Reconfigurable smart surface coefficient time domain rotation

Abstract

Certain aspects of the present disclosure provide a method for wireless communication at a network entity, the method generally including transmitting signaling that configures a time domain twiddle factor for at least one reconfigurable smart surface (RIS) to apply a time-varying reflection coefficient rotation, wherein the time domain twiddle factor is based on a Doppler frequency corresponding to a reflective link between the network entity and a user equipment (UE) via the at least one RIS; and communicating with the UE via the RIS after sending the signaling.

Description

Background Technology Technical Field

[0001] Various aspects of this disclosure relate to wireless communication, and more specifically, to techniques for configuring reconfigurable smart surface (RIS) elements.

[0002] Related technical descriptions

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunications services, such as telephone, video, data, messaging, broadcasting, or other similar services. These wireless communication systems may employ multiple access technologies that enable communication with multiple users by sharing available wireless communication system resources.

[0004] Despite significant technological advancements in wireless communication systems over the years, challenges remain. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and receivers. Therefore, there is a continuous expectation for improving the technical performance of wireless communication systems, including, for example: improving communication speed and data carrying capacity; improving the efficiency of shared communication media; reducing the power used by transmitters and receivers during communication; improving the reliability of wireless communication; avoiding redundant transmission and / or reception and related processing; improving the coverage area of ​​wireless communication; increasing the number and types of devices that can access the wireless communication system; increasing the ability of different types of devices to communicate with each other; and increasing the number and types of available wireless communication media. Therefore, there is a need for further improvements to wireless communication systems to overcome the aforementioned technical challenges and other obstacles. Summary of the Invention

[0005] One aspect provides a method for wireless communication at a network entity. The method includes: transmitting signaling to configure a time-domain rotation factor for at least one reconfigurable smart surface (RIS) to apply a time-varying reflection coefficient rotation, wherein the time-domain rotation factor is based on a Doppler frequency corresponding to a reflection link between the network entity and a user equipment (UE) via the at least one RIS; and communicating with the UE via the RIS after transmitting the signaling.

[0006] On the other hand, a method for wireless communication at a reconfigurable smart surface (RIS) controller is provided. The method includes: receiving signaling from a network entity indicating a time-domain rotation factor; and changing the reflection coefficient of one or more elements of at least one RIS by applying a time-varying reflection coefficient rotation based on the time-domain rotation factor.

[0007] On the other hand, a method for wireless communication at a user equipment (UE) is provided. The method includes: receiving from a network entity a signaling indicating a time-domain rotation period, the time-domain rotation period determining the frequency at which coefficients of at least one reconfigurable smart surface (RIS) element are updated; and updating Doppler processing performed at the UE based on the time-domain rotation period.

[0008] Other aspects provide: an apparatus capable of operating to, being configured to, or otherwise adapted to perform any or more of the foregoing methods and / or those methods described elsewhere herein; a non-transitory computer-readable medium comprising instructions that, when executed by a processor of the apparatus, cause the apparatus to perform the foregoing methods and those methods described elsewhere herein; a computer program product embodied on a computer-readable storage medium comprising: code for performing the foregoing methods and those methods described elsewhere herein; and / or an apparatus comprising components for performing the foregoing methods and those methods described elsewhere herein. By way of example, an apparatus may include a processing system, a device having a processing system, or a processing system cooperating via one or more networks.

[0009] For illustrative purposes, the following description and figures illustrate certain features. Attached Figure Description

[0010] The accompanying drawings depict certain features of the various aspects described herein and should not be considered as limiting the scope of this disclosure.

[0011] Figure 1 An example wireless communication network is depicted.

[0012] Figure 2 An example decomposed base station architecture is described.

[0013] Figure 3 Various aspects of the example base station and example user equipment are described.

[0014] Figure 4A , Figure 4B , Figure 4C and Figure 4D Various example aspects of data structures used in wireless communication networks are described.

[0015] Figure 5 An example wireless communication network obstructed by an obstacle is depicted.

[0016] Figure 6 An example wireless communication network with a reconfigurable smart surface (RIS) element array is depicted.

[0017] Figure 7A and Figure 7B An example RIS deployment is depicted.

[0018] Figure 8A and Figure 8B Example use cases for RIS deployment are described.

[0019] Figure 9 An example virtual RIS deployment is described.

[0020] Figure 10 A call flow diagram is depicted for communication between a network entity and a RIS controller in a network according to certain aspects of this disclosure.

[0021] Figure 11 A call flowchart for configuring a time-domain twisting factor for a RIS array, according to certain aspects of this disclosure, is depicted.

[0022] Figure 12 A call flowchart for determining the RIS time-domain rotation factor is depicted according to certain aspects of this disclosure.

[0023] Figure 13 Timing diagrams for applying the RIS time-domain twisting factor are depicted according to certain aspects of this disclosure.

[0024] Figure 14 Timing diagrams for applying the RIS time-domain twisting factor are depicted according to certain aspects of this disclosure.

[0025] Figure 15A and Figure 15B Examples of potential performance improvements that can be achieved using RIS time-domain twitch factors according to certain aspects of this disclosure are described.

[0026] Figure 16A and Figure 16B Examples of potential performance improvements that can be achieved using RIS time-domain twitch factors according to certain aspects of this disclosure are described.

[0027] Figure 17 A method for wireless communication is described.

[0028] Figure 18 A method for wireless communication is described.

[0029] Figure 19 A method for wireless communication is described.

[0030] Figure 20 Various aspects of the example communication device are described. Detailed Implementation

[0031] This disclosure provides apparatus, methods, processing systems, and computer-readable media for Doppler frequency mitigation in reconfigurable smart surface (RIS) assisted communications.

[0032] In some wireless systems, reconfigurable (or reflective) smart surfaces (RIS) can be deployed to reflect impact beams / signals in a desired direction. RIS typically refers to a low-cost, passive, and reconfigurable array of reflective elements that provides scalable coverage and improved spectral efficiency. RIS can be configurable via a RIS controller, allowing network entities to enhance end-to-end channel visibility for a target UE.

[0033] When a network entity (such as a base station, like a gNB) communicates with a UE moving at high speed, if the UE's direction of movement is not perpendicular to the direction of the incoming signal, the signal received at the UE may be affected by one or more Doppler frequencies. Doppler frequencies refer to the changes in radio wave frequency caused by the relative motion between the transmitting and receiving antennas. As a result of Doppler frequencies, the frequency received at the UE may shift (increase or decrease) relative to the frequency initially transmitted by the network entity. If this frequency shift is not compensated for, it can lead to signal interference and degradation, which may affect signal reception, decoding, and channel state information (CSI) measurements.

[0034] In RIS-assisted communication use cases, the UE may be receiving transmitted signals from multiple paths (e.g., a combination of direct links plus one or more reflective links via one or more RISs), which may generate two or more Doppler frequencies. While the UE may be able to compensate for one Doppler frequency, compensation may become increasingly difficult or impossible when the UE (e.g., in RIS-assisted communication use cases) is subjected to two or more Doppler frequencies, and therefore, the channel state may become time-varying. Time-varying channel state can affect composite channel gain, thereby reducing CSI accuracy and further leading to scheduling errors, which may result in decoding failures or spectral efficiency losses. While Doppler frequencies can be mitigated in part by increasing the frequency of CSI reporting, increasing CSI reporting will lead to increased UL signaling overhead.

[0035] Certain aspects of this disclosure provide techniques for mitigating the impact of multiple Doppler frequencies on RIS-assisted communication by configuring a time-domain rotation factor for the RIS. Based on the time-domain rotation factor, the RIS controller can rotate the reflection coefficient of the RIS element for a given period. By rotating the reflection coefficient, the composite channel gain degradation and fluctuations (e.g., channel state time variations) caused by multiple Doppler frequencies can be reduced, thereby improving CSI reporting accuracy without increasing the CSI reporting frequency, which can improve spectral efficiency.

[0036] Introduction to wireless communication networks

[0037] The techniques and methods described herein can be used in a variety of wireless communication networks. While aspects may be described herein using terms commonly associated with 3G, 4G, and / or 5G wireless technologies, aspects of this disclosure are equally applicable to other communication systems and standards not explicitly mentioned herein.

[0038] Figure 1 An example of a wireless communication network 100 in which the aspects described herein can be implemented is depicted.

[0039] Generally, wireless communication network 100 includes various network entities (optionally, network elements or network nodes). Network entities are typically communication devices and / or communication functions performed by communication devices (e.g., user equipment (UE), base station (BS), components of a BS, servers, etc.). For example, various functions of the network and various devices associated with and interacting with the network can be considered network entities. Furthermore, wireless communication network 100 includes terrestrial aspects, such as terrestrial network entities (e.g., BS 102), and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include onboard network entities (e.g., one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs) and user equipment.

[0040] In the depicted example, wireless communication network 100 includes BS 102, UE 104, and one or more core networks (such as Evolved Packet Core (EPC) 160 and 5G Core (5GC) network 190) that interoperate to provide communication services over various communication links, including wired and wireless links.

[0041] Figure 1 Various example UE 104s are described, which may more generally include: cellular phones, smartphones, Session Initiation Protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players, cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electricity meters, air pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, Internet of Things (IoT) devices, always-on (AON) devices, edge processing devices, or other similar devices. UE 104 may also be more generally referred to as mobile devices, wireless devices, wireless communication devices, stations, mobile stations, subscriber stations, mobile subscriber stations, mobile units, subscriber units, wireless units, remote units, remote devices, access terminals, mobile terminals, wireless terminals, remote terminals, mobile phones, and others.

[0042] BS102 communicates wirelessly with UE 104 via communication link 120 (e.g., transmitting or receiving signals to or from UE 104). Communication link 120 between BS102 and UE 104 may include uplink (UL) transmission (also referred to as reverse link) from UE 104 to BS102 and / or downlink (DL) transmission (also referred to as forward link) transmission from BS102 to UE 104. In various aspects, communication link 120 may utilize multiple-input multiple-output (MIMO) antenna techniques, including spatial multiplexing, beamforming, and / or transmit diversity.

[0043] BS102 may typically include: NodeB, enhanced NodeB (eNB), next-generation enhanced NodeB (ng-eNB), next-generation NodeB (gNB or gNodeB), access point, transceiver base station, radio base station, radio transceiver, transceiver functionality, transmit / receive point, and / or others. Each of BS102 may provide communication coverage for a corresponding geographic coverage area 110, which may sometimes be referred to as a cell, and in some cases may overlap (e.g., a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of a macro cell). For example, BS may provide communication coverage for macro cells (covering a relatively large geographic area), pico cells (covering a relatively small geographic area, such as a stadium), femtocells (covering a relatively small geographic area (e.g., a home)), and / or other types of cells.

[0044] Although the BS102 is described as a single communication device in various aspects, it can be implemented in a variety of configurations. For example, one or more components of the base station can be decomposed, including a central unit (CU), one or more distributed units (DU), one or more radio units (RU), a near-real-time (near-RT) RAN intelligent controller (RIC), or a non-real-time (non-RT) RIC, to name a few. In another example, various aspects of the base station can be virtualized. More generally, a base station (e.g., the BS102) can include components located at a single physical location or components located at various physical locations. In examples where the base station includes components located at various physical locations, the various components can each perform functions, such that the various components collectively achieve functionality similar to a base station located at a single physical location. In some aspects, a base station including components located at various physical locations can be referred to as a decomposed radio access network architecture (such as an open RAN (O-RAN) or virtualized RAN (VRAN) architecture). Figure 2 An example decomposed base station architecture is depicted and described.

[0045] Different BS102s within the wireless communication network 100 can also be configured to support different radio access technologies (such as 3G, 4G, and / or 5G). For example, a BS102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with EPC 160 via a first backhaul link 132 (e.g., the S1 interface). A BS102 configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN)) can interface with 5GC 190 via a second backhaul link 184. BS102s can communicate directly or indirectly with each other (e.g., via EPC 160 or 5GC 190) on a third backhaul link 134 (e.g., the X2 interface), which can be wired or wireless.

[0046] Wireless communication network 100 can subdivide the electromagnetic spectrum into various categories, bands, channels, or other characteristics. In some aspects, subdivision is provided based on wavelength and frequency, where frequency may also be referred to as carrier, subcarrier, channel, tone, or subband. For example, 3GPP currently defines frequency range 1 (FR1) as including 410MHz-7125MHz, which is often (interchangeably) referred to as “sub-6GHz”. Similarly, 3GPP currently defines frequency range 2 (FR2) as including 24,250MHz-52,600MHz, which is sometimes (interchangeably) referred to as “millimeter wave” (“mmW” or “mmWave”). Base stations configured to communicate using mmWave / near mmWave radio bands (e.g., mmWave base stations such as BS180) can utilize beamforming (e.g., 182) with UEs (e.g., 104) to improve path loss and range.

[0047] The communication link 120 between BS102 and, for example, UE 104 can be via one or more carriers, which may have different bandwidths (e.g., 5MHz, 10MHz, 15MHz, 20MHz, 100MHz, 400MHz and / or other MHz) and may be aggregated in various ways. The carriers may be adjacent to each other or may not be adjacent to each other. The allocation of carriers may be asymmetric for DL ​​and UL (e.g., more or fewer carriers may be allocated to DL compared to UL).

[0048] Compared to lower-frequency communication, communication using higher frequency bands may have higher path loss and shorter range. Therefore, some base stations (e.g., Figure 1The beamforming 180 of BS 180 and UE 104 can be used with UE 104 to improve path loss and range. For example, BS 180 and UE 104 may each include multiple antennas, such as antenna elements, antenna panels, and / or antenna arrays, to facilitate beamforming. In some cases, BS 180 may transmit beamformed signals to UE 104 in one or more transmit directions 182'. UE 104 may receive beamformed signals from BS 180 in one or more receive directions 182'. UE 104 may also transmit beamformed signals to BS 180 in one or more transmit directions 182'. BS 180 may also receive beamformed signals from UE 104 in one or more receive directions 182'. BS 180 and UE 104 may then perform beamforming training to determine the optimal receive and transmit directions for each of BS 180 and UE 104. It is worth noting that the transmit and receive directions of BS 180 may be the same or different. Similarly, the sending and receiving directions of UE 104 may be the same or different.

[0049] The wireless communication network 100 further includes a Wi-Fi AP 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in, for example, unlicensed spectrum in 2.4 GHz and / or 5 GHz.

[0050] Some UEs 104 may use device-to-device (D2D) communication link 158 to communicate with each other. The D2D communication link 158 may use one or more sidelink channels, such as physical sidelink broadcast channel (PSBCH), physical sidelink discovery channel (PSDCH), physical sidelink shared channel (PSSCH), physical sidelink control channel (PSCCH), and / or physical sidelink feedback channel (PSFCH).

[0051] EPC 160 may include various functional components, including: Mobility Management Entity (MME) 162, other MMEs 164, Serving Gateway 166, Multimedia Broadcast Multicast Service (MBMS) Gateway 168, Broadcast Multicast Service Center (BM-SC) 170, and / or Packet Data Network (PDN) Gateway 172, as in the illustrated example. MME 162 may communicate with Home Subscriber Server (HSS) 174. MME 162 is the control node that handles signaling between UE 104 and EPC 160. Generally, MME 162 provides bearer and connectivity management.

[0052] Generally, user Internet Protocol (IP) packets are transmitted through Serving Gateway 166, which is itself connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP service 176, which may include, for example, the Internet, intranet, IP Multimedia Subsystem (IMS), packet-switched (PS) streaming service, and / or other IP services.

[0053] The BM-SC 170 provides functions for MBMS user service dispatch and delivery. The BM-SC 170 can serve as an entry point for content provider MBMS transmission, can be used to authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and / or can be used to schedule MBMS transmissions. The MBMS gateway 168 can be used to distribute MBMS services to BS102 within a Broadcast-Specific Service Single Frequency Network (MBSFN) area, and / or can be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0054] 5GC 190 may include various functional components, including: Access and Mobility Management Function (AMF) 192, other AMFs 193, Session Management Function (SMF) 194, and User Plane Function (UPF) 195. AMF 192 can communicate with Unified Data Management (UDM) 196.

[0055] AMF 192 is the control node that handles signaling between UE 104 and 5GC 190. AMF 192 provides services such as Quality of Service (QoS) flow and session management.

[0056] Internet Protocol (IP) packets are transmitted via UPF 195, which connects to IP service 197 and provides the UE with IP address allocation and other functions for 5GC 190. IP service 197 may include, for example, the Internet, intranet, IMS, PS streaming service, and / or other IP services.

[0057] In various aspects, to give a few examples, network entities or network nodes can be implemented as aggregated base stations, decomposed base stations, components of base stations, integrated access and backhaul (IAB) nodes, relay nodes, and sidelink nodes.

[0058] Figure 2An example decomposed base station 200 architecture is depicted. The decomposed base station 200 architecture may include one or more central units (CUs) 210, which may communicate directly with the core network 220 via a backhaul link, or indirectly with the core network 220 through one or more decomposed base station units (such as a near real-time (near-RT) RAN Intelligent Controller (RIC) 225 via an E2 link, or a non-real-time (non-RT) RIC 215 associated with a Service Management and Orchestration (SMO) framework 205, or both). CUs 210 may communicate with one or more distributed units (DUs) 230 via corresponding midhaul links (such as F1 interfaces). DUs 230 may communicate with one or more radio units (RUs) 240 via corresponding fronthaul links. RUs 240 may communicate with corresponding UEs 104 via one or more radio frequency (RF) access links. In some implementations, UE 104 may be served simultaneously by multiple RUs 240.

[0059] Each of the units (e.g., CU 210, DU 230, RU 240, and near-RT RIC 225, non-RT RIC 215, and SMO frame 205) may include or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the unit's communication interface, may be configured to communicate with one or more other units via a transmission medium. For example, these units may include a wired interface configured to receive signals or transmit signals to one or more other units via a wired transmission medium. Additionally or alternatively, the unit may include a wireless interface that may include a receiver, transmitter, or transceiver (such as a radio frequency (RF) transceiver) configured to receive signals via a wireless transmission medium or transmit signals to one or more other units, or both.

[0060] In some aspects, CU 210 can host one or more higher-level control functions. Such control functions may include Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Serving Data Adaptation Protocol (SDAP), etc. Each control function can be implemented using an interface configured to signal to other control functions hosted by CU 210. CU 210 can be configured to handle user plane functions (e.g., Central Unit-User Plane (CU-UP)), control plane functions (e.g., Central Unit-Control Plane (CU-CP)), or combinations thereof. In some implementations, CU 210 can be logically divided into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, CU-UP units can communicate bidirectionally with CU-CP units via an interface (such as an E1 interface). CU 210 can be implemented to communicate with DU 230 for network control and signaling, as needed.

[0061] DU 230 may correspond to a logical unit including one or more base station functions for controlling the operation of one or more RU 240s. In some aspects, DU 230 may at least partially host one or more of the Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc.) according to functional splits (such as those defined by the 3rd Generation Partnership Project (3GPP). In some aspects, DU 230 may further host one or more low PHY layers. Each layer (or module) may be implemented using an interface configured to communicate signals with other layers (and modules) hosted by DU 230 or with control functions hosted by CU 210.

[0062] Lower-layer functionality can be implemented by one or more RU 240s. In some deployments, an RU240 controlled by a DU 230 may correspond to a logical node that hosts RF processing functions or low-PHY layer functions (such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, Physical Random Access Channel (PRACH) extraction and filtering, or both, based at least in part on functional decomposition (such as lower-layer functional decomposition). In such architectures, the RU 240 may be implemented to handle over-the-air (OTA) communications with one or more UE 104s. In some specific implementations, the real-time and non-real-time aspects of control plane and user plane communications with the RU 240 may be controlled by the corresponding DU 230. In some scenarios, this configuration enables the implementation of the DU 230 and CU 210 in cloud-based RAN architectures (such as vRAN architectures).

[0063] SMO framework 205 can be configured to support RAN deployment and provisioning of both non-virtualized and virtualized network elements. For non-virtualized network elements, SMO framework 205 can be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which can be managed via operation and maintenance interfaces such as the O1 interface. For virtualized network elements, SMO framework 205 can be configured to interact with a cloud computing platform (such as Open Cloud (O-Cloud) 290) to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface (such as the O2 interface). Such virtualized network elements may include, but are not limited to, CU 210, DU 230, RU 240, and near-RT RIC 225. In some implementations, SMO framework 205 can communicate with the hardware aspects of the 4G RAN (such as Open eNB (O-eNB) 211) via the O1 interface. Additionally, in some implementations, SMO framework 205 can communicate directly with one or more RU 240s via the O1 interface. SMO framework 205 may also include a non-RT RIC 215 configured to support the functionality of SMO framework 205.

[0064] The non-RT RIC 215 can be configured to include logical functions enabling non-real-time control and optimization of RAN elements and resources, including AI / ML workflows for model training and updates, or policy-based guidance for applications / features in the near-RT RIC 225. The non-RT RIC 215 can be coupled to or communicate with the near-RT RIC 225, such as via an A1 interface. The near-RT RIC 225 can be configured to include logical functions enabling near real-time control and optimization of RAN elements and resources via an interface, such as an E2 interface, connecting one or more CU 210s, one or more DU 230s, or both, and O-eNBs to the near-RT RIC 225.

[0065] In some implementations, to generate AI / ML models to be deployed in the near-RT RIC 225, the non-RT RIC 215 may receive parameters or external enrichment information from an external server. This information can be utilized by the near-RT RIC 225 and can be received from non-network data sources or network functions at the SMO framework 205 or the non-RT RIC 215. In some examples, the non-RT RIC 215 or near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the non-RT RIC 215 may monitor long-term trends and patterns in performance and employ AI / ML models to perform corrective actions via the SMO framework 205 (such as reconfiguration via O1) or by creating RAN management policies (such as A1 policies).

[0066] Figure 3 Various aspects of examples BS102 and UE 104 are described.

[0067] Generally, BS102 includes various processors (e.g., 320, 330, 338, and 340), antennas 334a-334t (collectively referred to as 334), transceivers 332a-332t (collectively referred to as 332) including modulators and demodulators, and other aspects that enable the wireless transmission of data (e.g., data source 312) and the wireless reception of data (e.g., data sink 339). For example, BS102 can transmit and receive data between BS102 and UE 104. BS102 includes a controller / processor 340 that can be configured to implement the various functions described herein related to wireless communication.

[0068] Generally, UE 104 includes various processors (e.g., 358, 364, 366, and 380), antennas 352a-352r (collectively referred to as 352), transceivers 354a-354r (collectively referred to as 354) including modulators and demodulators, and other aspects that enable the wireless transmission of data (e.g., retrieved from data source 362) and the wireless reception of data (e.g., provided to data sink 360). UE 104 includes a controller / processor 380 that can be configured to implement the various functions described herein related to wireless communication.

[0069] Regarding example downlink transmission, BS102 includes a transmission processor 320 that can receive data from data source 312 and control information from controller / processor 340. The control information may be for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical HARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), Group Shared PDCCH (GC PDCCH), and / or others. In some examples, the data may be for the Physical Downlink Shared Channel (PDSCH).

[0070] The transmitter processor 320 can process (e.g., encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. The transmitter processor 320 can also generate reference symbols (such as those for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS)).

[0071] The transmit (TX) multiple-input multiple-output (MIMO) processor 330 can perform spatial processing (e.g., pre-decoding) on ​​data symbols, control symbols, and / or reference symbols where applicable, and can provide the output symbol stream to the modulators (MODs) in transceivers 332a-332t. Each modulator in transceivers 332a-332t can process its corresponding output symbol stream to obtain an output sample stream. Each modulator can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signal from the modulators in transceivers 332a-332t can be transmitted via antennas 334a-334t respectively.

[0072] To receive downlink transmissions, UE 104 includes antennas 352a-352r that receive downlink signals from BS 102 and provide the received signals to demodulators (DEMODs) in transceivers 354a-354r respectively. Each demodulator in transceivers 354a-354r can adjust (e.g., filter, amplify, down-convert, and digitize) the corresponding received signal to obtain an input sample. Each demodulator can further process the input sample to obtain the received symbols.

[0073] The MIMO detector 356 acquires received symbols from all demodulators in transceivers 354a-354r, performs MIMO detection on the received symbols where applicable, and provides the detected symbols. The receive processor 358 processes (e.g., demodulates, deinterleaves, and decodes) the detected symbols, provides the decoded data for UE 104 to data sink 360, and provides the decoded control information to controller / processor 380.

[0074] Regarding the example uplink transmission, UE 104 further includes a transmission processor 364 that receives and processes data from data source 362 (e.g., for PUSCH) and control information from controller / processor 380 (e.g., for Physical Uplink Control Channel (PUCCH)). Transmission processor 364 can also generate reference symbols for reference signals (e.g., for Sounding Reference Signal (SRS)). Symbols from transmission processor 364 may be pre-decoded by TX MIMO processor 366, where applicable, further processed by modulators in transceivers 354a-354r (e.g., for SC-FDM), and transmitted to BS 102.

[0075] At BS102, uplink signals from UE 104 can be received by antennas 334a-334t, processed by demodulators in transceivers 332a-332t, detected by MIMO detector 336 where applicable, and further processed by receiver processor 338 to obtain decoded data and control information transmitted by UE 104. Receiver processor 338 can provide the decoded data to data sink 339 and the decoded control information to controller / processor 340.

[0076] Memory 342 and memory 382 can store data and program code for BS102 and UE 104, respectively.

[0077] Scheduler 344 can schedule UE to transmit data on the downlink and / or uplink.

[0078] In various respects, BS102 can be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, "transmitting" can refer to various mechanisms that output data, such as from data source 312, scheduler 344, memory 342, transmit processor 320, controller / processor 340, TX MIMO processor 330, transceiver 332a-332t, antenna 334a-334t, and / or other aspects described herein. Similarly, "receiving" can refer to various mechanisms that acquire data, such as from antenna 334a-334t, transceiver 332a-332t, RX MIMO detector 336, controller / processor 340, receive processor 338, scheduler 344, memory 342, and / or other aspects described herein.

[0079] In various respects, UE 104 can also be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” can refer to various mechanisms that output data, such as from data source 362, memory 382, ​​transmit processor 364, controller / processor 380, TX MIMO processor 366, transceiver 354a-354t, antenna 352a-352t, and / or other aspects described herein. Similarly, “receiving” can refer to various mechanisms that acquire data, such as from antenna 352a-352t, transceiver 354a-354t, RX MIMO detector 356, controller / processor 380, receive processor 358, memory 382, ​​and / or other aspects described herein.

[0080] In some respects, the processor can be configured to perform various operations (such as those associated with the methods described herein) and to send (output) data to or receive data from another interface configured to send or receive data, respectively.

[0081] Figure 4A , Figure 4B , Figure 4C and Figure 4D Describes the use of wireless communication networks (such as Figure 1 All aspects of the data structure of the wireless communication network 100.

[0082] Specifically, Figure 4A Figure 400 illustrates an example of the first subframe within a 5G (e.g., 5G NR) frame structure. Figure 4B Figure 430 illustrates an example of a DL channel within a 5G subframe. Figure 4C Figure 450 illustrates an example of the second subframe within a 5G frame structure, and Figure 4D Figure 480 illustrates an example of a UL channel within a 5G subframe.

[0083] Wireless communication systems can utilize Orthogonal Frequency Division Multiplexing (OFDM) with a cyclic prefix (CP) on both the uplink and downlink. Such systems can also support half-duplex operation using Time Division Duplex (TDD). OFDM and Single-Carrier Frequency Division Multiplexing (SC-FDM) will (e.g., as...) Figure 4B and Figure 4D The system bandwidth described herein is divided into multiple orthogonal subcarriers. Each subcarrier can be modulated with data. Modulation symbols can be transmitted in the frequency domain using OFDM and / or in the time domain using SC-FDM.

[0084] Wireless communication frame structures can be frequency division duplex (FDD), where for a specific set of subcarriers, subframes within that set are dedicated to either deep (DL) or ultra-low (UL). Wireless communication frame structures can also be time division duplex (TDD), where for a specific set of subcarriers, subframes within that set are dedicated to both DL and UL.

[0085] exist Figure 4A and Figure 4C In this example, the wireless communication frame structure is TDD, where D stands for DL, U for UL, and X is flexibly used between DL and UL. The UE can configure the time slot format via the received Slot Format Indicator (SFI) (dynamically configured via DL Control Information (DCI) or semi-statically / statically configured via Radio Resource Control (RRC) signaling). In the depicted example, a 10ms frame is divided into 10 equal-sized 1ms subframes. Each subframe may include one or more time slots. In some examples, each time slot may include 7 or 14 symbols, depending on the time slot format. Subframes may also include micro-slots, which typically have fewer symbols than the entire time slot. Other wireless communication technologies may have different frame structures and / or different channels.

[0086] In some respects, the number of slots within a subframe is based on the slot configuration and parameter set. For example, for slot configuration 0, different parameter sets (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter sets 0 to 2 allow for 2, 4, and 8 slots per subframe, respectively. Therefore, for slot configuration 0 and parameter set μ, there are 14 symbols / slots and 2μ slots / subframes. The subcarrier spacing and symbol length / duration are functions of the parameter set. The subcarrier spacing can be equal to 2. μ ×15kHz, where μ is the parameter set from 0 to 5. Therefore, parameter set μ = 0 has a subcarrier spacing of 15kHz, and parameter set μ = 5 has a subcarrier spacing of 480kHz. The symbol length / duration is negatively correlated with the subcarrier spacing. Figure 4A , Figure 4B , Figure 4C and Figure 4D Examples are provided for slot configuration 0 with 14 symbols per slot and parameter set μ=2 with 4 slots per subframe. The slot duration is 0.25ms, the subcarrier spacing is 60kHz, and the symbol duration is approximately 16.67μs.

[0087] like Figure 4A , Figure 4B , Figure 4C and Figure 4DAs depicted, the resource grid can be used to represent the frame structure. Each time slot includes a resource block (RB) (also known as a physical RB (PRB)) extending for, for example, 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0088] like Figure 4A As illustrated in the example, some REs in the RE carry information for the UE (e.g., Figure 1 and Figure 3 The reference (pilot) signal (RS) for the UE (104) may include a demodulation RS (DMRS) and / or a channel state information reference signal (CSI-RS) for channel estimation at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and / or a phase tracking RS (PT-RS).

[0089] Figure 4B Examples of various DL channels within a subframe of a frame are illustrated. The Physical Downlink Control Channel (PDCCH) carries the DCI within one or more Control Channel Elements (CCEs), each CCE comprising, for example, nine RE groups (REGs), each REG comprising, for example, four consecutive REs in an OFDM symbol.

[0090] The Primary Synchronization Signal (PSS) can be located within symbol 2 of a specific subframe of the frame. The PSS is generated by the UE (e.g., Figure 1 and Figure 3 104) is used to determine subframe / symbol timing and physical layer identifier.

[0091] The Secondary Synchronization Signal (SSS) can be located in symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identifier group number and radio frame timing.

[0092] Based on the Physical Layer Identifier and Physical Layer Cell Identifier Group Number, the UE can determine the Physical Cell Identifier (PCI). Based on the PCI, the UE can determine the location of the aforementioned DMRS. 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. The MIB provides the System Frame Number (SFN) and the number of Restricted Frames (RBs) in the system bandwidth. The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information (such as System Information Blocks (SIBs)) not transmitted via the PBCH, and / or paging messages.

[0093] like Figure 4CAs illustrated, some REs in the REs carry DMRS for channel estimation at the base station (indicated as R for a particular configuration, but other DMRS configurations are possible). The UE may transmit DMRS for PUCCH and DMRS for PUSCH. PUSCH DMRS may be transmitted, for example, in the first or second symbol preceding the PUSCH. PUCCH DMRS may be transmitted in different configurations depending on whether a short or long PUCCH is being transmitted and depending on the specific PUCCH format used. UE104 may transmit a Sounding Reference Signal (SRS). SRS may be transmitted, for example, in the last symbol of a subframe. SRS may have a comb structure, and the UE may transmit SRS on one of the comb teeth. SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling of the UL.

[0094] Figure 4D Examples of various UL channels within a subframe of a frame are illustrated. The PUCCH can be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), pre-decoding matrix indicators (PMI), rank indicators (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry buffer status reports (BSR), power clearance reports (PHR), and / or UCI.

[0095] Overview of Reconfigurable Smart Surfaces (RIS)

[0096] Massive multiple-input multiple-output (MIMO) configurations have the potential to significantly increase throughput. For example, MIMO can achieve high beamforming gain by using active antenna elements (AAUs) and can operate using a separate radio frequency (RF) chain for each antenna port. Unfortunately, the use of AAUs can significantly increase power consumption.

[0097] As discussed above, to further realize these advantages and extend coverage, reconfigurable (or reflective) smart surfaces (RIS) can be deployed to reflect impact beams / signals in desired directions. RIS has been proposed as a low-cost, passive, and reconfigurable array of reflective elements that can improve coverage and spectral efficiency. In some cases, these RIS can operate without significant power consumption when they operate passively to reflect or refract signals only from the transmitter device toward the receiver device. In some cases, the direction of reflection or refraction can be controlled by the network entity or by monitoring the user equipment (UE). The configurability of RIS allows the network to implement multiple anomalous reflections (each specified by a target incident direction and reflection direction pair) and assists in UE selection by enhancing the end-to-end channel seen by the UE.

[0098] Figure 5An example deployment 500 illustrating communication obstructions between wireless communication devices is shown. As illustrated, due to the obstruction, the first network entity can only send signals to the first UE but cannot reach the second UE because the obstruction prevents the signal from reaching the second UE. Similarly, the second network entity can only send signals to the second UE but cannot reach the first UE because the obstruction prevents the signal from reaching the first UE. The obstruction also prevents the first UE from establishing sidelink communication with the second UE. Thus, the second UE may be unable to communicate with either the first network entity or the first UE, and the first UE may be unable to communicate with either the second network entity or the second UE.

[0099] Figure 6 An example deployment 600 is illustrated using an array 620 of RIS elements 622 to overcome obstructions. As shown, RIS elements can be introduced to reflect or otherwise re-radiate radio signals to bypass obstructions. For example, communication between a network entity and a first UE can be achieved by the RIS re-radiating one or more signals from a network entity toward or in turn toward a first UE. Furthermore, the RIS elements can be reconfigured via a RIS controller 610 (i.e., directing incoming and outgoing beams at different angles) to enable a second UE and a first UE to establish sidelink communication.

[0100] In some cases, the RIS can be a full-duplex (FD) device. FD communication allows simultaneous transmission between devices. Half-duplex (HD) communication flows in one direction at a time. In operation, the RIS can immediately reflect the received signal from the transmitter device to the receiver device.

[0101] In some cases, the RIS may have a RIS-MT (Mobile Station Called) component (controller) for communicating with the gNB on the control link and a RIS-FWD (forwarding) component for forwarding / reflecting signals between the gNB and the UE.

[0102] In some cases, RIS can perform passive beamforming. For example, RIS can receive signal power from a transmitter device that is proportional to the number of elements (such as RIS elements of RIS). When RIS reflects or refracts radio signals, one or more RIS elements can cause a phase shift to perform beamforming or pre-decoding. The phase shift can be based on pre-decoding weights (e.g., offsets of multipliers or time delays) applied to one or more RIS elements. In some cases, for an array of RIS elements of RIS, the RIS controller of RIS can generate or assign pre-decoding weights for each RIS element.

[0103] In some cases, the RIS can be configured based on the direction of the target incident signal and the direction of the target reflected signal. The target incident signal typically refers to a signal traveling toward the RIS in the desired incident direction. The target reflected signal typically refers to a signal reflected by the RIS in the desired reflection direction (e.g., toward the target receiver). For example, the target reflected signal can be a reflected version of the target incident signal. As used herein, the target incident direction typically refers to the desired direction of the target incident signal, and the target reflection direction typically refers to the desired direction of the target reflected signal. The desired direction can be based on a desired target, such as gain optimization described in more detail below. In some cases, signals incident on and / or reflected by the RIS that do not propagate in the target direction can be considered non-target and / or non-desired signals.

[0104] As described above, a RIS generally refers to a structure with a surface containing multiple (densely arranged) reconfigurable elements that can reflect or refract EM waves toward a target direction. RIS structures can be formed from RIS elements that only reflect, only transmit (refract), or a combination thereof. In some cases, RIS structures may be able to simultaneously transmit and reflect (STAR), and such RIS structures may be referred to as hybrid RIS or omnidirectional RIS. Potential benefits of RIS structures include potentially low cost (e.g., formed using relatively inexpensive positive intrinsic-negative / varactor diodes) and low power (e.g., no radiated power, only control power required for RIS configuration).

[0105] Reflection beamforming via RIS can be referenced Figure 7A and Figure 7B For example, see Figures 700A and 700B for illustrative purposes. Figure 7B As illustrated in the example, an angle of incidence (θ) can be formed with respect to the reference (vertical / optical axis) line. i The incident direction (i) (d) i,n A signal is transmitted from base station 102 toward the nth RIS element 622. The RIS element can be configured to form a reflection angle (θ) with the line of sight. r The direction of reflection (r) (d) r,n The signal is reflected toward UE 104.

[0106] For the incident angle {θ} i,n} and reflection angle {θ r,n The reflection gain can depend on whether the RIS element 622 is in the near-field or far-field region of the base station 102 and / or UE 104. In general (e.g.) Figure 7A Under the near-field model shown, the incident angle {θ} i,n} and reflection angle {θ r,n The reflection gain of} can be described as:

[0107]

[0108] in It is the reflection coefficient of element n. In (for example) Figure 7B In the far-field case shown, the incident angle {θ} i,n} and reflection angle {θ r,n The reflection gain of} can be described as:

[0109]

[0110] In some cases, it may be desirable to have the following conditions:

[0111]

[0112] In fact, {α n ,φ n The values ​​of} are typically derived from an enumerated set based on the element implementation. For example, a finite number of configurations can be associated with a specific phase shift and amplitude response. This approach helps limit signaling overhead, allowing a finite number of bits to be used to select one configuration from four (e.g., a 2-bit value can select one of four configurations).

[0113] Aspects related to RIS coefficient rotation

[0114] In various example use cases utilizing RIS-assisted communication with high-speed UEs (e.g., where the UE is on a high-speed train HST), certain challenges may exist. Figure 8A The first example use case 800A is illustrated, in which a base station (e.g., gNB) 102 communicates with a high-speed UE 104 via a direct link and at least one RIS reflection link (from RIS 800). Figure 8B The example illustrates a first example use case 800B, in which base station 102 communicates with high-speed UE 104 via two or more RIS reflection links (RIS reflection link #1 and RIS reflection link #2) but (due to obstruction in the illustrated example) has no direct link.

[0115] In these example use cases, if each link in the chain satisfies a line-of-sight (LOS) channel type or has a dominant NLOS channel type that is much stronger than other non-LOS (NLOS) paths, then there may be only one dominant Doppler frequency at each link.

[0116] If multiple dominant NLOS paths exist in an NLOS channel type, the path direction can be obtained through beam scanning or channel estimation. For example... Figure 9As illustrated, in such a case, the RIS surface 900 can be divided into multiple sub-surfaces to generate multiple virtual RIS (e.g., a first virtual RIS 910 and a second virtual RIS 920). As illustrated, each sub-surface (virtual RIS) can be used to reflect signals along an NLOS path. In such a case, there may also be only one dominant Doppler frequency at each link of the virtual RIS.

[0117] As noted above, when a network entity (e.g., a gNB) communicates with a UE moving at high speed (in a direction not perpendicular to the direction of signal input), the signal received at the UE may be affected by the Doppler frequency. Figure 8A In the example shown, if the signal input direction of the direct link and the signal input direction of the RIS reflected link are different, the UE may experience two different Doppler frequencies. Similarly, in Figure 8B (and / or Figure 9 In the use case shown, if the signal input direction of the first (virtual) RIS reflection link #1 and the signal input direction of the (virtual) RIS reflection link #2 are different, the signal received by the UE may be subjected to two different Doppler frequencies.

[0118] As noted above, while a UE may be able to compensate for one Doppler frequency, compensation may become increasingly difficult or impossible when the UE is subjected to two or more Doppler frequencies. Therefore, the channel state may become time-varying. Time-varying channel states can affect composite channel gain, thereby reducing CSI accuracy and further leading to scheduling errors, which may result in decoding failures or spectral efficiency losses. While Doppler frequencies can be mitigated in part by increasing the frequency of CSI reporting, this will increase UL signaling overhead.

[0119] Certain aspects of this disclosure provide techniques for mitigating the effects of multiple Doppler frequencies on RIS-assisted communication by configuring a time-domain rotation factor for the RIS. Based on the time-domain rotation factor, the RIS controller can rotate the reflection coefficient of the RIS element for a given period. By rotating the reflection coefficient, the combined channel gain degradation and channel state time variations caused by multiple Doppler frequencies can be reduced.

[0120] According to certain aspects of this disclosure, techniques for mitigating the effects of multiple Doppler frequencies used in RIS-assisted communication can be referenced. Figure 10 To understand this, refer to the call flowchart 1000.

[0121] In some respects, Figure 10 ( Figure 11 and Figure 12 The UE shown in the diagram can be about Figure 1 and Figure 3 An example of UE 104 depicted and described. In some respects, Figure 10 ( Figure 11 and Figure 12 The network entities shown in the diagram can be about Figure 1 and Figure 3 Examples of BS102 (e.g., gNB) depicted and described, or about Figure 2 The decomposed base station described and illustrated.

[0122] As indicated at 1002, a network entity can configure a time-domain rotation factor for at least one reconfigurable smart surface (RIS) to apply time-varying reflection coefficient rotation. As will be described in more detail below, the time-domain rotation factor can be based on the Doppler frequency corresponding to the reflection link between the network entity and the UE via at least one RIS.

[0123] In some cases, the network entity can also configure a (TD rotation) period for at least one RIS, which determines the frequency at which the coefficients of the RIS elements of at least one RIS are updated based on a time-domain rotation factor. As indicated at 1004, the network entity can also configure a TD rotation period for the UE. As indicated at 1006, the UE can process reflected signals using updated Doppler processing based on the time-domain rotation period.

[0124] In some cases, network entities can also indicate the RIS reflection coefficient change gap (RRCCG) to the UE. The RRCCG can be based on at least one RIS capability regarding the RIS element coefficient change response time (which can be indicated by the RIS controller in the RIS capability report).

[0125] Figure 11 An example call flow diagram is illustrated for an example scenario with two RIS (RIS#1 and RIS#2). As illustrated at 1102, the network entity can determine the corresponding time-domain rotation factors (Δ1 and Δ2) for each RIS based on the Doppler frequency of the corresponding RIS reflection link, and configure each RIS accordingly.

[0126] As illustrated at 1104 and 1106, each RIS can reflect its corresponding incident signal by time-domain rotational reflection coefficient based on Δ1 and Δ2 and the TD rotation period.

[0127] As indicated at 1108, applying a time-domain rotation factor can make the Doppler frequency of the corresponding signal received at the UE zero (or have only a residual Doppler frequency that can be more easily compensated).

[0128] Figure 12Call flowchart 1200 illustrates how network entities can obtain various options for determining the Doppler frequency of the TD rotation factor.

[0129] According to the first option (Option 1), for example based on a UE measurement report of the downlink reference signal (DLRS) transmitted by the network entity, the Doppler frequency can be obtained by the network entity via downlink channel estimation. According to this option, the network entity can transmit the DL-RS (such as Channel State Information Reference Signal (CSI-RS) or Tracking Reference Signal (TRS)) to the UE via a direct link (if a direct link exists) and / or a RIS reflection link.

[0130] In this scenario, as illustrated at 1202, the UE can measure the Doppler frequency (for a given RIS). The UE can measure the Doppler frequency for each link based on at least two CSI-RS. The UE can then report the measured Doppler frequencies for each link for use by network entities to determine the TD rotation factor.

[0131] In some cases, the UE can be configured to report the Doppler frequency at a period longer than the CSI-RS transmission period. This can help reduce UL signaling overhead and radio resource consumption compared to reporting the Doppler frequency after each CSI-RS is received.

[0132] According to the second option (Option 2), the Doppler frequency can be obtained by the network entity via uplink channel estimation. With this option, the UE can transmit uplink RS (UL RS), such as a sounding reference signal (SRS), via a direct link (if one exists) and / or a RIS reflection link. As indicated at 1204, the network entity can then measure the Doppler frequency for each link.

[0133] Regardless of which option is used, at point 1206, the network entity can determine the TD rotation factor for each link based on the Doppler frequency.

[0134] In some cases, to avoid mutual interference or confusion of measurement results, for either option, the Doppler frequency measurement of each link can be performed at different times. For example, the network entity can be configured (via the RIS controller) to shut down all RISs in order to measure the direct links. The network entity can then sequentially configure each RIS to be turned on to measure the Doppler frequency of the reflected links for each RIS.

[0135] In measuring the Doppler frequency of a direct link (denoted as...) ) and the Doppler frequency of the RIS reflection link (denoted as ) After that, the network entity can determine the RIS time-domain rotation factor. The general goal of the RIS time-domain rotation factor is to compensate for the relative Doppler frequencies of multiple links, so that the UE suffers from zero or only one Doppler frequency.

[0136] Various options exist to achieve this goal. For example, according to the first option, if a direct link exists and the network entity does not compensate for the Doppler frequency in the direct link, the ideal time-domain rotation coefficients for RIS#m (RIS coefficients with applied rotation factors) can be expressed as:

[0137]

[0138] Therefore, the RIS time-domain twitch factor for any RIS#m is:

[0139]

[0140] In this way, the UE may only suffer from one Doppler frequency (e.g., assuming there is only one dominant Doppler frequency in the direct link and each RIS reflection link).

[0141] According to the other option, if a direct link exists and the network entity compensates for the Doppler frequency in the direct link, the ideal time-domain rotation coefficient for RIS#m can be expressed as:

[0142]

[0143] Therefore, the RIS time-domain twitch factor for any RIS#m is:

[0144]

[0145] In this way, the UE can avoid being subjected to any Doppler frequencies.

[0146] If no direct link exists, various options exist to determine the RIS time-domain rotation factor. According to one option, the ideal time-domain rotation factor can be expressed as:

[0147] For RIS#m≠m * ,

[0148] Where m * This is common to all RIS and can be chosen arbitrarily. Therefore, the RIS time-domain twitch factor for RIS#m is:

[0149]

[0150] In this way, the UE only suffers from one Doppler frequency. According to another option, the ideal time-domain rotation coefficient can be expressed as:

[0151]

[0152] For any RIS#m, therefore, the RIS time-domain twitch factor for RIS#m is...

[0153]

[0154] In this way, the UE can avoid being subjected to any Doppler frequencies.

[0155] Once the time-domain rotation factor is determined, the network entity can configure the corresponding RIS, for example, by signaling to the corresponding RIS controller. The network entity can configure the time-domain rotation factor Δ for RIS#m or virtual RIS (sub-surface)#m. m Because the Doppler frequency of a mobile UE is typically variable, this configuration can be transmitted via dynamic signaling messages such as downlink control information (DCI). However, in some cases, the configuration can be transmitted via radio resource control (RRC) or media access control (MAC) control element (CE) signaling.

[0156] RIS may require some response time to adjust the reflection coefficients of its components. As noted above, this response time can be reported as RIS capability. For example, for some RIS types, the length of the response time can be on the order of microseconds (μs).

[0157] Therefore, the RIS can report to the network entity its ability to change the response time of components. The network entity can then configure the reflection coefficient rotation period T for the RIS. rotate This reflection coefficient rotation period can correspond to the frequency at which the reflection coefficient is to be updated (rotated). In some cases, the reflection coefficient rotation period can be longer than the reported response time. As an example, for a parameter set with a subcarrier spacing (SCS) of 30 kHz, if the minimum timing gap is 2 μs, this represents approximately 5.6% of an OFDM symbol length (35.7 μs) and approximately 0.4% of a time slot (500 μs).

[0158] Considering that channel estimation based on a demodulation reference signal (DMRS) symbol can be used for signal reception across multiple symbols or the entire time slot, it is likely optimal if the RIS rotation coefficient does not change until the next DMRS symbol or remains unchanged within the duration of a time slot. For example, the reflection coefficient rotation period can be equal to the duration of one or more time slots, depending on the absolute value of the Doppler frequency. Generally, the larger the absolute value of the Doppler frequency, the shorter the reflection coefficient rotation period.

[0159] As pointed out above and as... Figure 13As illustrated in timing diagram 1300, when network entities are configured with time-domain rotation factors, a gap known as the RIS reflection coefficient change gap (RRCCG) can be allocated. Figure 13 As illustrated, RRCCG can correspond to the time period when the RIS reflection coefficient changes from the old reflection coefficient 1302 applied in the first OFDM symbol 1 to the new reflection coefficient 1304 applied in OFDM symbol 1+1. During RRCCG, data signals or reference signals may not be transmitted in the RIS reflection link.

[0160] As illustrated in the example, if the length of the RRCCG is much shorter than the CP length, the RRCCG can be placed at the beginning of the relevant OFDM symbol (l+1). Therefore, the OFDM symbol l+1 following the RRCCG has a shorter CP. In some cases, the length of this shorter CP, or the length of the RRCCG, can be configured by the network entity. The network entity can determine this length based on RIS capability reports regarding element change response times.

[0161] If the length of the RRCCG is similar to or greater than that of the CP, the RRCCG can be placed at the blank OFDM symbol. Generally speaking, the positioning of the RRCCG, shorter CP, and / or blank OFDM symbol can also be configured for the UE.

[0162] like Figure 14 As illustrated in timing diagram 1400, upon receiving the time-domain rotation factor Δ m and period T rotate After configuration, RISm uses these parameters to determine the reflection coefficient for each symbol / slot. In the illustrated example, T rotate =T slot .

[0163] For example, suppose when T rotate =T slot At that time, the basic reflection coefficient of the element n used in RISm is:

[0164]

[0165] The basic reflection coefficient is based on the target incident direction θ. i,m and reflection direction θ r,m It is determined. The "rotational" reflection coefficient of the element n used in RISm is...

[0166]

[0167] During the duration T rotate (l-1)≤t <T rotateWithin l, l = 1, 2, ... are the indices of the time-domain rotation period. Therefore, as shown at 1402, at time slot 1 (l = 1):

[0168]

[0169] As shown at 1404, at time slot 2 (l=2):

[0170] as well as

[0171] As shown at position 1406, at time slot L:

[0172]

[0173] In some cases, the reflection coefficient of the RIS element can be selected from a finite set of candidate values. Therefore, the actual reflection coefficient used can be the closest to... Candidate values.

[0174] To measure the Doppler frequency, some symbols (e.g., at the end of each time slot) can be used for CSI-RS. Therefore, as illustrated at 1410, for these symbols, RIS uses the basic reflection coefficient without reflection coefficient rotation.

[0175] Due to the rotation applied at the RIS, the UE can receive signals from the direct link and the RIS reflected link at either zero or one Doppler frequency. If the signal is received at zero Doppler frequency, the UE can take no action to compensate for the Doppler frequency offset. If the signal is received at one Doppler frequency, the UE can take action to compensate for the Doppler frequency offset. For example, the UE can estimate the Doppler frequency f based on DMRS. d Then the sequence Multiply by the received signal, where T s is the sampling interval, and k is the sample index.

[0176] As described above, network entities can indicate time-domain rotation periods to the UE, which can aid UE reception. For example, when a new period occurs, the UE can reset its DMRS-based Doppler estimation or compensation. In some cases, network entities indicate RIS reflection coefficient change gaps to the UE, during which the UE may not expect to receive signals from the RIS. This can affect rate matching and channel measurements performed at the UE.

[0177] Figure 15A , Figure 15B , Figure 16A and Figure 16B Example simulation results are depicted to demonstrate the potential performance improvements that can be achieved using the RIS time-domain twitch factor according to certain aspects of this disclosure.

[0178] For simplicity, these simulations can assume the use of narrowband signals. If a wideband OFDM signal is transmitted, the narrowband signal can be understood as a signal on a single subcarrier, and the wideband OFDM signal has a carrier frequency f. c =3.5GHz and targeting Figure 15A and Figure 15B The UE's moving speed v = 120 km / h (e.g., highway speed) or for Figure 16A and Figure 16B The UE moves at a speed of 350 km / h (e.g., high-speed train).

[0179] These simulations can also assume the direct link channel response h. direct and RIS reflection link channel response h RIS,m These are Rayleigh-distributed variables with the same mean and variance (coherent joint transmission can be achieved through appropriate RIS beamforming weights).

[0180] The angle between each link and the UE's direction of movement is θ. direct and θ eIs,m Therefore, the Doppler frequency at each link is:

[0181]

[0182] Figure 15A and Figure 16A Simulation results are shown for a first use case and options with a direct link and a RIS reflection link (for UE speeds of 120 km / h and 350 km / h, respectively), where the network entity does not compensate for the Doppler frequency, and the RIS rotates the reflection coefficient based on the following equation:

[0183]

[0184] Without RIS reflection coefficient rotation, as indicated at positions 1502 and 1602, the received signal is

[0185]

[0186] With RIS reflection coefficient rotation, as indicated at positions 1504 and 1604, the received signal is

[0187]

[0188] When the sample location k is within the rotation period l, i.e. T rotate (l-1)≤kT s <T rotate l hour.

[0189] Figure 15B and Figure 16B Simulation results are shown for a second use case and option with two RIS reflection links (for UE speeds of 120 km / h and 350 km / h, respectively). In this case, the RIS rotates the reflection coefficient based on the following equation:

[0190]

[0191] Without RIS reflection coefficient rotation, as indicated at positions 1506 and 1606, the received signal is

[0192]

[0193] With RIS reflection coefficient rotation, as indicated at positions 1508 and 1608, the received signal is

[0194]

[0195] When the sample location k is within the rotation period l, i.e. T rotate (l-1)≤kT s <T rotate l hour.

[0196] As demonstrated by the example simulations, without applying RIS reflection coefficient rotation, the composite channel gain (which involves the combination of channel gains across all links) can suffer from degradation and fluctuations, potentially leading to inaccurate CSI, scheduling errors, and loss of spectral efficiency. On the other hand, applying RIS reflection coefficient rotation significantly reduces composite channel gain degradation and fluctuations, which can improve CSI accuracy and spectral efficiency.

[0197] In some cases, various signaling mechanisms can be utilized (e.g., and defined in wireless standard specifications) to support the techniques presented herein. For example, these signaling mechanisms may include signaling messages that allow network entities (e.g., gNBs) to configure time-domain rotation factors and periods for the RIS (or virtual RIS). Signaling messages may also include messages that allow the RIS to report to the gNB its ability to change the response time of components. In some cases, due to the RIS reflection coefficient change gap (RRCCG), signaling messages may allow network entities to configure shorter CPs for OFDM symbols. In some cases, signaling messages may allow network entities to configure the UE's RRCCG, shorter CP, or blank OFDM symbol positioning. As noted above, during the gap, the UE may not expect to receive signals from the RIS. This can affect rate matching and channel measurements. In some cases, network entities can configure time-domain rotation periods for the UE, which can help with UE signal reception. For example, when a new period occurs, the UE can reset its DMRS-based Doppler estimation or compensation.

[0198] Example Operation

[0199] Figure 17 This shows the network entities (such as Figure 1 and Figure 3 (BS102) or as per BS102) Figure 2 An example of the method 1700 for wireless communication at the decomposed base station discussed.

[0200] Method 1700 begins at step 1705, wherein signaling is sent to configure a time-domain rotation factor for at least one reconfigurable smart surface (RIS) to apply time-varying reflection coefficient rotation, wherein the time-domain rotation factor is based on the Doppler frequency corresponding to the reflection link between the network entity and the user equipment (UE) via at least one RIS. In some cases, this step refers to the operation as described in reference Figure 20 The circuitry and / or code described for transmitting or that can be executed by the circuitry and / or the code.

[0201] Method 1700 then proceeds to step 1710, where communication with the UE is initiated via RIS after signaling is sent. In some cases, this step refers to the operation as described in reference [reference needed]. Figure 20 The circuitry and / or code used for communication described herein or that can be executed by the circuitry and / or the code.

[0202] In some aspects, method 1700 also includes obtaining information about the Doppler frequency corresponding to the reflection link. In some cases, this step refers to, as referenced... Figure 20 The circuit and / or code described are used to obtain or can be executed by the circuit and / or the code.

[0203] In some aspects, method 1700 also includes determining a time-domain rotation factor based at least on the Doppler frequency corresponding to the reflection link. In some cases, this step refers to... Figure 20 The circuit and / or code described are used for determination or can be executed by the circuit and / or the code.

[0204] In some respects, the determination of the time-domain rotation factor depends on at least one of the following: whether there is a direct link between the network entity and the UE, or whether the network entity compensates for the Doppler frequency corresponding to the direct link.

[0205] In some respects, obtaining information about the Doppler frequency includes receiving a measurement report from the UE indicating the Doppler frequency.

[0206] In some aspects, method 1700 also includes configuring at least one RIS to use a fundamental reflection coefficient in at least a portion of some symbols without rotation, to allow the UE to measure the Doppler frequency. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described are for configuration or can be executed by the circuitry and / or the code.

[0207] In some respects, obtaining information about the Doppler frequency includes determining the Doppler frequency based on measurements of the uplink reference signal from the UE.

[0208] In some aspects, method 1700 further includes disabling at least one RIS to determine a Doppler frequency corresponding to at least one of the following: a direct link between the network entity and the UE, or a reflected link between the network entity and the UE via at least one other RIS. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for switching or that can be executed by the circuitry and / or the code.

[0209] In some aspects, method 1700 further includes determining a time-domain rotation period, which is based on a time-domain rotation factor to determine the frequency at which the coefficients of at least one RIS element are updated. In some cases, this step refers to the operation as described in reference... Figure 20 The circuit and / or code described are used for determination or can be executed by the circuit and / or the code.

[0210] In some aspects, method 1700 further includes receiving signaling instructing at least one RIS to have a capability to change the response time of RIS element coefficients, wherein the time-domain rotation period is determined based on this capability. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0211] In some aspects, method 1700 further includes sending an indication of the time-domain rotation period to at least one of the following: a UE or at least one RIS. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for transmitting or that can be executed by the circuitry and / or the code.

[0212] In some aspects, method 1700 also includes determining the time interval for at least one RIS to change the coefficients of RIS elements based on a time-domain twisting factor. In some cases, this step refers to the operation as described in reference... Figure 20 The circuit and / or code described are used for determination or can be executed by the circuit and / or the code.

[0213] In some aspects, method 1700 further includes sending an indication of the time slot to at least one of the following: a UE or at least one RIS. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for transmitting or that can be executed by the circuitry and / or the code.

[0214] In one aspect, method 1700 or any aspect thereof can be made by means of a device (such as...) Figure 20 The communication device 2000 performs the method, which includes various components operable to, configured to, or adapted to perform the method 1700. The communication device 2000 is described in more detail below.

[0215] It should be noted that Figure 17 This is merely one example of a method, and other methods that include fewer, additional, or alternative steps may also be consistent with this disclosure.

[0216] Figure 18 This demonstrates the application of reconfigurable smart surface (RIS) controllers (such as...) Figure 1 and Figure 3 An example of a method 1800 for wireless communication at UE 104.

[0217] Method 1800 begins at step 1805, where signaling indicating a time-domain rotation factor is received from the network entity. In some cases, this step refers to the operation as described in reference [reference needed]. Figure 20 The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0218] Method 1800 then proceeds to step 1810, where the reflection coefficient of one or more elements of at least one RIS is changed by applying a time-varying reflection coefficient rotation based on a time-domain rotation factor. In some cases, this step refers to the operation as described in reference... Figure 20 The circuit and / or code described are either for modification or can be executed by the circuit and / or the code.

[0219] In some aspects, method 1800 further includes receiving signaling from a network entity for configuring at least one RIS to use a basic reflection coefficient in at least a portion of some symbols without rotation. In some cases, this step refers to operations as described in reference... Figure 20 The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0220] In some aspects, method 1800 further includes determining a time-domain rotation period, which determines the frequency at which the coefficients of at least one RIS element are updated based on a time-domain rotation factor. In some cases, this step refers to the operation as described in reference... Figure 20 The circuit and / or code described are used for determination or can be executed by the circuit and / or the code.

[0221] In some aspects, method 1800 further includes sending signaling to the network entity indicative of the capability of at least one RIS to change the response time with respect to RIS element coefficients, wherein the time-domain rotation period is determined based on this capability. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for transmitting or that can be executed by the circuitry and / or the code.

[0222] In some aspects, method 1800 also includes receiving an indication of the time-domain rotation period from a network entity. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0223] In some aspects, method 1800 also includes determining the time interval for changing the coefficients of the RIS elements based on a time-domain twisting factor. In some cases, this step refers to the operation as described in reference... Figure 20 The circuit and / or code described are used for determination or can be executed by the circuit and / or the code.

[0224] In some aspects, method 1800 also includes receiving an indication of a time slot from a network entity. In some cases, this step refers to the operation as described in reference... Figure 20The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0225] In one respect, method 1800 or any aspect thereof may be made by means of a device (such as...) Figure 20 The communication device 2000 performs the method, which includes various components operable to, configured to, or adapted to perform the method 1800. The communication device 2000 is described in more detail below.

[0226] It should be noted that Figure 18 This is merely one example of a method, and other methods that include fewer, additional, or alternative steps may also be consistent with this disclosure.

[0227] Figure 19 This illustrates the use of user equipment (UE) (such as...) Figure 1 and Figure 3 An example of a method for wireless communication at UE 104 (1900).

[0228] Method 1900 begins at step 1905, wherein signaling indicating a time-domain rotation period is received from the network entity, the time-domain rotation period determining the frequency at which the coefficients of at least one reconfigurable smart surface (RIS) element are updated. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0229] Method 1900 then proceeds to step 1910, where the Doppler processing performed at the UE is updated based on the time-domain rotation period. In some cases, this step refers to the operation as described in reference... Figure 20 The described circuitry for updating and / or the code for updating, or the circuitry for updating, or the code that can be executed by the circuitry and / or the code.

[0230] In some aspects, method 1900 also includes a process for measuring the Doppler frequency corresponding to the reflected link between the network entity and the UE via at least one RIS. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for participation or that can be executed by the circuitry and / or the code.

[0231] In some aspects, the process of measuring the Doppler frequency corresponding to the reflected link includes: measuring a downlink reference signal reflected from at least one RIS; determining the Doppler frequency corresponding to the reflected link based on the measurement; and sending a measurement report indicating the Doppler frequency corresponding to the reflected link.

[0232] In some aspects, the process involved in measuring the Doppler frequency corresponding to the reflected link includes: sending an uplink reference signal from the UE.

[0233] In some aspects, method 1900 further includes receiving from a network entity signaling an indication of a time interval for at least one RIS to change the coefficients of RIS elements. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0234] In some aspects, method 1900 also includes adjusting at least one of rate matching or channel measurements based on time intervals. In some cases, this step refers to operations such as those described in reference... Figure 20 The circuitry and / or code described for adjustment or that can be executed by the circuitry and / or the code.

[0235] In some aspects, method 1900 further includes receiving data signals from at least a reflected link between the network entity and the UE via at least one RIS. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for receiving are either the circuitry and / or the code for receiving or can be executed by the circuitry and / or the code.

[0236] In some aspects, method 1900 also includes processing the data signal in a manner that depends on whether the data signal is received at zero Doppler frequency or at at least one Doppler frequency. In some cases, this step refers to the operation as described in reference... Figure 20 The circuitry and / or code described for processing or that can be executed by the circuitry and / or the code.

[0237] In some aspects, the processing includes taking action to compensate for the Doppler frequency shift when the data signal is received at at least one Doppler frequency.

[0238] In one respect, method 1900 or any aspect thereof may be made by means of a device (such as...) Figure 20 The communication device 2000 performs the method, which includes various components operable to, configured to, or adapted to perform the method 1900. The communication device 2000 is described in more detail below.

[0239] It should be noted that Figure 19 This is merely one example of a method, and other methods that include fewer, additional, or alternative steps may also be consistent with this disclosure.

[0240] Example communication device

[0241] Figure 20Various aspects of the example communication device 2000 are described. In some aspects, the communication device 2000 is user equipment, such as those mentioned above. Figure 1 and Figure 3 The UE 104 is described. In some respects, the communication device 2000 is a network entity (such as...) Figure 1 and Figure 3 (BS 102) or as per BS 102) Figure 2 The decomposed base station under discussion.

[0242] Communication device 2000 includes a processing system 2002 coupled to transceiver 2058 (e.g., transmitter and / or receiver). In some aspects (e.g., when communication device 2000 is a network entity), processing system 2002 may be coupled to network interface 2062, which is configured to communicate via a communication link (such as, as described herein, etc.). Figure 2 The transceiver 2058 is configured to receive and transmit signals for the communication device 2000 via the described backhaul link, midhaul link, and / or fronthaul link. The transceiver 2058 is configured to transmit and receive signals for the communication device 2000, such as the various signals described herein, via the antenna 2060. The processing system 2002 can be configured to perform processing functions for the communication device 2000, including processing signals received by the communication device 2000 and / or to be transmitted by the communication device.

[0243] The processing system 2002 includes one or more processors 2004. In various aspects, the one or more processors 2004 may represent one or more of a receive processor 358, a transmit processor 364, a TX MIMO processor 366, and / or a controller / processor 380, as per [reference to...]. Figure 3 As described. In various respects, one or more processors 2004 may represent one or more of the following: receive processor 338, transmit processor 320, TX MIMO processor 330, and / or controller / processor 340, as per [reference to...]. Figure 3 As described. One or more processors 2004 are coupled to a computer-readable medium / memory 2030 via a bus 2056. In some aspects, the computer-readable medium / memory 2030 is configured to store instructions (e.g., computer-executable code) that, when executed by the one or more processors 2004, cause the one or more processors 2004 to execute: Regarding Figure 17 The method described in 1700 or any aspect thereof; regarding Figure 18 The described method 1800 or any aspect thereof; and regarding Figure 19 The method 1900 described herein or any aspect thereof. It should be noted that references to processors performing the functions of communication device 2000 may include one or more processors 2004 performing those functions of communication device 2000.

[0244] In the depicted example, computer-readable medium / memory 2030 stores code (e.g., executable instructions), such as code 2032 for sending, code 2034 for communication, code 2036 for obtaining, code 2038 for determining, code 2040 for configuration, code 2042 for switching, code 2044 for receiving, code 2046 for changing, code 2048 for updating, code 2050 for participating, code 2052 for adjusting, and code 2054 for processing. Processing the code 2032 for sending, the code 2034 for communication, the code 2036 for obtaining, the code 2038 for determining, the code 2040 for configuration, the code 2042 for switching, the code 2044 for receiving, the code 2046 for changing, the code 2048 for updating, the code 2050 for participating, the code 2052 for adjusting, and the code 2054 for processing can cause the communication device 2000 to execute: Regarding Figure 17 Method 1700, or any aspect thereof, described in relation to it; Figure 18 The described method 1800 or any aspect thereof; and regarding Figure 19 The method described in 1900 or any aspect thereof.

[0245] One or more processors 2004 include circuitry configured to implement (e.g., execute) code stored in computer-readable medium / memory 2030, including circuitry 2006 for transmitting, circuitry 2008 for communicating, circuitry 2010 for acquiring, circuitry 2012 for determining, circuitry 2014 for configuring, circuitry 2016 for switching, circuitry 2018 for receiving, circuitry 2020 for changing, circuitry 2022 for updating, circuitry 2024 for participating, circuitry 2026 for adjusting, and circuitry 2028 for processing. The communication device 2000 can perform the following operations by utilizing the circuits 2006 for transmitting, 2008 for communicating, 2010 for acquiring, 2012 for determining, 2014 for configuring, 2016 for switching, 2018 for receiving, 2020 for changing, 2022 for updating, 2024 for participating, 2026 for adjusting, and 2028 for processing: Regarding Figure 17 Method 1700, or any aspect thereof, described in relation to it; Figure 18 The described method 1800 or any aspect thereof; and regarding Figure 19 The method described in 1900 or any aspect thereof.

[0246] The various components of the communication device 2000 can provide parts for performing the following operations: performing operations related to... Figure 17 The method described in 1700 or any aspect thereof; regarding Figure 18 The described method 1800 or any aspect thereof; and regarding Figure 19 The described method 1900 or any aspect thereof. For example, components for sending, transmitting, or outputting for use in sending may include... Figure 3 The transceiver 354 and / or antenna 352 of UE 104 illustrated herein Figure 3 The transceiver 332 and / or antenna 334 of the BS102 illustrated herein Figure 20 The communication device 2000 includes a transceiver 2058 and an antenna 2060. Components for receiving or acquiring data may include... Figure 3 The transceiver 354 and / or antenna 352 of UE 104 illustrated herein Figure 3 The transceiver 332 and / or antenna 334 of the BS102 illustrated herein and / or Figure 20 The transceiver 2058 and antenna 2060 of the communication equipment 2000.

[0247] Example Terms

[0248] Specific implementation examples are described in the following numbered clauses:

[0249] Clause 1: A method for wireless communication at a network entity, comprising: transmitting signaling to configure a time-domain rotation factor for at least one reconfigurable smart surface (RIS) to apply time-varying reflection coefficient rotation, wherein the time-domain rotation factor is based on a Doppler frequency corresponding to a reflection link between the network entity and a user equipment (UE) via the at least one RIS; and communicating with the UE via the RIS after transmitting the signaling.

[0250] Clause 2: The method according to Clause 1 further includes: obtaining information about the Doppler frequency corresponding to the reflection link; and determining the time-domain rotation factor based at least on the Doppler frequency corresponding to the reflection link.

[0251] Clause 3: The method according to Clause 2, wherein the determination of the time-domain rotation factor depends on at least one of the following: whether there is a direct link between the network entity and the UE, or whether the network entity compensates for the Doppler frequency corresponding to the direct link.

[0252] Clause 4: The method according to Clause 2, wherein obtaining information about the Doppler frequency includes: receiving a measurement report from the UE indicating the Doppler frequency.

[0253] Clause 5: The method according to Clause 4 further includes configuring the at least one RIS to use a basic reflection coefficient in at least a portion of some symbols without rotation, so as to allow the UE to measure the Doppler frequency.

[0254] Clause 6: The method according to Clause 2, wherein obtaining information about the Doppler frequency includes: determining the Doppler frequency based on measurements of an uplink reference signal from the UE.

[0255] Clause 7: The method according to Clause 2 further includes disabling the at least one RIS to determine a Doppler frequency corresponding to at least one of the following: a direct link between the network entity and the UE, or a reflected link between the network entity and the UE via at least one other RIS.

[0256] Clause 8: The method according to any one of Clauses 1 to 7 further comprises: determining a time-domain rotation period, said time-domain rotation period being based on the time-domain rotation factor to determine the frequency at which the coefficients of the RIS element of the at least one RIS are updated.

[0257] Clause 9: The method according to Clause 8 further includes: receiving signaling indicating the capability of the at least one RIS to change the response time of the RIS element coefficients, wherein the time-domain rotation period is determined based on the capability.

[0258] Clause 10: The method according to Clause 8 further comprises: sending an indication of the time-domain rotation period to at least one of the following: the UE or the at least one RIS.

[0259] Clause 11: The method according to any one of Clauses 1 to 10 further includes: determining a time interval for changing the coefficients of the at least one RIS element based on the time-domain rotation factor.

[0260] Clause 12: The method according to Clause 11 further includes sending an indication of the time gap to at least one of the following: the UE or the at least one RIS.

[0261] Clause 13: A method for wireless communication at a reconfigurable smart surface (RIS) controller, comprising: receiving signaling from a network entity indicating a time-domain rotation factor; and, based on the time-domain rotation factor, altering the reflection coefficient of one or more elements of at least one RIS by applying a time-varying reflection coefficient rotation.

[0262] Clause 14: The method according to Clause 13 further includes receiving from the network entity signaling for configuring the at least one RIS to use a basic reflection coefficient in at least a portion of some symbols without rotation.

[0263] Clause 15: The method according to any one of Clauses 13 to 14 further comprises: determining a time-domain rotation period, said time-domain rotation period being based on the time-domain rotation factor to determine the frequency at which the coefficients of the RIS element of the at least one RIS are updated.

[0264] Clause 16: The method according to Clause 15 further comprises: sending signaling to the network entity indicating the capability of the at least one RIS to change the response time with respect to the RIS element coefficients, wherein the time-domain rotation period is determined based on the capability.

[0265] Clause 17: The method according to Clause 15 further includes receiving an indication of the time-domain rotation period from the network entity.

[0266] Clause 18: The method according to any one of Clauses 13 to 17 further includes: determining the time interval for changing the coefficients of the RIS element based on the time-domain rotation factor.

[0267] Clause 19: The method described in Clause 18 further includes receiving an indication of the time interval from the network entity.

[0268] Clause 20: A method for wireless communication at a user equipment (UE), comprising: receiving from a network entity a signaling indicating a time-domain rotation period, the time-domain rotation period determining the frequency at which coefficients of at least one reconfigurable smart surface (RIS) element are updated; and updating Doppler processing performed at the UE based on the time-domain rotation period.

[0269] Clause 21: The method according to Clause 20 further includes participating in a process for measuring the Doppler frequency corresponding to the reflection link between the network entity and the UE via the at least one RIS.

[0270] Clause 22: The method according to Clause 21, wherein the process of participating in measuring the Doppler frequency corresponding to the reflected link includes: measuring a downlink reference signal reflected from the at least one RIS; determining the Doppler frequency corresponding to the reflected link based on the measurement; and sending a measurement report indicating the Doppler frequency corresponding to the reflected link.

[0271] Clause 23: The method according to Clause 21, wherein participating in the process for measuring the Doppler frequency corresponding to the reflected link includes: transmitting an uplink reference signal from the UE.

[0272] Clause 24: The method according to any one of Clauses 20 to 23 further includes: receiving from the network entity a signaling instructing a time interval for the at least one RIS to change the coefficients of RIS elements.

[0273] Clause 25: The method described in Clause 24 further includes adjusting at least one of rate matching or channel measurement based on the time gap.

[0274] Clause 26: The method according to any one of Clauses 20 to 25 further includes: receiving a data signal from at least a reflected link between the network entity and the UE via the at least one RIS; and processing the data signal in a manner that depends on whether the data signal is received at zero Doppler frequency or at at least one Doppler frequency.

[0275] Clause 27: The method according to Clause 26, wherein the processing includes: taking action to compensate for Doppler frequency offset when the data signal is received at at least one Doppler frequency.

[0276] Clause 28: An apparatus comprising: a memory including executable instructions; and a processor configured to execute the executable instructions and cause the apparatus to perform a method according to any one of Clauses 1 to 27.

[0277] Clause 29: An apparatus comprising components for performing the method according to any one of Clauses 1 to 27.

[0278] Clause 30: A non-transitory computer-readable medium comprising executable instructions that, when executed by a processor of a device, cause the device to perform the method according to any one of Clauses 1 to 27.

[0279] Clause 31: A computer program product embodied on a computer-readable storage medium, said computer-readable storage medium including code for performing a method according to any one of Clauses 1 to 27.

[0280] Additional Notes

[0281] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein do not limit the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, the function and arrangement of the elements discussed may be changed without departing from the scope of this disclosure. Various processes or components may be omitted, substituted, or added as appropriate in various examples. For example, the described methods may be performed in a different order than described, and various actions may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement an apparatus or practice. Additionally, the scope of this disclosure is intended to cover such apparatuses or methods practiced using other structures, functionalities, or structures and functionalities that complement or replace the various aspects of this disclosure set forth herein. It should be understood that any aspect of the disclosure herein may be embodied by one or more elements of these claims.

[0282] The various exemplary logic blocks, modules, and circuits described in this disclosure can be implemented or executed using a general-purpose processor, digital signal processor (DSP), ASIC, field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic unit, discrete hardware component, or any combination thereof designed to perform the functions described herein. While the general-purpose processor may be a microprocessor, in alternative embodiments, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, a system-on-a-chip (SoC), or any other such configuration.

[0283] As used in this article, the phrase “at least one of” in a list of items refers to any combination of those items (including single members). For example, “at least one of a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0284] As used herein, the term "determine" encompasses a wide variety of actions. For example, "determine" can include calculation, operation, processing, deduction, investigation, lookup (e.g., searching in a table, database, or other data structure), assertion, and so on. Additionally, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), and so on. Furthermore, "determine" can include parsing, selecting, picking, building, and so on.

[0285] The methods disclosed herein include one or more actions for implementing the methods. These actions may be interchanged without departing from the scope of the claims. In other words, unless a specified order of actions is given, the order and / or use of a particular action may be modified without departing from the scope of the claims. Furthermore, the various operations of the methods described above may be performed by any suitable component capable of performing the corresponding function. This component may include various hardware and / or software components and / or modules, including but not limited to circuits, application-specific integrated circuits (ASICs), or processors.

[0286] The following claims are not intended to be limited to the aspects shown herein, but should be given the full scope consistent with the language of the claims. Within the claims, unless specifically stated otherwise, reference to the singular form of an element is not intended to mean “one and only one,” but rather “one or more.” Unless otherwise specifically stated, the term “some” refers to one or more. No element of any claim shall be interpreted in accordance with the provisions of 35 U.S.SC §112(f) unless that element is explicitly stated using the phrase “for a component of.” All structural and functional equivalents of the elements throughout the various aspects described herein that are known to a person skilled in the art or will later be known are expressly incorporated herein by reference and are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be offered to the public, whether or not such disclosure is explicitly recited in the claims.

Claims

1. An apparatus for wireless communication at a network entity, comprising: processor; A memory coupled to the processor; and Instructions, which are stored in the memory and can be executed by the processor, to cause the device to: Sending signaling to configure a time-domain rotation factor for at least one reconfigurable smart surface (RIS) to apply time-varying reflection coefficient rotation, wherein the time-domain rotation factor is based on the Doppler frequency corresponding to the reflection link between the network entity and the user equipment (UE) via the at least one RIS; as well as After sending the signaling, the system communicates with the UE via the at least one RIS.

2. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to: Obtain information about the Doppler frequency corresponding to the reflected link; and The time-domain rotation factor is determined at least based on the Doppler frequency corresponding to the reflection link.

3. The apparatus of claim 2, wherein the determination of the time-domain rotation factor depends on at least one of the following: whether there is a direct link between the network entity and the UE, or whether the network entity compensates for the Doppler frequency corresponding to the direct link.

4. The apparatus of claim 2, wherein obtaining information about the Doppler frequency comprises: The UE receives a measurement report indicating the Doppler frequency.

5. The apparatus of claim 4, wherein the instructions are further executable by the processor to configure the apparatus to use a fundamental reflection coefficient in at least a portion of some symbols without rotation, so as to allow the UE to measure the Doppler frequency.

6. The apparatus of claim 2, wherein obtaining information about the Doppler frequency comprises: The Doppler frequency is determined based on measurements of the uplink reference signal from the UE.

7. The apparatus of claim 2, wherein the instructions are further executable by the processor to cause the apparatus to: Turn off at least one RIS to determine a Doppler frequency corresponding to at least one of the following: The direct link between the network entity and the UE; or The network entity and the UE are connected via a reflection link from at least one other RIS.

8. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to determine a time-domain rotation period, the time-domain rotation period being based on the time-domain rotation factor to determine the frequency at which the coefficients of the at least one RIS element are updated.

9. The apparatus of claim 8, wherein the instructions are further executable by the processor to cause the apparatus to receive signaling instructing the at least one RIS to have a response time for a change in RIS element coefficients, wherein the time-domain rotation period is determined based on the capability.

10. The apparatus of claim 8, wherein the instructions are further executable by the processor to cause the apparatus to send an indication of the time-domain rotation period to at least one of the following: the UE or the at least one RIS.

11. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to: The time interval for changing the coefficients of the at least one RIS element is determined based on the time-domain rotation factor.

12. The apparatus of claim 11, wherein the instructions are further executable by the processor to cause the apparatus to send an indication of the time gap to at least one of the following: the UE or the at least one RIS.

13. An apparatus for wireless communication at a reconfigurable smart surface (RIS) controller, comprising: processor; A memory coupled to the processor; and Instructions, which are stored in the memory and can be executed by the processor, to cause the device to: Receive signaling from network entities indicating the time-domain rotation factor; as well as Based on the time-domain rotation factor, the reflection coefficient of one or more components of at least one RIS is changed by applying time-varying reflection coefficient rotation.

14. The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to: Receive signaling from the network entity for configuring the at least one RIS to use a basic reflection coefficient in at least a portion of some symbols without rotation.

15. The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to: A time-domain rotation period is determined, which is based on the time-domain rotation factor to determine the frequency at which the coefficients of the RIS elements of the at least one RIS are updated.

16. The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to: A signal instructing the network entity on the ability of at least one RIS to change the response time with respect to RIS element coefficients is sent, wherein the time-domain rotation period is determined based on the capability.

17. The apparatus of claim 15, wherein the instructions are further executable by the processor to cause the apparatus to receive an indication of the time-domain rotation period from the network entity.

18. The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to: The time interval for changing the coefficients of RIS components is determined based on the time-domain rotation factor.

19. The apparatus of claim 18, wherein the instructions are further executable by the processor to cause the apparatus to receive an indication of the time slot from the network entity.

20. An apparatus for conducting wireless communication at a user equipment (UE), comprising: processor; A memory coupled to the processor; and Instructions, which are stored in the memory and can be executed by the processor, to cause the device to: Receive signaling from network entities indicating a time-domain rotation period, the time-domain rotation period determining the frequency at which the coefficients of at least one RIS element of a reconfigurable smart surface (RIS) are updated; as well as The Doppler processing performed at the UE is updated based on the time-domain rotation period.

21. The apparatus of claim 20, wherein the instructions are further executable by the processor to cause the apparatus to participate in a process for measuring a Doppler frequency corresponding to a reflection link between the network entity and the UE via the at least one RIS.

22. The apparatus of claim 21, wherein the process of measuring the Doppler frequency corresponding to the reflection link comprises: Measure the downlink reference signal reflected from the at least one RIS; The Doppler frequency corresponding to the reflection link is determined based on the measurement; as well as Send a measurement report indicating the Doppler frequency corresponding to the reflected link.

23. The apparatus of claim 21, wherein the process of measuring the Doppler frequency corresponding to the reflected link comprises: Send an uplink reference signal from the UE.

24. The apparatus of claim 20, wherein the instructions are further executable by the processor to cause the apparatus to: Receive signaling from the network entity instructing the time interval for the at least one RIS to change the coefficients of RIS elements.

25. The apparatus of claim 24, wherein the instructions are further executable by the processor to cause the apparatus to adjust at least one of rate matching or channel measurement based on the time gap.

26. The apparatus of claim 20, wherein the instructions are further executable by the processor to cause the apparatus to: Data signals are received from at least a reflection link between the network entity and the UE via the at least one RIS; and The data signal is processed in a manner that depends on whether the data signal is received at zero Doppler frequency or at at least one Doppler frequency.

27. The apparatus of claim 26, wherein the process comprises: If the data signal is received at at least one Doppler frequency, an action is taken to compensate for the Doppler frequency shift.

28. A method for conducting wireless communication at a user equipment (UE), comprising: Receive signaling from network entities indicating a time-domain rotation period, the time-domain rotation period determining the frequency at which the coefficients of at least one RIS element of a reconfigurable smart surface (RIS) are updated; as well as The Doppler processing performed at the UE is updated based on the time-domain rotation period.

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