Multiplexed input / output transmission using adaptive phase change devices

Abstract

Techniques and apparatus for multiple-input multiple-output (MIMO) transmission using adaptive phase change devices are described. In an aspect, a base station (120) selects (1010) one or more adaptive phase change devices (APDs) (180) for use in at least one communication path for multiple-input multiple-output (MIMO) transmission. The base station (120) can perform a channel characterization process (1105) for the at least one communication path using the at least one APD (180) and at least one UE (110). Based on the results of the channel characterization process, the base station (120) configures the at least one APD (180) for performing single-user-MIMO transmission with one UE or multi-user-MIMO transmission with multiple UEs (1045). By doing so, the base station (120) can perform MIMO transmission using the APD to communicate with one or more UEs (110) using the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

Description

[Background technology]

[0001] Evolving wireless communication systems, such as fifth-generation (5G) and sixth-generation (6G) technologies, use various techniques to increase data capacity over previous wireless networks. As one example, 5G technology transmits data using higher frequency regions, such as bands above 6 gigahertz (GHz), sometimes referred to as the millimeter wave (mm wave) region. As another example, 5G technology increases the data capacity of wireless networks by using multiple-input multiple-output (MIMO) transmission.

[0002] While these techniques can increase data rates, transmitting and recovering information using higher frequency regions poses additional challenges: higher frequency signals are more susceptible to obstructions, atmospheric conditions, multipath fading, and other types of path loss, which can lead to recovery errors at the receiver, reduced throughput, or degradation of the wireless link. Summary of the Invention

[0003] This specification describes techniques and devices that enable multiple-input multiple-output (MIMO) transmission using adaptive phase-changing devices (APDs). In an aspect, a base station selects one or more APDs to use in at least one communication path for MIMO transmission. The base station can perform a channel characterization process for the at least one communication path using the one or more APDs and one or more user equipments (UEs). Based on the results of the channel characterization process (e.g., uplink or downlink channel measurements), the base station configures one or more APDs to perform single-user-MIMO (SU-MIMO) transmission with one UE or multi-user-MIMO (MU-MIMO) transmission with multiple UEs. By doing so, the base station can perform MIMO transmission using the APDs to communicate with one or more UEs that use the same time and frequency resources in different spatial resources, thereby improving the spectral efficiency of the wireless network.

[0004] Details of one or more embodiments of MIMO transmission using APDs are provided in the accompanying drawings and the following description. Other features and advantages will become apparent from the description and drawings, as well as the appended claims. This Summary is intended to introduce the subject matter, which is further described in the Detailed Description and the drawings. As such, this Summary should not be considered as describing essential features, nor should it be used to limit the scope of the claimed subject matter.

[0005] The details of one or more aspects of multiple input / output (MIMO) transmission using adaptive phase change devices (APDs) are described with reference to the drawings, described below, in which like numbers are used to denote like features and components throughout. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 illustrates an example of an operating environment in which various aspects of MIMO transmission using APDs can be implemented. [Diagram 2] 1 illustrates an example apparatus diagram of an entity capable of implementing various aspects of MIMO transmission using APDs. [Diagram 3] 1 shows an example apparatus diagram of an APD that can be used to implement various aspects of MIMO transmission using APDs. [Figure 4] 1 illustrates an example of a base station that configures an APD in accordance with various aspects of MIMO transmission using the APD. [Figure 5A] FIG. 1 illustrates an example of a channel characterization process that can be used to implement various aspects of MIMO transmission using APDs. [Figure 5B] FIG. 1 illustrates an example of a channel characterization process that can be used to implement various aspects of MIMO transmission using APDs. [Figure 6] 1 illustrates an example of using multiple APDs for MIMO transmission with multiple user devices in accordance with one or more aspects. [Figure 7] 1 illustrates an example of using multiple APDs for MIMO transmission with a user device in accordance with one or more aspects. [Figure 8] 1 illustrates an example of using multiple APD surface partitions for MIMO transmission with multiple user devices in accordance with one or more aspects. [Figure 9] 1 illustrates an example of using multiple APD surface partitions for MIMO transmission with a user device in accordance with one or more aspects. [Figure 10] FIG. 1 illustrates example details of signaling and control transactions that can be used to implement various aspects of MIMO transmission using APD. [Figure 11] FIG. 1 illustrates example details of signaling and control transactions that can be used to perform channel characterization in accordance with one or more aspects. [Figure 12] 1 illustrates an example method that can be used to implement various aspects of MIMO transmission using APD. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] While higher frequencies and MIMO transmissions bring higher data throughput, channel conditions can adversely affect these technologies. As an example, mmWave signals have high throughput under line-of-sight (LoS) conditions, but reflections cause multipath and frequency selective fading that can increase recovery errors at the receiver. Various environments, such as dense urban areas, contain multiple obstacles that further degrade signal quality, making the deployment of high frequency communications in these environments more difficult.

[0008] An adaptive phase change device (APD) includes a reconfigurable intelligent surface (RIS), which, when properly configured, modifies a propagating signal to correct or reduce errors caused by the communication path(s) (e.g., various obstacles), small-scale fading, and fading MIMO channels. Typically, a RIS includes a configurable surface material. The configurable surface material determines how an incident signal impinging on the surface of the material is transformed and reflected. For example, the configuration of the surface material can affect the phase, amplitude, direction, spatial coverage area, and / or polarization of the transformed signal. Thus, changing the surface configuration of the RIS changes how the incident signal is transformed when it reflects off the RIS. This can be useful to provide additional, modified, or alternative communication paths between a base station and one or more UEs for downlink and / or uplink communications. However, using an APD in a communication path typically requires that the RIS of the APD is configured specifically for the communication path, which can change over time due to dynamic channel conditions, UE movement, air interface resource allocation, etc. For example, adding an APD to a channel changes the propagation delay through the channel, particularly the round trip propagation delay for uplink and downlink communications. Thus, specific configuration of APDs and UEs by a base station to support MIMO transmission over a communication path may be challenging due to these time-varying channel conditions and communication constraints.

[0009] In an aspect of MIMO transmission using APD, a base station may use APD to route and / or transform MIMO transmissions to improve the signal quality of MIMO transmissions exchanged between the base station and UE(s). This results in performance benefits (e.g., improved signal quality, increased data capacity) without requiring LoS between the base station and the UE. For example, a transmitting device (e.g., a base station or user equipment) may use APD to route a wireless signal toward a second (receiving) wireless device (e.g., a user equipment or base station) by routing the wireless signal around obstacles that may cause recovery errors at the receiver and / or may prevent the wireless signal from reaching the receiver. In an aspect, a base station may adjust timing calculations (e.g., timing advance calculations) for one or more communication paths (e.g., to account for propagation delays), in which case the APD and / or UE operation for MIMO transmissions may be adjusted such that MIMO transmissions (e.g., APD-reflected UE or BS transmissions) arrive at the receiving device at approximately the same time (e.g., within a cyclic prefix). Alternatively or additionally, the base station selects a surface configuration of the APD that transforms characteristics of the wireless signal to improve signal quality (e.g., a surface configuration selected to mitigate destructive interference). Also, by using the APD to route and / or transform MIMO transmissions, the base station can reuse air interface resources (e.g., time and frequency resources) for different MIMO transmissions and use spatial resources to improve the spectral efficiency and data throughput of the wireless network.

[0010] In an aspect, a base station selects one or more APDs to include in at least one communication path for MIMO transmission with one or more UEs. As an example, the base station may select a candidate APD in response to detecting a worsening channel condition for communicating with one or more UEs. Typically, the base station may initiate or execute a channel characterization process to aid in selecting an APD, selecting a UE, and / or configuring each surface of the APD for MIMO transmission. This may include the base station directing each APD to change between multiple surface configurations, transmitting a channel state information reference signal (CSI-RS) toward each surface of the APD, and receiving feedback (e.g., downlink signal quality measurements) from the UE. These provide data on which surface configuration results in the best observed signal quality at the UE compared to other surface configurations. For the uplink, the channel characterization process may include the base station having each UE transmit a sounding reference signal (SRS) while the APD is changing between multiple surface configurations, and the base station generating metrics (e.g., uplink signal quality measurements) for the received SRS. The base station then selects the surface configuration of the APD based on the signal quality measurements (and / or link quality measurements), as further described with reference to Figures 5A and 5B. Alternatively or additionally, the base station may use measurements from a channel characterization process to select which UE and / or which APD to use for MIMO transmission. In some aspects, the base station may apply the reciprocity principle to use uplink or downlink channel measurements to configure the APD and / or UE for communication on the reverse link (e.g., downlink channel characterization to configure uplink communication). This may be used in time division duplex (TDD) or frequency division duplex (FDD) systems that use nearby or adjacent uplink and downlink frequency bands.

[0011] As an example, a base station selects two UEs to pair for MU-MIMO transmission using the same frequency and time slot but different beam directions. The base station selects a first APD to include in a first communication path for MIMO transmission with a first UE of the pair and selects a second APD to include in a second communication path for MIMO transmission with a second UE of the pair. Alternatively or additionally, the base station determines to include two APDs in two communication paths to a single UE for SU-MIMO transmission. In some aspects, the base station determines to utilize a single APD in the communication paths for MU-MIMO and / or SU-MIMO transmission using panel division or sub-panels of the APD, such that for one or more respective UEs, a first panel set on the single APD reflects the first MIMO transmission and a second panel set on the single APD reflects the second MIMO transmission. By doing so, the base station can route and / or convert MU-MIMO or SU-MIMO transmissions using APD, which allows the base station to reuse air interface resources (e.g., time and frequency resources) with different spatial resources for different MIMO transmissions and can improve the spectral efficiency and data throughput of the wireless network.

[0012] Although the features and concepts of the present systems and methods for MIMO transmission using APDs may be implemented in any number of different environments, systems, devices, and / or various configurations, various aspects of MIMO transmission using APDs will be described with reference to the following example environments, devices, systems, and configurations.

[0013] Example Environment 1 illustrates an exemplary environment 100 including multiple user equipments 110 (UE 110), shown as UE 111 and UE 112. Each UE can communicate with one or more base stations 120 (shown as base station 121 and base station 122) via one or more wireless communication links 130 (wireless link 130), shown as wireless links 131 and 132. The wireless links also include wireless link 133 and / or wireless link 134 that base station 120 uses to communicate with one or more adaptive phase change devices 180 (APD 180), shown as APD 181 and APD 182. In an aspect, base station 120 communicates with APD 180 to control surface configuration, position, and / or APD timing adjustments for applying surface configuration and / or positioning APD 180. In another embodiment, base station 120 includes a wired interface for communicating APD control information (e.g., surface configuration, timing adjustment, position information) to APD 180. For simplicity, the UE 110 is embodied as a smartphone, but may be embodied as any suitable computing or electronic device, such as a mobile communications device, a modem, a mobile phone, a gaming device, a navigation device, a media device, a laptop computer, a desktop computer, a tablet computer, a smart appliance, an in-vehicle communication system, or an Internet of Things (IoT) device, such as a sensor, a relay, or an actuator. The base station 120 (e.g., an Evolved Universal Terrestrial Radio Access Network Node B, E-UTRAN Node B, evolved Node B, eNodeB, eNB, next generation Node B, gNode B, gNB, ng-eNB, etc.) may be embodied in the form of a macro cell, a micro cell, a small cell, a pico cell, a distributed base station, etc., or any combination thereof.

[0014] One or more base stations 120 communicate with UE 110 using radio links 131 and 132, which may be implemented as any suitable type of radio link. In one example, base station 121 communicates with UE 111 using radio link 131 and the surface of APD 181 to route and / or transform wireless signals along communication path 161 (e.g., a non-LoS path). Radio link 131 or other radio links described herein may include wireless signals corresponding to MIMO transmissions with UE 111, which may include SU-MIMO transmissions or MU-MIMO transmissions that allow for reuse of the same time and frequency resources. In environment 100, base station 121 communicates with UE 112 using radio link 132 and the surface of APD 182 to route and / or transform wireless signals along communication path 162 in a manner similar to that further described for UE 111 and APD 181. This may include wireless signals corresponding to MIMO transmissions with UE 112, which may include MU-MIMO or SU-MIMO transmissions on the downlink or uplink of a wireless connection. Environment 100 illustrates base station 120 performing MU-MIMO with UE 111 and UE 112 and multiple APDs in a manner similar to that described with reference to FIG. 6. However, various aspects described with respect to environment 100 may alternatively or additionally be utilized to perform SU-MIMO with a single UE using multiple APDs (e.g., as described with reference to FIG. 7), to perform MU-MIMO with multiple UEs by panel splitting a single APD (e.g., FIG. 8), and / or to perform SU-MIMO with a single UE by panel splitting a single APD (e.g., FIG. 9).

[0015] Radio links 131 and 132 include control plane information and / or user plane data (e.g., downlink user plane data and control plane information communicated from base station 120 to UE 110, uplink and control plane information for another user plane data communicated from UE 110 to base station 120, or both). Radio link 130 may include one or more radio links (e.g., radio links) or bearers implemented using any suitable communications protocol or standard, or combination of communications protocols or standards (e.g., 3rd Generation Partnership Project Long Term Evolution (3GPP® LTE), 5th Generation New Radio (5GNR), 6th Generation (6G), etc.). In various aspects, base station 120 and UE 110 may be implemented for operation in sub-gigahertz bands, sub-6 GHz bands (e.g., Frequency Band 1), and / or above 6 GHz bands (e.g., Frequency Band 2, millimeter wave (mm wave) bands) defined by one or more of the 3GPP LTE, 5G NR, or 6G communications standards. As an example, the multiple wireless links may include a first sub-6 gigahertz (GHz) anchor link and a second above-6 GHz auxiliary link. For example, referring to FIG. 6, the wireless link 131 may include a first wireless anchor link (e.g., low-bandwidth connection 521) using a sub-6 GHz radio signal and a second wireless link (e.g., wireless link 621) using an above-6 GHz radio signal. The multiple wireless links 130 may be aggregated using carrier aggregation or multi-connectivity techniques to provide a higher data rate to the UE 110. The multiple wireless links 130 from the multiple base stations 120 may be configured for coordinated multipoint (CoMP) communication with the UE 110.

[0016] In some embodiments, the wireless links (e.g., wireless links 131 and 132) utilize radio signals that are reflected or transformed (e.g., reflected to route the radio signals around obstacles 170 (illustrated as obstacles 171 and 172) by one or more intermediate devices (e.g., APD 180). Although obstacles 171 and 172 are shown as buildings and foliage, the obstacles may range from more temporary obstacles such as water vapor or moving vehicles to seasonal obstacles such as deciduous trees as shown, to more permanent obstacles such as buildings as shown. For example, base station 121 uses APD 181 to propagate light beam(s) 190, shown as signal beam 191, signal beam 192, and signal beam 193, to (and / or receive from) UE 111. In environment 100, signal beam 190 corresponds to individual beams of narrow beam or wide beam (including up to omnidirectional) radio signals used to implement wireless link 131. The wireless signal may be, for example, a downlink wireless signal from base station 121 to UE 111 (shown in FIG. 1) and / or an uplink wireless signal from UE 111 to base station 121 (not shown in FIG. 1).

[0017] As part of communicating with UE 111 over wireless link 131, base station 121 transmits a first downlink wireless signal intended for UE 111, corresponding to a MIMO transmission. A first ray (e.g., signal ray 191) of the first downlink wireless signal propagates toward UE 111 in a line-of-sight (LoS) manner, where an obstacle 171 dynamically blocks and / or attenuates LoS signal ray 191. A second ray (e.g., signal ray 192) of the first downlink wireless signal propagates toward APD 181. Second signal ray 192 strikes a surface of APD 181 and turns into a third signal ray 193 that propagates along communication path 161 toward UE 111. Similarly, base station 121 transmits a second downlink signal to UE 112 using the surface of APD 182, which routes and / or transforms the wireless signal along communication path 162.

[0018] Base station 120 can configure the RIS of APD 180 to control the manner in which the RIS changes the signal characteristics (e.g., direction, phase, amplitude, and / or polarization) of an incident radio signal. In an aspect, base station 120 performs a channel characterization process to determine the surface configuration of APD(s) 180, as further described with reference to FIGS. 5A and 5B. In an aspect, base station 120 communicates the respective RIS surface configuration information to APD 181 and APD 182 using wireless link 133 and / or wireless link 134 (e.g., APD control channel). This can include an adaptive phase change device physical downlink shared channel (APD-PDSCH), an adaptive phase change device physical uplink shared channel (APD-PUSCH), an adaptive phase change device physical downlink control channel (APD-PDCCH), and / or an adaptive phase change device physical uplink control channel (APD-PUCCH). Alternatively or additionally, base station 120 determines the surface configuration(s) of APD 180 based on location information, downlink signal quality measurements / parameters received from UE 110, uplink signal quality measurements / parameters generated by base station 120, historical records of previous successful and unsuccessful uplink and / or downlink wireless communications (with and / or without APDs in the communication path), APD location, UE location, downlink / uplink (DL / UL) signal strength / quality measurement reports, APD surface configurations (e.g., index), APD surface configuration codebooks, etc. In some cases, base station 120 determines and communicates timing adjustments (e.g., timing advance, timing delay) for the APD to APD(s) 180 using wireless link 133 and / or wireless link 134.

[0019] The base stations 120 together form at least a part of a radio access network 140 (RAN 140, e.g., RAN, Evolved Universal Terrestrial Radio Access Network, E-UTRAN, 5G NR RAN or NR RAN). The base stations 121 and 122 connect to the core network 150 at 102 and 104, respectively, via an NG2 interface for control plane signaling and an NG3 interface for user plane data communication. In this case, the base stations 121 and 122 use an S1 interface for control plane signaling and user plane data communication when connecting to a 5G core network or an Evolved Packet Core (EPC) network. The UE 110 can connect to a public network, such as the Internet, via the RAN 140 and the core network 150 to interact with remote services (not shown in FIG. 1).

[0020] The base stations 121 and 122 can communicate at 106 using the Xn Application Protocol (XnAP) over the Xn interface or the X2 Application Protocol (X2AP) over the X2 interface to exchange user plane data and control plane data. Alternatively or additionally, the base stations 121 and 122 can communicate with each other using a wireless Integrated Access Backhaul (IAB) link (not shown in FIG. 1 ), where one of the base stations functions as a donor base station and the other functions as a node base station. In some aspects, the base stations 121 and 122 include one or more APDs 180 surface in the communication path for the IAB link, such that the APDs route and / or convert wireless signals associated with the IAB link communication.

[0021] Exemplary Apparatus FIG. 2 illustrates an example device diagram 200 of a user equipment 110 and a base station 120. In general, the device diagram 200 illustrates network entities that may implement various aspects of MIMO transmission using APDs. FIG. 2 illustrates an example of a UE 110 and a base station 120, respectively. The UE 110 or the base station 120 may include additional functionality and interfaces, which are omitted from FIG. 2 for clarity. The UE 110 includes an antenna 202, a radio frequency front end 204 (RF front end 204), and one or more radio transceivers 206 (e.g., radio frequency transceivers), such as any combination of LTE transceivers, 5G NR transceivers, and / or 6G transceivers, for communicating with the base station 120 in the RAN 140. In an aspect, the antenna 202 (e.g., an antenna array), the radio frequency (RF) front end 204, and the radio transceiver 206 may be implemented as radio modules of the UE 110. For example, the UE 110 may include one or more radio modules (e.g., 5G NR or mmWave modules) capable of performing respective transmit and / or receive functions. The RF front end 204 of the UE 110 may couple or connect a radio transceiver 206 to the antenna 202 to facilitate various types of wireless communication.

[0022] The antenna 202 of the UE 110 may include an array of multiple antennas configured similarly or differently from one another. The antenna 202 and the RF front end 204 may be tuned and / or tunable to one or more frequency bands defined by various communication standards (e.g., 3GPP LTE, 5G NR, 6G) and implemented by the radio transceiver 206. Additionally, the antenna 202, the RF front end 204, and / or the radio transceiver(s) 206 may be configured to support beam sweeping for transmission and reception of communication signals to and from the base station 120. By way of example and not limitation, the antenna 202 and the RF front end 204 may be implemented for operation in sub-gigahertz bands, sub-6 GHz bands, and / or above 6 GHz bands (e.g., bands described with reference to FIG. 1) defined by the 3GPP LTE, 5G NR, or 6G communication standards.

[0023] The UE 110 also includes a processor(s) 208 and a computer-readable storage medium 210 (CRM 210). The processor 208 may be a single-core processor or a multi-core processor built with homogenous or heterogeneous core structures. The computer-readable storage medium described herein does not include a propagating signal. The CRM 210 may include any suitable memory or storage device usable to store device data 212 of the UE 110, such as random access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or flash. The device data 212 includes any combination of user data, multimedia data, applications, and / or operating system of the UE 110. In an embodiment, the device data 212 stores processor-executable instructions executable by the processor(s) 208 to enable the UE 110 to communicate user plane data and / or control plane information as well as various user interactions (e.g., applications or user interfaces).

[0024] In this example, the CRM 210 of the UE 110 also includes a user equipment adaptive phase change device manager 214 (UE APD manager 214) for managing the usage of APDs in an access link with the base station 120. The UE APD manager 214 may be implemented in whole or in part as hardware logic or circuitry integrated with other components of the UE 110 (e.g., the radio transceiver 206) or separate. In an aspect, the UE APD manager 214 receives APD access information for using the surface of the APD. Such APD access information may be, for example, reflection access information indicating a time alignment for when to apply the APD surface and / or configurable surface element information indicating a portion of the APD surface available to the UE 110. In an aspect, the UE APD manager 214 of the UE 110 decodes a reflection identifier or beam identifier (e.g., a CSI reference signal (CSI-RS) resource index or a synchronization signal block (SSB) index), analyzes link quality parameters, and generates feedback messages for various APDs or channels to the base station 120. The UE APD manager 214 may also maintain a low-band connection (e.g., anchor connection) with the base station 120 via a low-frequency band (e.g., sub-6 GHz) to provide signal reflection information or beam information for high-frequency signals (e.g., above 6 GHz). This information is used to implement aspects of MIMO transmission using APD. The UE 110 may also receive beam sweeping information or phase steering configurations from the base station 120 via the low-band connection. Thus, the UE 110 may implement carrier aggregation (CA) to communicate in two frequency bands when communicating with the base station 120 to implement aspects of MIMO transmission using APD. Alternatively or additionally, the UE APD manager 214 causes the UE 110 to send communication signals (e.g., uplink sounding signals) to the base station 120 via an APD-enabled communication channel (e.g., based on APD access information) or via a non-APD communication path (e.g., direct UE-base station communication).

[0025] The equipment diagram of the base station 120 shown in FIG. 2 includes a single network node (e.g., gNodeB). The functionality of the base station 120 may be distributed across multiple network nodes or devices, and may be distributed in any manner suitable for performing the functions described herein. Nomenclature for this distributed base station functionality varies and includes terms such as central unit (CU), distributed unit (DU), baseband unit (BBU), remote radio head (RRH), and / or remote radio unit (RRU). The base station 120 includes an antenna 252, a radio frequency front end 254 (RF front end 254), and one or more radio transceiver(s) 256 (e.g., LTE transceiver, 5G NR transceiver, and / or 6G transceiver) for communicating with the UE 110, other UEs (not shown), and / or other base stations 120.

[0026] The RF front end 254 of the base station 120 may couple or connect a radio transceiver 256 (e.g., a radio frequency transceiver) to the antenna 252 to facilitate various types of wireless communication. The antenna 252 of the base station 120 may include an array of multiple antennas (e.g., antenna panels or antenna elements) configured similarly or differently to one another. The antenna 252 and the RF front end 254 may be tuned and / or tunable to one or more frequency bands defined by various communication standards (e.g., 3GPP LTE, 5G NR, and / or 6G) and implemented by the radio transceiver 256. Additionally, the antenna 252, the RF front end 254, and / or the radio transceiver 256 may be configured to support beamforming, such as MU-MIMO, SU-MIMO, and / or massive-MIMO, for transmission and reception of communication signals with the UE 110, other UEs, and / or another base station 120.

[0027] The base station 120 also includes a processor(s) 258 and a computer readable storage medium 260 (CRM 260). The processor 258 may be a single-core processor or a multi-core processor constructed from various materials such as silicon, polysilicon, high-K dielectrics, copper, etc. The CRM 260 may include any suitable memory or storage such as RAM, SRAM, DRAM, NVRAM, ROM, or flash memory that may be used to store device data 262 of the base station 120. The device data 262 includes network scheduling data, radio resource management data, applications, and / or operating systems of the base station 120 that are executable by the processor(s) 258 to enable communication with other base stations 120, core network entities, and / or UEs 110. The device data 262 also includes a code book 264 and APD information 266 for the APD 180 associated with the base station 120. The code book 264 may include any suitable type or combination of code books. Such codebooks include a surface configuration codebook that stores surface configuration information of the RIS of the APD, and a beam-sweeping codebook that stores pattern, sequence, or timing information (e.g., propagation delay or timing advance) for realizing multiple surface configurations useful for making the APD perform various reflective beamforming (e.g., APD-compatible MIMO transmission). In some aspects, the surface configuration codebook and the beam-sweeping codebook include phase vector information, angle information (e.g., calibrated to the respective phase vector), and / or beam configuration information. The APD information 266 may include respective identifiers, capabilities, command and control information, location, orientation (e.g., fixed or last known), range, and propagation delay for the APDs 180 with which the base station 120 communicates. The base station 120 may generate or modify the APD information 266 to add new APDs 180 that are detected, update information for known APDs 180, or remove existing APDs 180 that are not preferred.

[0028] In an aspect, the CRM 260 includes an APD-enabled MIMO function 268 (MIMO function 268) that manages or implements aspects of MIMO transmission using the APDs. Alternatively or additionally, the MIMO function 268 may be implemented in whole or in part as hardware logic or circuitry integrated with or separate from other components of the base station 120. Typically, the MIMO function 268 may select one or more APDs to use in at least one communication path for MIMO transmission. For example, the base station 120 may select candidate APDs that may provide a respective non-LoS communication path to one or more UEs 110 (e.g., UEs with degraded link quality, impaired LoS, increased throughput demands, etc.) to communicate using MIMO transmission. The base station may then perform a channel characterization process for at least one communication path using one or more APDs and one or more UEs, as described with reference to FIGS. 5A, 5B, and / or 11. Based on the results of the channel characterization process (e.g., uplink or downlink channel measurements), the base station can select a combination of UEs and APDs for conducting Multi-User-MIMO (MU-MIMO) communications utilizing MIMO transmission (e.g., as described with reference to FIGS. 6, 8, and / or 10) or for conducting Single-User-MIMO (SU-MIMO) communications (e.g., as described with reference to FIGS. 7, 9, and / or 10). By doing so, the base station can communicate with multiple UEs or communicate additional data with a single UE using the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0029] The CRM 260 also includes a base station manager 270 for managing various functions and communication interfaces of the base station 120. Alternatively or additionally, the base station manager 270 may be implemented in whole or in part as hardware logic or circuitry integrated with or separate from other components of the base station 120. In at least some aspects, the base station manager 270 configures the antennas 252, the RF front end 254, and the radio transceiver(s) 256 for communication with the UE 110, the APD 180, and / or for communication with a core network. The base station 120 includes an inter-base station interface 272, such as an Xn interface and / or an X2 interface. The base station manager 270 configures the inter-base station interface 272 to exchange user plane data and control plane information with other base stations 120 and manages communication between the base station 120 and the UE 110. The base station 120 also includes a core network interface (not shown) for the base station manager 270 to configure the core network interface (not shown) for exchanging user plane data and control plane information with core network functions and / or entities.

[0030] 3 illustrates an example device diagram 300 of the APD 180. While the device diagram 300 generally illustrates an example entity capable of implementing various aspects of MIMO transmission using the APD, additional functionality and interfaces may be included, which are omitted from FIG. 3 for clarity. The APD 180 includes one or more antenna(s) 302, a radio frequency front end 304 (RF front end 304), and one or more radio frequency transceivers 306 (e.g., a radio frequency transceiver, an LTE transceiver, a 5G NR transceiver, or a 6G transceiver) for wireless communication with the base station 120 and / or the UE 110. The APD 180 may also include a position sensor, such as a Global Navigation Satellite System (GNSS) module, that provides location information based on the location of the APD 180.

[0031] The antenna(s) 302 of the APD 180 may include an array of multiple antennas configured in a similar or different manner to each other. Additionally, the antenna 302, the RF front end 304, and the transceiver(s) 306 may be configured to support beamforming for transmitting and receiving communication signals with the base station 120 and / or the UE 110. By way of example and not limitation, the antenna 302 and the RF front end 304 may be implemented for operation in sub-gigahertz bands, sub-6 GHz bands, and / or above 6 GHz bands, which may include various frequencies described with reference to FIG. 1. Thus, the antenna 302, the RF front end 304, and the transceiver(s) 306 provide the APD 180 with the capability to receive and / or transmit communication signals with the base station 120 and / or the UE 110 (e.g., transmitting information using an APD control channel (e.g., an APD slow control channel or an APD fast control channel), as described further below).

[0032] The APD 180 includes a processor(s) 310 and a computer-readable storage medium 312 (CRM 312). The processor 310 may be a single-core processor or a multi-core processor built with a homogenous or heterogeneous core structure. The computer-readable storage medium described herein does not include a propagating signal. The CRM 312 of the APD 180 may include any suitable memory or storage device, such as RAM, SRAM, DRAM, NVRAM, ROM, or flash memory, that can be used to store device data 314 of the APD 180. The device data 314 includes configuration data, RIS information, applications, and / or operating systems of the APD 180, which are executable by the processor(s) 310 to enable dynamic configuration of the APD 180, as further described. The device data 314 also includes one or more codebooks 316 of any suitable type or combination, and location information 318 of the APD 180. The location information 318 may be obtained or configured using the location sensor 308 or may be programmed into the APD 180, such as during installation. The location information 318 indicates the location of the APD 180 and may include location, geographic coordinates, orientation, elevation information, etc. The base station 120, the MIMO function 268, and / or the UE 110 may use the location information 318 in calculating angle or distance information, such as for a communication path between the base station 120 and the APD 180 and / or between the APD 180 and a target UE 110. The codebook 316 may include a surface configuration codebook that stores surface configuration information for the RIS of the APD and a beam sweeping codebook that stores pattern, sequence, or timing information (e.g., phase vectors and reflection identifiers) for implementing multiple surface configurations useful for causing the APD to perform various reflection beamforming. In some aspects, the surface configuration codebook and the beam sweeping codebook include phase vector information, angle information (eg, calibrated to the respective phase vectors), identifier information, and / or beam configuration information.

[0033] In an aspect of MIMO transmission using APDs, the CRM 312 of the APD 180 includes an adaptive phase change device manager 320 (APD manager 320). Alternatively or additionally, the APD manager 320 may be implemented in whole or in part as hardware logic or circuitry integrated with or separate from other components of the APD 180. Typically, the APD manager 320 processes information exchanged with a base station over the wireless link(s) 133 and then uses that information to manage the surface configuration of the APD 180, such as by configuring a reconfigurable intelligent surface 322 (RIS 322) of the APD 180. For example, the APD manager 320 receives an indication of the surface configuration over the wireless link 133 (APD control channel), uses the indication to extract a surface configuration from the codebook 316, and applies the surface configuration to the RIS 322. Alternatively or additionally, the APD manager 320 initiates transmission of uplink messages to the base station over the wireless link 133, such as acknowledgements / negative acknowledgements (ACK / NACK) for various APD configuration or management commands. In some aspects, the APD manager 320 receives indications of beam sweeping patterns (e.g., beam sweeping pattern indexes) over the wireless links 133 and / or 134, and applies a sequence of various surface configurations to the RIS based on the beam sweeping patterns and / or according to synchronization or pattern timing indicated by or received with the indication. In some cases, the beam sweeping patterns may include reflection identifier information, which causes the APD 180 to modulate or apply one or more reflection identifiers to downlink reference signals or uplink sounding signals reflected by the APD 180 (e.g., using the RIS).

[0034] In some aspects, the APD manager 320 receives timing information in a surface configuration communication, where the timing information indicates when to apply the surface configuration to the RIS 322 (e.g., start time, duration, timing advance, periodic time information, dynamic time information). Alternatively or additionally, the APD manager 320 receives direction information along with the surface configuration, which indicates to configure the surface to reflect the signal of the RIS 322 based on the direction information. For example, if the direction information indicates a communication direction from the BS to the UE, the APD manager 320 selects a first surface configuration having a first inter-reflection angle that reflects a wireless signal from the base station 120 to the UE 110. If the direction indicates a communication direction from the UE to the BS, the APD manager 320 selects a second surface configuration having a second inter-reflection angle that reflects a wireless signal from the UE 110 to the base station 120.

[0035] The RIS 322 of the APD 180 includes one or more configurable surface element(s) 324, such as configurable electromagnetic elements, configurable resonator elements, or configurable reflectarray antenna elements. Typically, the configurable surface elements 324 can be selectively or programmatically configured to control how the RIS 322 reflects (e.g., directivity) and / or transforms an incident waveform. By way of example and not limitation, the configurable electromagnetic elements include scattering particles that are electronically connected (e.g., via PIN diodes). An embodiment uses electronic connections to position the scattering particles, such as based on principles of reflection, to control the directivity, phase, amplitude, and / or polarization of the transformed (from the incident) waveform. The RIS 322 can include an array(s) of independently configurable surface element(s) 324, and the array can include any number of elements having any size.

[0036] In some embodiments, the position and / or orientation of the APD 180 is configurable, and the APD 180 includes a motor controller 326 in communication with one or more motor(s) 328 operatively coupled to the physical chassis of the APD 180. Based on command and control information, such as that received from the base station 120, the motor controller 326 can send commands to the motors 328 to modify one or more kinematic behaviors of the motors 328, which may include any suitable type of stepper motor or servo. For example, the motor controller 326 can issue commands or control signals that specify the shaft rotation speed of the stepper motor in degrees, the revolutions per minute (RPM) that is the shaft rotation speed of the stepper motor, the linear motion of the linear motor in millimeters, and the linear velocity of the linear motor in meters per second (m / s). The one or more motors 328 may then be coupled to mechanisms that mechanically position the physical chassis or platform that supports the APD 180 (e.g., avionics in a drone, drives for a linear rail system, gimbals in a base station, linear bearings in a base station). The physical position, location, or orientation of the APD 180 (and / or the platform supporting the APD 180) may be changed via commands and signals generated and sent by the motor controller 326 to the motor 328. In response to receiving a position configuration from the base station, the APD manager 320 communicates movement commands to the motor controller 326 based on the position configuration, such as via a software interface and / or a hardware address. In an aspect of MIMO transmission using APDs, the base station 120 may reposition or reorient one or more APDs 180 to improve or enable reflection of wireless signals (e.g., uplink and / or downlink signals) between the base station 120 and the UE 110.

[0037] Typically, the APD 180 can include multiple motors, each motor corresponding to a different rotational or linear motion. Examples of motor(s) 328 that can be used to control the orientation and position of the APD include (i) linear servo motors that can be part of a rail system mount for the APD, (ii) motors that control the direction and pitch, yaw, and roll of a drone carrying the APD, (iii) radial servo or stepper motors that rotate axes when the APD is in a fixed position or on a gimbal, and the like. For clarity, the motor controller 326 and motors 328 are shown as part of the APD 180, but in alternative or additional embodiments, the APD 180 communicates with motor controllers and / or motors external to the APD. For example, the APD manager 320 communicates the position configuration to a motor controller that mechanically positions the platform or chassis that supports the APD 180. In an aspect, the APD manager 320 communicates the position configuration to a motor controller using a local wireless link, such as Bluetooth, Zigbee, IEEE 802.15.4, or a hardwire link. The motor controller then adjusts the platform based on the position configuration using one or more motors. The platform may correspond to or be attached to any suitable mechanism that supports rotatable and / or linear adjustments, such as a drone, an aircraft, a non-stationary ground station (e.g., a vehicle-towable APD tower / module), a rail propulsion system, a hydraulic lift system, etc.

[0038] As shown in FIG. 3, the position of the APD 180 may be defined relative to a three-dimensional coordinate system, in which an X-axis 330, a Y-axis 332, and a Z-axis 334 define a spatial area and provide a framework for indicating position configurations through rotational and / or linear adjustments. These axes are typically designated as X-axis, Y-axis, and Z-axis, although other frameworks may be used to indicate position configurations (e.g., azimuth and elevation). For example, a flight framework may refer to a vertical axis (yaw), a lateral axis (pitch), and a longitudinal axis (roll), while other motion frameworks may refer to a vertical axis, a sagittal axis, and a frontal axis. As an example, position 336 refers to a center position of the APD 180, which typically corresponds to a baseline position (e.g., position (0,0,0) using XYZ coordinates).

[0039] In one aspect, the APD manager 320 communicates rotational adjustments (e.g., rotational adjustments 338) about the X-axis 330 to the motor controller 326, where the rotational adjustments include a direction of rotation (e.g., clockwise or counterclockwise), an amount of rotation (e.g., degrees), and / or a speed of rotation. Alternatively or additionally, the APD manager 320 communicates linear adjustments 340 along the X-axis, where the linear adjustments include any combination of a direction, speed, and / or distance of the adjustment. In some cases, the APD manager 320 communicates adjustments about other axes as well, e.g., any combination of a rotational adjustment 342 about the Y-axis 332, a linear adjustment 344 along the Y-axis 332, a rotational adjustment 346 about the Z-axis 334, and / or a linear adjustment 348 along the Z-axis 334. Thus, the position configuration may include a combination of rotational and / or linear adjustments in all three spatial degrees of freedom in addition to the movement supported by the frame or platform (e.g., avionics drone or vehicle) on which the APD is mounted, thereby enabling the APD manager 320 to communicate the physical adjustments to the APD 180. Alternatively or additionally, the APD manager communicates the RIS surface configuration, beam sweeping index, and / or timing information, as further described.

[0040] 4 illustrates at 400 an example base station constituting an adaptive phase change device in accordance with various aspects. Example 400 includes example base station 120 and APD 180, which may be implemented similarly to those described with reference to FIGS. 1-3. The RIS implemented by APD 180 includes an array of "N" independently selectable and configurable surface elements, such as configurable surface element 402, configurable surface element 404, configurable surface element 406, surface partitions, sub-panels, etc., where "N" represents the number of configurable surface elements of the RIS.

[0041] In an embodiment, the base station 120 or the MIMO function 268 manages the configuration of the RIS of the APD 180 using a surface configuration codebook 408. The surface configuration codebook 408 may be pre-configured and / or known by both the base station 120 and the APD 180. Alternatively or additionally, the base station 120 may also manage the time-dependent configuration of the RIS of the APD 180 by using a beam-sweeping codebook or a beam-sweeping index as described with reference to FIGS. 5A and 5B. In some cases, the base station 120 transmits the surface configuration codebook 408 and / or the beam-sweeping codebook using the wireless link 133, such as over the APD slow control channel using one or more messages. In some aspects, the base station 120 uses the APD slow control channel to communicate large amounts of data, to communicate data without low latency requirements, and / or to communicate data without timing requirements. In some cases, the base station 120 transmits multiple surface configuration codebooks to the APD 180. The multiple surface configuration codebooks may be, for example, a first surface configuration codebook for downlink communication, a second surface configuration codebook for uplink communication, a phase vector codebook, a beam sweeping codebook, timing advance information, etc. In response, the APD 180 stores the surface configuration codebook(s) 408 and / or other codebooks in the CRM. This represents the codebook(s) 316 of the CRM 312 as described with reference to FIG. 3. Alternatively or additionally, the APD 180 obtains the surface configuration codebook and other codebooks through a manufacturing (e.g., programming), calibration, or installation process. Such a process stores the surface configuration codebook(s) 408 and other codebooks in the CRM 312 of the APD 180 during assembly, installation, calibration, verification, network association, or by an operator manually adding or updating the codebook(s).

[0042] The surface configuration codebook 408 includes configuration information that specifies surface configurations for some or all of the configurable surface elements (e.g., elements 324) that form the RIS of the APD 180. For example, in some embodiments, a phase vector defines a set of waveform transformation characteristics (e.g., phase delay, reflection angle / direction, polarization, amplitude). The configurable surface elements apply such waveform transformation characteristics to an incident signal (e.g., incident waveform, incident signal light) and transform the incident signal into a reflected signal (e.g., reflected waveform, reflected signal light) that is characterized by one or more transformation characteristics. With respect to the surface configuration codebook 408, when configured by phase vectors or surface configurations, each configuration entry may correspond to a phase vector and / or surface configuration associated with a set of waveform transformation characteristics provided by a respective configurable surface element of the APD.

[0043] A surface configuration may include (or indicate) a surface element hardware configuration (e.g., for one or more PIN diodes) for each configurable surface element of the APD. In an embodiment, each surface element hardware configuration of a surface configuration may correspond to a respective entry in the phasor vector. That is, each surface element hardware configuration arranges the surface of each configurable surface element such that each configurable surface element transforms an incident waveform into a reflected waveform having waveform characteristics indicated by the corresponding entry in the phasor vector. This may include an absolute transformation based on the phasor vector (e.g., generating a reflected waveform to within a threshold / standard deviation of the waveform characteristic indicated by the phasor vector), or a relative transformation to within a threshold / standard deviation of the waveform characteristic (e.g., generating a reflected waveform based on altering the incident waveform with the waveform characteristic indicated by the phasor vector).

[0044] As an example, each index of the codebook corresponds to a phase vector and configuration information for each configurable surface element of the APD 180. For example, index 0 maps phase configuration 0 to configurable surface element 402, phase configuration 1 to configurable surface element 404, phase configuration 2 to configurable surface element 406, etc. Similarly, index 1 maps phase configuration 3 to configurable surface element 402, phase configuration 4 to configurable surface element 404, phase configuration 5 to configurable surface element 406, etc. The surface configuration codebook 408 may include any number of phase vectors that specify configurations of any number of configurable surface elements, such that a first phase vector corresponds to a first surface configuration of the APD 180 (through each configurable surface element in the RIS), a second phase vector corresponds to a second surface configuration of the APD 180, etc. Alternatively or additionally, the phase vectors or surface configurations of the surface configuration codebook 408 may be mapped or calibrated to specific angle information of incident and / or reflected radio signals (e.g., reference signals), signal rays, beamformed transmit signals of the base station 120, beamformed transmit signals of the UE 110, etc. In various embodiments, the base station 120 may use this angle information corresponding to the surface configurations or phase vectors to calculate angle information for use in determining the phase vector of the APD 180, the phase steering vector of the base station 120, or the phase steering vector of the UE 110 to implement MIMO transmission using the APD.

[0045] While the surface configuration codebook 408 of FIG. 4 includes phasor information, alternative or additional codebooks may store beam configuration information (e.g., a first surface configuration specifying a first beam having a first (propagation) direction, a second surface configuration specifying a second beam having a second direction, etc.). For example, similar to the phasor surface configuration codebook, the beam codebook includes surface element hardware configurations corresponding to respective beam configurations. That is, each surface element hardware configuration arranges the surface of each configurable surface element such that the respective configurable surface element transforms an incident waveform into a reflected waveform having beam characteristics (e.g., directions) indicated in the beam codebook. Thus, in various embodiments, the surface configuration codebook 408 corresponds to a beam codebook. Similarly, to configure the surface of the APD 180, the base station determines a desired beam configuration for the transformed signal and identifies a beam codebook entry corresponding to the desired beam configuration (e.g., by identifying a beam codebook index that maps to a corresponding beam configuration or phasor entry).

[0046] In some aspects, the phase sweeping codebook indicates a pattern of surface configurations and / or beam configurations, such as the surface configurations and / or beam configurations indicated by the surface configuration codebook 408 and the beam configurations specified by the beam codebook. For example, the phase sweeping codebook indicates the order of the surface configurations to be repeated. Alternatively or additionally, the phase sweeping codebook indicates the duration for applying each surface configuration. The surface configuration information stored in the codebook may correspond to a full configuration, specifying an exact configuration (e.g., configure with this value), or may correspond to a delta configuration, specifying a relative configuration (e.g., modify the current state with this value). In one or more embodiments, the phase configuration information specifies a phase shift and / or phase adjustment between the incident signal and the transformed signal. For example, phase configuration 0 may specify a phase shift configuration of the configurable surface element 404 such that the element 404 transforms the incident waveform with a relative phase shift of "phase configuration 0".

[0047] In the environment 400, the base station 120 communicates an indication 410 to the APD 180 that specifies a surface configuration. For example, the indication 410 specifies an index (e.g., the index 410) that maps to a corresponding surface configuration, phase vector, or beam sweeping pattern in accordance with one or more aspects. In response to receiving the indication, the APD manager 320 uses the index to retrieve the surface configuration, phase vector, or beam sweeping pattern from a corresponding codebook (e.g., the surface configuration codebook 408) and applies the surface configuration(s) to the RIS (e.g., configure each configurable surface element with the configuration and / or timing specified by the codebook).

[0048] In various embodiments, the base station 120 communicates timing information (not shown) to the APD 180 that may be included with the surface configuration or beam sweeping index. For example, a start time for application of the indicated surface configuration or beam sweeping pattern. In some aspects, the base station 120 communicates a stop time indicating when to remove and / or change the surface configuration or beam sweeping pattern. Alternatively or additionally, the base station 120 communicates an APD timing adjustment (e.g., timing advance, timing delay) indicating the relative adjustment to make. In some cases, the timing information for the surface configuration or beam sweeping pattern includes a period during which one or more different surface configurations are applied to one of the configurable surface elements of the APD 180. When changing the surface configuration, the APD 180, via the APD manager 320, may apply a default surface configuration, revert to a previous surface configuration (e.g., a surface configuration used before the indicated surface configuration), and / or apply a new surface configuration to control the direction in which the APD 180 reflects wireless signals. To maintain synchronized timing between the base station 120, the APD 180, and / or the UE 110 (e.g., with respect to incident radio signals for beam sweeping and / or MIMO transmission), the APD 180 may receive and / or process synchronization signals from the base station or network (e.g., a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) for SSB).

[0049] By specifying the timing information, the base station 120 can synchronize and / or configure the APD 180 for use in a channel sounding process, a channel state information (CSI) process, and / or a MIMO transmission (e.g., coordinated uplink or downlink transmission) with one or more UEs 110 in accordance with various aspects of MIMO transmission using the APD. In some embodiments, the base station 120 configures one or more APDs 180 with respective surface configurations and timing information (e.g., start times, stop times, and / or timing advance / delay for time slots assigned to a particular UE(s)) corresponding to MIMO transmissions to or from the UE. In an aspect, the base station 120 transmits the surface configuration indication and / or timing information using the APD fast control channel. This allows the base station 120 to dynamically configure the APD 180 on a slot-by-slot basis. For example, the base station 120 transmits a surface configuration schedule to the APD indicating when to apply different surface configurations to the RIS / configurable surface elements to support scheduled MIMO transmissions. Alternatively or additionally, the base station 120 communicates surface configuration changes on a slot-by-slot basis using signaling on the APD fast control channel. These timing and control aspects allow the base station to configure the APD to support MIMO transmissions for one or more UEs, for example in scenarios where different UEs are assigned the same time slot or frequency resources, or to configure the APD to enable SU-MIMO transmissions for one UE, or to enable MU-MIMO transmissions for multiple UEs. This can improve data rates, spectral efficiency, data throughput, or reliability for multiple UEs and the corresponding wireless network.

[0050] MIMO Transmission Using Adaptive Phase-Change Devices To facilitate MIMO transmission at higher frequencies (e.g., 6 GHz or higher), the base station 120 may use one or more APDs 180 to mitigate LoS conditions or obstacles that impair communication between the base station 120 and one or more UEs 110. Before communicating over an APD-enabled communication path, the base station 120 or the MIMO function 268 may characterize the communication channel for at least one APD-enabled communication path and configure phase vectors and timing adjustments for each of the APD(s) 180 based on the results of this channel characterization. Alternatively or additionally, the base station 120 (or the MIMO function 268) may select one or more of the APDs 180 and / or one or more of the UEs 110 for MIMO transmission based on the results of the channel characterization (e.g., measurement reports). To do so, the base station 120 may perform a downlink channel state information (CSI) process or may have the UEs 110 perform an uplink sounding reference signal (SRS) process over the channel or communication path that includes the respective APDs 180. Typically, base station 120 may associate (e.g., synchronize) the respective resources of the uplink SRS process or downlink CSI process with the implementation of a phase vector by the APD(s) to direct reflections of the uplink sounding signal or downlink CSI signal to the receiving entity. In doing so, base station 120 may select a phase vector and / or timing adjustment of APD 180 to use when reflecting a subsequent MIMO transmission between the base station and one or more UEs based on signal quality parameters of the reflections received by the base station or UE. Alternatively or additionally, base station 120 may use information from the channel characterization process to select or group combinations of APDs and / or UEs for various downlink or uplink SU-MIMO or MU-MIMO transmissions.

[0051] 5A-9 illustrate various examples of a base station communicating with one or more UEs using respective APDs according to one or more aspects of MIMO transmission using APDs. The examples illustrated in FIGS. 5A and 5B include using the APDs to reflect downlink reference signals toward each UE as part of a downlink channel characterization process (e.g., a CSI procedure) or using the APDs to reflect respective uplink reference signals toward the base station as part of an uplink channel characterization process (e.g., an SRS procedure). Based on the results of the channel characterization process, the base station may select and configure different combinations of APDs and UEs to implement various scenarios of MIMO transmission using APDs according to one or more aspects. As described with reference to FIG. 6, the base station may implement MU-MIMO transmission with multiple UEs using multiple respective APDs. Alternatively, the base station may implement SU-MIMO transmission with a single UE using multiple APDs as described with reference to FIG. 7. Other examples include a base station using respective panel partitions of a single APD to perform MU-MIMO transmission with multiple UEs, as described with reference to FIG. 8, or a base station using multiple panel partitions of an APD to perform SU-MIMO transmission with a single UE, as described with reference to FIG. 9.

[0052] The aspects described with respect to one example may be combined with other examples, transactions of Figures 10 and 11, or the method of Figure 12 to perform operation of MIMO transmission using the APD in various ways or scenarios. For example, the base station or MIMO function 268 may configure the UE and APD to perform beam sweeping of the respective patterns of beams and reflections of the uplink reference signal and generate channel measurements that enable selection of a combination of UE beam / steering vectors, APD phase vectors, or respective timing adjustments to be used for the uplink MIMO transmission. Alternatively, the base station may configure the APD to perform beam sweeping of the respective patterns of reflections of the downlink reference signal and generate channel measurements that enable selection of a combination of BS beam / steering vectors, APD phase vectors, or respective timing adjustments to be used for the downlink MIMO transmission. In an aspect, the base station may apply the reciprocity theorem to use the results from the downlink channel characterization or MIMO transmission to select the configuration of the APD and UE to perform the uplink MIMO transmission and vice versa. Therefore, if the reciprocity theorem can be applied to previously obtained channel measurements or communication path data for the reverse link direction, a two-way channel characterization process may be performed for each downlink or uplink MIMO transmission as required.

[0053] 5A and 5B illustrate examples of channel characterization processes that a base station or MIMO function 268 may implement in accordance with one or more aspects of MIMO transmission using APDs. In an aspect, a base station may implement various operations, configurations, or channel measurements described with respect to the examples of FIG. 5A or 5B to perform a channel characterization process (e.g., APD-enabled CSI or SRS procedures) useful for enabling MIMO transmission using APDs. Although illustrated in the context of two APDs 180 and two UEs 110, the described embodiments may apply to any suitable communication scenario, which may include multiple UEs and a single APD, a single UE and multiple APDs, multiple UEs and multiple APDs, and / or with transition states between the described configurations or scenarios based on the results of the process or measurements. That is, a base station may implement MIMO transmissions adaptive to dynamic channel conditions or UE movement by reselecting or regrouping APDs and / or UEs.

[0054] FIG. 5A illustrates, at 500, an example of a base station performing a downlink channel characterization process that can be used to perform various aspects of MIMO transmission using APDs. The downlink (DL) channel characterization process may include a CSI reference signal (CSI-RS) process that provides the base station with information useful for calculating DL MIMO transmission configurations (e.g., phase vectors and timing adjustments) or for calculating mutual information and / or timing information for uplink (UL) MIMO transmission. In general, the example 500 includes the base station 120 using the APDs 181 and 182 to steer, steer, or sweep a reflected beam of each DL wireless reference signal transmitted by the base station 120 toward the UEs 111 and / or 112. The described DL channel characterization process may be performed simultaneously with each APD and reference signal receiving UE, or sequentially with the APD and one or more reference signal receiving UEs. In an aspect, the base station may perform a DL channel characterization process to enable MU-MIMO transmission with multiple UEs or SU-MIMO transmission with a single UE.

[0055] As shown in FIG. 5A, the base station 120 can use APDs 181 and 182 to reflect a beam of a downlink wireless signal (e.g., a signal above 6 GHz) around an obstacle 171 or 172 that blocks the LoS communication path between the base station and the UEs 111 and 112. Note that the UEs 111 and 112 can be located at different distances from the base station 120, with the UE 111 being located further away than the UE 112. In this example, the UE 112 is located closer to the base station than the UE 111 (e.g., 3 / 4 the distance of the UE 111), but does not have a LoS communication path. In this way, the lengths of the respective LoS and non-LoS communication paths between the base station and each UE are different, resulting in different propagation delays (e.g., one-way or round trip) through the channel of each communication path. In an aspect, the base station 120 or the MIMO function 268 may calculate respective timing adjustments (e.g., in addition to the Timing Advance (TA)) for the base station originated downlink (e.g., DL MIMO transmission), the phase vector of the APD 180 (e.g., reflection of a DL or UL MIMO transmission), and / or the UE originated uplink 110 (e.g., UL MIMO transmission) to account for their different or varying propagation delays such that the MIMO transmission reaches the receiving device (e.g., base station or UE in SU-MIMO mode) within a sufficient amount of time (e.g., cyclic prefix) to enable decoding of the received MIMO transmission signal.

[0056] In an aspect, the base station 120 may determine to use an APD or establish an APD-enabled communication path in response to detecting an obstacle or deteriorating channel condition in a communication path (e.g., LoS or non-LoS path) to communicate with a respective UE. For example, the base station may detect an obstacle or impaired channel condition when a link signal quality or signal strength of a received UE-originated transmission signal is below a threshold. These conditions may result from UE movement, APD movement, movement of temporary obstacles (e.g., foliage or vehicles), atmospheric changes (e.g., fog, rain, or water vapor), and the like. In some cases, the base station may determine to add an APD-enabled communication path in response to a data rate or throughput with the UE dropping below a threshold. In doing so, the base station may alleviate such communication problems by enabling MIMO transmission utilizing the APD-enabled communication path to improve communication performance.

[0057] As part of the downlink or uplink channel characterization process, the base station 120 may select one or more APDs 180 (e.g., candidate APDs) to evaluate for use in a communication path or to provide an APD-enabled communication path with the UE 110. Typically, the base station 120 (e.g., a terrestrial or non-terrestrial base station or radio head) is at a known location from which the base station 120 manages or coordinates the respective channel characterization process or MIMO transmissions of various entities. In many cases, the APD 180 is also at a known location, which may include the location of the APD 180 (e.g., relative to the base station 120) and the orientation of the face of the APD 180. For example, the APD 180 may be at a fixed location, which is set at installation or determined by the APD 180 position sensor 308 (GNSS receiver). In an aspect, the base station 120 or the MIMO function 268 obtains location and / or orientation information from the APD 180 via an APD control channel (e.g., APD control channel 511, APD control channel 512). The APD control channel may include an APD slow control channel or an APD fast control channel implemented over wireless link 133 or wireless link 134. In this example, the APD control channel is implemented as separate APD control channels 511 and 512 between base station 120 and APDs 181 and 182. Although shown as separate APD control channels, base station 120 may communicate with both APD 181 and APD 182 using the same wide beam communication or different narrow beam communication. Alternatively or additionally, base station 120 may query a server for location information and / or capabilities of APDs 180 proximate base station 120 or UE 110, such as by contacting a server included in core network 150 of FIG. 1.

[0058] Based on the location information of one or more APDs 180, the base station 120 can select an APD 180 to use for MIMO transmission with the UE 110. For example, the base station 120 can select an APD 180 that is near the UE 110 (e.g., an estimated location of the UE), select an APD 180 that is located near a LoS communication path between the base station and the UE, or select an APD 180 that is likely to provide an APD-compatible communication path between the base station and the UE (e.g., based on historical records or recent APD activity). Alternatively or additionally, the base station 120 can estimate or receive a location of the UE 110, such as via a low-bandwidth connection 521 or a low-bandwidth connection 522 (e.g., UE location signaling via GNSS or base station-UE low-bandwidth signaling). In an aspect, the base station 120 can select and / or configure an APD 180 to participate in the channel characterization process and / or MIMO transmission based on the location (e.g., location and orientation) of the APD 180 and / or the estimated location of the UE.

[0059] In example 500, base station 120 selects APDs 181 and 182 to use for communication with UEs 111 and 112 based on the APDs' respective proximity to the UEs. To perform downlink channel characterization of a communication path including APDs 181 and 182, base station 120 may associate or bind resources of a downlink CSI process or synchronization process (e.g., a particular beam) with one or more corresponding phase vectors and downlink reference signal identifiers of APD 180. These identifiers (IDs) may include a BS modulation signal ID or an APD modulation reflection ID, which result in an indexed CSI downlink reference signal and / or its reflection. For example, base station 120 may determine the CSI process of a particular APD by associating parameters of the CSI-RS with corresponding configuration settings of the APD. In an aspect, the CSI process determined by the base station may include the antenna port, the precoding matrix, the beam identifier (beam ID), the BS modulated signal ID of the CSI-RS bound or associated with the APD index (APD ID), and the phase vector of the APD (e.g., of the beam sweeping pattern) on which the CSI process is performed. In some cases, the base station can associate, assign, or map the surface configuration of the APD to the surface configuration or the respective APD phase vector of the beam sweeping pattern performed by the APD during the channel characterization process.

[0060] Alternatively or additionally, the APD may modulate the reference signal reflection with an identifier associated with the reference signal index, the air interface resource of the reference signal, or the APD phase vector to enable analysis of the reflection by the receiving device. In such a case, the phase vector of the beam-sweeping pattern may be associated or mapped to the APD-modulated reflection identifier. In this manner, the UE 110 may identify and measure signal quality parameters for the LoS downlink reference signal or reflection (e.g., reflection 552 or reflection 554) arriving at the UE, which may result in information (e.g., CSI) being provided to the base station via a downlink (DL) signal report (e.g., DL signal report 561 or 562) for analysis of the downlink beam (e.g., downlink beam 541 or 542) and APD vector. Based on analysis of the signal report, the base station may determine which combination of downlink beam(s), timing information, and / or APD vector(s) enables a communication path for MIMO transmission between the base station and one or more UEs.

[0061] In example 500, base station 120 determines the respective CSI processes for APDs 181 and 182 by associating respective identifiers, resources, or parameters of the CSI-RS with the phase vectors or respective surface configurations of the beam-sweeping patterns selected for each of the APDs. The base station may select the surface configurations, phase vectors, or beam-sweeping patterns based on the location of the APDs relative to the base station and the estimated location of UE 110 (e.g., UE 111 or UE 112). Base station 120 then transmits the respective beam-sweeping indexes 531 and 532 to APDs 181 and 182 via APD control channel 511 and APD control channel 512 (e.g., separate low-bandwidth control channels). Base station 120 may also transmit timing information to APDs 181 and / or 182 to implement the phase vectors of the beam-sweeping patterns in synchronization with the downlink reference signal. To implement the CSI process, with respect to APD 181, base station 120 has the APD apply a phase vector of a beam sweeping pattern while the base station transmits a downlink beam 541 of the CSI-RS toward the RIS 322 of APD 181. This sweeps reflected beams 551, 552, and 553 from APD 181 toward UE 111, some of which may reach UE 112. Base station 120 may perform a similar operation for APD 182. Such an operation may include transmitting a downlink beam 542 toward the RIS 322 of APD 182, while the APD implements a phase vector of its beam sweeping pattern to direct reflected beams 554, 555, and 556 toward UE 112, some of which may reach UE 111. Thus, in some cases, UE 111 may receive APD reflected signals from multiple APDs. In the context of FIG. 5A, such signals may include reflected beams 554 or 555 from APD 182, as well as reflected beams 552 and 551.

[0062] Based on various combinations of downlink beams 541, 542 and phase vectors implemented by the respective APDs during the CSI process, UE 111 and 112 may receive one or more reflections of the downlink reference signal from either or both APDs. For example, UE 111 may receive reflections from APD 181 as part of a first CSI process and reflections from APD 182 as part of a second CSI process. The second CSI process may be implemented simultaneously or sequentially with respect to the first process. Typically, UE 110 may generate a downlink signal report (e.g., DL signal report 561 or 562) based on received reflections of the reference signal from one or more APDs. The received reflections of the reference signal enable base station 120 to identify and / or analyze channel state information corresponding to each combination of downlink beams and APD phase vectors that result in a reflection reaching the UE. The downlink signal report may include a signal or link quality measurement for a signal received by the UE. Such a signal may include a directly received downlink signal or a reflection of the downlink signal. For example, the UE may decode an identifier of a received reflection or may collect information (e.g., antenna port, precoding matrix, air interface resource) useful to the base station to identify the CSI index (e.g., DL beam and / or APD phase vector) of the reflection reaching the UE. Furthermore, the downlink signal report may include timing information (e.g., arrival time) useful for determining the propagation delay between the base station and the UE or the respective intervals of the propagation delay between the base station and the APD (BS-APD propagation delay) and the propagation delay between the APD and the UE (APD-UE propagation delay).

[0063] In an aspect, one or more of UEs 110 provide DL signal reports to the base station via low band connection 521 or low band connection 522. The DL signal reports indicate at least one CSI-RS index (e.g., highest Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), Signal-to-Noise Ratio (SNR), Signal-to-Interference-plus-Noise Ratio (SINR), or CSI-RS index prioritized by signal strength / quality). Based on the DL signal reports, the base station can determine the respective APD IDs and phase vectors for the reflections reaching the UE. As a result of this embodiment, UEs 111 and 112 generate DL signal reports 561 and 562 for the reflections of the downlink reference signals received from APDs 181 and / or APDs 182 as part of their respective CSI processes. UE 111 then transmits DL signal report 561 to the base station via low band connection 521, and UE 112 transmits DL signal report 562 to the base station via low band connection 522. In some embodiments, DL signal reports 561 and / or 562 include respective CSI-RS indices and signal quality measurements for one or more reflections received by one of UEs 110 from APD 181 and / or APD 182. Based on the results of the downlink channel characterization or CSI process, base station 120 can analyze the signal reports to determine respective MIMO transmission configurations for the base station, one or more APDs, and / or one or more UEs, examples of which are described with respect to the transactions of Figures 6-9, Figures 10 and 11, or the method of Figure 12.

[0064] FIG. 5B illustrates, at 501, an example of a base station performing an uplink channel characterization process that can be used to perform various aspects of MIMO transmission using APDs. The uplink (UL) channel characterization process may include an SRS process. The SRS process provides the base station with information useful for calculating UL MIMO transmission configurations (e.g., phase vectors and timing adjustments) or calculating reciprocal configurations for downlink (DL) MIMO transmissions. In general, the example 501 includes the base station 120 using the APDs 181 and 182 to steer, steer, or sweep the beams of each UL wireless reference signal transmitted by the UEs 111 and / or 112. Note that since the spatial orientation of the UE 110 relative to the APD or base station is unknown, the UE may perform multiple iterations from wide uplink beam sweeping to narrow uplink beam sweeping to refine transmissions directed to the APDs. The described UL channel characterization process may be performed simultaneously with each APD and UE for transmitting reference signals, or sequentially with the APD and one or more UEs for transmitting reference signals. A base station may perform an UL channel characterization process to enable MU-MIMO transmission with multiple UEs or SU-MIMO transmission with a single UE. For simplicity of explanation, the entities in FIG. 5B may position, communicate, and perform uplink channel characterization aspects similar to or interrelated with the positioning (e.g., distance, propagation delay, obstacles, APD selection, etc.), communication, and downlink channel characterization aspects described with reference to FIG. 5A.

[0065] In an aspect, the uplink operation may utilize downlink characterization or performance measurements, or may perform an uplink channel characterization process to use directional SRS to find feasible uplink APDs and respective APD configurations (e.g., phase vectors) for MIMO transmission. Furthermore, the base station 120 may determine uplink timing advance information. The uplink timing advance information includes timing advance commands or parameters that may account for different propagation distances through different APD-enabled communication paths. In some cases, the timing information determined by the base station includes a first timing advance (TA) value for the UE to apply to the initial UL transmission, and a second timing advance value for the APD to apply when applying the phase vector to reflect the UL transmission such that respective reflections of UL signals from different UEs (or the same UE in case of SU mode) arrive at the base station simultaneously (e.g., within one cyclic prefix) for proper MU-MIMO reception by the base station.

[0066] In the context of example 501, base station 120 selects APDs 181 and 182 as candidate APDs to use for communication with UEs 111 and 112 based on the APDs' respective proximity to the UEs or historical records indicating viable APD-enabled communication paths provided by APDs 181 and 182. To enable uplink channel characterization of the communication paths including APDs 181 and 182, base station 120 can associate or bind resources of an uplink SRS process performed by the UE (e.g., SRS parameters 571, 572) to corresponding one or more phase vectors and uplink reference signal identifiers (e.g., signal identifiers or reflection identifiers) of one or more APDs 180. This can result in indexed SRS uplink reference signals and / or their reflections that are useful for selecting or configuring an APD for MIMO transmission. For example, base station 120 determines an SRS process for a particular APD by associating parameters of the SRS with the configuration settings of the APD (e.g., phase vectors and beam sweeping timing parameters). In an aspect, the SRS process determined by the base station may include the antenna port, the precoding matrix, the beam identifier (beam ID), the UE modulated signal ID of the SRS bound or associated with the APD index (APD ID), and / or the phase vector of the APD (e.g., of the beam sweeping index) by which the SRS process is performed. In some cases, the base station may associate, assign, or map the surface configuration of the APD to the respective APD phase vector or surface configuration implemented by the APD during the channel characterization process. By doing so, the base station may select a surface configuration for MIMO transmission based on the APD phase vector surface configuration that results in the highest uplink signal metric (e.g., RSRP, SNR) during the channel characterization process.

[0067] Alternatively or additionally, the APD may modulate the reflection of the reference signal with an identifier associated with the reference signal or APD phase vector to enable analysis of the reflection by the receiving device. In such a case, the phase vector of the beam-sweeping pattern may be associated or mapped to the APD-modulated reflection identifier. By doing so, the BS 120 may identify and measure signal quality parameters for the reflection or LoS uplink reference signal reaching the base station to provide uplink signal metrics (e.g., uplink signal reports) for the uplink channel characterization process. Based on the analysis of the uplink signal metrics or reports, the base station may determine which combination of uplink beam(s) 580, timing information, and / or APD vectors enables a communication path for MIMO transmission between the base station and one or more UEs.

[0068] In example 501, base station 120 determines the respective SRS processes for APDs 181 and 182 by associating respective identifiers, resources, or parameters of the SRS with the phase vector of the beam sweeping pattern selected for the APD or respective surface configuration. To configure UEs 111 and 112 for the SRS processes, base station 120 transmits SRS parameters 571 to UE 111 using low-bandwidth connection 521 and SRS parameters 572 to UE 112 using low-bandwidth connection 522. The base station may select the surface configuration, phase vector, or beam sweeping pattern based on the location of the APD relative to the base station and the estimated location of each one of UE 111 or UE 112. Base station 120 then transmits respective beam sweeping indexes 533 and 534 to APDs 181 and 182 via APD control channels 511 and 512 (e.g., separate low-bandwidth control channels). Base station 120 may also transmit timing information to APDs 181 and / or 182 to implement the phase vectors of the beam-sweeping pattern in synchronization with the transmission of SRS by UEs 111 and 112.

[0069] To implement the SRS process, with respect to the APD 181, the base station 120 applies a phase vector of a beam sweeping pattern to the APD, during which the UE 111 transmits uplink beams 581, 582, 583, and 584 of the SRS according to the SRS parameters 571, and the uplink beam 584 reaches the RIS 322 of the APD 181. This sweeps the reflected beams 591, 592, and 593 from the APD 181 toward the base station. Note that the uplink beam 583 may also reach the APD 182, which may further realize a simultaneous beam sweeping pattern, with the reflected beams being swept similarly as those shown as beams 594, 595, and 596. Thus, the reflection of the SRS transmitted by the UE 111 may reach the base station from one or both of the APDs 181 and 182, allowing the base station to configure multiple APD-enabled communication paths to the UE. The base station 120 may perform a similar operation for the APD 182. A similar operation involves having UE 112 transmit uplink beams 585, 586, 587, and 588, with uplink beam 587 reaching RIS 322 of APD 182. Meanwhile, the APD implements the phase vector of its beam sweeping pattern, which directs reflected beams 594, 595, and 596 towards the base station for reception and subsequent measurement to provide uplink signal metrics. Similar to the SRS process of UE 111, the uplink beam of UE 112 may reach APD 181, which may result in another reflection of the uplink beam (e.g., UL from UE 112 to APD 181 for base station 120) that may reach the base station, allowing the base station to configure multiple APD-enabled communication paths to UE 112.

[0070] In an aspect, the base station may associate SRS from different UEs (e.g., 111, 112) with corresponding APD indices (or APD identifiers). For example, the base station 120 may instruct the UEs 111 and 112 to sweep their respective SRS signals to detect which APD (having a corresponding index) results in the highest SNR or RSRP upon reception by the base station. The base station may then associate the received SRS with the respective particular APD index or identifier for which the SNR or RSRP is highest (e.g., the SRS of UE 111 has the highest SNR reflected from APD 181). Based on the association of SRS measurements with APD indices, the base station may schedule the two UEs with different APDs having associated indices for MU-MIMO.

[0071] Typically, the base station 120 may receive one or more reflections of the uplink reference signal from either or both APDs based on various combinations of phase vectors and uplink beams (e.g., 583, 584, 587, and 588) implemented by the respective APDs during the SRS process. For example, the base station may receive a reflection (e.g., uplink beam 583) from APD 181 as part of a first SRS process with UE 111 and a reflection (e.g., uplink beam 588) from APD 182 as part of a second SRS process with UE 112. The second SRS process may be performed simultaneously or sequentially with respect to the first process. Typically, the base station 120 may generate an uplink signal report (not shown) based on the received reflections of the reference signal from one or more APDs. The received reflections of the reference signal allow the base station 120 to identify and / or analyze channel state information for the combination of APD phase vectors and uplink beams that result in the reflection reaching the base station. The uplink signal report may include signal or link quality measurements for signals received by the base station, which may include directly received uplink signals or reflections of uplink signals. For example, the base station may decode an identifier of the received reflection or may have access to information (e.g., antenna port, precoding matrix, air interface resource) useful to the base station to identify the SRS index (e.g., UL beam and / or APD phase vector) of the reflection reaching the base station. Additionally, the uplink signal report may include timing information (e.g., time of arrival) useful for determining the propagation delay between the UE and the base station, or the respective intervals of the propagation delay between the UE and the APD and between the APD and the base station.

[0072] In an aspect, the base station determines a UL signal report indicating at least one SRS index (e.g., highest RSRP, SRS index prioritized by signal strength). This allows the base station to determine the APD ID and phase vector for each reflection arriving at the base station. As a result of this embodiment, the base station 120 generates a UL signal report (not shown) for reflections of uplink reference signals received from the APD 181 and / or the APD 182 as part of the respective SRS processes performed by the UE 111 and the UE 112. In some embodiments, the UL signal report includes a respective SRS index and a signal quality measurement for one or more reflections received by the base station from the APD 181 and / or the APD 182. Based on the results of the uplink channel characterization, the base station 120 can analyze the signal report to determine respective MIMO transmission configurations for the base station, one or more APDs, and / or one or more UEs. Examples thereof are described with respect to the transactions of FIGS. 6-9, 10 and 11, or the method of FIG. 12.

[0073] 6-9 illustrate various examples of base stations communicating with one or more UEs using respective APDs according to various aspects of MIMO transmission using APDs. The base station 120 may implement aspects of the described examples based on the results of one or more channel characterization processes, or may apply the reciprocity theorem to use the results from the channel characterization process and communicate in the reverse link direction (e.g., using the uplink results to implement aspects of the downlink in a TDD scheme or in a nearby or adjacent FDD band). In general, the examples of FIG. 6-9 may include selecting and grouping combinations of APDs and UEs for MIMO transmission, determining respective MIMO configurations for the APDs and UEs, transmitting various parameters of the MIMO configurations to the APDs and UEs, and implementing the MIMO transmission via communication paths enabled by the configured APDs and UEs. These non-limiting examples include performing MU-MIMO transmission with multiple UEs using respective APDs (FIG. 6), performing SU-MIMO transmission with a single UE and multiple APDs (FIG. 7), performing MIMO transmission with multiple UEs using respective panel partitions of a single APD (e.g., FIG. 8), and performing SU-MIMO transmission with a single UE using multiple panel partitions of an APD (e.g., FIG. 9). Aspects described with respect to one example may be combined with other examples, transactions of FIGS. 10 and 11, or the method of FIG. 12 to perform operations of MIMO transmission using APDs in various ways or scenarios.

[0074] In various aspects, the base station 120 uses the results from the channel characterization process to select, group, and / or schedule one or more UEs and one or more APDs for performing MU-MIMO or SU-MIMO transmissions. With reference to FIG. 5A, 5B, or 6-9, the UE (e.g., UE 111, UE 112) may feedback at least one CSI-RS index (e.g., highest signal strength, or prioritized by signal strength) to the base station 120 indicating the APD index (or identifier) ​​and phase vector. Alternatively, the base station may receive the respective SRS from the UE along with an indication useful for identifying the APD index and phase vector that causes the reflection of the SRS to reach the base station. In an aspect, the base station may use the CSI feedback (or SRS measurement) to determine the APD and phase vector that enable a communication path for MIMO transmission by the APD. For example, UE 111 may feed back its top three CSI-RS indexes as APD 181 of phase vector 1, APD 181 of phase vector 2, and APD 182 of phase vector 3. Similarly, UE 112 may feed back its top CSI-RS index as APD 182 of phase vector 4. Based on the results of these channel characterizations (or similar SRS measurements), base station 120 may select APD 181 of phase vector 1 for UE 111 and APD 182 of phase vector 4 for UE 112 and implement MU-MIMO accordingly (e.g., FIG. 6). In other cases, if only one UE is present or if the base station cannot receive feedback from a second UE (or receives SRS from one UE), the base station may select to implement SU-MIMO with UE 111 using APD 181 of phase vector 1 and APD 182 of phase vector 3 (e.g., FIG. 7).

[0075] Alternatively or additionally, the base station may associate a UE in MU-MIMO scheduling where the CSI process selected by the UE corresponds to a particular APD index. For example, the UE 111 may receive reflected CSI-RS signals from both APDs 181 and 182 and report back to the base station the CSI-RS index (e.g., the index of the CSI-RS and associated APD) corresponding to the APD where the CSI-RS signal is received with better signal strength. The base station 120 may then pair or group the UEs together for MU-MIMO scheduling based on the respective CSI feedback provided by the UEs corresponding to the different APD indexes. If a UE receives CSI-RS signals from the base station via multiple APDs, the base station may schedule the UE for SU-MIMO. To facilitate MIMO transmission, the base station may determine a MIMO transmission configuration for the APD and / or the UE. The base station may transmit parameters of the MIMO transmission configuration to the APD or the UE via the APD control channel and the low band connection, respectively. When configured according to the determined MIMO transmission configuration, the base station may then perform downlink or uplink MIMO transmission as described herein. These and other examples of APD-enabled MIMO transmission are described with respect to the examples of Figures 6-9, the transactions of Figures 10 and 11, and the method of Figure 12.

[0076] FIG. 6 illustrates, at 600, an example of using multiple APDs for MU-MIMO transmission with multiple UEs in accordance with one or more aspects. The environment of the example 600 includes the base station 120, APD 181, APD 182, UE 111, and UE 112 of FIG. 1, which may communicate as described with reference to FIGS. 1-5B. As shown in FIG. 6, in a manner similar to that described with respect to the wireless link 130 of FIG. 1, the base station 120 may communicate with the UE 111 using a high band connection 621 (e.g., above 6 GHz) including the RIS 322 of the APD 181 and / or a low band connection 521 (e.g., below 6 GHz, sub-6 GHz). The base station may also communicate with the UE 112 using a high band connection 622 and / or a low band connection 522 including the RIS 322 of the APD 182. In this example, the base station 120 may perform downlink and / or uplink MU-MIMO transmission with the UE 111 and the UE 112 via the high band connections 621 and 622. In an aspect, the base station may determine to use an APD-enabled communication path or implement MIMO transmission with APDs in response to a failed attempt to establish high bandwidth communication over the LoS communication path, or may analyze signal and / or link quality measurements to detect channel impairments or detect that the signal and / or link quality measurements are trending below an acceptable performance level. To configure and operate the application of downlink or uplink phasors, the base station may communicate with multiple APDs 180 using a wide-beam low-bandwidth APD control channel, or with multiple APDs 180 using respective narrow-beam or wired APD control channels 511 and 512.

[0077] To enable the MU-MIMO transmission shown in FIG. 6, the base station 120 may select a group of candidate APDs 180 including APDs 181 and 182, and perform a channel characterization process as described with reference to FIGS. 5A, 5B, 10, 11, and / or 12 to obtain uplink or downlink signal reports (e.g., signaling metrics). Based on the uplink signal reports and / or downlink signal reports, the base station 120 selects multiple UEs for performing MIMO transmission. Here, it is assumed that the CSI-RS index provided by the UE 111 indicates that the phase vector 7 of the APD 181 provided the highest RSRP value, and the CSI-RS index of the UE 112 indicates that the phase vector 24 of the APD 182 provided the highest SNR value. Thus, the base station 120 pairs the UE 111 with the APD 181 and pairs the UE 112 with the APD 182 to schedule MU-MIMO transmission over the respective communication paths shown in FIG. 6.

[0078] In an aspect, the base station 120 or the MIMO function 268 determines a MIMO transmission configuration for the selected APD and / or UE based on a channel characterization process. The base station may determine or generate a MIMO transmission configuration including one or more of a transmit beam configuration (e.g., beam ID or precoding matrix), an APD surface configuration, an APD timing advance, a UE timing advance, etc. For example, the base station may analyze signal or link quality measurements of an uplink or downlink signal report generated by the channel characterization process. Based on the analysis, the base station may select a respective surface configuration of the APD, which may include an APD phase vector that results in a maximum signal power or a highest signal quality value at the base station (e.g., SRS) or UE (e.g., CSI-RS). The base station may generate separate MIMO transmission configurations for downlink and uplink transmissions, or may generate a composite MIMO transmission configuration that includes parameters that enable MIMO transmission in either link direction.

[0079] In some implementations, as part of the channel characterization process, the base station may assign a respective MIMO transmission configuration to each surface configuration included in the beam sweeping pattern of the APD. To configure the APD, the base station can then identify a MIMO transmission configuration for the MIMO transmission based on the channel characterization process and the assigned APD phase vector that results in the highest or strongest signal metric for the reflection reaching the UE or base station during the channel characterization. Alternatively or additionally, the base station can determine a respective timing advance value for application of the phase vector by the APD or uplink transmission of the UE based on the respective positions of the APD and UE and the subframe or slot timing of the shared physical channel (e.g., Physical Downlink Shared Channel (PDSCH) or Physical Uplink Shared Channel (PUSCH)) for scheduling the MIMO transmission. By doing so, the base station 120 can adjust the arrival of the MIMO transmission at the receiver within a sufficient amount of time (e.g., cyclic prefix) to allow for decoding of the received transmitted signal, taking into account different amounts of propagation delay (or distance) over the APD-enabled communication path.

[0080] Returning to FIG. 6, the base station 120 identifies a MIMO transmission configuration including a surface configuration of the APDs 181 and 182 for downlink transmission to the UEs 111 and 112 based on the results of the channel characterization process. In this example, the base station determines a surface configuration 611 for the APD 181 and a surface configuration 612 for the APD 182. Based on the results of the aforementioned channel characterization process, the surface configuration 611 may include an indication of the phase vector 7 of the APD 181 and an APD timing advance (TA) value based on the propagation delay between the base station and the APD 181. The surface configuration 612 may include an indication of the phase vector 24 of the APD 182 and another APD TA value based on the propagation delay between the base station and the APD 182. In some cases, the APD surface configuration may further include a reference or indication to a slot or subframe of the physical shared channel for scheduling of the MIMO transmission by the base station. 6 is not shown to scale, and it should be noted that the APD 181 may be located much further away from the base station than the APD 182. Thus, the APD TA value of the APD 181 may be much larger than the APD TA value of the APD 182 or other APDs 180 near the base station.

[0081] Alternatively or additionally, the base station may identify a MIMO transmission configuration for UE uplink transmission, which may include a surface configuration and a UE timing advance value, based on the results of the channel characterization process. Based on the reciprocity principle, the uplink surface configurations 611 and 612 may use the same phase vector as a downlink configuration with the same timing advance value (e.g., similar path distance) or different timing advance value (or vice versa). For example, the base station may determine the UE timing advance based on the total path length or propagation delay, and may determine the (uplink) APD timing advance based on the path length or propagation delay between the UE and the APD. Thus, the MIMO transmission configuration for the communication path may include a UE TA value and a surface configuration with an indication of the phase vector and an uplink APD TA value. As mentioned above, the downlink APD TA value and the uplink APD TA value may include different amounts of time, such as when the APD is not equidistant from the base station and the UE.

[0082] Continuing with the described embodiment, base station 120 generates or updates a MIMO transmission configuration using uplink parameters for surface configuration 611 of APD 181, surface configuration 612 of APD 182, UE TA value of UE 111, and UE TA value of UE 112. For uplink transmission, surface configuration 611 may include an APD TA value based on an indication of phase vector 7 of APD 181 and a propagation delay between UE 111 and APD 181. Surface configuration 612 may include an indication of phase vector 24 of APD 182 and another APD TA value based on a propagation delay between UE 112 and APD 182. The base station may configure the uplink APD TA value to apply each surface configuration to the APD at a time coincident with the arrival of an uplink transmission by the corresponding UE resulting in a reflection of the uplink MIMO transmission to the base station. For UEs 111 and 112, the base station determines a UE TA value 631 for UE 111 based on a propagation delay between UE 111 and the base station, and determines a UE TA value 632 for UE 112 based on a propagation delay between UE 112 and the base station. The base station may configure the UE TA values ​​631 and 632 such that uplink MIMO transmissions arrive at the base station within a time window (e.g., a cyclic prefix) that allows the base station to simultaneously decode the received MIMO transmission signals.

[0083] In an aspect, the base station 120 configures the APD 180 and / or the UE 110 for MIMO transmission by transmitting a surface configuration to the APD over an APD control channel (APD control channel 511 or 512) and a UE TA value to the UE over a low-band connection (e.g., low-band connection 512 or low-band connection 522). The base station 120 may transmit the surface configuration as a full configuration message (or command) or may transmit the surface configuration as a partial configuration message (or command). In some cases, the partial surface command may correspond to a subset of configuration parameters for an uplink APD MIMO setting or another subset of configuration parameters for a downlink APD MIMO setting. Alternatively or additionally, the surface configuration transmitted by the base station may indicate an absolute value for a phase vector or TA setting or may indicate a delta value to be applied by the APD to a current (e.g., previously configured) phase vector or TA setting.

[0084] 6, the base station transmits a surface configuration 611 to the APD 181 using the APD control channel 511 and transmits a UE TA value 631 (e.g., for uplink MIMO) to the UE 111 using the low-band connection 521 to enable a first communication path for MIMO transmission. The base station also transmits a surface configuration 612 to the APD 182 using the APD control channel 512 and transmits a UE TA value 632 to the UE 112 using the low-band connection 521 to enable a second communication path for MIMO transmission. Based on the surface configurations 611 and 612, the base station 120 may cause the corresponding APDs 180 of the communication paths to implement multiple simultaneous phase vectors at the same time or in the same time slot according to various MIMO configurations described herein.

[0085] For downlink MU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs can be time-aligned with the PDSCH of the base station's downlink transmission. In some embodiments, the base station associates each APD phase vector with a downlink MU-MIMO antenna port or beam to a particular UE. As shown in FIG. 6, the base station may associate a first MU-MIMO downlink beam including signal ray 641 with phase vector 7 of the APD 181, which is applied in alignment with the PDSCH of the MU-MIMO transmission (e.g., using the APD TA value). The base station 120 may also associate a second MU-MIMO downlink beam including signal ray 642 with phase vector 24 of the APD 182, which is applied in alignment with the PDSCH of the MU-MIMO transmission. Based on the incident downlink signal rays 641 and 642, APD 181 directs reflected signal ray 651 of the first reflected beam to UE 111, and APD 182 directs reflected signal ray 652 of the second reflected beam to UE 112. Thus, base station 120 can use APDs 181 and 182 to perform downlink MU-MIMO transmission to UEs 111 and 112 utilizing the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0086] When implementing uplink MU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs are time-aligned with the respective PDSCHs of the UEs. In some embodiments, the base station associates each APD phase vector with a respective uplink antenna port of the corresponding UE. In the context of FIG. 6, the base station may associate a first antenna port of an uplink beam including the signal ray 661 with phase vector 7 of the APD 181, which is applied in alignment with the PUSCH of the UE-originated MU-MIMO transmission (e.g., using the APD TA value). The base station 120 may also associate a second antenna port of an uplink beam including the signal ray 662 with phase vector 24 of the APD 182, which is applied in alignment with the PUSCH of the UE-originated MU-MIMO transmission.

[0087] As described herein, the base station 120 may transmit respective timing advance information to the APD to time-align the application of the APD phase vector associated with a UE with the corresponding PUSCH transmission from that UE. Thus, the base station may provide a TA value (if necessary) to each associated uplink phase vector associated with one of the corresponding UEs of the scheduled MU-MIMO transmission. Note that the base station 120 may transmit the APD TA value as a separate command to the APD (e.g., from a surface configuration) to control the timing of the implementation or application of the phase vector by the APD. In some cases, the APD timing advance command is separate (although related) from the timing advance command (e.g., TA value 631 or 632) that the base station transmits to the corresponding UE to adjust the UE's uplink transmission timing. Thus, the base station may calculate the APD TA value based on the timing advance command transmitted to the corresponding UE and / or the PUSCH timing of the corresponding UE.

[0088] Based on the incident uplink signal rays 661 and 662, the APD 181 reflects the signal ray 671 of the first reflected beam toward the base station 120, and the APD 182 reflects the signal ray 672 of the second reflected beam toward the base station. In an aspect, the base station may schedule each UE uplink transmission, configure a UE TA value, and / or configure an APD TA value to provide a reflected uplink MU-MIMO transmission that reaches the base station within an amount of time (e.g., cyclic prefix) that allows for decoding of the received MU-MIMO transmission signal. Thus, the base station 120 may use the APDs 181 and 182 to implement uplink MU-MIMO transmissions from the UEs 111 and 112 that utilize the same time and frequency resources. This may improve the spectral efficiency of the wireless network.

[0089] FIG. 7 illustrates, at 700, an example of using multiple APDs for SU-MIMO transmission with a UE in accordance with one or more aspects. The environment of the example 700 includes the base station 120, the APD 181, the APD 182, and the UE 111 of FIG. 1, which may communicate as described with reference to FIGS. 1-6. As shown in FIG. 7, the base station 120 may communicate with the UE 111 using a low band connection 521 (e.g., less than 6 GHz, sub-6 GHz) in a manner similar to that described with respect to the wireless link 130 of FIG. 1. In this example, the base station 120 also communicates with the UE 111 using a first high band connection 721 including the RIS 322 of the APD 181 and a second high band connection 722 including the RIS 322 of the APD 182.

[0090] Generally, the aspect of SU-MIMO transmission described with reference to FIG. 7 may be implemented similarly to the transmission with a single UE (UE 111) described with reference to FIG. 6. Here, assume that the CSI-RS index provided by UE 111 indicates that phasor 8 and phasor 27 of APD 181 provide the highest two RSRP values, and that no CSI-RS index was received from other UEs. Thus, base station 120 groups UE 111 with APD 181 and APD 182 for scheduling SU-MIMO transmission over the respective communication paths shown in FIG. 7. In this example, base station determines a surface configuration 711 of APD 181 and a surface configuration 712 of APD 182. Based on the results of the channel characterization process described above, surface configuration 711 may include an indication of phasor 8 of APD 181 and one or more APD TA values ​​based on a propagation delay between the base station and APD 181 or between UE 111 and APD 181. The surface configuration 712 may include an indication of the phase vector 27 of the APD 182 and one or more other APD TA values ​​based on a propagation delay between the base station and the APD 182 or between the UE 111 and the APD 182. In an aspect, the surface configuration may be implemented as a combined configuration including parameters for uplink and downlink MIMO transmission as described herein, or may be implemented as separate configurations. To configure the APD for SU-MIMO, the base station 120 transmits the surface configuration 711 to the APD 181 using the APD control channel 511 and transmits the surface configuration 712 to the APD 182 using the APD control channel 512, as shown in FIG. 7.

[0091] For uplink SU-MIMO transmission, the base station may determine a UE TA value 731 for the UE 111 based on a propagation delay between the UE 111 and the base station using the APD 181 and / or based on a propagation delay between the UE 111 and the base station using the APD 182. The base station may configure the UE TA value 731 such that the uplink MIMO transmissions over each APD-enabled communication path reach the base station within a time window (e.g., cyclic prefix) during which the base station can simultaneously decode the received SU-MIMO transmission signals. As shown in FIG. 7, the base station transmits the UE TA value 731 (e.g., for uplink MIMO) to the UE 111 using the low bandwidth connection 521 to enable the first and second communication paths for uplink SU-MIMO transmission. Based on the surface configurations 711 and 712, the base station 120 may cause the corresponding APDs 180 of the communication paths to implement multiple simultaneous phase vectors at the same time or in the same time slot according to various MIMO configurations described herein.

[0092] To implement downlink SU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs can be time-aligned with the PDSCH of the base station's downlink transmission. In some cases, the base station associates each APD phase vector with a downlink SU-MIMO antenna port or beam to the UE via a specific communication path. As shown in FIG. 7, the base station may associate a first SU-MIMO downlink beam including a signal ray 741 with phase vector 8 of the APD 181, which is applied in alignment with the PDSCH of the SU-MIMO transmission (e.g., using the APD TA value). The base station 120 may further associate a second SU-MIMO downlink beam including a signal ray 742 with phase vector 27 of the APD 182, which is applied in alignment with the PDSCH of the SU-MIMO transmission. Based on the incident downlink signal rays 741 and 742, APD 181 directs reflected signal ray 751 of the first reflected beam to UE 111, and APD 182 directs reflected signal ray 752 of the second reflected beam to UE 111. Thus, base station 120 can use APDs 181 and 182 to perform downlink SU-MIMO transmission to UE 111 utilizing the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0093] When implementing uplink SU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs are time-aligned with the UE's PDSCH. In some cases, the base station associates each APD phase vector with a respective uplink antenna port of the UE. As shown in FIG. 7, the base station may associate a first antenna port of an uplink beam including a signal ray 761 with phase vector 8 of the APD 181, which is applied in alignment with the UE's PUSCH (e.g., using the APD TA value). The base station 120 may also associate a second antenna port of an uplink beam including a signal ray 762 with phase vector 27 of the APD 182, which is applied in alignment with the UE's PUSCH. Based on the incident uplink signal rays 761 and 762, the APD 181 reflects the signal ray 771 of the first reflected beam toward the base station 120, and the APD 182 reflects the signal ray 772 of the second reflected beam toward the base station. In an aspect, the base station may schedule the UE uplink transmission, configure the UE TA value, and / or configure the APD TA value to provide a reflected uplink SU-MIMO transmission that reaches the base station within an amount of time (e.g., cyclic prefix) that allows for decoding of the received SU-MIMO transmission signal. Thus, the base station 120 may use the APDs 181 and 182 to implement an uplink SU-MIMO transmission from the UE 111 that utilizes the same time and frequency resources. This may improve the spectral efficiency of the wireless network.

[0094] FIG. 8 illustrates, at 800, an example of using multiple APD surface partitions for MU-MIMO transmission with multiple UEs in accordance with one or more aspects. The environment of the example 800 includes the base station 120, APD 181, UE 111, and UE 112 of FIG. 1, which may communicate as described with reference to FIGS. 1-7. As shown in FIG. 8, in a manner similar to that described with respect to the wireless link 130 of FIG. 1, the base station 120 may communicate with the UE 111 using a low band connection 521 (e.g., less than 6 GHz, sub-6 GHz) and may communicate with the UE 112 using a low band connection 522. In this example, the base station 120 also communicates with the UE 111 using a high band connection 821 that includes a first partition 881 (e.g., a first RIS) of the APD 181, and communicates with the UE 112 using a high band connection 822 that includes a second partition 882 (e.g., a second RIS) of the APD 181.

[0095] In general, the aspects of SU-MIMO transmission described with reference to Figure 8 may be implemented similarly to the transmission with a single APD (APD 181) described with reference to Figure 6. Here, assume that the CSI-RS index provided by UE 111 indicates that phase vector 5 of APD 181 provided the highest RSRP value, and the CSI-RS index of UE 112 indicates that phase vector 9 of APD 181 provided the highest RSRP value for the channel characterization process. In this MU-MIMO example, the CSI-RS index of each of UE 111 and UE 112 may not include a measurement of the other APD, or may indicate that the reflection of the CRS or SRS provided by the other APD is unlikely to support MIMO transmission (e.g., low RSRP or excessive signal fading). Thus, base station 120 pairs UE 111 with a first partition 881 of APD 181 and pairs UE 112 with a second partition 882 of APD 181 for scheduling MU-MIMO transmission over the respective communication paths shown in FIG.

[0096] In an aspect, the base station 120 or the MIMO function 268 determines the MIMO transmission configuration for the APD partitions and / or UEs by analyzing signal metrics of the channel characterization process described herein. The MIMO transmission configuration may include, for each APD partition, a respective phase vector, an APD partition TA value, a UE TA value, etc. Thus, the base station 120 may determine and / or select a surface configuration based on distributing access to the APD 180, such as panel-divided access or APD sub-panel access. As an example, the base station 120 selects the surface configuration 811 based on the panel division (e.g., allocation of configurable surface elements), and thus the base station contemporaneously and / or simultaneously sends respective MIMO transmission signals to each receiving UE using APD partitions 881 and 882, as shown in example 800.

[0097] For example, base station 120 may distribute the configurable surface elements of APD 181 into subsets of configurable surface elements, such as a horizontal partition that groups a first subset of configurable surface elements (of the RIS) that are in the same horizontal row (e.g., APD partitions 881 and 882), a vertical partition that groups a second subset of configurable surface elements that are in the same vertical column, a quadrant partition that groups a subset of configurable surface elements that are in the same quadrant of the RIS, and / or any other combination of suitable partition geometries. Based on the distributed access, base station 120 may select a first surface configuration to modify the first subset of configurable surface elements of APD 181, select a second surface configuration to modify the second subset of configurable surface elements of APD 181, etc. If each surface configuration uses different configurable surface elements of the APD 181 and / or different APD timing advance values, the base station 120 can contemporaneously and / or simultaneously direct separate spatial streams of MIMO transmissions to the APD surface by directing the MIMO transmission spatial streams to respective subsets of the configurable surface elements. In an aspect, the same APD can be used for multiple streams of MIMO transmissions by using respective different polarizations of transmit signals and / or APD phase vectors. For example, a transmitter (e.g., base station or UE(s)) can apply different polarizations (e.g., vertical, horizontal, linear, circular, etc.) to separate streams of MIMO transmissions, and the APD can apply corresponding polarization phase vectors to provide reflections of the MIMO transmissions to the receiver(s).

[0098] Briefly, the base station 120 of FIG. 8 may determine a MIMO transmission configuration for an APD-enabled communication path formed by APD partition 881, APD partition 882, APD 182, and UE 111, in a manner similar to that described with respect to the transactions of FIGS. 5A-7, 9, 10 and 11, and / or the method of FIG. 12. In this example, the base station determines a surface configuration 811 for APD partition 881 of APD 181 and respective surface configuration APD partition 882. Based on the results of the channel characterization process described above, the surface configuration 811 may include an indication of phase vector 5 for APD partition 881, an indication of phase vector 9 for APD partition 882, and one or more APD TA values ​​based on propagation delays between the base station and APD 181, between APD 181 and UE 111, or between APD 181 and UE 112. In an aspect, the surface configuration may be implemented as a combined configuration including parameters for uplink and downlink MIMO transmission as described herein, or may be implemented as separate configurations. To configure the APD for MU-MIMO, the base station 120 transmits the surface configuration 811 to the APD 181 using the APD control channel 511, as shown in FIG.

[0099] For uplink MU-MIMO transmission, the base station may determine a UE TA value 831 for UE 111 based on a propagation delay between UE 111 and the base station, and may determine a UE TA value 832 for UE 112 based on a propagation delay between UE 112 and the base station. The base station may configure the UE TA values ​​831 and 832 to reach the base station within a time window (e.g., cyclic prefix) that allows the uplink MIMO transmission to simultaneously decode the received MIMO transmission signals. As shown in FIG. 8, the base station transmits UE TA value 831 to UE 111 using low-bandwidth connection 521 and transmits UE TA value 832 to UE 112 using low-bandwidth connection 522, enabling first and second communication paths including APD partition 881 and APD partition 882 for uplink MU-MIMO transmission. Based on the surface configuration 711, the base station 120 may cause corresponding APD partitions 881 and 882 of a communication path to implement multiple simultaneous phase vectors at the same time or in the same time slot according to various MIMO configurations described herein.

[0100] To implement downlink MU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs can be time-aligned with the PDSCH of the base station's downlink transmission. In some cases, the base station associates each APD partition phase vector with a downlink MU-MIMO antenna port or beam to a particular UE. As shown in FIG. 8, the base station may associate a first MU-MIMO downlink beam including signal ray 841 with phase vector 5 of APD partition 881, which is applied in alignment with the PDSCH of the MU-MIMO transmission (e.g., using the APD TA value). The base station 120 may also associate a second MU-MIMO downlink beam including signal ray 842 with phase vector 9 of APD partition 882, which is applied in alignment with the PDSCH of the MU-MIMO transmission. Based on the incident downlink signal rays 841 and 842, APD partition 881 directs reflected signal ray 851 of the first reflected beam to UE 111, and APD partition 882 directs reflected signal ray 852 of the second reflected beam to UE 112. Thus, base station 120 can use APD partitions 881 and 882 to perform downlink MU-MIMO transmissions to UEs 111 and 112 that utilize the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0101] When implementing uplink MU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs are time-aligned with the respective PUSCHs of the UEs. In some embodiments, the base station associates each APD partition phase vector with a respective uplink antenna port of the corresponding UE. As shown in FIG. 8, the base station may associate a first antenna port of an uplink beam including the signal ray 861 with phase vector 5 of the APD partition 881, which is applied in alignment with the PUSCH of the UE 111 (e.g., using the APD TA value). The base station 120 may also associate a second antenna port of an uplink beam including the signal ray 862 with phase vector 9 of the APD partition 882, which is applied in alignment with the PUSCH of the UE 112.

[0102] As described herein, the base station 120 may transmit respective timing advance information to the APD to time-align the application of an APD phase vector associated with a UE with a corresponding PUSCH transmission from that UE. Thus, the base station may provide a TA value (if necessary) to each associated uplink phase vector associated with one of the corresponding UEs of the scheduled MU-MIMO transmission. Based on the incident uplink signal rays 861 and 862, the APD partition 881 reflects the signal ray 871 of the first reflected beam toward the base station 120, and the APD partition 882 reflects the signal ray 872 of the second reflected beam toward the base station. In an aspect, the base station may schedule each UE uplink transmission, configure the UE TA value, and / or configure the APD partition TA value to provide a reflected uplink MU-MIMO transmission that reaches the base station within an amount of time (e.g., cyclic prefix) that allows for decoding of the received MU-MIMO transmission signal. Therefore, the base station 120 can use the APD partitions 881 and 882 to implement uplink MU-MIMO transmissions from the UEs 111 and 112 utilizing the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0103] FIG. 9 illustrates, at 900, an example of using multiple APD partitions for SU-MIMO transmission with a UE in accordance with one or more aspects. The environment of the example 900 includes the base station 120, the APD 181, and the UE 111 of FIG. 1, which may communicate as described with reference to FIGS. 1-8. As shown in FIG. 9, the base station 120 may communicate with the UE 111 using a low band connection 521 (e.g., less than 6 GHz, sub-6 GHz) in a manner similar to that described with respect to the wireless link 130 of FIG. 1. In this example, the base station 120 also communicates with the UE 111 using a first high band connection 921 including a first partition 881 (e.g., a first RIS) of the APD 181 and a second high band connection 922 including a second partition 882 (e.g., a second RIS) of the APD 181. To configure and operate the application of the downlink phase vector or the uplink phase vector, the base station communicates with the APD 181 using an APD control channel 511 (which may be a wide-beam low-band APD control channel or a narrow-beam APD control channel).

[0104] To enable the SU-MIMO transmission shown in FIG. 9, the base station 120 may select a group of candidate APDs 180 including APD 181 and perform a channel characterization process as described with reference to FIGS. 5A, 5B, 10, 11, and / or 12 to obtain uplink or downlink signal reports (e.g., signaling metrics). Based on the uplink signal reports and / or downlink signal reports, the base station 120 selects one UE for performing MIMO transmission. Here, assume that the SRS received by the base station indicates that phase vector 6 of APD partition 881 provided the UE 111 with the highest RSRP value and phase vector 7 of APD partition 882 provided the UE 111 with the next highest RSRP value. Further assume that the base station has not received SRS reflections from other combinations of APDs and UEs indicating viable APD-enabled communication paths. Accordingly, the base station 120 groups the UE 111 with a first partition 881 and a second partition 882 of the APD 181 for scheduling SU-MIMO transmissions over the respective communication paths shown in FIG.

[0105] In an aspect, the base station determines a MIMO transmission configuration for the APD partition and the selected UE by analyzing signal metrics of the channel characterization process described herein. The MIMO transmission configuration may include an APD partition phase vector, an APD partition TA value, a UE TA value, etc. Briefly, the base station 120 of FIG. 9 may determine a MIMO transmission configuration for the APD-enabled communication path formed by the APD partition 881, the APD partition 882, and the UE 111, similar to that described with respect to the transactions of FIGS. 5A-8, 10 and 11, and / or the method of FIG. 12. In this example, the base station determines a surface configuration 911 for the APD partitions 881 and 882 of the APD 181. Based on the results of the channel characterization process described above, the surface configuration 911 may include an indication of phase vector 6 for both the APD partition 881 and the APD partition 882, and one or more APD TA values ​​based on a propagation delay between the base station and the APD 181 or between the APD 181 and the UE 111. In other cases, such as for large APDs, the surface configuration may include different phase vectors for multiple partitions of the APD. In an aspect, the surface configuration may be implemented as a combined configuration including parameters for uplink and downlink MIMO transmission as described herein, or may be implemented as separate configurations. To configure the APD for MU-MIMO, the base station 120 transmits the surface configuration 911 to the APD 181 using the APD control channel 511, as shown in FIG. 9.

[0106] For uplink SU-MIMO transmission, the base station may determine a UE TA value 931 for the UE 111 based on a propagation delay between the UE 111 and the base station when using the APD 181 and / or the PUSCH of the UE 111. In some cases, the base station may determine multiple UE TA values ​​such that uplink MIMO transmissions over each APD partition-enabled communication path reach the base station within a time window (e.g., cyclic prefix) during which the base station can simultaneously decode the received SU-MIMO transmission signals. As shown in FIG. 9, the base station transmits a UE TA value 951 to the UE 111 using the low bandwidth connection 521 to enable the first and second communication paths for uplink SU-MIMO transmission. Based on the surface configuration 911, the base station 120 may cause corresponding partitions of the APD 181 of the communication paths to implement multiple simultaneous phase vectors at the same time or in the same time slot according to various MIMO configurations described herein.

[0107] To implement downlink SU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs can be time-aligned with the PDSCH of the base station's downlink transmission. As described herein, the base station may associate each APD partition phase vector with a downlink SU-MIMO antenna port or beam to the UE via a particular communication path. As shown in FIG. 9, the base station associates a first SU-MIMO downlink beam including signal ray 941 with phase vector 6 of APD partition 881, which is applied in alignment with the PDSCH of the SU-MIMO transmission (e.g., using the APD TA value). The base station 120 also associates a second SU-MIMO downlink beam including signal ray 942 with phase vector 6 of APD partition 882, which is applied in alignment with the PDSCH of the SU-MIMO transmission. Based on the incident downlink signal rays 941 and 942, APD partition 881 directs reflected signal ray 951 of the first reflected beam to UE 111, and APD partition 882 directs reflected signal ray 952 of the second reflected beam to UE 111. Thus, base station 120 can use APD partitions 881 and 882 to perform downlink SU-MIMO transmission to UE 111 utilizing the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0108] When implementing uplink SU-MIMO transmission, the base station 120 uses the MIMO transmission configuration to coordinate the application of simultaneous phase vectors such that the respective phase vectors applied by the APDs are time-aligned with the respective PUSCHs of the UE. In some cases, the base station associates each APD partition phase vector with a respective uplink antenna port of the UE. As shown in FIG. 9, the base station associates a first antenna port of an uplink beam including a signal ray 961 with phase vector 6 of APD partition 881, which is applied in alignment with the PUSCH of the UE 111 (e.g., using the APD TA value). The base station 120 also associates a second antenna port of an uplink beam including a signal ray 962 with phase vector 6 of APD partition 882, which is applied in alignment with the PUSCH of the UE 111. Based on the incident uplink signal rays 961 and 962, the APD partition 881 reflects the signal ray 971 of the first reflected beam toward the base station 120, and the APD partition 882 reflects the signal ray 972 of the second reflected beam toward the base station. In an aspect, the base station may schedule UE uplink transmissions, configure the UE TA value(s), and / or configure the APD TA value to provide a reflected uplink SU-MIMO transmission that reaches the base station within an amount of time (e.g., cyclic prefix) that allows for decoding of the received SU-MIMO transmission signal. Thus, the base station 120 may use the APD partitions 881 and 882 to implement an uplink SU-MIMO transmission by the UE 111 that utilizes the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0109] Transaction on MIMO transmission using APD Various aspects of MIMO transmission using APDs enable a base station to use one or more APDs in at least one communication path for MIMO transmission with each UE. Typically, a base station can select and configure one or more APDs for performing MU-MIMO transmission with multiple UEs or SU-MIMO transmission with a UE based on channel information or the result of a channel characterization process. By doing so, the base station can perform MIMO communication using the APDs to communicate with UEs that use the same time and frequency resources, thereby improving the spectral efficiency of the wireless network.

[0110] 10 and 11 illustrate some example signaling and control transactions performed between entities such as a base station (e.g., base station 120), APDs (e.g., APDs 181 and 182 and / or APD partitions 881 and 882), and UEs (e.g., UEs 111 and 112) to implement various aspects of MIMO transmission using APD1. The illustrated examples include a base station configuring various combinations of APDs and UEs to communicate using MIMO transmission (e.g., FIG. 10) and APDs, and performing a downlink or uplink channel characterization process (e.g., FIG. 11). The various operations described with reference to FIGS. 10 and 11 may be performed by any of the entities described with reference to FIGS. 1-4, in combination with the operations of the other examples of FIGS. 5A-9, and / or in combination with the operations of the method illustrated in FIG. 12.

[0111] 10 illustrates example signaling and control transactions for MIMO transmission using APDs, according to one or more aspects. Signaling and control transaction diagram 1100 includes signaling and control transactions between base station 120, APD 181, APD 182, UE 111, and UE 112, which may be performed as described with reference to FIGS. 1-9. Generally, the illustrated transactions may enable base station 120 or MIMO function 268 to configure and use APD 181 and / or APD 182 for SU-MIMO transmission with a UE (e.g., UE 111 or UE 112) or for MU-MIMO transmission with multiple UEs (e.g., UE 111 and UE 112).

[0112] At 1005, the base station 120 establishes a respective wireless connection with at least one of the UE 111 and the UE 112. Each wireless connection established with the UE may include a low-band connection that enables non-LoS communication between either the base station and the UE. In some cases, the base station may also establish a high-band connection with the UE, either directly or via a communication path that includes the surface of the APD 181 or the APD 182. For example, the base station may establish a low-band connection and a high-band connection with the UE to enable communication between the UE and the base station in frequency bands below 6 GHz and above 6 GHz.

[0113] In an aspect, the base station may also determine to use one or more APDs for MIMO transmission with at least one of the UEs at 1005. The base station may thus schedule downlink MIMO transmission to one or more of the UEs or schedule uplink MIMO transmission from one or more of the UEs. Alternatively or additionally, the base station may determine to include an APD-enabled communication path to enable MIMO transmission with at least one of the UEs. As an example, the base station may fail an attempt to establish a high-bandwidth wireless connection with the UE. For example, the base station 120 attempts to establish a high-bandwidth wireless link with the UE 111, but signal failure occurs because an obstacle (e.g., obstacle 171 or 172) blocks the LoS communication path. In other cases, the base station may analyze signal and / or link quality measurements to detect channel impairments or detect that the signal and / or link quality measurements are trending below an acceptable performance level. As another example, base station 120 can use the UE location information to analyze historical records to determine that the UE location has been historically associated with APD wireless communication or that UE 110 is moving toward a location historically associated with APD communication.

[0114] At 1010, the base station selects one or more APDs to use for MIMO transmission with UE 111 and / or UE 112. For example, the base station may select a set or group of candidate APDs for evaluation for use in MIMO transmission based on the proximity (e.g., within a threshold distance) of the APDs to the location of one of the UEs or based on historical usage records of APDs communicating with UEs proximate to the UE's location. Alternatively or additionally, the base station can monitor respective APD-broadcast signals from the APDs, access APD records indicating APDs within a cell coverage area, query a server that stores APD information, use the UE location information to identify APDs within operating range of UE 110, and so forth.

[0115] At 1015, the base station performs a channel characterization process using one or more APDs to obtain uplink or downlink signal metrics. The channel characterization process may include binding resources or parameters of the channel characterization process with the APD beam sweeping pattern to enable the receiving device to identify a reflection of a reference signal received from the APD. In an aspect, while the base station is transmitting a downlink reference signal or while the UE is transmitting an uplink reference signal, the base station configures one or more APDs to perform a beam sweeping pattern to enable characterization of the channel between the base station and the UE. In some cases, the base station performs a CSI process (e.g., FIG. 5A) with the at least one APD and one or more of the UE to obtain downlink signal reports for reflections of CSI-RS reaching the one or more UEs from the at least one APD. Alternatively or additionally, the base station can perform an SRS process (e.g., FIG. 5B) with the at least one APD and one or more of the UE to obtain uplink signal measurements of reflections of SRS reaching the base station from the at least one APD.

[0116] At 1020, the base station 120 groups the APD(s) 180 and the UE(s) 110 for MIMO transmission. Based on the results of the channel characterization process, the base station can group various combinations of UEs and APDs to perform uplink and / or downlink MIMO transmission. In an aspect, the base station selects multiple UEs to communicate using MU-MIMO or selects one UE to communicate using SU-MIMO based on the channel characterization process. For example, the base station can group multiple UEs with respective APDs to perform MU-MIMO transmission as described with reference to FIG. 6. In other cases, the base station can group one UE with multiple APDs to perform SU-MIMO transmission as described with reference to FIG. 7. As another example, the base station can group multiple APDs with respective partitions of a single APD to perform MU-MIMO transmission as described with reference to FIG. 8. Alternatively, the base station can group a single UE with multiple partitions of an APD to perform SU-MIMO using one APD as described with reference to FIG. 9.

[0117] Optionally, at 1025, the base station determines a UE timing advance value for uplink MIMO transmission. For example, the base station 120 can determine uplink timing advance information including respective timing advance commands or values, which may take into account different propagation distances through each APD-enabled communication path of the UE. In some cases, the UE timing advance command is separate (albeit related) from the APD timing advance command that the base station sends to the corresponding APD. As described herein, the APD timing advance can adjust the timing of application of a phase vector by the APD to match the UE's uplink transmission timing, which is changed based on the UE timing advance.

[0118] At 1030, the base station determines a surface configuration of one or more APDs. Typically, the base station uses the results of the channel characterization process to determine respective phase vectors for one or more APDs or APD partitions to enable MIMO communication over the APD-enabled communication paths. Alternatively or additionally, the base station may determine an APD timing advance value to time-align the application of the phase vector by the APD with an uplink or downlink transmission. Thus, the surface configuration of the APD (or APD partition) may include a phase vector, an indication of a physical channel timing (e.g., PUSCH or PDSCH) or a time slot during which the phase vector is applied, and an APD timing advance value that adjusts the relative timing application of the phase vector specified in the physical channel. In some cases, the APD timing adjustment value is based on a corresponding UE timing advance value of the uplink communication. The respective APD timing adjustment value may also be determined based on a propagation delay calculated for communication between the base station and the APD and / or between the UE and the APD.

[0119] At 1035, the base station transmits an indication of the respective surface configuration to at least one of the APDs selected for MIMO transmission. In some cases, the base station transmits the respective surface configuration to multiple APDs. The respective surface configurations enable the respective APD-compatible communication paths for MU-MIMO with multiple UEs (e.g., FIG. 6) or enable the respective APD-compatible communication paths for SU-MIMO with one UE (e.g., FIG. 7). In other cases, the base station transmits the surface configuration to one APD. The surface configurations enable the respective communication paths using APD partitions for MU-MIMO with multiple UEs (e.g., FIG. 8) or enable the respective communication paths using APD partitions for SU-MIMO with one UE (e.g., FIG. 9).

[0120] Optionally, at 1040, the base station transmits an indication of the respective UE timing advance value to at least one of the UEs selected for MIMO transmission. For example, the base station may transmit the indication of the respective UE timing advance value to multiple UEs to adjust corresponding uplink transmission times such that uplink MU-MIMO transmissions from the multiple UEs reach the base station within an amount of time (e.g., cyclic prefix) that allows for decoding of received transmission signals. Alternatively, the base station may transmit a UE timing advance to a UE that communicates with the base station via multiple APD-enabled communication paths such that uplink SU-MIMO transmissions reach the base station within an amount of time that allows for decoding of received transmission signals.

[0121] At 1045, the base station communicates with the UE using MIMO transmission. In an aspect, the base station may communicate with multiple UEs or one UE (e.g., SU-MIMO) using a surface configuration transmitted to one or more APDs. In some cases, the base station implements MU-MIMO (e.g., as indicated at 1045) and transmits downlink transmission signals or receives uplink transmission signals with multiple UEs using multiple APDs as described with reference to FIG. 6. Alternatively, although not shown in the transaction at 1045, the base station may implement other aspects of MIMO transmission using APDs as described herein. For example, the base station may implement SU-MIMO and transmit downlink transmission signals or receive uplink transmission signals with one UE using multiple APDs as described with reference to FIG. 7. In other cases, the base station may implement MU-MIMO and transmit downlink transmission signals or receive uplink transmission signals with multiple UEs using APD partitions as described with reference to FIG. 8. In still other cases, the base station may implement SU-MIMO and send downlink transmissions or receive uplink transmissions with one UE using the APD partition as described with reference to Figure 9. From the transaction of 1045, the base station may return to any of the preceding transactions, such as the transaction of subdiagram 1015, to recharacterize one or more communication paths and implement further iterations of MIMO transmission using APDs.

[0122] 11 illustrates, at 1100, example details of signaling and control transactions that may be used to perform channel characterization in accordance with one or more aspects. The illustrated transactions may enable the base station 120 or MIMO function 268 to use one or more APDs to sweep a reflected downlink or uplink beam through a respective communication path that includes one of the APDs. Although illustrated with transactions for two APDs 181 and 182 and two UEs 111 and 112, any of the transactions or subdiagrams illustrated in FIG. 11 may be implemented with any combination or group of APD(s), APD partitions, and UE(s) described herein.

[0123] The base station 120, the APD 180, and / or the UE 110 may be implemented similarly to the entities described with reference to Figures 1-9. Although this example is shown in the context of performing a channel characterization process, the operations described with reference to Figure 11 may be initiated or performed by entities unrelated to the channel characterization process, for example, to perform various transactions and / or operations described in connection with the methods of Figures 5A-10 or Figure 12. For example, the base station 120 may select, group, configure, and / or control the APD 180 and the UE 110 to perform various aspects of MIMO transmission using the APDs, as described with reference to Figures 5A-10 and / or Figure 12. In an aspect, the transactions of Figure 11 may correspond to subdiagram 1015 of Figure 10 performing a channel characterization process to obtain uplink or downlink signal metrics. Those metrics may be used to enable aspects of MIMO transmission using the APDs.

[0124] At 1105, the base station 120 configures the APD 180 and the UE for a channel characterization process. In an aspect, the base station may associate the air interface resources of the uplink or downlink channel characterization process with the respective phase vectors of the beam sweeping patterns assigned to the APD. The base station may then transmit the index of the beam sweeping patterns that the APD 181 and the APD 182 implement during the channel characterization process to reflect the beam of the downlink reference signal or the uplink reference signal, as shown at 1105. Alternatively or additionally, the base station may transmit the SRS parameters associated with the respective APD beam sweeping pattern phase vectors to the UEs 111 and 112 to enable the uplink channel characterization process shown at 1105. From 1105, the transaction may proceed to subdiagram 1110, where the base station, the APD, and the UE perform the transaction of the downlink channel characterization process. Alternatively, from 1105, the transaction may proceed to subdiagram 1115, where the base station, the APD, and the UE perform an uplink channel characterization process transaction.

[0125] The entities of FIG. 11 may perform the operations of subdiagram 1110 to perform a downlink channel characterization process for a communication path including APDs 181 and 182. As an example, the base station may perform a downlink channel characterization process (CSI procedure) as described with reference to FIG. 5A. Based on the configuration of 1105, the first APD 181 applies a first surface configuration to the RIS of the first APD at 1120, and the second APD 182 applies a second surface configuration to the RIS of the second APD at 1125. At 1130, the base station transmits a downlink wireless signal (e.g., CSI-RS). The downlink wireless signal (e.g., CSI-RS) may utilize the surface of the APD to cause reflections of the downlink wireless signal reaching one or both of the UE 111 and the UE 112. At 1135, the first UE 111 generates a downlink signal report (e.g., CSI feedback) of measurements on reflections of the downlink wireless signal reaching the first UE. Similarly, at 1140, the second UE 112 generates a downlink signal report of measurements of reflections of the downlink wireless signal reaching the second UE. If various combinations of downlink beams and APD phase vectors do not result in reflections reaching the UE, the UE may receive reflections of the downlink wireless signal from one APD, multiple APDs, or no APD, as described with reference to FIG. 5A. At 1145, the first UE 111 and the second UE 112 communicate their respective downlink signal reports to the base station. This allows the base station to perform other operations of the MIMO transmission with the APDs. Optionally, at 1150, the base station may perform another iteration of subdiagram 1110 to perform another channel characterization process. For example, the base station may use at least one of the downlink signal reports provided by the UEs 111 and 112 to refine parameters for downlink beam or APD phase vector selection for a subsequent iteration of channel characterization. Once the downlink channel characterization is complete, the base station may then group the APDs and UEs as described with reference to FIGS.

[0126] In an aspect, the entities of FIG. 11 may perform the operations of subdiagram 1110 to perform an uplink channel characterization process for a communication path including APDs 181 and 182. As an example, the base station may perform the uplink channel characterization process (SRS procedure) described with reference to FIG. 5B. Based on the configuration of 1105, the first APD 181 applies a first surface configuration to the RIS of the first APD at 1155, and the second APD 182 applies a second surface configuration to the RIS of the second APD at 1160. At 1165, the first UE and the second UE transmit respective uplink wireless signals (e.g., SRS). The respective uplink wireless signals (e.g., SRS) may utilize the surfaces of the APDs to cause reflections of the uplink wireless signals reaching one or both of the UEs 111 and 112. At 1170, the base station generates an uplink signal report of measurements (e.g., SRS metrics) on reflections of the uplink wireless signals reaching the base stations. If various combinations of uplink beams and APD phase vectors do not result in reflections reaching the base station, the base station may receive reflections of the downlink wireless signal from one APD, multiple APDs, or no reflections of the downlink wireless signal from the APDs, as described with reference to FIG. 5B. Based on the uplink signal reports, the base station may perform other operations for MIMO transmission with the APDs. Optionally, at 1175, the base station may perform another iteration of subdiagram 1115 to perform another channel characterization process. For example, the base station may use the uplink signal reports to refine parameters for uplink beam or APD phase vector selection for a subsequent iteration of channel characterization. Once the uplink channel characterization is complete, the base station may then group the APDs and UEs, as described with reference to FIGS. 5B-10 and 12.

[0127] Example method of MIMO transmission using APD Figure 12 illustrates example method(s) 1200 that can be used to implement various aspects of MIMO transmission using an APD. In various embodiments, operations of method 1200 are performed by or in conjunction with a base station, UE(s), and APD(s) as described with reference to any of Figures 1-11. In some cases, aspects of method 1200 are performed in conjunction with operations described with reference to Figures 5A-9 and / or transactions described with reference to Figures 10 and 11 to implement aspects of MIMO transmission using an APD.

[0128] At 1205, the base station selects one or more APDs to use for at least one communication path for MIMO transmission with one or more UEs. For example, the base station can select candidate APDs within a threshold distance from one or more UEs experiencing degraded signal or link quality measurements. For example, the base station (e.g., base station 120) selects one or more APDs (e.g., APD 181, APD 182) for use in a communication path to one or more UEs (e.g., UE 111, UE 112) in response to identifying signal degradation indicated by signal and / or link quality measurements as described with reference to FIG. 6, FIG. 8, and / or FIG. 10.

[0129] At 1210, the base station performs a channel characterization process using one or more APDs and one or more UEs. The base station 120 performs the channel characterization process as described, for example, with reference to Figures 5A, 5B, 1015 of Figure 10, and / or 11. This may include the base station 120 having the APD 181 and / or the APD 182 apply multiple surface configurations, the base station 120 transmitting a downlink CSI-RS, and / or the UE 110 transmitting an uplink SRS. In performing the channel characterization process, the base station 120 may receive a downlink signal quality measurement from the UE 110 (e.g., subdiagram 1110 of Figure 5A or Figure 11) or may generate an uplink signal quality measurement based on the uplink SRS (e.g., subdiagram 1115 of Figure 5B or Figure 11).

[0130] Optionally, at 1215, the base station groups multiple UEs with at least one APD for MU-MIMO transmission. For example, the base station 120 selects UE 111 and UE 112 to be paired or grouped for MU-MIMO transmission, as described with respect to 1020 of FIG. 6, FIG. 8, or FIG. 10. Optionally, at 1220, the base station groups one UE with at least one APD for SU-MIMO transmission. For example, the base station 120 groups UE 110 with multiple APDs 181 and 182 or partitions of APD 181 for SU-MIMO transmission, as described with reference to FIG. 7 and / or FIG. 9.

[0131] At 1225, the base station configures one or more APDs for MIMO transmission based on the channel characterization process. For example, the base station 120 causes the APD 181 to apply a first surface configuration and the APD 182 to apply a second surface configuration, as shown at 1035 in FIG. 10. Alternatively or additionally, the base station 120 determines an APD timing adjustment, as shown at 1030 (e.g., using a link quality measurement, using UE location information, using APD location information), and configures one or more APDs with the timing adjustment, as shown at 1035. In some aspects, the base station 120 determines a UE timing adjustment and indicates the UE timing adjustment to the UE(s) 110, as shown at 1040 in FIG. 10. In some cases, the base station 120 configures a single APD using panel division or sub-panels, as described with reference to FIG. 7 or FIG. 9.

[0132] At 1230, the base station communicates with one or more UEs using MIMO transmissions and respective surfaces of one or more APDs. As a first example, the base station 120 communicates with the UEs 111 and 112 using APDs 181 and 182 for MU-MIMO transmissions, as shown at 1045 in FIG. 10 or with respect to FIG. 6. As a second example, the base station 120 communicates with the UEs 111 and 112 using APDs 181 and 182 for SU-MIMO transmissions, as described with respect to FIG. 7. As a third example, the base station 120 communicates with the UEs 111 and 112 using APDs 181 (with panel splitting) for MU-MIMO transmissions, as described with respect to FIG. 8. As a fourth example, the base station 120 communicates with the UEs 111 and 112 using APDs 181 (with panel splitting) for SU-MIMO transmissions, as described with respect to FIG. 9.

[0133] The order in which the method blocks are shown is not intended to be construed as a limitation, and any number of the shown method blocks may be omitted or any number of the shown method blocks may be combined in any order to implement one or another method. In general, any of the components, modules, methods, and operations described herein may be implemented using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or any combination thereof. Some operations of the exemplary methods may be described in the general context of executable instructions stored in a computer-readable storage memory that is local and / or remote to a computer processing system, and implementations may include software applications, programs, functions, and the like. Alternatively or additionally, any of the functions described herein may be performed, at least in part, by one or more hardware logic components. Such hardware logic components may be, for example, but not limited to, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SoCs), complex programmable logic devices (CPLDs), and the like.

[0134] Although aspects of MIMO transmission using APDs have been described in language specific to features and / or methods, the subject matter of the appended claims is not necessarily limited to the specific features or methods described. Rather, certain features and methods have been disclosed as exemplary implementations of MIMO transmission using APDs, and other equivalent features and methods are intended to be within the scope of the appended claims. Thus, the features recited in the appended claims may be selected in "any combination," including combining the recited features in any number and in any combination. Moreover, while various different aspects are described, it is to be understood that each described aspect may be practiced independently or in conjunction with one or more of the other described aspects.

[0135] Next, some exemplary aspects are presented. Aspect 1. A method performed by a base station for communicating with at least one user equipment (UE) in a wireless network using multiple-input multiple-output (MIMO) transmissions and at least one adaptive phase change device (APD), the method including: selecting the at least one APD for use in at least one communication path for the MIMO transmissions; performing a channel characterization process for the at least one communication path using the at least one APD and the at least one UE; configuring the at least one APD for the MIMO transmissions based on the channel characterization process; and communicating with the at least one UE via the at least one communication path using the MIMO transmissions and a respective surface of each of the at least one APD.

[0136] 2. The method of claim 1, further comprising: A single UE of the at least one UE may be selected based on the channel characterization process, and the MIMO transmission may be implemented as a Single-User-MIMO (SU-MIMO) transmission between the base station and the single UE. Multiple UEs of the at least one UE may be selected based on the channel characterization process, and the MIMO transmission may be implemented as a Multi-User-MIMO (MU-MIMO) transmission between the base station and the multiple UEs.

[0137] Performing the channel characterization process may include transmitting one or more channel state information reference signals (CSI-RS) toward the respective surfaces of at least one APD. Performing the channel characterization process may include receiving one or more sounding reference signals (SRS) from the at least one UE using the respective surfaces of the at least one APD. Performing the channel characterization process may include receiving quality measurements of one or more respective downlink signals or links from the at least one UE in response to transmitting the one or more CSI-RS. Performing the channel characterization process may include generating quality measurements of one or more respective uplink signals or links in response to receiving the one or more SRS. Configuring the at least one APD for MIMO transmission based on the channel characterization process may include analyzing at least one of the quality measurements of the one or more respective downlink signals or links or the quality measurements of the one or more respective uplink signals or links. A respective surface configuration may be selected for each of the at least one APD based on the analyzing.

[0138] Performing the channel characterization process may include selecting, for each APD of the at least one APD, a respective beam sweeping pattern to apply during the channel characterization process. Each APD of the at least one APD may be caused to apply the respective beam sweeping pattern during the channel characterization process. Performing the channel characterization process may include associating each CSI-RS of the one or more CSI-RS with a respective surface configuration included in the respective beam sweeping pattern. Performing the channel characterization process may include associating each SRS of the one or more SRS with the respective surface configuration included in the respective beam sweeping pattern. Performing the channel characterization process may include assigning a respective MIMO transmission configuration to the respective surface configuration. Configuring the APD may include identifying a MIMO transmission configuration for the MIMO transmission based on the channel characterization process and the assigning. Communicating with the at least one UE may include communicating with each UE of the at least one UE using the MIMO transmission configuration for the MIMO transmission.

[0139] Configuring the at least one APD for MIMO transmission may include indicating a respective APD timing adjustment to each APD of the at least one APD. The at least one APD may be adapted to the surface configuration using the respective APD timing adjustment. The at least one APD may include at least two APDs, and a respective APD timing adjustment may be indicated to each APD of the at least two APDs.

[0140] Determining the respective APD timing adjustment may be based on at least one of a physical downlink shared channel (PDSCH) MIMO transmission time, a physical uplink shared channel (PUSCH) MIMO transmission time, a respective position of each UE in the at least one UE, or a respective position of each APD in the at least one APD.

[0141] Indicating the respective APD timing adjustment to each APD of the at least one APD may include communicating the respective APD timing adjustment to each APD of the at least one APD using an APD control channel utilizing frequency transmission in a frequency band lower than a frequency band of the MIMO transmission.

[0142] Selecting the at least one UE for MIMO transmission may include selecting a first UE and a second UE for MU-MIMO communication. Communicating with the first UE and the second UE using the MIMO transmission may include performing the MU-MIMO communication by communicating with the first UE by using a first MIMO transmission of the MIMO transmissions and including a first APD of the at least one APD in a first communication path for the first MIMO transmission, and communicating with the second UE by using a second MIMO transmission of the MIMO transmissions and including a second APD of the at least one APD in a second communication path for the second MIMO transmission.

[0143] Configuring the at least one APD for MIMO transmission may include at least one of selecting a first surface configuration of the first APD based at least in part on a first MU-MIMO transmission configuration specific to the first UE or selecting a second surface configuration of the second APD based at least in part on a second MU-MIMO transmission configuration specific to the second UE.

[0144] Selecting at least one UE for the MIMO transmission may include selecting a single UE for SU-MIMO communication. Communicating with the single UE using the MIMO transmission may include performing the SU-MIMO communication by communicating with the single UE by using a first MIMO transmission of the MIMO transmissions and including a first APD of the at least one APD in a first communication path for the first MIMO transmission, and communicating with the single UE by using a second MIMO transmission of the MIMO transmissions and including a second APD of the at least one APD in a second communication path for the second MIMO transmission.

[0145] Configuring the at least one APD for MIMO transmission may include at least one of selecting a first surface configuration of the first APD based at least in part on a SU-MIMO transmission configuration of the single UE or selecting a second surface configuration of the second APD based at least in part on a SU-MIMO transmission configuration of the single UE.

[0146] Selecting the at least one UE for MIMO transmission may include selecting a first UE and a second UE for MU-MIMO communication. Communicating with the first UE and the second UE using the MIMO transmission may include performing the MU-MIMO communication by communicating with the first UE by using a first MIMO transmission of the MIMO transmissions and including a first APD surface partition of a single APD of the at least one APD in a first communication path for the first MIMO transmission, and communicating with the second UE by using a second MIMO transmission of the MIMO transmissions and including a second APD surface partition of the single APD in a second communication path for the second MIMO transmission. Configuring the at least one APD for MIMO transmission includes at least one of selecting a first surface configuration of the first APD surface partition of the single APD based at least in part on a first MU-MIMO transmission configuration specific to the first UE or selecting a second surface configuration of the second APD surface partition of the single APD based at least in part on a second MU-MIMO transmission configuration specific to the second UE.

[0147] Selecting at least one UE for MIMO transmission may include selecting a single UE for SU-MIMO communication. Communicating with the single UE using the MIMO transmission may include performing the SU-MIMO communication by communicating with the single UE by using a first MIMO transmission of the MIMO transmissions and including a first APD surface partition of a single APD of the at least one APD in a first communication path for the first MIMO transmission and communicating with the single UE by using a second MIMO transmission of the MIMO transmissions and including a second APD surface partition of the single APD in a second communication path for the second MIMO transmission. Configuring the at least one APD for MIMO transmission may include at least one of selecting a first surface configuration of a first APD surface partition of the single APD based at least in part on a SU-MIMO transmission configuration of the single UE, or selecting a second surface configuration of the second APD surface partition of the single APD based at least in part on a SU-MIMO transmission configuration of the single UE.

[0148] Aspect 2. A base station comprising at least one wireless transceiver, at least one processor, and a computer-readable storage medium containing instructions that, in response to execution by the at least one processor, cause the base station to perform the method of aspect 1.

[0149] Aspect 3. A computer-readable storage medium comprising instructions that, when executed by a processor, cause the method set forth in aspect 1 to be performed.

Claims

1. 1. A method performed by a base station for communicating with a plurality of user equipment units (UEs) in a wireless network using multiple-input multiple-output (MIMO) transmission and at least one adaptive phase change device (APD), comprising: selecting the at least one APD for use in at least one communication path for the MIMO transmission; performing a channel characterization process for the at least one communication path using the at least one APD and the UE; configuring the at least one APD for the MIMO transmission based on the channel characterization process; and communicating with the UE via the at least one communication path using the MIMO transmission and a respective surface of each of the at least one APD; A method comprising:

2. said performing said channel characterization process further comprising: transmitting one or more channel state information reference signals (CSI-RS) toward the respective surfaces of the at least one APD; or receiving one or more sounding reference signals (SRS) from the UE using the respective surfaces of the at least one APD; The method of claim 1 , comprising:

3. said performing said channel characterization process further comprising: receiving one or more respective downlink signal or link quality measurements from the UE in response to transmitting the one or more CSI-RS; or generating one or more respective uplink signal or link quality measurements in response to receiving the one or more SRS; Configuring the at least one APD for the MIMO transmission based on the channel characterization process includes: a quality measurement of said one or more respective downlink signals or links; or a quality measurement of said one or more respective uplink signals or links; and analyzing at least one of selecting a respective surface configuration for each of the at least one APD based on said analyzing; and The method of claim 2 , comprising:

4. said performing said channel characterization process further comprising: selecting, for each APD of the at least one APD, a respective beam sweeping pattern to be applied during the channel characterization process; applying the respective beam sweeping pattern to each APD of the at least one APD during the channel characterization process; and assigning a respective MIMO transmission configuration to said respective surface configuration; The configuring of the APD includes: identifying a MIMO transmission configuration for the MIMO transmission based on the channel characterization process and the allocating; The communicating with the UE comprises: communicating with the UE using the MIMO transmission configuration for the MIMO transmission. The method according to any one of claims 1 to 3.

5. said performing said channel characterization process further comprising: Associating each CSI-RS of the one or more CSI-RS with a respective surface configuration included in the respective beam sweeping pattern; or associating each SRS of the one or more SRSs with a respective surface configuration included in the respective beam sweeping pattern; The method according to claim 4 when dependent on claim 2, comprising:

6. The configuring of the at least one APD for the MIMO transmission includes: indicating a respective APD timing adjustment to each APD of the at least one APD; causing the at least one APD to apply the surface configuration using the respective APD timing adjustments; The method according to any one of claims 1 to 5, comprising:

7. Physical Downlink Shared Channel (PDSCH) MIMO transmission time; Physical Uplink Shared Channel (PUSCH) MIMO transmission time; a respective location of each of said UEs; or a respective position of each APD in the at least one APD; 7. The method of claim 6, further comprising determining the respective APD timing adjustment based on at least one of:

8. The indicating the respective APD timing adjustment to each APD of the at least one APD includes: communicating the respective APD timing adjustments to each APD of the at least one APD using an APD control channel utilizing frequency transmissions in a frequency band lower than a frequency band of the MIMO transmission; The method of claim 6 or claim 7, comprising:

9. The selecting the UEs for the MIMO transmission includes selecting a first UE and a second UE for MU-MIMO communication; The communicating with the first UE and the second UE using the MIMO transmission comprises: communicating with the first UE by using a first MIMO transmission of the MIMO transmissions and including a first APD of the at least one APD in a first communication path for the first MIMO transmission; communicating with the second UE by using a second MIMO transmission of the MIMO transmissions and including a second APD of the at least one APD in a second communication path for the second MIMO transmission; 4. The method of any one of the preceding claims, comprising performing the MU-MIMO communication by:

10. The configuring of the at least one APD for the MIMO transmission includes: selecting a first surface configuration for the first APD based at least in part on a first MU-MIMO transmission configuration specific to the first UE; or selecting a second surface configuration for the second APD based at least in part on a second MU-MIMO transmission configuration specific to the second UE; The method of claim 9 , comprising at least one of:

11. The selecting the UEs for the MIMO transmission includes selecting a first UE and a second UE for MU-MIMO communication; Communicating with the first UE and the second UE using the MIMO transmission includes: communicating with the first UE by using a first MIMO transmission of the MIMO transmissions and including a first APD surface partition of a single APD of the at least one APD in a first communication path for the first MIMO transmission; communicating with the second UE using a second MIMO transmission of the MIMO transmissions and by including a second APD surface partition of the single APD in a second communication path for the second MIMO transmission; performing the MU-MIMO communication by 10. A method according to any one of the preceding claims.

12. The configuring of the at least one APD for the MIMO transmission includes: selecting a first surface configuration for the first APD surface partition of the single APD based at least in part on a first MU-MIMO transmission configuration specific to the first UE; or selecting a second surface configuration for the second APD surface partition of the single APD based at least in part on a second MU-MIMO transmission configuration specific to the second UE; The method of claim 11 , comprising at least one of:

13. A base station, at least one wireless transceiver; At least one processor; and A base station comprising a computer readable storage medium containing instructions which, upon execution by said at least one processor, cause said base station to perform one of the methods of claims 1-12.

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