Methods, systems, and devices for wireless communications are described. Generally, the described techniques allow a channel engineering device (CED) to identify a suitable configuration for deflecting uplink transmissions from a user equipment (UE) to a base station. The base station may transmit control signaling to the CED indicating multiple configurations for deflecting uplink reference signals. The UE may then transmit the uplink reference signals to the CED, and the CED may deflect the uplink reference signals using the indicated configurations. The base station may receive the uplink reference signals from the UE via the CED, and the base station may perform measurements on the uplink reference signals. The base station may then identify a configuration for the CED to use to deflect subsequent transmissions from the UE to the base station based on the measurements, and the base station may transmit an indication of the configuration to the CED.