Patent Application
20240345214
This application claims the benefit of Greek patent application No. 20210100887, entitled “FLEXIBLE OFDM WAVEFORM FOR JOINT COMMUNICATION AND RF SENSING” and filed on Dec. 16, 2021, which is expressly incorporated by reference herein in its entirety.
The present disclosure relates generally to communication systems, and more particularly, to wireless communications involving positioning.
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable low latency communications (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There exists a need for further improvements in 5G NR technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies. Some communication systems may also support a number of cellular network-based positioning technologies, where the geographic location of a wireless device may be determined based on measuring radio signals exchanged between the wireless device and other wireless devices. For example, a distance between a wireless device and a transmission reception point (TRP) may be estimated based on the time it takes for a reference signal (e.g., a positioning reference signal (PRS)) transmitted from the TRP to reach the wireless device. Other examples of cellular network-based positioning technologies may include downlink-based, uplink-based, and/or downlink-and-uplink-based positioning methods.
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus transmits a radio frequency (RF) sensing signal in a first time duration of a symbol in an RF sensing session. The apparatus monitors for a reflected RS sensing signal in a second time duration of the symbol that does not overlap with the first time duration, the symbol including a cyclic prefix (CP) that does not overlap with the first time duration and the second time duration.
In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus switches between a communication mode and an RF sensing mode during a first time duration of a symbol, the symbol not including a CP. The apparatus transmits or receives an RF sensing signal based on the RF sensing mode or a communication message based on the communication mode during a second time duration of the symbol. The apparatus switches between the communication mode and the RF sensing mode during a third time duration of the symbol, the first time duration, the second time duration, and the third time duration not overlapping with each other.
To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.
By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.
Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.
While aspects and implementations are described in this application by illustration to some examples, those skilled in the art will understand that additional implementations and use cases may come about in many different arrangements and scenarios. Innovations described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, implementations and/or uses may come about via integrated chip implementations and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, artificial intelligence (AI)-enabled devices, etc.). While some examples may or may not be specifically directed to use cases or applications, a wide assortment of applicability of described innovations may occur. Implementations may range a spectrum from chip-level or modular components to non-modular, non-chip-level implementations and further to aggregate, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more aspects of the described innovations. In some practical settings, devices incorporating described aspects and features may also include additional components and features for implementation and practice of claimed and described aspect. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes (e.g., hardware components including antenna, RF-chains, power amplifiers, modulators, buffer, processor(s), interleaver, adders/summers, etc.). It is intended that innovations described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc. of varying sizes, shapes, and constitution.
To reduce unnecessary signal transmissions and/or receptions, and also to achieve energy/power saving at radar transmitters/receivers (e.g., UEs, base stations, TRPs, RF sensing nodes, etc.), aspects presented herein provide flexible OFDM waveform designs for joint communication and RF sensing. For example, aspects presented herein may enable the symbol duration and/or the CP duration of an RF sensing signal to be flexibly configured, such that OFDM symbols used for RF sensing may be different from OFDM symbols used for communications. As different RF sensing scenarios may have different specifications on sensing signal symbol duration and CP duration (e.g., the CP and symbol duration may determine the unambiguity monostatic sensing range), a more flexible OFDM waveform configuration may enable a radar transmitter to transmit RF sensing signals using different OFDM waveforms based on the scenarios. In addition, as there may be a bandwidth switch and/or a beam switch between RF sensing signals and communication signals that may introduce some switch latency, a more flexible OFDM waveform configuration may enable a radar transmitter to utilize the switching symbol for RF sensing signals or communication signals if the switching delay is larger than CP. Aspects presented herein also provides slot-level alignment between sensing OFDM signals and communications OFDM signals. In some examples, symbol-level alignment may also be provided for a uniform transceiver design.
In certain aspects, an RF sensing node, which may be a UE 104 or a base station 102/180, may include an RF sensing component 198 configured to transmit RF sensing signals based on OFDM symbols that may be flexibly configured, such that OFDM symbols used for RF sensing may be different from OFDM symbols used for communications. In one configuration, the RF sensing component 198 may be configured to transmit an RF sensing signal in a first time duration of a symbol in an RF sensing session. In such configuration, the RF sensing component 198 may monitor for a reflected RS sensing signal in a second time duration of the symbol that does not overlap with the first time duration, the symbol including a CP that does not overlap with the first time duration and the second time duration.
In another configuration, the RF sensing component 198 may be configured to switch between a communication mode and an RF sensing mode during a first time duration of a symbol, the symbol not including a CP. In such configuration, the RF sensing component 198 may transmit or receive an RF sensing signal based on the RF sensing mode or a communication message based on the communication mode during a second time duration of the symbol. In such configuration, the RF sensing component 198 may switch between the communication mode and the RF sensing mode during a third time duration of the symbol, the first time duration, the second time duration, and the third time duration not overlapping with each other.
The base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 through first backhaul links 132 (e.g., SI interface). The base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network 190 through second backhaul links 184. In addition to other functions, the base stations 102 may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate directly or indirectly (e.g., through the EPC 160 or core network 190) with each other over third backhaul links 134 (e.g., X2 interface). The first backhaul links 132, the second backhaul links 184, and the third backhaul links 134 may be wired or wireless.
In some aspects, a base station 102 or 180 may be referred as a RAN and may include aggregated or disaggregated components. As an example of a disaggregated RAN, a base station may include a central unit (CU) 103, one or more distributed units (DU) 105, and/or one or more remote units (RU) 109, as illustrated in
An access network may include one or more integrated access and backhaul (IAB) nodes 111 that exchange wireless communication with a UE 104 or other IAB node 111 to provide access and backhaul to a core network. In an IAB network of multiple IAB nodes, an anchor node may be referred to as an IAB donor. The IAB donor may be a base station 102 or 180 that provides access to a core network 190 or EPC 160 and/or control to one or more IAB nodes 111. The IAB donor may include a CU 103 and a DU 105. IAB nodes 111 may include a DU 105 and a mobile termination (MT) 113. The DU 105 of an IAB node 111 may operate as a parent node, and the MT 113 may operate as a child node.
The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102′ may have a coverage area 110′ that overlaps the coverage area 110 of one or more macro base stations 102. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links 120 between the base stations 102 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a base station 102 and/or downlink (DL) (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations 102/UEs 104 may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell).
Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.
The wireless communications system may further include a Wi-Fi access point (AP) 150 in communication with Wi-Fi stations (STAs) 152 via communication links 154, e.g., in a 5 GHz unlicensed frequency spectrum or the like. When communicating in an unlicensed frequency spectrum, the STAs 152/AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.
The small cell 102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102′ may employ NR and use the same unlicensed frequency spectrum (e.g., 5 GHZ, or the like) as used by the Wi-Fi AP 150. The small cell 102′, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.
The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHZ-7.125 GHZ) and FR2 (24.25 GHz-52.6 GHZ). Although a portion of FR1 is greater than 6 GHZ, FR1 is often referred to (interchangeably) as a “sub-6 GHz” band in various documents and articles. A similar nomenclature issue sometimes occurs with regard to FR2, which is often referred to (interchangeably) as a “millimeter wave” band in documents and articles, despite being different from the extremely high frequency (EHF) band (30 GHz-300 GHz) which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band.
The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified an operating band for these mid-band frequencies as frequency range designation FR3 (7.125 GHZ-24.25 GHZ). Frequency bands falling within FR3 may inherit FR1 characteristics and/or FR2 characteristics, and thus may effectively extend features of FR1 and/or FR2 into mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as frequency range designations FR2-2 (52.6 GHZ-71 GHZ), FR4 (52.6 GHZ-114.25 GHZ), and FR5 (114.25 GHZ-300 GHz). Each of these higher frequency bands falls within the EHF band.
With the above aspects in mind, unless specifically stated otherwise, it should be understood that the term “sub-6 GHz” or the like if used herein may broadly represent frequencies that may be less than 6 GHZ, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, it should be understood that the term “millimeter wave” or the like if used herein may broadly represent frequencies that may include mid-band frequencies, may be within FR2, FR4, FR2-2, and/or FR5, or may be within the EHF band.
A base station 102, whether a small cell 102′ or a large cell (e.g., macro base station), may include and/or be referred to as an eNB, gNodeB (gNB), or another type of base station. Some base stations, such as gNB 180 may operate in a traditional sub 6 GHZ spectrum, in millimeter wave frequencies, and/or near millimeter wave frequencies in communication with the UE 104. When the gNB 180 operates in millimeter wave or near millimeter wave frequencies, the gNB 180 may be referred to as a millimeter wave base station. The millimeter wave base station 180 may utilize beamforming 182 with the UE 104 to compensate for the path loss and short range. The base station 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming. The base station 180 may transmit a beamformed signal to the UE 104 in one or more transmit directions 182′. The UE 104 may receive the beamformed signal from the base station 180 in one or more receive directions 182″. The UE 104 may also transmit a beamformed signal to the base station 180 in one or more transmit directions. The base station 180 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 180/UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180/UE 104. The transmit and receive directions for the base station 180 may or may not be the same. The transmit and receive directions for the UE 104 may or may not be the same.
The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation as well as other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to the base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.
The core network 190 may include an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is the control node that processes the signaling between the UEs 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF 195. The UPF 195 provides UE IP address allocation as well as other functions. The UPF 195 is connected to the IP Services 197. The IP Services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a Packet Switch (PS) Streaming (PSS) Service, and/or other IP services.
The base station may include and/or be referred to as a gNB, Node B, eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or core network 190 for a UE 104. Examples of UEs 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc.). The UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. In some scenarios, the term UE may also apply to one or more companion devices such as in a device constellation arrangement. One or more of these devices may collectively access the network and/or individually access the network.
For normal CP (14 symbols/slot), different numerologies μ 0 to 4 allow for 1, 2, 4, 8, and 16 slots, respectively, per subframe. For extended CP, the numerology 2 allows for 4 slots per subframe. Accordingly, for normal CP and numerology μ, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing may be equal to 2μ*15 kHz, where u is the numerology 0 to 4. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=4 has a subcarrier spacing of 240 kHz. The symbol length/duration is inversely related to the subcarrier spacing.
A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.
As illustrated in
As illustrated in
The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles mapping to signal constellations 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 an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) 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 stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318 TX. Each transmitter 318 TX may modulate a radio frequency (RF) carrier with a respective spatial stream for transmission.
At the UE 350, each receiver 354 RX receives a signal through its respective antenna 352. Each receiver 354 RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller/processor 359, which implements layer 3 and layer 2 functionality.
The controller/processor 359 can be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 359 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.
Similar to the functionality described in connection with the DL transmission by the base station 310, the controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation 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 TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.
Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antenna 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.
The UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.
The controller/processor 375 can be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from the controller/processor 375 may be provided to the EPC 160. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.
In some examples, at least one of the TX processor 368, the RX processor 356, and the controller/processor 359 may be configured to perform aspects in connection with the RF sensing component 198 of
A network may support a number of cellular network-based positioning technologies, such as downlink-based, uplink-based, and/or downlink-and-uplink-based positioning methods. Downlink-based positioning methods may include an observed time difference of arrival (OTDOA) (e.g., in LTE), a downlink time difference of arrival (DL-TDOA) (e.g., in NR), and/or a downlink angle-of-departure (DL-AoD) (e.g., in NR). In an OTDOA or DL-TDOA positioning procedure, a UE may measure the differences between each time of arrival (ToA) of reference signals (e.g., positioning reference signals (PRSs)) received from pairs of base stations, referred to as reference signal time difference (RSTD) measurements or time difference of arrival (TDOA) measurements, and report them to a positioning entity (e.g., a location management function (LMF)). For example, the UE may receive identifiers (IDs) of a reference base station (which may also be referred to as a reference cell or a reference gNB) and at least one non-reference base station in assistance data (AD). The UE may then measure the RSTD between the reference base station and each of the non-reference base stations. Based on the known locations of the involved base stations and the RSTD measurements, the positioning entity may estimate a location of the UE. In other words, a position of the UE may be estimated based on measuring reference signals transmitted between the UE and one or more base stations and/or transmission-reception points (TRPs) of the one or more base stations. As such, the PRSs may enable UEs to detect and measure neighbor TRPs, and to perform positioning based on the measurement. For purposes of the present disclosure, the suffixes “-based” and “-assisted” may refer respectively to the node that is responsible for making the positioning calculation (and which may also provide measurements) and a node that provides measurements (but which may not make the positioning calculation). For example, an operation in which measurements are provided by a UE to a base station/positioning entity to be used in the computation of a position estimate may be described as “UE-assisted,” “UE-assisted positioning,” and/or “UE-assisted position calculation” while an operation in which a UE computes its own position may be described as “UE-based,” “UE-based positioning,” and/or “UE-based position calculation.”
In some examples, the term “TRP” may refer to one or more antennas of a base station whereas the term “base station” may refer to a complete unit (e.g., the base station 102/180) that includes aggregated or disaggregated components, such as described in connection with
For DL-AoD positioning, the positioning entity may use a beam report from the UE of received signal strength measurements of multiple downlink transmit beams to determine the angle(s) between the UE and the transmitting base station(s). The positioning entity may then estimate the location of the UE based on the determined angle(s) and the known location(s) of the transmitting base station(s).
Uplink-based positioning methods may include UL-TDOA and UL-AoA. UL-TDOA is similar to DL-TDOA, but is based on uplink reference signals (e.g., sounding reference signals (SRSs)) transmitted by the UE. For UL-AoA positioning, one or more base stations may measure the received signal strength of one or more uplink reference signals (e.g., SRSs) received from a UE on one or more uplink receive beams. The positioning entity may use the signal strength measurements and the angle(s) of the receive beam(s) to determine the angle(s) between the UE and the base station(s). Based on the determined angle(s) and the known location(s) of the base station(s), the positioning entity can then estimate the location of the UE.
Downlink-and-uplink-based positioning methods may include enhanced cell-ID (E-CID) positioning and multi-round-trip-time (RTT) positioning (also referred to as “multi-cell RTT”). In an RTT procedure, an initiator (a base station or a UE) transmits an RTT measurement signal (e.g., a PRS or SRS) to a responder (a UE or a base station), which transmits an RTT response signal (e.g., an SRS or a PRS) back to the initiator. The RTT response signal may include the difference between the ToA of the RTT measurement signal and the transmission time of the RTT response signal, referred to as the reception-to-transmission (Rx-Tx) time difference. The initiator may calculate the difference between the transmission time of the RTT measurement signal and the ToA of the RTT response signal, referred to as the transmission-to-reception (Tx-Rx) time difference. The propagation time (also referred to as the “time of flight”) between the initiator and the responder may be calculated from the Tx-Rx and Rx-Tx time differences. Based on the propagation time and the known speed of light, the distance between the initiator and the responder may be determined. For multi-RTT positioning, a UE may perform an RTT procedure with multiple base stations to enable its location to be determined (e.g., using multilateration) based on the known locations of the base stations. RTT and multi-RTT methods may be combined with other positioning techniques, such as UL-AoA and DL-AoD, to improve location accuracy.
The E-CID positioning method may be based on radio resource management (RRM) measurements. In E-CID, the UE may report the serving cell ID and the timing advance (TA), as well as the identifiers, estimated timing, and signal strength of detected neighbor base stations. The location of the UE is then estimated based on this information and the known locations of the base station(s).
To assist positioning operations, a location server (e.g., a location server, an LMF, or an SLP) may provide assistance data (AD) to the UE. For example, the assistance data may include identifiers of the base stations (or the cells/TRPs of the base stations) from which to measure reference signals, the reference signal configuration parameters (e.g., the number of consecutive positioning subframes, periodicity of positioning subframes, muting sequence, frequency hopping sequence, reference signal identifier, reference signal bandwidth, etc.), and/or other parameters applicable to the particular positioning method. Alternatively, the assistance data may originate directly from the base stations (e.g., in periodically broadcasted overhead messages, etc.). In some cases, the UE may be able to detect neighbor network nodes without the use of assistance data.
In the case of an OTDOA or DL-TDOA positioning procedure, the assistance data may further include an expected RSTD value and an associated uncertainty (e.g., a search space window) around the expected RSTD. In some cases, the value range of the expected RSTD may be plus-minus (+/−) 500 microseconds (μs). In some cases, when any of the resources used for the positioning measurement are in FR1, the value range for the uncertainty of the expected RSTD may be +/−32 μs. In other cases, when all of the resources used for the positioning measurement(s) are in FR2, the value range for the uncertainty of the expected RSTD may be +/−8 μs. In this context, “RSTD” may refer to one or more measurements indicative of a difference in time of arrival between a PRS transmitted by a base station, referred to herein as a “neighbor base station” or a “measuring base station,” and a PRS transmitted by a reference base station. A reference base station may be selected by a location server and/or by a UE to provide good or sufficient signal strength observed at a UE, such that a PRS may be more accurately and/or more quickly acquired and/or measured, such as without any special assistance from a serving base station.
A location estimate may also be referred to as a position estimate, location, position, position fix, fix, or the like. A location estimate may be geodetic and include coordinates (e.g., latitude, longitude, and possibly altitude) or may be civic and include a street address, postal address, or some other verbal description of a location. A location estimate may further be defined relative to some other known location or defined in absolute terms (e.g., using latitude, longitude, and possibly altitude). A location estimate may include an expected error or uncertainty (e.g., by including an area or volume within which the location is expected to be included with some specified or default level of confidence). For purposes of the present disclosure, reference signals may include PRS, tracking reference signals (TRS), phase tracking reference signals (PTRS), cell-specific reference signals (CRS), CSI-RS, demodulation reference signals (DMRS), PSS, SSS, SSBs, SRS, etc., depending on whether the illustrated frame structure is used for uplink or downlink communication. In some examples, a collection of resource elements (REs) that are used for transmission of PRS may be referred to as a “PRS resource.” The collection of resource elements may span multiple PRBs in the frequency domain and one or more consecutive symbol(s) within a slot in the time domain. In a given OFDM symbol in the time domain, a PRS resource may occupy consecutive PRBs in the frequency domain. In other examples, a “PRS resource set” may refer to a set of PRS resources used for the transmission of PRS signals, where each PRS resource may have a PRS resource ID. In addition, the PRS resources in a PRS resource set may be associated with a same TRP. A PRS resource set may be identified by a PRS resource set ID and may be associated with a particular TRP (e.g., identified by a TRP ID). In addition, the PRS resources in a PRS resource set may have a same periodicity, a common muting pattern configuration, and/or a same repetition factor across slots. The periodicity may be a time from a first repetition of a first PRS resource of a first PRS instance to the same first repetition of the same first PRS resource of the next PRS instance. For example, the periodicity may have a length selected from 2{circumflex over ( )}μ*{4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 160, 320, 640, 1280, 2560, 5120, 10240} slots, where μ=0, 1, 2, 3. The repetition factor may have a length selected from {1, 2, 4, 6, 8, 16, 32} slots. A PRS resource ID in a PRS resource set may be associated with a single beam (or beam ID) transmitted from a single TRP (where a TRP may transmit one or more beams). That is, each PRS resource of a PRS resource set may be transmitted on a different beam, and as such, a “PRS resource,” or simply “resource,” also can be referred to as a “beam.” In some examples, a “PRS instance” or “PRS occasion” may be one instance of a periodically repeated time window (such as a group of one or more consecutive slots) where PRS are expected to be transmitted. A PRS occasion also may be referred to as a “PRS positioning occasion,” a “PRS positioning instance,” a “positioning occasion,” “a positioning instance,” a “positioning repetition,” or simply an “occasion,” an “instance,” and/or a “repetition,” etc.
A positioning frequency layer (PFL) (which may also be referred to as a “frequency layer”) may be a collection of one or more PRS resource sets across one or more TRPs that have the same values for certain parameters. Specifically, the collection of PRS resource sets may have a same subcarrier spacing and cyclic prefix (CP) type (e.g., meaning all numerologies supported for PDSCHs are also supported for PRS), the same Point A, the same value of the downlink PRS bandwidth, the same start PRB (and center frequency), and/or the same comb-size, etc. The Point A parameter may take the value of a parameter ARFCN-ValueNR (where “ARFCN” stands for “absolute radio-frequency channel number”) and may be an identifier/code that specifics a pair of physical radio channel used for transmission and reception. In some examples, a downlink PRS bandwidth may have a granularity of four PRBs, with a minimum of 24 PRBs and a maximum of 272 PRBs. In other examples, up to four frequency layers may be configured, and up to two PRS resource sets may be configured per TRP per frequency layer.
The concept of a frequency layer may be similar to a component carrier (CC) and a BWP, where CCs and BWPs may be used by one base station (or a macro cell base station and a small cell base station) to transmit data channels, while frequency layers may be used by multiple (e.g., three or more) base stations to transmit PRS. A UE may indicate the number of frequency layers it is capable of supporting when the UE sends the network its positioning capabilities, such as during a positioning protocol session. For example, a UE may indicate whether it is capable of supporting one or four PFLs.
In other examples, a position of a UE may be estimated based on multiple antenna beam measurements, where a downlink angle of departure (DL-AoD) and/or uplink angle of arrival (UL-AoA) of transmissions between a UE and one or more TRPs may be used to estimate the position of the UE and/or the distance of the UE with respect to each TRP. For example, referring back to
In some examples, each symbol of the DL-PRS may be configured with a comb-structure in frequency, where the DL-PRS from a TRP of a base station may occupy every Nth subcarrier. The comb value N may be configured to be 2, 4, 6, or 12. The length of the PRS within one slot may be a multiple of N symbols and the position of the first symbol within a slot may be flexible as long as the slot consists of at least N PRS symbols. The diagram 500A shows an example of a comb-6 DL-PRS configuration, where the pattern for the DL-PRS from different TRPs may be repeated after six (6) symbols.
Note that the terms “positioning reference signal” and “PRS” generally refer to specific reference signals that are used for positioning in NR and LTE systems. However, as used herein, the terms “positioning reference signal” and “PRS” may also refer to any type of reference signal that can be used for positioning, such as but not limited to, PRS as defined in LTE and NR, TRS, PTRS, CRS, CSI-RS, DMRS, PSS, SSS, SSB, SRS, UL-PRS, etc. In addition, the terms “positioning reference signal” and “PRS” may refer to downlink or uplink positioning reference signals, unless otherwise indicated by the context. If needed to further distinguish the type of PRS, a downlink positioning reference signal may be referred to as a “DL-PRS,” and an uplink positioning reference signal (e.g., an SRS-for-positioning, PTRS) may be referred to as an “UL-PRS.” In addition, for signals that may be transmitted in both the uplink and downlink (e.g., DMRS, PTRS), the signals may be prepended with “UL” or “DL” to distinguish the direction. For example, “UL-DMRS” may be differentiated from “DL-DMRS.”
At 710, an LMF 706 may request one or more positioning capabilities from a UE 702 (e.g., from a target device). In some examples, the request for the one or more positioning capabilities from the UE 702 may be associated with an LTE Positioning Protocol (LPP). For example, the LMF 706 may request the positioning capabilities of the UE 702 using an LPP capability transfer procedure.
At 712, the LMF 706 may request UL SRS configuration information for the UE 702. The LMF 706 may also provide assistance data specified by a serving base station 704 (e.g., pathloss reference, spatial relation, and/or SSB configuration(s), etc.). For example, the LMF 706 may send an NR Positioning Protocol A (NRPPa) positioning information request message to the serving base station 704 to request UL information for the UE 702.
At 714, the serving base station 704 may determine resources available for UL SRS, and at 716, the serving base station 704 may configure the UE 702 with one or more UL SRS resource sets based on the available resources.
At 718, the serving base station 704 may provide UL SRS configuration information to the LMF 706, such as via an NRPPa positioning information response message.
At 720, the LMF 706 may select one or more candidate neighbor BSs/TRPs 708, and the LMF 706 may provide an UL SRS configuration to the one or more candidate neighbor BSs/TRPs 708 and/or the serving base station 704, such as via an NRPPa measurement request message. The message may include information for enabling the one or more candidate neighbor BSs/TRPs 708 and/or the serving base station to perform the UL measurements.
At 722, the LMF 706 may send an LPP provide assistance data message to the UE 702. The message may include specified assistance data for the UE 702 to perform the DL measurements.
At 724, the LMF 706 may send an LPP request location information message to the UE 702 to request multi-RTT measurements.
At 726, for semi-persistent or aperiodic UL SRS, the LMF 706 may request the serving base station 704 to activate/trigger the UL SRS in the UE 702. For example, the LMF 706 may request activation of UE SRS transmission by sending an NRPPa positioning activation request message to the serving base station 704.
At 728, the serving base station 704 may activate the UE SRS transmission and send an NRPPa positioning activation response message. In response, the UE 702 may begin the UL-SRS transmission according to the time domain behavior of UL SRS resource configuration.
At 730, the UE 702 may perform the DL measurements from the one or more candidate neighbor BSs/TRPs 708 and/or the serving base station 704 provided in the assistance data. At 732, each of the configured one or more candidate neighbor BSs/TRPs 708 and/or the serving base station 704 may perform the UL measurements.
At 734, the UE 702 may report the DL measurements to the LMF 706, such as via an LPP provide location information message.
At 736, each of the one or more candidate neighbor BSs/TRPs 708 and/or the serving base station 704 may report the UL measurements to the LMF 706, such as via an NRPPa measurement response message.
At 738, the LMF 706 may determine the RTTs from the UE 702 and BS/TRP Rx-Tx time difference measurements for each of the one or more candidate neighbor BSs/TRPs 708 and/or the serving base station 704 for which corresponding UL and DL measurements were provided at 734 and 736, and the LMF 706 may calculate the position of the UE 702.
In addition to network-based UE positioning technologies, a wireless device (e.g., a base station, a UE, etc.) may also be configured to include radar capabilities, which may be referred to as “radio frequency (RF) sensing” and/or “cellular-based RF sensing.” For example, a wireless device may transmit radar reference signals (RRSs) and measure the RRSs reflected from one or more objects. Based at least in part on the measurement, the wireless device may determine or estimate a distance between the wireless device and the one or more objects based. In another example, a first wireless device may also receive RRSs transmitted from one or more wireless devices, where the first wireless device may determine or estimate a distance between the first wireless device and one or more wireless devices based at least in part on the received RRS. As such, in some examples, RF sensing techniques may be used for UE positioning and/or for assisting UE positioning.
After a chirp signal (e.g., chirp signal 802, 810, 812, etc.) is transmitted by the wireless device 803, the transmitted chirp signal may reach the object 820 and reflect back to the wireless device 803, such as shown by the reflected chirp signals 814, 816, and 818, which may correspond to the transmitted chirp signals 802, 810, and 812, respectively. As there may be a distance between the wireless device 803 and the object 820 and/or it may take time for a transmitted chirp signal to reach the object 820 and reflect back to the wireless device 803, a delay may exist between a transmitted chirp signal and its corresponding reflected chirp signal. The delay may be proportional to a range between the wireless device 803 and the object 820 (e.g., the further the target, the larger the delay and vice versa). Thus, the wireless device 803 may be able to measure or estimate a distance between the wireless device 803 and the object 820 based on the delay.
In some examples, the wireless device 803 may also measure a difference in frequency between the transmitted chirp signal and the reflected chirp signal, which may also be proportional to the distance between the wireless device 803 and the object 820. In other words, as the frequency difference between the reflected chirp signal and the transmitted chirp signal increases with the delay, and the delay is linearly proportional to the range, the distance of the object 820 from the wireless device 803 may also be determined based on the difference in frequency. Thus, the reflected chirp signal from the object 820 may be mixed with the transmitted chirp signal and down-converted to produce a beat signal (fb) which may be linearly proportional to the range after demodulation. For example, the wireless device 803 may determine a beat signal 822 by mixing the transmitted chirp signal 802 and its corresponding reflected chirp signal 814. While examples in the diagram illustrate using an FMCW waveform for the RRSs, other types of radar waveforms may also be used by the wireless device 803 for the RRSs.
Due to an increased amount of bandwidth (BW) being allocated for cellular communications systems (e.g., 5G and beyond) and an increased amount of applications (e.g., use cases) being introduced with cellular communications systems, joint communication and RF sensing may become an important feature for cellular systems. For example, a wireless device (e.g., a base station, a TRP, a UE, etc.) may be configured to transmit communication signals with radar signals together or simultaneously. In addition, OFDM waveform (or its variants) may likely be considered as the waveform for joint communication/RF sensing as the OFDM waveform may enable in-band multiplexing with other cellular reference signals and physical channels. As such, the radar signals may be multiplexed with communication signals based on OFDM waveform. For purposes of the present disclosure, a wireless device that performs an RF sensing based on OFDM waveform(s) or transmits RRS based on OFDM waveform(s) may be referred to as an “OFDM radar.”
An OFDM radar may provide a large degree of flexibility in waveform choices, which may enable communication and radar capabilities to be combined by embedding communication information into the radar waveform. In some examples, OFDM waveforms may be used for digital or software-defined radar that may be independent of the communication aspect. In addition, for many OFDM radar applications, unlike the OFDM waveforms used by a UE or a base station for communications, the OFDM waveforms used by the OFDM radar applications may not include a cyclic prefix (CP) or a sufficiently long CP. Thus, these OFDM radar waveforms may sometimes be treated as different kinds of radar waveforms by a receiver, and the receiver may receive or monitor these OFDM radar waveforms based on matched filtering. Matched filtering may refer to a process for detecting a known piece of signal or wavelet that is embedded in noise. As such, an OFDM waveform may be a natural waveform option for joint communication and RF sensing for future wireless communications as it may enable in-band multiplexing with other cellular reference signals and physical (PHY) channels.
A CP may refer to a set of samples that are duplicated (e.g., copied and pasted) from the end of each transmitted symbol to its beginning. In addition, the CP may function as a guard interval that may be used for eliminating inter-symbol interference (ISI) (e.g., interference between transmitting data via multiple symbols), such as without using additional hardware. Thus, when there is sufficient CP insertion (or CP duration) in an OFDM waveform, an ISI channel may be converted into multiple ISI-free subchannels in a wireless communications system. Similarly, or analogously, a sufficient CP insertion may also enable an inter-range-cell interference (IRCI)-free (high range resolution) RF sensing for radar systems. For example, by using a sufficient CP, the IRCI-free and ideally zero range sidelobes for range reconstruction may be obtained, which may provide an opportunity for high range resolution synthetic aperture radar (SAR) imaging. In other words, OFDM signals with a sufficient CP may be used for solving IRCI-related problems. For purposes of the present disclosure, a range resolution may refer to the capability of a radar system to distinguish or resolve nearby adjacent target(s) or different parts of one target in the range. The degree of range resolution may depend on the width of the transmitted pulse, the types and sizes of targets, and the efficiency of the receiver and indicator, etc.
To achieve IRCI-free RF sensing for an OFMD waveform, the CP length Tcp for the OFDM waveform may be specified to be greater than or equal to the time delay difference (To) from a first range cell of a tracking zone to a last range cell of the tracking zone (e.g., satisfy Tcp≥To). A range cell may refer to the smallest range increment a radar is capable of detecting, and a range (for a radar) may refer to the length of a straight line between the radar and a target. For example, if a radar has a range resolution of 1 yard and a total range of 100 yards, then there may be 100 range cells (e.g., 100/1=100).
where c may be the speed of light, B may be the bandwidth of a radar signal, M may be the number of range cells in the tracking zone, and R may be the range solution that is obtained based on R=c/(2B). In one example, to minimize unnecessary transmission energy, and without loss of generality, the CP length of an OFDM form may be chosen to be equal to the time delay difference (e.g., Tcp=To). Note for MIMO OFDM radars, the minimum CP duration may also be considered for the maximal relative time delay difference among all the transmitter and receiver pairs. For most target detections, the CP design for communication based on OFDM waveforms is likely to be greater than or equal to the time delay difference (To). In other words, for regular targets, the existing CP OFDM design for communication may meet the specifications for achieving the IRCI-free RF sensing.
To reduce unnecessary signal transmissions and/or receptions, and also to achieve energy/power saving at radar transmitters/receivers (e.g., UEs, base stations, TRPs, RF sensing nodes, etc.), aspects presented herein provide flexible OFDM waveform designs for joint communication and RF sensing. For example, aspects presented herein may enable the symbol duration and/or the CP duration of an RF sensing signal to be flexibly configured, such that OFDM symbols used for RF sensing may be different from OFDM symbols used for communications. As different RF sensing scenarios may have different specifications on sensing signal symbol duration and CP duration (e.g., the CP and symbol duration may determine the unambiguity monostatic sensing range), a more flexible OFDM waveform configuration may enable a radar transmitter to transmit RF sensing signals using different OFDM waveforms based on the scenarios. In addition, as there may be a bandwidth switch and/or a beam switch between RF sensing signals and communication signals that may introduce some switch latency, a more flexible OFDM waveform configuration may enable a radar transmitter to utilize the switching symbol for RF sensing signals or communication signals if the switching delay is larger than CP. Aspects presented herein also provides slot-level alignment between sensing OFDM signals and communications OFDM signals. In some examples, symbol-level alignment may also be provided for a uniform transceiver design.
For example, as shown by the diagram 1000, an RF sensing symbol 1002 may include a first portion 1004 (may be referred to as a “RF sensing window” hereafter) that is configured for transmitting RF sensing signals (e.g., RRSs) and a second portion 1006 (may be referred to as a “receive time window” hereafter) that is configured for receiving/monitoring the reflected RF sensing signals. Thus, a wireless device configured with the RF sensing symbol 1002 may use the first portion 1004 of the RF sensing symbol 1002 for transmitting RF sensing signals, and the wireless device may use the second portion 1006 for receiving or monitoring the reflected RF sensing signals. The wireless device may also be configured to refrain from transmitting during the second portion 1006 of the RF sensing symbol 1002. For example, there may be no signals scheduled for the second portion 1006 of the RF sensing symbol 1002, where zeros (e.g., zero paddings) may be padded during the second portion 1006, and/or the transmitter(s) of the wireless device may be turned off or switch to an idle/inactive mode, etc.
In some examples, the RF sensing symbol 1002 may be suitable for short-range mono-static RF sensing, where the symbol duration for RF sensing signals may be short. The mono-static RF sensing may refer to a wireless device that both transmits the RF sensing signals and receive the reflected RF sensing signals. For example, a mono-static radar may be a radar in which the transmitter(s) and receiver(s) of the radar are collocated. Thus, if the RF sensing is mono-static based sensing, the first portion 1004 and the second portion 1006 (e.g., the receive time window) may be jointly configured in the same symbol.
In another aspect, the duration of a CP 1008 that is associated with the RF sensing symbol 1002 may also be flexibly configured, and the duration of the CP 1008 may be shorter compared to a CP 1012 that is associated with the communication symbol 1010. In addition, the duration of the CP 1008 may also be optimized for the RF sensing, where the duration of the CP 1008 (Tcp) may be configured to be greater than or equal to the time delay difference (To) from a first range cell of a tracking zone to a last range cell of the tracking zone (e.g., Tcp≥To), such as described in connection with
where c may be the speed of light, B may be the bandwidth of a radar signal, M may be the number of range cells in the tracking zone, and R may be the range solution that is obtained based on R=c/(2B). In one example, to minimize transmission energy, the CP 1008 (Tcp) may be chosen to be equal to the time delay difference (e.g., Tcp=To). In another example, the duration of the second portion 1006 may be configured to be greater than the first portion 1004 (e.g., the receive time window>RF sensing window+To).
In some examples, a different subcarrier spacing (SCS) may be configured for the RF sensing symbol 1002 within a slot, where the slot may include both sensing symbol(s) and communication symbol(s), such as shown by the diagram 1000. For example, the communication symbol 1010 may be configured with a first SCS that provides a longer/shorter duration for a symbol, and the RF sensing symbol may be configured with a second (and different) SCS that provides a shorter/longer duration for a symbol, etc.
In another aspect of the present disclosure, an OFDM symbol without CP (may be referred to as a “switch symbol,” a “zero CP OFDM symbol/waveform,” or simply a “zero CP symbol/waveform” hereafter) may be configured for RF sensing and communications.
For example, as shown by the diagram 1100, a zero CP symbol 1102 may include a first switch time duration 1104 (e.g., Switch time 1) that is configured for the wireless device to perform a first antenna/beam switching, such as switching from antenna(s)/beam(s) used for communication to antenna(s)/beam(s) used for RF sensing or switching from antenna(s)/beam(s) used for RF sensing to antenna(s)/beam(s) used for communication, etc. In addition, the zero CP symbol 1102 may further include a second switch time duration 1106 (e.g., Switch time 2) that is configured for the wireless device to perform a second antenna/beam switching (e.g., between communication and RF sensing antennas/beams). In some examples, the wireless device may also be configured to refrain from transmitting/receiving during the first switch time duration 1104 and the second switch time duration 1106 of the zero CP symbol 1102. For example, there may be no signals scheduled for the first switch time duration 1104 and the second switch time duration 1106 of the zero CP symbol 1102, where zeros (e.g., zero paddings) may be padded during the first switch time duration 1104 and the second switch time duration 1106. In addition, the wireless device may also perform a fast Fourier transform (FFT) operation during at least one of the first switch time duration 1104 or the second switch time duration 1106.
In some examples, the zero CP symbol 1102 may also include a fractional symbol 1108 between the first switch time duration 1104 and the second switch time duration 1106, where the fractional symbol 1108 may be used by the wireless device for communication (e.g., transmitting or receiving data) or for RF sensing (e.g., for transmitting or receiving RRSs). In other words, the non-zero portion (e.g., the fractional symbol 1108) of the zero CP symbol 1102 may still be used for carrying RF sensing signals or communication signals. As such, based on detecting the waveform of the zero CP symbol 1102, the wireless device may determine to use the zero CP symbol 1102 to perform at least one antenna/beam switching.
In addition, the length of the first switch time duration 1104 and/or the length of the second switch time duration 1106 (e.g., number of zero paddings in the zero CP symbol 1102 (or a switch symbol)) may depend on the antenna/beam switch delay associated with the wireless device. As such, the wireless device may be configured to report its antenna/beam switch delay to a network entity (e.g., a location server, an LMF, and/or a serving base station, etc.). For example, a UE may report to a base station regarding its antenna/beam switch delay time, and in response, a serving base station may configure a zero CP symbol for the UE that includes at least one switch time (e.g., the first switch time duration 1104 and/or the second switch time duration 1106) that is greater than or equal to the antenna/beam switch delay reported by the UE.
In some examples, as shown by diagram 1200 of
If the wireless device reports both the antenna/beam switch delay, as described in connection with
In some scenarios, the wireless device may be configured to signal the planned time (or instance) for the antenna/beam or bandwidth switch, which may include a system frame number (SFN), a slot index, or a symbol index for switching the antenna/beam or the bandwidth. In addition, the wireless device may also indicate whether the antenna/beam switch or bandwidth switch is to be performed at the beginning of the zero CP symbol 1102, at the end of the zero CP symbol 1102, or both.
In another example, the beam/antenna switch duration and/or the bandwidth switch duration (e.g., the length of the first switch time duration 1104 and/or the length of the second switch time duration 1106) may be predefined (e.g., based on a table) for the wireless device. Then, the wireless device may indicate the index of switch duration being used. For example, a first index may correspond to a first switch duration, a second index may correspond to a second switch duration, and a third index may correspond to a third switch duration, etc. If the wireless device is specified to use the second switch duration to perform the antenna/beam switch and/or the bandwidth switch, the wireless device may signal the second index to the network entity/base station. In other words, the wireless device may signal the expected (or maximum) switch duration for a specific switch.
In another aspect of the present disclosure, if the wireless device (e.g., the RF sensing node) is a UE, configuration(s) for the flexible waveform described in connection with
On the other hand, if the wireless device is a base station, the flexible waveform configuration may be signaled to the base station through upper layer signaling. For example, the positioning protocol such as NRPPA (e.g., as described in connection with
At 1302, the RF sensing node may transmit an RF sensing signal in a first time duration of a symbol in an RF sensing session, such as described in connection with
At 1304, the RF sensing node may monitor for a reflected RS sensing signal in a second time duration of the symbol that does not overlap with the first time duration, the symbol including a CP that does not overlap with the first time duration and the second time duration, such as described in connection with
In one example, the RF sensing node may refrain from transmitting any signals during the second time duration.
In another example, the second time duration may include a set of zero paddings.
In another example, the RF sensing signal may correspond to an OFDM waveform.
In another example, the RF sensing node may be a base station (or TRP of a base station) or a UE.
In another example, the CP has a length (Tcp) that is greater than or equal to a time delay difference (To) between a first range cell of a tracking zone and a last range cell of the tracking zone, and the time delay difference (To) is calculated based on: To=2 (M−1)R/c=(M−1)/B, where c is a speed of light, B is a bandwidth of the RF sensing signal, M is a number of range cells in the tracking zone, and R is a range solution obtained based on R=c/(2B).
In another example, the first time duration may be shorter than the second time duration.
In another example, the second time duration may be longer than the first time duration plus the CP.
In another example, the RF sensing session may be based on a mono-static sensing.
In another example, the symbol may be a sensing symbol of a slot that includes one or more sensing symbols and one or more communication symbols. In such an example, the one or more sensing symbols may have a different SCS than the one or more communication symbols.
The communication manager 1432 includes an RF sensing signal configuration component 1440 that transmits an RF sensing signal in a first time duration of a symbol in an RF sensing session, e.g., as described in connection with 1302 of
The apparatus may include additional components that perform each of the blocks of the algorithm in the flowchart of
As shown, the apparatus 1402 may include a variety of components configured for various functions. In one configuration, the apparatus 1402, and in particular the baseband unit 1404, includes means for transmitting an RF sensing signal in a first time duration of a symbol in an RF sensing session (e.g., the RF sensing signal configuration component 1440 and/or the transmission component 1434). The apparatus 1402 includes means for monitoring for a reflected RS sensing signal in a second time duration of the symbol that does not overlap with the first time duration, the symbol including a CP that does not overlap with the first time duration and the second time duration (e.g., the reflected RF sensing signal process component 1442 and/or the reception component 1430).
In one configuration, the RF sensing node may refrain from transmitting any signals during the second time duration.
In another configuration, the second time duration may include a set of zero paddings.
In another configuration, the RF sensing signal may correspond to an OFDM waveform.
In another configuration, the RF sensing node may be a base station (or TRP of a base station) or a UE.
In another configuration, the CP has a length (Tcp) that is greater than or equal to a time delay difference (To) between a first range cell of a tracking zone and a last range cell of the tracking zone, and the time delay difference (To) is calculated based on: To=2 (M−1) R/c=(M−1)/B, where c is a speed of light, B is a bandwidth of the RF sensing signal, M is a number of range cells in the tracking zone, and R is a range solution obtained based on R=c/(2B).
In another configuration, the first time duration may be shorter than the second time duration.
In another configuration, the second time duration may be longer than the first time duration plus the CP.
In another configuration, the RF sensing session may be based on a mono-static sensing.
In another configuration, the symbol may be a sensing symbol of a slot that includes one or more sensing symbols and one or more communication symbols. In such a configuration, the one or more sensing symbols may have a different SCS than the one or more communication symbols.
The means may be one or more of the components of the apparatus 1402 configured to perform the functions recited by the means. As described supra, the apparatus 1402 may include the TX Processor 316, the RX Processor 370, and the controller/processor 375. As such, in one configuration, the means may be the TX Processor 316, the RX Processor 370, and the controller/processor 375 configured to perform the functions recited by the means.
At 1502, the RF sensing node may switch between a communication mode and an RF sensing mode during a first time duration of a symbol, the symbol not including a CP, such as described in connection with
At 1504, the RF sensing node may transmit or receive an RF sensing signal based on the RF sensing mode or a communication message based on the communication mode during a second time duration of the symbol, such as described in connection with
At 1506, the RF sensing node may switch between the communication mode and the RF sensing mode during a third time duration of the symbol, the first time duration, the second time duration, and the third time duration not overlapping with each other, such as described in connection with
In one example, the communication mode may be associated with transmitting or receiving communication data and the RF sensing mode may be associated with a radar operation.
In another example, the first time duration and the third time duration may include zero paddings. In such an example, a number of zero paddings may be configured based on a switching delay associated with the RF sensing node.
In another example, the RF sensing node may perform an FFT operation during at least one of the first time duration or the third time duration.
In another example, the RF sensing signal corresponds to an OFDM waveform.
In another example, the RF sensing node may be a base station or a UE.
In another example, to switch between the communication mode and the RF sensing mode, the RF sensing node may switch between at least one first beam associated with the communication mode or the RF sensing node and at least one second beam associated with the communication mode or the RF sensing mode. In such an example, the RF sensing node may transmit, to a network entity or a base station, a beam switch time associated with switching between the at least one first beam and the at least one second beam, where the beam switch time may include one or more of an SFN, a slot index, or a symbol index for switching between the at least one first beam and the at least one second beam.
In another example, to switch between the communication mode and the RF sensing mode, the RF sensing node may switch between a first bandwidth associated with the communication mode or the RF sensing mode and a second bandwidth associated with the communication mode or the RF sensing mode. In such an example, the RF sensing node may transmit, to a network entity or a base station, a bandwidth switch time associated with switching between the first bandwidth and the second bandwidth, where the bandwidth switch time may include one or more of an SFN, a slot index, or a symbol index for switching between the first bandwidth and the second bandwidth.
In another example, the RF sensing node may transmit, to a network entity (e.g., a location server or LMF) or a base station, an indication of the first time duration and the third time duration, and receive, from the network entity or the base station, a configuration to switch between the communication mode and the RF sensing mode during the first time duration and the third time duration.
In another example, the RF sensing node may transmit, to a network entity (e.g., a location server or LMF) or a base station, an indication of whether the RF sensing node switches between the communication mode and the RF sensing mode during the first time duration, during the third time duration, or during both the first time duration and the third time duration.
In another example, the first time duration and the third time duration may be based on a defined table that includes a maximum value and a minimum value for each of the first time duration and the third time duration.
In another example, if the RF sensing node is a UE, the RF sensing node may receive, from a base station, a configuration for the symbol via at least one of DCI, an RRC message, or a MAC-CE. In such an example, the configuration may further be associated with a BWP configuration.
In another example, if the RF sensing node is a base station, the RF sensing node may receive, via upper layer signaling, a configuration for the symbol.
The communication manager 1632 includes a communication and RF sensing switch component 1640 that switches between a communication mode and an RF sensing mode during a first time duration of a symbol, the symbol not including a CP, and switches between the communication mode and the RF sensing mode during a third time duration of the symbol, the first time duration, the second time duration, and the third time duration not overlapping with each other, e.g., as described in connection with 1502 and 1506 of
The apparatus may include additional components that perform each of the blocks of the algorithm in the flowchart of
As shown, the apparatus 1602 may include a variety of components configured for various functions. In one configuration, the apparatus 1602, and in particular the baseband unit 1604, includes means for switching between a communication mode and an RF sensing mode during a first time duration of a symbol, the symbol not including a CP (e.g., the communication and RF sensing switch component 1640, the reception component 1630, and/or the transmission component 1634). The apparatus 1602 includes means for transmitting or receiving an RF sensing signal based on the RF sensing mode or a communication message based on the communication mode during a second time duration of the symbol (e.g., the signal configuration component 1642, the reception component 1630, and/or the transmission component 1634). The apparatus 1602 includes means for switching between the communication mode and the RF sensing mode during a third time duration of the symbol, the first time duration, the second time duration, and the third time duration not overlapping with each other (e.g., the communication and RF sensing switch component 1640, the reception component 1630, and/or the transmission component 1634).
In one configuration, the communication mode may be associated with transmitting or receiving communication data and the RF sensing mode may be associated with a radar operation.
In another configuration, the first time duration and the third time duration may include zero paddings. In such a configuration, a number of zero paddings may be configured based on a switching delay associated with the RF sensing node.
In another configuration, the RF sensing node may perform an FFT operation during at least one of the first time duration or the third time duration.
In another configuration, the RF sensing signal corresponds to an OFDM waveform.
In another configuration, the RF sensing node may be a base station or a UE.
In another configuration, to switch between the communication mode and the RF sensing mode, the apparatus 1602 includes means for switching between at least one first beam associated with the communication mode or the RF sensing node and at least one second beam associated with the communication mode or the RF sensing mode. In such a configuration, the apparatus 1602 includes means for transmitting, to a network entity or a base station, a beam switch time associated with switching between the at least one first beam and the at least one second beam, where the beam switch time includes one or more of an SFN, a slot index, or a symbol index for switching between the at least one first beam and the at least one second beam.
In another configuration, to switch between the communication mode and the RF sensing mode, the apparatus 1602 includes means for switching between a first bandwidth associated with the communication mode or the RF sensing mode and a second bandwidth associated with the communication mode or the RF sensing mode. In such a configuration, the apparatus 1602 includes means for transmitting, to a network entity or a base station, a bandwidth switch time associated with switching between the first bandwidth and the second bandwidth, where the bandwidth switch time includes one or more of an SFN, a slot index, or a symbol index for switching between the first bandwidth and the second bandwidth.
In another configuration, the apparatus 1602 includes means for transmitting, to a network entity or a base station, an indication of the first time duration and the third time duration, and means for receiving, from the network entity of the base station, a configuration to switch between the communication mode and the RF sensing mode during the first time duration and the third time duration.
In another configuration, the apparatus 1602 includes means for transmitting, to a network entity or a base station, an indication of whether the RF sensing node switches between the communication mode and the RF sensing mode during the first time duration, during the third time duration, or during both the first time duration and the third time duration.
In another configuration, the first time duration and the third time duration may be based on a defined table that includes a maximum value and a minimum value for each of the first time duration and the third time duration.
In another configuration, if the RF sensing node is a UE, the apparatus 1602 includes means for receiving, from a base station, a configuration for the symbol via at least one of DCI, an RRC message, or a MAC-CE. In such a configuration, the configuration may further be associated with a BWP configuration.
In another configuration, if the RF sensing node is a base station, the apparatus 1602 includes means for receiving, via upper layer signaling, a configuration for the symbol.
The means may be one or more of the components of the apparatus 1602 configured to perform the functions recited by the means. As described supra, the apparatus 1602 may include the TX Processor 316, the RX Processor 370, and the controller/processor 375. As such, in one configuration, the means may be the TX Processor 316, the RX Processor 370, and the controller/processor 375 configured to perform the functions recited by the means.
It is understood that the specific order or hierarchy of blocks in the processes/flowcharts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes/flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Terms such as “if,” “when,” and “while” should be interpreted to mean “under the condition that” rather than imply an immediate temporal relationship or reaction. That is, these phrases, e.g., “when,” do not imply an immediate action in response to or during the occurrence of an action, but simply imply that if a condition is met then an action will occur, but without requiring a specific or immediate time constraint for the action to occur. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”
The following aspects are illustrative only and may be combined with other aspects or teachings described herein, without limitation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20210100887 | Dec 2021 | GR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/048873 | 11/3/2022 | WO |
