Methods, systems, and devices for wireless communications at a user equipment (UE) are described. A UE may receive a signal indicating a configuration for a symbol reserved for automatic gain control. Based on the configuration for the symbol reserved for automatic gain control, the UE may multiplex assistance data with the symbol reserved for automatic gain control. In some examples, the UE may multiplex physical sidelink shared channel data or physical sidelink control channel data or both physical sidelink shared channel data and physical sidelink control channel data with the symbol reserved for automatic gain control. The UE may then transmit the multiplexed assistance data in the symbol reserved for automatic gain control.