second wireless network component an indication of the radar slot format, wherein the reference radar signal and the at least one target radar signal are time division multiplexed (TDM), and The reference radar signal and the at least one target radar signal are associated with radio frequency (RF) sensing procedures of at least one target object separate from the second wireless network component.

28. The radar controller according to claim 27, wherein the first link corresponds to a line-of-sight (LOS) link from the first wireless network component to the second wireless network component, and The at least one second link corresponds to at least one non-line-of-sight (NLOS) link from the first wireless network component to the second wireless network component.

29. The radar controller according to claim 28, wherein the reference radar signal is transmitted on the LOS link via a default beam, and The at least one target radar signal is transmitted on the at least one NLOS link via a dynamically determined beam set.

30. The radar controller of claim 27, wherein the radar slot format explicitly specifies the first symbol for the reference radar signal.

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