Method and apparatus for frequency synchronization communication

Abstract

The present disclosure relates to methods and apparatus for wireless communication at a wireless device or an integrated access and backhaul (IAB) node. In one aspect, the wireless device may determine a frequency synchronization accuracy of the wireless device. The wireless device may also transmit an indication of the determined frequency synchronization accuracy of the wireless device. Additionally, the wireless device may determine an absolute frequency based on a combination of measurements from at least one synchronization source and a frequency of the wireless device, wherein the frequency synchronization accuracy is based on the absolute frequency.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 937,186, filed on November 18, 2019, entitled “METHODS AND APPARATUS FOR FREQUENCY SYNCHRONIZATION COMMUNICATION,” and U.S. Patent Application No. 17 / 001,313, filed on August 24, 2020, entitled “METHODS AND APPARATUS FOR FREQUENCY SYNCHRONIZATION COMMUNICATION,” all of which are expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to communication systems and, more particularly, to wireless communications including synchronization. Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. 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.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide common protocols that enable different wireless devices to communicate at city, country, region, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is a part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5GNR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Some aspects of 5G NR can be based on 4G Long Term Evolution (LTE) standards. There is a need for further improvements to 5G NR technology. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define 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 a more detailed description that will be presented later.

[0007] An integrated access and backhaul (IAB) network may include multiple cells communicating with each other to provide an access network and a backhaul network to a core network.

[0008] In one aspect of the present disclosure, a method, a computer readable medium, and an apparatus are provided. The apparatus may be a wireless device. In some aspects, the wireless device may determine a frequency synchronization accuracy of the wireless device. The wireless device may also transmit an indication of the determined frequency synchronization accuracy of the wireless device. Additionally, the wireless device may determine an absolute frequency based on a combination of measurements from at least one synchronization source and a frequency of the wireless device, wherein the frequency synchronization accuracy is based on the absolute frequency.

[0009] In another aspect of the present disclosure, a method, a computer readable medium, and an apparatus are provided. The apparatus may be a first wireless device. In some aspects, the first wireless device may receive an indication of frequency synchronization accuracy of a second wireless device. The first wireless device may also perform frequency synchronization based on the frequency of the second wireless device and using the indication of frequency synchronization accuracy of the second wireless device.

[0010] In another aspect of the present disclosure, a method, a computer readable medium, and an apparatus are provided. The apparatus may be a central entity in a wireless device network. In some aspects, the central entity may receive an indication of frequency synchronization accuracy from each of a plurality of wireless devices. The central entity may also send frequency synchronization accuracy information about each of the plurality of wireless devices.

[0011] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are merely indicative of several of the various ways in which the principles of the various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0013] Figure 2A , 2B, 2C, and 2D are diagrams illustrating examples of a first 5G / NR frame, a DL channel within a 5G / NR subframe, a second 5G / NR frame, and a UL channel within a 5G / NR subframe, respectively.

[0014] Figure 3 is a diagram illustrating an example of an IAB node and a user equipment (UE) in a network.

[0015] Figure 4 is a diagram illustrating an example IAB network.

[0016] Figure 5 is a diagram illustrating an example IAB network and its components.

[0017] Figure 6 is a diagram illustrating an example call flow between various IAB nodes.

[0018] Figure 7 is a flow chart of a wireless communication method.

[0019] Figure 8 is a conceptual data flow diagram illustrating the flow of data between different devices / components in an example device.

[0020] Fig. 9 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

[0021] Fig.10 is a flow chart of a wireless communication method.

[0022] Fig.11 is a conceptual data flow diagram illustrating the flow of data between different devices / components in an example device.

[0023] Fig.12 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

[0024] Fig.13 is a flow chart of a wireless communication method.

[0025] Fig.14 is a conceptual data flow diagram illustrating the flow of data between different devices / components in an example arrangement.

[0026] Fig.15 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system. DETAILED DESCRIPTION

[0027] The detailed description set forth below in conjunction with the accompanying 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. This detailed description includes specific details to provide a thorough understanding of the 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 diluting such concepts.

[0028] 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 on the specific application and the design constraints imposed on the overall system.

[0029] As an example, an element, or any part of an element, or any combination of elements may be implemented as a "processing system" including 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 chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform various functionalities described throughout this disclosure. One or more processors in a processing system may execute software. Software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether it is described in software, firmware, middleware, microcode, hardware description languages, or other terms.

[0030] Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, these functions may be stored or encoded on a computer-readable medium as one or more instructions or codes. Computer-readable media include computer storage media. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the above types, or any other medium that may be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0031] Figure 1 1 is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0032] The base station 102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with the EPC 160 via a first backhaul link 132 (e.g., an S1 interface). The base station 102 configured for 5G NR (collectively referred to as the Next Generation RAN (NG-RAN)) can interface with the core network 190 via a second backhaul link 184. Among other functions, the base station 102 can also perform one or more of the following functions: delivery of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (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 (eg, through the EPC 160 or the core network 190) over a third backhaul link 134 (eg, an X2 interface). The first backhaul link 132, the second backhaul link 184, and the third backhaul link 134 may be wired or wireless.

[0033] Base stations 102 may communicate wirelessly with UEs 104. Each base station 102 may provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved B node (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). A communication link 120 between a base station 102 and a UE 104 may include an uplink (UL) (also referred to as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may be through one or more carriers. The base station 102 / UE 104 may use spectrum of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) bandwidth for each carrier allocated in the carrier aggregation for a total of up to Yx MHz (x component carriers) for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0034] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use 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). The D2D communication may be through a variety of wireless D2D communication 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.

[0035] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

[0036] The small cell 102' may operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may boost the coverage of the access network and / or increase the capacity of the access network.

[0037] Whether a small cell 102' or a large cell (e.g., a macro base station), the base station 102 may include and / or be referred to as an eNB, a gB node (gNB), or another type of base station. Some base stations (such as gNB 180) may operate in traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 mm and 10 mm. The radio waves in this band may be referred to as millimeter waves. Near mmW can extend down to 3 GHz frequencies with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, which is also referred to as centimeter waves. The frequency range bands include frequency range 1 (FR1), which includes frequency bands below 7.225 GHz, and frequency range 2 (FR2), which includes frequency bands above 24.250 GHz. Communications using mmW / near mmW radio frequency (RF) bands (e.g., 3 GHz–300 GHz) have extremely high path loss and short range. The base station / UE may operate within one or more frequency range bands. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range. The base station 180 and the UE 104 may each include multiple antennas, such as antenna elements, antenna panels, and / or antenna arrays to facilitate beamforming.

[0038] Base station 180 may transmit beamformed signals to UE 104 in one or more transmit directions 182'. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182". UE 104 may also transmit beamformed signals to base station 180 in one or more transmit directions. Base station 180 may receive beamformed signals from UE 104 in one or more receive directions. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit direction and receive direction of base station 180 may be the same or may be different. The transmit direction and receive direction of UE 104 may be the same or may be different.

[0039] 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 a control node that handles signaling between the UE 104 and the EPC 160. In general, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to 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 functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, 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 base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and for collecting eMBMS-related charging information.

[0040] 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 a control node that handles signaling between the UE 104 and the core network 190. In general, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are delivered through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a packet switching (PS) streaming (PSS) service, and / or other IP services.

[0041] A base station may include and / or be referred to as a gNB, a Node B, an 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 transmission reception point (TRP), or some other suitable term. In an IAB network, a base station may also be an IAB node 103. The base station 102 provides an access point for UE 104 to the EPC 160 or the core network 190. Examples of UE 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., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a health care device, an implant, a sensor / actuator, a display, or any other similar functional device. Some UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, ovens, vehicles, heart monitors, etc.) 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 communication 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.

[0042] Refer again Figure 1In certain aspects, a wireless device (e.g., an IAB node 103) may include a determining component 198 configured to determine a frequency synchronization accuracy of the wireless device. The determining component 198 may also be configured to transmit an indication of the determined frequency synchronization accuracy of the wireless device. The determining component 198 may also be configured to determine an absolute frequency based on a combination of measurements from at least one synchronization source and the frequency of the wireless device, wherein the frequency synchronization accuracy may be based on the absolute frequency.

[0043] Refer again Figure 1 In certain aspects, the first wireless device (e.g., IAB node 103) may further include a receiving component 199 configured to receive an indication of frequency synchronization accuracy of a second wireless device (e.g., another IAB node). The receiving component 199 may also be configured to perform frequency synchronization based on the frequency of the second wireless device and using the indication of frequency synchronization accuracy of the second wireless device.

[0044] Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0045] Figure 2A 200 is a diagram illustrating an example of a first subframe within a 5G / NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G / NR subframe. Figure 2C 250 is a diagram illustrating an example of a second subframe within a 5G / NR frame structure. Figure 2D 280 is a diagram illustrating an example of an UL channel within a 5G / NR subframe. The 5G / NR frame structure can be frequency division duplex (FDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL; or can be time division duplex (TDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL. Figure 2A , 2CIn the example provided, the 5G / NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (mostly DL) and subframe 3 is configured with slot format 34 (mostly UL), where D is DL, U is UL, and F is for flexible use between DL / UL. Although subframes 3 and 4 are shown as having slot formats 34 and 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mixture of DL, UL, and flexible symbols. The UE is configured with a slot format (dynamically configured by DL control information (DCI) or semi-statically / statically configured by radio resource control (RRC) signaling) through the received slot format indicator (SFI). Note that the following description also applies to the 5G / NR frame structure for TDD.

[0046] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include mini-slots, which may include 7, 4, or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also known as single carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios; limited to single stream transmission). The number of time slots within a subframe is based on the time slot configuration and parameter design. For slot configuration 0, different parameter designs μ of 0 to 4 allow 1, 2, 4, 8, and 16 slots per subframe, respectively. For slot configuration 1, different parameter designs 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Accordingly, for slot configuration 0 and parameter design μ, there are 14 symbols per slot and 2 per subframe. μ time slots. The subcarrier spacing and symbol length / duration vary depending on parameter design. The subcarrier spacing can be equal to 2 μ *15kHz, where μ is parameter design 0 to 4. Thus, parameter design μ=0 has a subcarrier spacing of 15kHz, while parameter design μ=4 has a subcarrier spacing of 240kHz. The symbol length / duration is inversely related to the subcarrier spacing. Figures 2A-2DAn example of a slot configuration 0 with 14 symbols per slot and a parameter design μ=2 with 4 slots per subframe is provided. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs. Within a frame set, there may be one or more different bandwidth parts (BWPs) that are frequency division multiplexed (see 2B). Each BWP may have a specific parameter design.

[0047] A resource grid may be used to represent the frame structure. Each slot includes a resource block (RB) (also called a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a number of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0048] like Figure 2A As explained in the illustration, some REs carry reference (pilot) signals (RS) for UEs. RSs may include demodulation RSs (DM-RSs) for channel estimation at the UE (indicated as R for a particular configuration). x , where 100x is the port number, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS). RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0049] Figure 2B An example of various DL channels within a subframe of a frame is illustrated. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including 9 RE groups (REGs), each REG including 4 consecutive REs in an OFDM symbol. The PDCCH within a BWP may be referred to as a control resource set (CORESET). Additional BWPs may be located at higher and / or lower frequencies across the channel bandwidth. The primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of a frame. The PSS is used by the UE 104 to determine subframe / symbol timing and physical layer identity. The secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of a frame. The SSS is used by the UE to determine the physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE may determine the physical cell identifier (PCI). Based on the PCI, the UE may determine the location of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block (also referred to as an SS block (SSB)). The MIB provides the number of RBs in the system bandwidth, and the system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted over the PBCH (such as the system information block (SIB)), and paging messages.

[0050] As in Figure 2C As explained in , some REs carry DM-RSs for channel estimation at the base station (indicated as R for one specific configuration, but other DM-RS configurations are possible). The UE may transmit DM-RSs for the physical uplink control channel (PUCCH) and DM-RSs for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first or first two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether a short PUCCH or a long PUCCH is transmitted and on the specific PUCCH format used. The UE may transmit a sounding reference signal (SRS). The SRS may be transmitted in the last symbol of the subframe. The SRS may have a comb structure, and the UE may transmit the SRS on one of the comb teeth. The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0051] Figure 2D An example of various UL channels within a subframe of an illustration frame. The PUCCH may be located at a position as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), and hybrid automatic repeat request (HARQ) ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0052] Figure 33 is a block diagram of an IAB node 310 in communication with a UE 350 in an access network. In the DL, IP packets from the EPC 160 or the core network 190 may be provided to the controller / processor 375. The controller / processor 375 implements layer 3 and / or layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, the functionality of which may be performed if the IAB node is a donor IAB node. Layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a media access control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration of UE measurement reports; PDCP layer functionality associated with header compression / decompression, security (ciphering, cipher decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (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 transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0053] The transmit (TX) processor 316 and the receive (RX) processor 370 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) encoding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 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 an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain 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 generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from reference signals 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 318TX. Each transmitter 318TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0054] At UE 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. TX processor 368 and RX processor 356 implement layer 1 functionality associated with various signal processing functions. RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for UE 350. If there are multiple spatial streams destined for the UE 350, they can be combined into a single OFDM symbol stream by RX processor 356. RX processor 356 then uses a fast Fourier transform (FFT) to transform the OFDM symbol stream from the time domain to the frequency domain. The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbol on each subcarrier and the reference signal are recovered and demodulated by determining the signal constellation point most likely to be transmitted by IAB node 310. These soft decisions can be based on the channel estimate calculated by channel estimator 358. These soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by the IAB node 310. These data and control signals are then provided to the controller / processor 359 that implements layer 3 and layer 2 functionality.

[0055] The controller / processor 359 may 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 channels and logical channels, packet reassembly, cipher interpretation, 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 ACK and / or NACK protocols to support HARQ operations.

[0056] Similar to the functionality described in conjunction with DL transmissions performed by the IAB node 310, the controller / processor 359 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 (encryption, decryption, 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, 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.

[0057] Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the IAB node 310 may be used by a 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 antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0058] UL transmissions are processed at the IAB node 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives signals through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

[0059] The controller / processor 375 may 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 channels and logical channels, packet reassembly, cipher decoding, header decompression, and control signal processing to recover IP packets from the UE 350. If the IAB node is not a donor IAB node, the IP packets from the controller / processor 375 may be provided to the EPC 160 or the core network 190, for example, via the donor IAB node. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0060] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform operations related to Figure 1 The determination component 198 combines various aspects.

[0061] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform operations related to Figure 1 The receiving component 199 combines various aspects.

[0062] Figure 4 4 is a diagram illustrating an IAB network 400. The IAB network 400 may include an anchor node (which may be referred to herein as an "IAB donor") 410 and an access node (which may be referred to herein as an "IAB node") 420. The IAB donor 410 may be a base station (e.g., Figure 1 The IAB donor 410 and the IAB node 420 may share resources to provide to the core network 490 (e.g., Figure 1 For example, resources may be shared between access links and backhaul links in an IAB network.

[0063] UE 430 (e.g. Figure 14 and 5. The UE 104 of the embodiment of the present invention interfaces with the IAB node 420 or the IAB donor 410 via the access link 470. The IAB nodes 420 communicate with each other and with the IAB donor 410 via the backhaul link 460. The IAB donor 410 is connected to the core network 490 via the wired backhaul link 450. The UE 430 communicates with the core network by relaying uplink messages to the IAB node 420 via their respective access links 470, which then relay the uplink messages to the IAB donor 410 via the backhaul link 460 for communication to the core network via the wired backhaul link 450. Similarly, the core network can communicate with the UE 430 by sending messages to the IAB donor 410 via the wired backhaul link 450. The IAB donor 410 transmits a downlink message to the IAB node 420 connected to the UE 430 via the backhaul link 460 in the IAB network 400 , and the IAB node 420 transmits the downlink message to the UE 430 via the access link 470 .

[0064] Each IAB node (e.g., including the IAB donor 410 and each IAB node 420) can use a PCI value. The PCI value can be used as an identifier of the IAB donor 410 or the IAB node 420. The PCI value can be used to determine the scrambling sequence applied to the physical signal and / or channel transmitted by a specific IAB node. For example, the PSS and / or SSS transmitted by the corresponding IAB donor 410 or the IAB node 420 can be scrambled using a scrambling sequence based on the PCI used by the corresponding IAB node. The network may have a limited number of available PCI values. For example, a 5G NR system may support PCI values. Accordingly, a given PCI value may be reused in the same network.

[0065] Figure 5 5 is a diagram illustrating an IAB network 500 and its components. The IAB network 500 includes an IAB donor 510 and an IAB node 520. The IAB node and the IAB donor may provide a wireless access link to a UE 530. The IAB network 500, the IAB donor 510, the IAB node 520, and the UE 530 may correspond to Figure 4 An IAB network 400, an IAB donor 410, an IAB node 420 and a UE 430 are shown.

[0066] The IAB donor 510 may be considered as the root node of the tree structure of the IAB network 500. The IAB donor node 510 may be connected to the core network 590 (e.g., the core network 190, 490) via a wired connection 591. The wired connection may include, for example, a wired optical fiber. The IAB donor node 510 may provide a connection to one or more IAB nodes 520a. The IAB nodes 520a may each be referred to as a child node of the IAB donor node 510. The IAB donor node 510 may also provide a connection to one or more UEs 530a, which may be referred to as child UEs of the IAB donor 510. The IAB donor 510 may be connected to its child IAB node 520a via a backhaul link 560, and may be connected to the child UE 530a via an access link 570. The IAB node 520a, which is a child node of the IAB node 510, may also have (all) IAB nodes 520b and / or (all) UE 530b as child nodes. For example, the IAB node 520b may be further connected to a sub-node and / or a sub-UE. Figure 5 The IAB node 520b providing access links to UE 530c respectively is illustrated. The IAB donor 510 may include a central unit (CU) and a distributed unit (DU). The central unit CU may provide control of the IAB nodes 520a, 520b in the IAB network 500. For example, the CU may be responsible for the configuration of the IAB network 500. The CU may perform RRC / PDCP layer functions. The DU may perform scheduling. For example, the DU may schedule resources for communication by the child IAB node 520a and / or the UE 530a of the IAB donor 510.

[0067] The IAB nodes 520a, 520b may include a mobile terminal (MT) and a DU. The MT of the IAB node 520a may operate as a scheduled node, and may be scheduled by the DU of the parent node (e.g., IAB donor 510) similarly to the UE 530a. The MT of the IAB node 520b may operate as a scheduled node of the IAB node 520a. The DU of the IAB node 520a may schedule the child IAB node 520b and the UE 530b of the IAB node 520a. Since the IAB node may provide a connection to an IAB node, which in turn provides a connection for another IAB node, the pattern in which the parent IAB node includes a DU that schedules the child IAB node / child UE may continue.

[0068] Over-the-air (OTA) synchronization is a method for integrated access backhaul (IAB) nodes. In OTA synchronization, a given IAB node can derive an estimate of its downlink transmission timing based on a downlink signal received from its parent node and additional information provided by the parent node. In some aspects, the information provided may include two quantities: timing advance (TA) and T_delta. TA may refer to a mechanism for aligning the reception of uplink signals from different UEs at a base station. This can be reused in an IAB node to derive an estimate of the one-way propagation delay between a node and its parent node. T_delta may also refer to an additional item provided to the node by the parent node of the node, which represents an additional correction factor for compensating for transmission and / or reception timing misalignment at the parent node. In turn, this may result in TA not being an accurate estimate of the round-trip delay between two nodes. In some aspects of the IAB, it may be desirable for each IAB node to be time-aligned from the perspective of downlink signal transmission. A node may also be referred to as a wireless device.

[0069] In some aspects, the IAB may support an OTA synchronization mechanism to synchronize all IAB nodes in a distributed manner. For example, there may be a network of IAB nodes (i.e., a wireless backhaul network), and the network may be synchronized. In OTA synchronization, signals may be transmitted by the nodes over the air, and thus an additional or alternative synchronization source may be provided, rather than an external synchronization source (such as GPS or Ethernet) that may not always be available. The IAB nodes may also use OTA technology (e.g., OTA signals) to connect to multiple parent nodes. The network may be synchronized using OTA technology. By doing so, an external synchronization source (e.g., GPS) may not be required.

[0070] In OTA synchronization, each IAB node MT may follow the synchronization procedures for UE to synchronize to its parent node(s). MT may operate in a manner similar to UE to communicate with the parent node, including receiving control communications from the parent node. The IAB node may also operate in a manner similar to a base station in communication with its child nodes (e.g., UE or other IAB nodes). In some aspects, the IAB node DU may provide a synchronization source, such as by following procedures similar to the access network, such as by transmitting synchronization signals, estimating uplink synchronization, and / or providing timing advance commands to compensate for propagation delays. The DU may provide signaling (e.g., T_delta) to achieve a more accurate estimate of the round trip time (RTT) at the child node.

[0071] Once an IAB node is synchronized with a parent node, this same synchronization can be used by the DU of the IAB node to provide a reference for the child nodes of the IAB node. The DU can transmit signals and receive signals from the child nodes to optimize synchronization. Accordingly, the IAB node can synchronize with its parent node and then use the same synchronization technology to synchronize with its child nodes or other cellular cells. Additionally, if the IAB node is connected to multiple synchronization sources, it can receive multiple estimates or measurements for timing and combine them to achieve better synchronization.

[0072] In some instances, OTA synchronization may suffer from cumulative errors across multiple hops (i.e., the number of intermediate devices through which data or communications may pass between a source and a destination). Therefore, the maximum tolerable error on each hop and the synchronization accuracy specification may specify the maximum number of hops that can support OTA synchronization. The maximum allowable error may thus be added over multiple hops until an error threshold is reached. In any case, multi-hop OTA synchronization (e.g., up to five or six hops) may still meet the timing synchronization accuracy specification. These specifications may be certain time periods (e.g., 3 μs) between any two cellular cells with overlapping coverage.

[0073] In addition to timing synchronization, OTA synchronization can also provide frequency synchronization. In some aspects, nodes can synchronize both timing (e.g., a timing reference for their communications) and frequency. In some instances, inaccurate frequency may result in performance degradation, for example, when there is a non-negligible relative frequency offset between two communicating nodes. For example, a frequency offset may exist between a base station and a UE or between an IAB node and its parent node. This may affect the signal-to-noise ratio (SNR) in the network. Large absolute frequency errors may also result in transmissions that leak into adjacent channels, and thus degrade the performance of other nodes operating in adjacent channels. For example, even if the UE and base station may include similar relative frequencies, if their frequencies are offset in an absolute sense, this may also result in transmission leakage.

[0074] Some aspects of the present disclosure may include frequency synchronization thresholds for wireless devices (such as IAB nodes). The thresholds may be similar to the frequency synchronization thresholds for base stations or UEs. For example, a local base station may include an accuracy indication or frequency error minimum requirement of plus or minus 0.1 parts per million (±0.1ppm). A medium-range base station may also include an accuracy indication of ±0.1ppm. And a wide-range base station may include an accuracy indication of ±0.05ppm. The frequency error may be a measure of the difference between the actual BS transmit frequency and the assigned frequency, and may be in the form of ppm. In addition, the carrier frequency modulated by the UE may be accurate to within 0.1ppm observed over a 1ms period compared to the carrier frequency received from the base station.

[0075] IAB MT and DU may also include frequency synchronization specifications. For example, the specifications for IAB MT may be similar to UE, i.e., relative accuracy within 0.1ppm relative to its parent node. In addition, the specifications for IAB DU may be similar to base stations, i.e., absolute accuracy of 0.1ppm.

[0076] In some aspects, the OTA synchronization procedure may not be able to rely on frequency synchronization. Therefore, the IAB node may rely on other external synchronization sources (e.g., GPS). This may limit the IAB deployment flexibility and may limit indoor deployment. This may also increase the cost of IAB deployment. The present disclosure provides aspects that enable an IAB node to synchronize its frequency at least in part using OTA signaling from a parent node.

[0077] Frequency synchronization may be to an absolute frequency (e.g., an assigned frequency) rather than a relative frequency received from a parent node. In some instances, an IAB node may achieve an improved level of frequency synchronization accuracy (e.g., less than 0.1 ppm) by enhancing its receiver algorithms, using better components, and / or taking more measurements. Thus, in addition to absolute specifications, aspects of the present disclosure may support stricter relative frequency synchronization specifications and support multi-hop OTA frequency synchronization.

[0078] Even if an IAB node synchronizes its frequency with that of its parent node to a small residual (e.g., 0.01 ppm), the IAB node may still not meet the absolute frequency specification because the IAB node may not know the frequency of the parent node relative to an absolute reference. Aspects of the present disclosure enable the IAB node to address the possibility that the parent node has a different level of frequency synchronization accuracy when performing an OTA synchronization procedure for frequency synchronization.

[0079] Aspects of the present disclosure may support communicating frequency synchronization accuracy between IAB nodes. In some aspects, the present disclosure may support broadcasting or signaling indicating the frequency synchronization accuracy level of an IAB node. For example, if an IAB node includes frequency accuracy within an absolute frequency specification, this may be broadcasted or advertised. In some aspects, such a broadcast may be to another node (e.g., a parent node or a child node) within the network, or to a node outside the network.

[0080] In some aspects, the IAB node may measure or estimate its frequency synchronization accuracy based on several different factors, such as the frequency synchronization accuracy of its synchronization source. In addition, the IAB node may measure or estimate its frequency synchronization accuracy based on its own capabilities (e.g., the IAB node has a disciplined crystal oscillator). The IAB node may also measure or estimate its frequency synchronization accuracy based on the quality of the link to the synchronization source (e.g., the link to the parent node). In addition, the IAB node may measure or estimate its frequency synchronization accuracy based on several measurements (i.e., related to how long it has been measuring and improving its frequency estimate). In addition, the IAB node may measure or estimate its frequency synchronization accuracy based on the mobility state of the IAB node.

[0081] In some examples, the IAB node may estimate the absolute frequency by combining all measurements from other synchronization sources and its own frequency. In some aspects, the combination of these measurements may be determined based at least in part on the advertised accuracy levels broadcast by the synchronization sources. For example, when all measurements are combined, a higher accuracy level may be given a greater weight than a lower accuracy level.

[0082] Aspects of the present disclosure may include: one IAB node determining its frequency synchronization accuracy and / or communicating or broadcasting its frequency synchronization accuracy. Another node may receive the broadcasted frequency synchronization accuracy and / or determine its own frequency synchronization accuracy and broadcast the frequency synchronization accuracy.

[0083] As indicated above, the IAB node may indicate its frequency synchronization accuracy through signaling. The signaling may be local, for example, sent directly over the air by the IAB node. The signaling may also be sent by the DU through a downlink transmission in a SIB, dedicated RRC, MAC, or DCI. In some aspects, the transmission may be to a child node. Additionally, the signaling may be sent by the MT through an uplink communication in a MAC-CE or UCI (e.g., to a parent node).

[0084] The frequency synchronization accuracy signaled from the IAB node can also be centralized, for example, the IAB node can send an indication to a central entity (such as a central unit (CU)) and receive the quality of other synchronization sources from the central entity. In this way, the protocol can be implemented by the DU or the CU. There can also be an interface between the DU and the CU. In some aspects, both local and centralized signaling can be supported simultaneously. This signaling can also be dynamic or semi-static and can also be sent periodically.

[0085] In some aspects, the content of the signaling may include an absolute frequency synchronization accuracy level. For example, the signaling may include a ppm value. Some quantized ppm values ​​may be configured in the specification and an index may be indicated, for example, 0.025, 0.05, 0.075, or 0.1ppm. The content of the signaling may also include whether the IAB node has an external synchronization source (e.g., GPS) or the number of hops to a node with a GPS connection. In some aspects, the synchronization source with GPS may be among the child nodes of the IAB node. Additionally, the content of the signaling may include whether the IAB node can be used as a frequency synchronization source. In addition, the content of the signaling may include a capability, feature, or category indication (e.g., whether the node is able to synchronize with a reference within a specific ppm relative accuracy).

[0086] Figure 6 6 is a call flow diagram 600 illustrating an example of communication between a first IAB node 602 and a second IAB node 604 in an IAB network. The IAB nodes 602, 604 may also communicate with an IAB donor 606 in the IAB network. Figure 5 , in one example, the first IAB node 602 may correspond to the IAB node 520a, and the second IAB node 604 may correspond to the IAB node 520b. Thus, in one example, the first IAB node may be the parent node of the second IAB node. In another example, the first IAB node 602 may correspond to the IAB node 520b, and the second IAB node may correspond to the IAB node 520a. Thus, in one example, the first IAB node may be the child node of the second IAB node. The IAB donor 606 may correspond to the IAB donor 510.

[0087] At 608, the first IAB node 602 determines the frequency synchronization accuracy of the first IAB node. Figure 5 , the IAB node 520a may measure or estimate its frequency synchronization accuracy based on a number of different factors, such as the frequency synchronization accuracy of its synchronization source (e.g., its parent and / or child IAB nodes, the IAB donor 510, or the UE 530), its own capabilities (e.g., if the IAB node 520a has a disciplined crystal oscillator), the quality of the link to the synchronization source (e.g., the link to the parent node), the number of measurements (e.g., related to how long the IAB node 520a has been measuring and improving its frequency estimate), or the mobility state of the IAB node 520a.

[0088] At 610, the first IAB node 602 determines an absolute frequency based on a combination of measurements from at least one synchronization source and the frequency of the first IAB node. The frequency synchronization accuracy determined at 608 may be based on the absolute frequency. For example, referring to Figure 5, the IAB node 520a can estimate the absolute frequency by combining all measurements from other synchronization sources and its own frequency. In some aspects, the combined weight of these measurements can be determined at least in part based on the advertised accuracy levels broadcast by these synchronization sources. For example, when all measurements are combined together, a higher accuracy level can be given a greater weight than a lower accuracy level.

[0089] After determining the frequency synchronization accuracy, the first IAB node 602 transmits an indication 612 of the determined frequency synchronization accuracy of the first IAB node. Figure 5 , when it is determined that the frequency accuracy is within the absolute frequency specification, the frequency synchronization accuracy level of the IAB node 520a may be broadcast or signaled to other IAB nodes 520b within the IAB network (e.g., a parent node or a child node, or a node outside the network). The content of the indication 612 may include the absolute frequency synchronization accuracy level. For example, the indication may include an index indicating a ppm value (determined at 608) among several configured quantized ppm values ​​(e.g., 0.025, 0.05, 0.075, or 0.1ppm). The content of the indication may also include whether the IAB node 520a has an external synchronization source (e.g., GPS) or the number of hops to another node with a GPS connection. In some aspects, the synchronization source with GPS may be among the child nodes of the IAB node 520a. Additionally, the content of the indication may include whether the IAB node 520a can be used as a frequency synchronization source. In addition, the content of the indication may include capabilities, features, or categories (e.g., whether the IAB node 520a is capable of synchronizing with a reference within a certain ppm relative accuracy).

[0090] The first IAB node 602 may indicate its frequency synchronization accuracy via local signaling (eg, sent directly over the air by the first IAB node). Figure 5 , the signaling may be sent by the DU of the IAB node 520a to the child node via downlink transmission in SIB, dedicated RRC, MAC or DCI, or the signaling may be sent by the MT of the IAB node 520a to the parent node via uplink communication in MAC-CE or UCI. When the frequency synchronization accuracy is centralized, the first IAB node 602 may also send an indication to the IAB donor 606 (e.g., the CU of the IAB donor 510) and receive the quality of other synchronization sources from the IAB donor. Both local and centralized signaling may be supported simultaneously. In response to determining at 608 that the frequency synchronization accuracy of the first IAB node 602 has changed from the previously indicated frequency synchronization accuracy, the indication may be dynamically signaled. Alternatively, the indication may be signaled semi-statically or periodically.

[0091] Subsequently, the second IAB node 604 receives an indication 612 of the frequency synchronization accuracy of the first IAB node 602. Figure 5 In one example, when the second IAB node is a child node (e.g., IAB node 520b) of the first IAB node (e.g., IAB node 520a), the second IAB node may receive the indication as local signaling from the first IAB node in a SIB, dedicated RRC, MAC, or DCI in a downlink transmission. In another example, when the second IAB node is a parent node (e.g., IAB node 520a) of the first IAB node (e.g., IAB node 520b), the second IAB node may receive the indication as local signaling from the first IAB node in a MAC-CE or UCI in an uplink transmission. When the frequency synchronization accuracy is centralized, the second IAB node 604 may also receive the indication from the IAB donor 606 (e.g., the CU of the IAB donor 510). The indication may be received from the first IAB node or the IAB donor dynamically (e.g., in response to a change in the frequency synchronization accuracy of the first IAB node 602), or semi-statically or periodically.

[0092] Thereafter, at 614, the second IAB node 604 uses the indication 612 and performs frequency synchronization based on the frequency of the first IAB node 602. For example, referring to Figure 5 , IAB node 520b can estimate the absolute frequency by combining all measurements from other synchronization sources (including IAB node 520a). In some aspects, the combination weight of these measurements can be determined at least in part based on the advertised accuracy levels broadcast by these synchronization sources. For example, when all measurements are combined together, a higher accuracy level can be given a greater weight than a lower accuracy level.

[0093] Although Figure 6The above example of cites that the first IAB node determines the frequency synchronization accuracy and sends the indication to the second IAB node for performing frequency synchronization, but the roles may be reversed. For example, at 609, the second IAB node 604 may also determine the frequency synchronization accuracy (e.g., based on the absolute frequency determined at 611), and the second IAB node 604 may transmit an indication 616 of its own frequency synchronization accuracy. For example, the second IAB node 604 may perform operations similar to 608 and 610 of the first IAB node 602, and the second IAB node may transmit an indication of its own frequency synchronization accuracy to the first IAB node, the IAB donor 606, or other IAB nodes. The content of the indication 616 may be similar to the content of the indication 612. Similarly, the first IAB node 602 may receive an indication 616 of frequency synchronization accuracy from the second IAB node, from the IAB donor 606, or from other IAB nodes, and at 615, the first IAB node may perform frequency synchronization based on the frequency of other IAB nodes (similar to the operation at 614).

[0094] In the case where the frequency synchronization accuracy is centralized, then at 618, the IAB donor 606 may receive indications 612, 616 of the frequency synchronization accuracy from the respective IAB nodes from the first IAB node 602 and the second IAB node 604. The indication(s) 612, 616 may be received from the IAB node(s) dynamically (e.g., in response to respective changes in the frequency synchronization accuracy of the first or second IAB node), or semi-statically or periodically. Subsequently, the IAB donor 606 may send frequency synchronization accuracy information 618 about the first IAB node and the second IAB node. For example, referring to Figure 5 , the IAB donor 510 may send frequency synchronization accuracy information 618 about the IAB node 520a and the IAB node 520b to the corresponding IAB nodes, respectively. The IAB nodes may then perform frequency synchronization based on the frequency synchronization accuracy information (eg, at 614, 615).

[0095] Figure 7 700 is a flow chart of a wireless communication method. The method may be performed by a wireless device (such as an IAB node) or a component of the wireless device (e.g., an IAB node 103, 310, 410, 420, 520, 850; equipment 802 / 802'; processing system 914, which may include memory 376 and may be the entire IAB node 310 or a component of the IAB node 310, such as TX processor 316, RX processor 370, and / or controller / processor 375). In one example, the method may be performed by Figure 6 In another example, the method may be performed by the first IAB node 602. Figure 6The method described herein may provide several benefits, such as improved communication signaling, resource utilization, and / or power conservation of IAB nodes.

[0096] At 702, the wireless device or IAB node may determine the frequency synchronization accuracy of the wireless device, such as in conjunction with Figure 4 and 5 Examples in , and Figure 6 (eg, as described at 608, 609). For example, the determining component 806 of the equipment 802 can determine the frequency synchronization accuracy of the wireless device.

[0097] At 704, the wireless device or IAB node may determine an absolute frequency based on a combination of measurements from at least one synchronization source and the frequency of the wireless device, wherein the frequency synchronization accuracy may be based on the absolute frequency, such as in combination with Figure 4 and 5 Examples in , and Figure 6 (eg, as described at 610, 611). For example, the determining component 806 of the apparatus 802 can determine the absolute frequency based on a combination of measurements from at least one synchronization source and the frequency of the wireless device.

[0098] At 706, the wireless device or IAB node may transmit an indication of the determined frequency synchronization accuracy of the wireless device, such as in conjunction with Figure 4 and 5 Examples in , and Figure 6 For example, transmission component 808 of equipment 802 can transmit an indication of the determined frequency synchronization accuracy of the wireless device.

[0099] In some aspects, the frequency synchronization accuracy may be determined based on at least one of: a source synchronization accuracy of at least one synchronization source, a capability of the wireless device, a link quality to the at least one synchronization source, a number of measurements used by the wireless device for frequency synchronization, or a mobility state of the wireless device or the at least one synchronization source. In addition, the wireless device may determine the absolute frequency based on a combination of measurements for a plurality of synchronization sources, the combination of measurements for a plurality of synchronization sources using a weight for each synchronization source based on a corresponding frequency synchronization accuracy level of each of the plurality of synchronization sources.

[0100] Additionally, the wireless device may transmit an indication of the determined frequency synchronization accuracy of the wireless device in a downlink transmission, the downlink transmission comprising at least one of: system information; a radio resource control (RRC) message; a medium access control (MAC) message; or downlink control information (DCI). Furthermore, the wireless device may transmit an indication of the determined frequency synchronization accuracy of the wireless device in an uplink transmission, the uplink transmission comprising at least one of: a medium access control-control element (MAC-CE); or uplink control information (UCI).

[0101] In some examples, the wireless device may transmit an indication of the determined frequency synchronization accuracy of the wireless device to a central entity, such as an IAB donor 606. Furthermore, the wireless device may dynamically transmit the indication of the determined frequency synchronization accuracy of the wireless device in response to a change in the frequency synchronization accuracy of the wireless device. The wireless device may also transmit the indication of the determined frequency synchronization accuracy of the wireless device periodically or in a semi-static mode. Furthermore, the indication of the determined frequency synchronization accuracy of the wireless device may include an index to a quantized accuracy value.

[0102] The indication of the determined frequency synchronization accuracy of the wireless device may include synchronization source information about the wireless device. In some aspects, the source information may indicate an external synchronization source or a number of hops to a node with a GPS connection. In addition, the indication of the determined frequency synchronization accuracy may further indicate a capability to serve as a frequency synchronization source. In some instances, the indication of the determined frequency synchronization accuracy of the wireless device may include an indication of a capability, feature, or category of the wireless device to be synchronized to a reference frequency within an accuracy threshold. In addition, the wireless device may be an integrated access and backhaul (IAB) node.

[0103] Figure 8 800 is a conceptual data flow diagram illustrating the data flow between different devices / components in an example apparatus 802. The apparatus may be a wireless device such as an IAB node in communication with another IAB node 850. For example, the apparatus may correspond to Figure 6 The first IAB node 602, and another IAB node 850 may correspond to Figure 6 Alternatively, the equipment may correspond to a second IAB node 604. Figure 6 The second IAB node 604, and another IAB node 850 may correspond to Figure 6The apparatus includes a first IAB node 602 of the wireless device. The apparatus includes a receiving component 804 configured to receive a communication (e.g., from an IAB node 850). The apparatus also includes a determining component 806 configured to determine a frequency synchronization accuracy of the wireless device, e.g., as described above in conjunction with step 702. The determining component 806 may also be configured to determine an absolute frequency based on a combination of measurements from at least one synchronization source and a frequency of the wireless device, e.g., as described above in conjunction with step 704. The apparatus also includes a transmitting component 808 configured to transmit an indication of the determined frequency synchronization accuracy of the wireless device, e.g., as described above in conjunction with step 706.

[0104] The equipment may include performing Figure 7 The additional components of each box of the algorithm in the preceding flowchart. Thus, Figure 7 Each block in the aforementioned flow chart of can be performed by a component and the equipment may include one or more of those components. These components can be one or more hardware components specially configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0105] Fig. 9 900 is a diagram illustrating an example of a hardware implementation of an apparatus 802' employing a processing system 914. The processing system 914 may be implemented with a bus architecture generally represented by a bus 924. Depending on the specific application of the processing system 914 and the overall design constraints, the bus 924 may include any number of interconnecting buses and bridges. The bus 924 links together various circuits including one or more processors and / or hardware components (represented by the processor 904, components 804, 806, 808, and computer readable media / memory 906). The bus 924 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0106] The processing system 914 may be coupled to the transceiver 910. The transceiver 910 is coupled to one or more antennas 920. The transceiver 910 provides a means for communicating with various other devices via a transmission medium. The transceiver 910 receives signals from the one or more antennas 920, extracts information from the received signals, and provides the extracted information to the processing system 914 (specifically, the receiving component 804). In addition, the transceiver 910 receives information from the processing system 914 (specifically, the transmission component 808), and generates signals to be applied to the one or more antennas 920 based on the received information. The processing system 914 includes a processor 904 coupled to a computer-readable medium / memory 906. The processor 904 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 906. The software, when executed by the processor 904, causes the processing system 914 to perform the various functions described above for any specific device. The computer-readable medium / memory 906 may also be used to store data manipulated by the processor 904 when executing the software. The processing system 914 further includes at least one of the components 804, 806, 808. These components may be software components running in the processor 904, software components resident / stored in the computer-readable medium / memory 906, one or more hardware components coupled to the processor 904, or some combination thereof. The processing system 914 may be a component of the IAB node 310 and may include the memory 376 and / or include at least one of the TX processor 316, the RX processor 370, and the controller / processor 375. Alternatively, the processing system 914 may be the entire IAB node (e.g., see Figure 3 310).

[0107] In one configuration, the equipment 802 / 802' for wireless communication includes a device for determining the frequency synchronization accuracy of the wireless device. The equipment also includes a device for determining an absolute frequency based on a combination of measurements from at least one synchronization source and the frequency of the wireless device. The equipment also includes a device for transmitting an indication of the determined frequency synchronization accuracy of the wireless device. The aforementioned device may be one or more of the aforementioned components of the equipment 802 and / or the processing system 914 of the equipment 802' configured to perform the functions described by the aforementioned device. As described above, the processing system 914 may include a TX processor 316, an RX processor 370, and a controller / processor 375. Thus, in one configuration, the aforementioned device may be a TX processor 316, an RX processor 370, and a controller / processor 375 configured to perform the functions described by the aforementioned device.

[0108] Fig.101000 is a flow chart of a wireless communication method. The method may be performed by a first wireless device (such as an IAB node) or a component of the first wireless device (e.g., an IAB node 103, 310, 410, 420, 520, 1150; an apparatus 1102 / 1102'; a processing system 1214, which may include a memory 376 and may be the entire IAB node 310 or a component of the IAB node 310, such as a TX processor 316, an RX processor 370, and / or a controller / processor 375). In one example, the method may be performed by Figure 6 In another example, the method may be performed by the second IAB node 604. Figure 6 The method described herein may provide several benefits, such as improving communication signaling, resource utilization, and / or power conservation of IAB nodes.

[0109] At 1002, a first wireless device may receive an indication of frequency synchronization accuracy of a second wireless device, such as in conjunction with Figure 4 and 5 Examples in , and Figure 6 (e.g., indications 612, 616). For example, the receiving component 1104 of the equipment 1102 can receive an indication of the frequency synchronization accuracy of the second wireless device. For example, the first wireless device (e.g., IAB node 604) can receive the indication 612 of the second wireless device (e.g., IAB node 602). Alternatively, the first wireless device (e.g., IAB node 602) can receive the indication 616 of the second wireless device (e.g., IAB node 604).

[0110] At 1004, the first wireless device may perform frequency synchronization based on the frequency of the second wireless device and using the indication of the frequency synchronization accuracy of the second wireless device, such as in conjunction with Figure 4 and 5 Examples in , and Figure 6 For example, the executing component 1106 of the equipment 1102 can perform frequency synchronization based on the frequency of the second wireless device and using the indication of the frequency synchronization accuracy of the second wireless device.

[0111] In some aspects, performing the frequency synchronization may include determining an absolute frequency based on a combination of measurements for multiple synchronization sources including the second wireless device (e.g., at 610, 611), wherein the first wireless device may use a weight for each synchronization source based on a corresponding frequency synchronization accuracy level of each of the multiple synchronization sources.

[0112] Alternatively, the first wireless device may receive an indication of frequency synchronization accuracy for the second wireless device in a downlink transmission, the downlink transmission comprising at least one of: system information; a radio resource control (RRC) message; a medium access control (MAC) message; or downlink control information (DCI). In addition, the first wireless device may receive an indication of frequency synchronization accuracy for the second wireless device in an uplink transmission, the uplink transmission comprising at least one of: a medium access control-control element (MAC-CE); or uplink control information (UCI).

[0113] In some examples, the first wireless device may receive an indication of the frequency synchronization accuracy of the second wireless device from a central entity, such as the IAB donor 606. Furthermore, the first wireless device may dynamically receive the indication of the frequency synchronization accuracy of the second wireless device in response to a change in the frequency synchronization accuracy of the second wireless device. The first wireless device may also receive the indication of the frequency synchronization accuracy of the second wireless device periodically or in a semi-static mode.

[0114] In some aspects, the indication of the frequency synchronization accuracy of the second wireless device may include an index to a quantized accuracy value. The indication of the frequency synchronization accuracy of the second wireless device may also include synchronization source information about the second wireless device. Additionally, the indication of the frequency synchronization accuracy may further indicate a capability to serve as a frequency synchronization source. Furthermore, the indication of the frequency synchronization accuracy of the second wireless device may include an indication of a capability, feature, or category of the second wireless device to be synchronized to a reference frequency within an accuracy threshold.

[0115] In some aspects, the frequency synchronization accuracy is based on at least one of: a source synchronization accuracy of at least one synchronization source, a capability of the second wireless device, a link quality to the at least one synchronization source, a number of measurements used by the second wireless device for the frequency synchronization, or a mobility state of the second wireless device. In addition, the first wireless device may be a first integrated access and backhaul (IAB) node and the second wireless device is a second IAB node.

[0116] Fig.11 1100 is a conceptual data flow diagram illustrating the data flow between different devices / components in an example apparatus 1102. The apparatus may be a wireless device such as an IAB node in communication with another IAB node 1150. For example, the apparatus may correspond to Figure 6 The second IAB node 604, and another IAB node 1150 may correspond to Figure 6 Alternatively, the equipment may correspond to a first IAB node 602. Figure 6 The first IAB node 602, and another IAB node 1150 may correspond to Figure 6The apparatus includes a receiving component 1104 configured to receive an indication of frequency synchronization accuracy of the second wireless device, e.g., as described above in connection with step 1002. The apparatus also includes an executing component 1106 configured to perform frequency synchronization based on the frequency of the second wireless device and using the indication of frequency synchronization accuracy of the second wireless device, e.g., as described above in connection with step 1004. The apparatus also includes a transmitting component 1108 configured to transmit the communication (e.g., to the IAB node 1150).

[0117] The equipment may include performing Fig.10 The additional components of each box of the algorithm in the preceding flowchart. Thus, Fig.10 Each block in the aforementioned flow chart of can be performed by a component and the equipment may include one or more of those components. These components can be one or more hardware components specially configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0118] Fig.12 12 is a diagram illustrating an example of a hardware implementation of an apparatus 1102' employing a processing system 1214. The processing system 1214 may be implemented with a bus architecture generally represented by a bus 1224. Depending on the specific application of the processing system 1214 and the overall design constraints, the bus 1224 may include any number of interconnecting buses and bridges. The bus 1224 links various circuits together, including one or more processors and / or hardware components (represented by the processor 1204, components 1104, 1106, 1108, and computer readable medium / memory 1206). The bus 1224 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0119] The processing system 1214 may be coupled to the transceiver 1210. The transceiver 1210 is coupled to one or more antennas 1220. The transceiver 1210 provides a means for communicating with various other equipment over a transmission medium. The transceiver 1210 receives signals from the one or more antennas 1220, extracts information from the received signals, and provides the extracted information to the processing system 1214 (specifically, the receiving component 1104). In addition, the transceiver 1210 receives information from the processing system 1214 (specifically, the transmitting component 1108) and generates signals to be applied to the one or more antennas 1220 based on the received information. The processing system 1214 includes a processor 1204 coupled to a computer-readable medium / memory 1206. The processor 1204 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1206. The software, when executed by the processor 1204, causes the processing system 1214 to perform the various functions described above for any particular equipment. The computer-readable medium / memory 1206 may also be used to store data manipulated by the processor 1204 when executing software. The processing system 1214 further includes at least one of the components 1104, 1106, 1108. These components may be software components running in the processor 1204, software components resident / stored in the computer-readable medium / memory 1206, one or more hardware components coupled to the processor 1204, or some combination thereof. The processing system 1214 may be a component of the IAB node 310 and may include the memory 376 and / or include at least one of the TX processor 316, the RX processor 370, and the controller / processor 375. Alternatively, the processing system 1214 may be the entire IAB node (e.g., see Figure 3 310).

[0120] In one configuration, the equipment 1102 / 1102' for wireless communication may include a device for receiving an indication of frequency synchronization accuracy of a second wireless device. The equipment may also include a device for performing frequency synchronization based on the frequency of the second wireless device and using the indication of frequency synchronization accuracy of the second wireless device. The aforementioned means may be one or more of the aforementioned components of the equipment 1102 and / or the processing system 1214 of the equipment 1102' configured to perform the functions described by the aforementioned means. As described above, the processing system 1214 may include a TX processor 316, an RX processor 370, and a controller / processor 375. As such, in one configuration, the aforementioned means may be a TX processor 316, an RX processor 370, and a controller / processor 375 configured to perform the functions described by the aforementioned means.

[0121] Fig.131300 is a flow chart of a wireless communication method. The method may be performed by a wireless device in a wireless device network (such as a central entity) or a component of a wireless device in the wireless device network (e.g., wireless device 103, 310, 410, 510, 606; equipment 1402 / 1402'; processing system 1514, which may include memory 376 and may be the entire wireless device 310 or a component of the wireless device 310, such as TX processor 316, RX processor 370, and / or controller / processor 375). For example, the method may be performed by Figure 6 The method described herein may provide several benefits, such as improved communication signaling, resource utilization, and / or power conservation of IAB nodes.

[0122] At 1302, the wireless device or the central entity may receive an indication of frequency synchronization accuracy from each of the plurality of wireless devices, such as in conjunction with Figure 4 and 5 Examples in , and Figure 6 (e.g., instructions 612, 616). For example, receiving component 1404 of equipment 1402 can receive an indication of frequency synchronization accuracy from each wireless device in the plurality of wireless devices. For example, referring to Figure 6 , the IAB donor 606 may receive indications 612, 616 from the IAB nodes 602, 604, respectively.

[0123] At 1304, the wireless device or the central entity may send frequency synchronization accuracy information about each of the plurality of wireless devices, such as in conjunction with Figure 4 and 5 Examples in , and Figure 6 For example, the transmitting component 1406 of the equipment 1402 can transmit the frequency synchronization accuracy information about each wireless device in the plurality of wireless devices.

[0124] In some aspects, the wireless device or central entity may dynamically receive an indication of frequency synchronization accuracy in response to a change in frequency synchronization accuracy. The wireless device or central entity may also receive an indication of frequency synchronization accuracy periodically or in a semi-static mode. The indication of frequency synchronization accuracy may include an index to a quantized accuracy value. In addition, the corresponding indication of frequency synchronization accuracy may include synchronization source information about the corresponding wireless device.

[0125] In some aspects, the indication of frequency synchronization accuracy may further indicate a capability to serve as a frequency synchronization source. Additionally, the respective indication of frequency synchronization accuracy may include an indication of a capability, characteristic, or category of the respective wireless device to be synchronized to a reference frequency within an accuracy threshold. Furthermore, the wireless device network may be an integrated access and backhaul (IAB) network, and the plurality of wireless devices are a plurality of IAB nodes.

[0126] Fig.14 1400 is a conceptual data flow diagram illustrating the data flow between different devices / components in an example apparatus 1402. The apparatus may be a wireless device (such as a central entity) in a wireless device network in communication with an IAB node 1450. For example, the apparatus may correspond to Figure 6 The apparatus may include a receiving component 1404 configured to receive an indication of frequency synchronization accuracy from each of the plurality of wireless devices, e.g., as described above in connection with step 1302. The apparatus may also include a transmitting component 1406 configured to send frequency synchronization accuracy information about each of the plurality of wireless devices, e.g., as described above in connection with step 1304.

[0127] The equipment may include performing Fig.13 The additional components of each box of the algorithm in the preceding flowchart. Thus, Fig.13 Each block in the aforementioned flow chart of can be performed by a component and the equipment may include one or more of those components. These components can be one or more hardware components specially configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0128] Fig.15 1500 is a diagram illustrating an example of a hardware implementation of an apparatus 1402' employing a processing system 1514. The processing system 1514 may be implemented with a bus architecture generally represented by a bus 1524. Depending on the specific application of the processing system 1514 and the overall design constraints, the bus 1524 may include any number of interconnecting buses and bridges. The bus 1524 links together various circuits including one or more processors and / or hardware components (represented by the processor 1504, components 1404 and 1406, and computer readable medium / memory 1506). The bus 1524 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0129] The processing system 1514 may be coupled to the transceiver 1510. The transceiver 1510 is coupled to one or more antennas 1520. The transceiver 1510 provides a means for communicating with various other equipment via a transmission medium. The transceiver 1510 receives signals from the one or more antennas 1520, extracts information from the received signals, and provides the extracted information to the processing system 1514 (specifically, the receiving component 1404). In addition, the transceiver 1510 receives information from the processing system 1514 (specifically, the transmitting component 1406) and generates signals to be applied to the one or more antennas 1520 based on the received information. The processing system 1514 includes a processor 1504 coupled to a computer-readable medium / memory 1506. The processor 1504 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1506. The software, when executed by the processor 1504, causes the processing system 1514 to perform the various functions described above for any particular equipment. The computer-readable medium / memory 1506 may also be used to store data manipulated by the processor 1504 when executing software. The processing system 1514 further includes at least one of the components 1404 and 1406. These components may be software components running in the processor 1504, software components resident / stored in the computer-readable medium / memory 1506, one or more hardware components coupled to the processor 1504, or some combination thereof. The processing system 1514 may be a component of the IAB node 310 and may include the memory 376 and / or include at least one of the TX processor 316, the RX processor 370, and the controller / processor 375. Alternatively, the processing system 1514 may be the entire IAB node (e.g., see Figure 3 310).

[0130] In one configuration, the equipment 1402 / 1402' for wireless communication includes a device for receiving an indication of frequency synchronization accuracy from each of a plurality of wireless devices. The equipment may also include a device for sending frequency synchronization accuracy information about each of the plurality of wireless devices. The aforementioned means may be one or more of the aforementioned components of the equipment 1402 and / or the processing system 1514 of the equipment 1402' configured to perform the functions described by the aforementioned means. As described above, the processing system 1514 may include a TX processor 316, an RX processor 370, and a controller / processor 375. Thus, in one configuration, the aforementioned means may be a TX processor 316, an RX processor 370, and a controller / processor 375 configured to perform the functions described by the aforementioned means.

[0131] It should be understood that the specific order or hierarchy of each box in the disclosed process / flowchart is an illustration of an example approach. It should be understood that the specific order or hierarchy of each box in these process / flowcharts can be rearranged based on design preferences. In addition, some boxes can be combined or omitted. The attached method claims present the elements of various boxes in an exemplary order and are not meant to be limited to the specific order or hierarchy presented.

[0132] 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 easily understood by those skilled in the art, and the universal principles defined in this article can be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown in this article, but should be granted the full scope consistent with the claims in language, wherein the singular reference of the elements is not intended to represent "there is and only one", but "one or more", unless otherwise stated. Terms such as "if", "when..." and "when..." should be interpreted as meaning "under the condition", rather than implying a direct time relationship or reaction. That is, these phrases (e.g., "when...") do not imply an immediate action in response to the occurrence of an action or during the occurrence of an action, but only imply that an action will occur when the condition is met, and no specific or immediate time constraints are required for the action to occur. The wording "exemplary" is used herein to mean "used as an example, instance or explanation". Any aspect described as "exemplary" herein need not be interpreted as being superior to or superior to other aspects. Unless otherwise stated, the term "some / certain" 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 multiple A, multiple B, or multiple 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 only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout the disclosure that are currently or later known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly recited in the claims. The terms "module," "mechanism," "element," "device," etc. may not be a substitute for the term "means." Thus, no claim element should be construed as a means-plus-function unless the element is explicitly recited using the phrase "means for..."

[0133] The following examples are merely illustrative and may be combined with other embodiments or aspects of the teachings described herein without limitation.

[0134] Example 1 is a method of wireless communication at a wireless device, comprising: determining a frequency synchronization accuracy of the wireless device; and transmitting an indication of the determined frequency synchronization accuracy to the wireless device.

[0135] Example 2 is the method of Example 1, wherein the frequency synchronization accuracy is determined based on at least one of: source synchronization accuracy of at least one synchronization source, capabilities of the wireless device, link quality to the at least one synchronization source, a number of measurements used by the wireless device for frequency synchronization, or a mobility state of the wireless device or the at least one synchronization source.

[0136] Example 3 is the method of any of Examples 1 and 2, further comprising: determining an absolute frequency based on a combination of measurements from at least one synchronization source and a frequency of the wireless device, wherein the frequency synchronization accuracy is based on the absolute frequency.

[0137] Example 4 is a method of any one of Examples 1 to 3, wherein the wireless device determines the absolute frequency based on a combination of measurements for multiple synchronization sources, and the combination of measurements for multiple synchronization sources uses a weight for each synchronization source based on the corresponding frequency synchronization accuracy level of each synchronization source in the multiple synchronization sources.

[0138] Example 5 is a method of any one of Examples 1 to 4, wherein the wireless device transmits an indication of a determined frequency synchronization accuracy of the wireless device in a downlink transmission, the downlink transmission comprising at least one of: system information; a radio resource control (RRC) message; a media access control (MAC) message; or downlink control information (DCI).

[0139] Example 6 is a method of any one of Examples 1 to 5, wherein the wireless device transmits an indication of the determined frequency synchronization accuracy of the wireless device in an uplink transmission, the uplink transmission comprising at least one of: a media access control-control element (MAC-CE); or uplink control information (UCI).

[0140] Example 7 is the method of any of Examples 1-6, wherein the wireless device transmits an indication of the determined frequency synchronization accuracy of the wireless device to the central entity.

[0141] Example 8 is the method of any of Examples 1 to 7, wherein the wireless device dynamically transmits an indication of the determined frequency synchronization accuracy of the wireless device in response to a change in the frequency synchronization accuracy of the wireless device.

[0142] Example 9 is the method of any of Examples 1 to 8, wherein the wireless device transmits an indication of the determined frequency synchronization accuracy of the wireless device periodically or in a semi-static pattern.

[0143] Example 10 is the method of any of Examples 1 to 9, wherein the indication of the determined frequency synchronization accuracy of the wireless device comprises an index to a quantized accuracy value.

[0144] Example 11 is the method of any of Examples 1 to 10, wherein the indication of the determined frequency synchronization accuracy for the wireless device includes synchronization source information about the wireless device.

[0145] Example 12 is the method of any of Examples 1-11, wherein the indication of the determined frequency synchronization accuracy further indicates a capability to function as a frequency synchronization source.

[0146] Example 13 is the method of any of Examples 1 to 12, wherein the indication of the determined frequency synchronization accuracy of the wireless device comprises a capability, characteristic, or class indication indicating that the wireless device is synchronized to a reference frequency within an accuracy threshold.

[0147] Example 14 is the method of any one of Examples 1 to 13, wherein the wireless device is an integrated access and backhaul (IAB) node.

[0148] Example 15 is a device comprising one or more processors and one or more memories in electronic communication with the one or more processors, the one or more memories storing instructions executable by the one or more processors to cause the device to implement a method as in any one of Examples 1-14.

[0149] Example 16 is an apparatus comprising means for implementing the method or apparatus as in any of Examples 1-14.

[0150] Example 17 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of Examples 1-14.

[0151] Example 18 is a method of wireless communication at a first wireless device, the method comprising: receiving an indication of frequency synchronization accuracy of a second wireless device; and performing frequency synchronization based on a frequency of the second wireless device and using the indication of frequency synchronization accuracy of the second wireless device.

[0152] Example 19 is the method of Example 18, wherein performing the frequency synchronization includes: determining the absolute frequency based on a measurement combination for multiple synchronization sources including the second wireless device, wherein the first wireless device uses a weight for each synchronization source based on the corresponding frequency synchronization accuracy level of each synchronization source in the multiple synchronization sources.

[0153] Example 20 is a method of any of Examples 18 and 19, wherein a first wireless device receives an indication of frequency synchronization accuracy for a second wireless device in a downlink transmission, the downlink transmission comprising at least one of: system information; a radio resource control (RRC) message; a media access control (MAC) message; or downlink control information (DCI).

[0154] Example 21 is a method of any of Examples 18 to 20, wherein a first wireless device receives an indication of frequency synchronization accuracy of a second wireless device in an uplink transmission, the uplink transmission comprising at least one of: a media access control-control element (MAC-CE); or uplink control information (UCI).

[0155] Example 22 is the method of any of Examples 18 to 21, wherein the first wireless device receives an indication of frequency synchronization accuracy of the second wireless device from the central entity.

[0156] Example 23 is the method of any of Examples 18 to 22, wherein the first wireless device dynamically receives an indication of a frequency synchronization accuracy of the second wireless device in response to a change in the frequency synchronization accuracy of the second wireless device.

[0157] Example 24 is the method of any of Examples 18 to 23, wherein the first wireless device receives an indication of frequency synchronization accuracy of the second wireless device periodically or in a semi-static mode.

[0158] Example 25 is the method of any of Examples 18 to 24, wherein the indication of the frequency synchronization accuracy of the second wireless device comprises an index to a quantized accuracy value.

[0159] Example 26 is the method of any of Examples 18 to 25, wherein the indication of frequency synchronization accuracy of the second wireless device includes synchronization source information about the second wireless device.

[0160] Example 27 is the method of any of Examples 18 to 26, wherein the indication of frequency synchronization accuracy further indicates a capability to function as a frequency synchronization source.

[0161] Example 28 is the method of any of Examples 18 to 27, wherein the indication of frequency synchronization accuracy of the second wireless device comprises a capability, characteristic, or class indication indicating that the second wireless device is synchronized to a reference frequency within an accuracy threshold.

[0162] Example 29 is a method of any one of Examples 18 to 28, wherein the frequency synchronization accuracy is based on at least one of: a source synchronization accuracy of at least one synchronization source, a capability of the second wireless device, a link quality to the at least one synchronization source, a number of measurements used by the second wireless device for the frequency synchronization, or a mobility state of the second wireless device.

[0163] Example 30 is the method of any one of Examples 18 to 29, wherein the first wireless device is a first integrated access and backhaul (IAB) node and the second wireless device is a second IAB node.

[0164] Example 31 is a device comprising one or more processors and one or more memories in electronic communication with the one or more processors, the one or more memories storing instructions executable by the one or more processors to cause the device to implement a method as in any of Examples 18-30.

[0165] Example 32 is an apparatus comprising means for implementing the method or apparatus as in any of Examples 18-30.

[0166] Example 33 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of Examples 18-30.

[0167] Example 34 is a method of wirelessly communicating at a central entity in a wireless device network, comprising: receiving an indication of frequency synchronization accuracy from each of a plurality of wireless devices; and sending frequency synchronization accuracy information about each of the plurality of wireless devices.

[0168] Example 35 is the method of Example 34, wherein the central entity dynamically receives the indication of the frequency synchronization accuracy in response to a change in the frequency synchronization accuracy.

[0169] Example 36 is the method of any of Examples 34 and 35, wherein the central entity receives the indication of frequency synchronization accuracy periodically or in a semi-static mode.

[0170] Example 37 is the method of any of Examples 34 to 36, wherein the indication of the frequency synchronization accuracy comprises an index to a quantization accuracy value.

[0171] Example 38 is the method of any of Examples 34 to 37, wherein the respective indication of frequency synchronization accuracy includes synchronization source information about the respective wireless device.

[0172] Example 39 is the method of any of Examples 34 to 38, wherein the indication of frequency synchronization accuracy further indicates capability to serve as a frequency synchronization source.

[0173] Example 40 is the method of any of Examples 34 to 39, wherein the respective indication of frequency synchronization accuracy comprises an indication of a capability, characteristic, or class of the respective wireless device to be synchronized to a reference frequency within an accuracy threshold.

[0174] Example 41 is the method of any one of Examples 34 to 40, wherein the wireless device network is an integrated access and backhaul (IAB) network, and the plurality of wireless devices are a plurality of IAB nodes.

[0175] Example 42 is a device comprising one or more processors and one or more memories in electronic communication with the one or more processors, the one or more memories storing instructions executable by the one or more processors to cause the device to implement a method as in any of Examples 34-41.

[0176] Example 43 is an apparatus comprising means for implementing the method or apparatus as in any of Examples 34-41.

[0177] Example 44 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of Examples 34-41.

Claims

1. A method for wireless communication at a wireless device, comprising: determining a frequency synchronization accuracy of the wireless device; as well as An indication of the determined frequency synchronization accuracy to the wireless device is transmitted in a downlink or uplink transmission, wherein the transmission comprises a medium access control (MAC) message or a medium access control-control element (MAC-CE).

2. The method of claim 1 , wherein the frequency synchronization accuracy is determined based on at least one of the following: the source synchronization accuracy of at least one synchronization source, the capabilities of the wireless device, a link quality to the at least one synchronization source, the number of measurements made by the wireless device for frequency synchronization, or A mobility state of the wireless device or the at least one synchronization source.

3. The method of claim 1, further comprising: An absolute frequency is determined based on a combination of measurements from at least one synchronization source and a frequency of the wireless device, wherein the frequency synchronization accuracy is based on the absolute frequency.

4. The method of claim 3, wherein the wireless device determines the absolute frequency based on a combination of measurements for a plurality of synchronization sources, the combination of measurements for the plurality of synchronization sources using a weight for each synchronization source based on a corresponding frequency synchronization accuracy level of each of the plurality of synchronization sources.

5. The method of claim 1, wherein the wireless device transmits the indication of the determined frequency synchronization accuracy of the wireless device to a central entity.

6. The method of claim 1, wherein the wireless device dynamically transmits the indication of the determined frequency synchronization accuracy of the wireless device in response to a change in the frequency synchronization accuracy of the wireless device.

7. The method of claim 1, wherein the wireless device transmits the indication of the determined frequency synchronization accuracy of the wireless device periodically or in a semi-static mode.

8. The method of claim 1, wherein the indication of the determined frequency synchronization accuracy of the wireless device comprises an index to a quantized accuracy value.

9. The method of claim 1, wherein the indication of the determined frequency synchronization accuracy of the wireless device comprises synchronization source information about the wireless device.

10. The method of claim 1, wherein the indication of the determined frequency synchronization accuracy further indicates a capability to function as a frequency synchronization source.

11. The method of claim 1 , wherein the indication of the determined frequency synchronization accuracy of the wireless device comprises a capability, feature, or class indication indicating that the wireless device is synchronized to a reference frequency within an accuracy threshold.

12. An apparatus for wireless communication at a wireless device, comprising: Memory; as well as At least one processor is coupled to the memory and is configured to perform the steps of the method according to any one of claims 1-11.

13. An apparatus for wireless communication at a wireless device, comprising: Apparatus for performing the steps of the method according to any one of claims 1-11.

14. A non-transitory computer readable medium having program code recorded thereon, wherein the program code, when executed by a processor of a wireless device, causes the processor to perform the steps of the method of any one of claims 1-11.

15. A method of wireless communication at a first wireless device, comprising: receiving an indication of frequency synchronization accuracy for a second wireless device in a downlink or uplink transmission, wherein the transmission comprises a medium access control (MAC) message or a medium access control-control element (MAC-CE); and Frequency synchronization is performed based on a frequency of the second wireless device and using the indication of the frequency synchronization accuracy of the second wireless device.

16. The method of claim 15, wherein performing the frequency synchronization comprises: An absolute frequency is determined based on a combination of measurements for a plurality of synchronization sources including the second wireless device, wherein the first wireless device uses a weight for each of the plurality of synchronization sources based on a respective frequency synchronization accuracy level of each synchronization source.

17. The method of claim 15, wherein the first wireless device receives the indication of the frequency synchronization accuracy of the second wireless device from a central entity.

18. The method of claim 15, wherein the first wireless device dynamically receives the indication of the frequency synchronization accuracy of the second wireless device in response to a change in the frequency synchronization accuracy of the second wireless device.

19. The method of claim 15, wherein the first wireless device receives the indication of the frequency synchronization accuracy of the second wireless device periodically or in a semi-static mode.

20. The method of claim 15, wherein the indication of the frequency synchronization accuracy of the second wireless device comprises an index to a quantized accuracy value.

21. The method of claim 15, wherein the indication of the frequency synchronization accuracy of the second wireless device comprises synchronization source information about the second wireless device.

22. The method of claim 15, wherein the indication of the frequency synchronization accuracy further indicates a capability to function as a frequency synchronization source.

23. The method of claim 15, wherein the indication of the frequency synchronization accuracy of the second wireless device comprises a capability, feature, or class indication indicating that the second wireless device is synchronized to a reference frequency within an accuracy threshold.

24. The method of claim 15, wherein the frequency synchronization accuracy is based on at least one of: the source synchronization accuracy of at least one synchronization source, the capability of the second wireless device, a link quality to the at least one synchronization source, the number of measurements performed by the second wireless device for the frequency synchronization, or A mobility state of the second wireless device.

25. An apparatus for wireless communication at a first wireless device, comprising: Memory; as well as At least one processor is coupled to the memory and is configured to perform the steps of the method of any one of claims 15-24.

26. An apparatus for wireless communication at a first wireless device, comprising: Apparatus for performing the steps of the method as claimed in any one of claims 15-24.

27. A non-transitory computer readable medium having program code recorded thereon, wherein the program code, when executed by a processor of a first wireless device, causes the processor to perform the steps of the method of any one of claims 15-24.

28. A method of wirelessly communicating at a central entity in a wireless device network, comprising: receiving an indication of frequency synchronization accuracy from each of the plurality of wireless devices in a downlink or uplink transmission, wherein the transmission comprises a medium access control (MAC) message or a medium access control-control element (MAC-CE); as well as Frequency synchronization accuracy information is transmitted regarding each wireless device of the plurality of wireless devices.

29. The method of claim 28, wherein the central entity receives the indication of the frequency synchronization accuracy dynamically in response to a change in the frequency synchronization accuracy.

30. The method of claim 28, wherein the central entity receives the indication of the frequency synchronization accuracy periodically or in a semi-static mode.

31. An apparatus for wireless communication at a central entity in a wireless device network, comprising: Memory; as well as At least one processor is coupled to the memory and is configured to perform the steps of the method of any one of claims 28-30.

32. An apparatus for wireless communication at a central entity in a wireless device network, comprising: Apparatus for performing the steps of the method as claimed in any one of claims 28 to 30.

33. A non-transitory computer readable medium having program code recorded thereon, wherein the program code, when executed by a processor of a central entity in a wireless device network, causes the processor to perform the steps of the method of any one of claims 28-30.

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