A method, apparatus, and system for barring at least one UE from communicating with one or more RISs is disclosed. A base station may determine to bar at least one UE from communicating with one or more RISs of a plurality of RISs. The base station may transmit, to the at least one UE, a barring indication for the one or more RISs. The barring indication may identify the one or more RISs with which the at least one UE is barred from communicating. The UE may determine to refrain from communicating with the one or more RISs based on the barring indication. The UE may communicate with the base station based on the determination to refrain from communicating with the one or more RISs.

Certain aspects of the present disclosure provide techniques for configuring a reconfigurable intelligent surface (RIS) for wireless communication. A method that may be performed by a base station (BS) includes transmitting one or more parameters corresponding to a time period for the RIS to adapt to user equipment (UE) configuration information, the UE configuration information for configuring the RIS for RIS-assisted communication between the BS and a UE, the one or more parameters comprising a number of symbols indicative of a duration of time. The method also includes transmitting, via the RIS and separately from transmitting the one or more parameters, a control channel to the UE scheduling communication of a data channel with the UE via the RIS. The method also includes communicating, via the RIS, the data channel with the UE the duration of time after transmitting the control channel to the UE.

Disclosed are techniques for wireless communication, and specifically for reconfigurable intelligent surface (RIS)-aided positioning. An example method of wireless communication performed by a base station includes determining a capability of a RIS, determining configuration information for a positioning reference signal, wherein the configuration information is based at least in part on the capability of the RIS, and transmitting a positioning signal based on the configuration information in a direction of the RIS.

Methods, systems, and devices for wireless communications are described. The described techniques support decoupled uplink and downlink communications via reconfigurable intelligent surfaces. Generally, the described techniques provide for using different passive network nodes for uplink and downlink communications. A user equipment (UE) may receive, from a base station, an indication of a first transmission configuration indicator state for downlink communications with the base station and a second transmission configuration indicator state for uplink communications with the base station. The UE may receive, from the base station via a first passive device (e.g., a first reconfigurable intelligent surface (RIS)) associated with the first transmission configuration indicator state, a downlink message in a radio frame. The UE may transmit, to the base station via a second passive device (e.g., a second RIS) associated with the second transmission configuration indicator state, an uplink message in the radio frame.

Aspects of the disclosure related to devices, wireless communication apparatuses, methods, and other aspects of passive multiple input multiple output. In some aspects, an apparatus is provided that includes a first radio frequency (RF) transmission line having a first terminated with a quarter wavelength grounded transmission line, and a first array of antennas including a plurality of antenna elements. The apparatus also includes a switch array including a corresponding switch for each antenna element of the plurality of antenna elements of the first array of antennas, to selectively connect each antenna element to the first RF transmission line, and path lengths selectable by the switches at half wavelength distances for passive transmission. The apparatus also includes or more lens elements configured to modify wireless inputs signals to the first array of antennas and to modify wireless output signals from the first array of antennas.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a first signal associated with a downlink control channel, wherein the first signal uses a modulation signature that identifies a first security key associated with a reconfigurable intelligent surface (RIS), and wherein the first signal includes a second security key. The UE may receive a second signal associated with a downlink shared channel, wherein the second signal includes a third security key, and wherein the second signal is authenticated by the UE based at least in part on the first security key, the second security key, and the third security key. Numerous other aspects are described.

A method for measuring the performance of a reconfigurable intelligent surface is provided. Said method comprises the steps of transmitting (100) a transmit signal to the reconfigurable intelligent surface, receiving (101) the corresponding refection from the reconfigurable intelligent surface as a receive signal, and comparing (102) the transmit signal and the receive signal to determine or derive phase and/or amplitude changes imposed by the reconfigurable intelligent surface.

In an aspect, a relay UE transmits sidelink reference signals for positioning (SL-RS-P) off first and second reconfigurable intelligent surfaces (RISs). The target UE measures the reflected SL-RS-Ps. In an aspect, the SL-RS-Ps may be associated with configurations that are configured by a base station. In an aspect, a position estimation entity may obtain measurement information associated with the reflected SL-RS-Ps and determine a position estimate of the target UE based at least in part upon the measurement information.

The technology described herein is directed towards increasing the secrecy capacity/performance of an intelligent reflective surface (IRS)-assisted communication system. Described is determining a location for placement of the IRS to achieve the maximum secrecy capacity with respect to a receiver in an environment. Gradient descent along with ray tracing, facilitates determination of the optimal placement, which can be used along with an alignment strategy of tile-allocation and phase-shift adjustment for the IRS to optimize the secrecy capacity within constraints. When implemented at the determined location, IRS-assisted communications result in significant improvement of the secrecy capacity performance for an (e.g., indoor) media communication network.

Methods, systems, and devices for wireless communications are described. A UE may receive, from a base station, an indication of a degree of UE loading for at least one of a set of reconfigurable reflective surfaces that are configured to assist in communications between the UE and the base station. The UE may select a reconfigurable reflective surface for use in the communications between the UE and the base station based on the degree of UE loading of the selected reconfigurable reflective surface, and transmit a signal to the base station via the selected reconfigurable reflective surface. In some cases, the UE may receive, from the base station, an indication for the UE to use a different reconfigurable reflective surface than the selected reconfigurable reflective surface, and may transmit a second signal to the base station via a second reconfigurable reflective surface based on the indication.