A method of controlling a radio-frequency (RF) transaction region comprises: determining a value of a characteristic associated with an ability of roadside equipment, associated with an RF transaction, to obtain information from a user equipment (UE) in the RF transaction region; determining, based on the value of the characteristic, a value of a parameter affecting the ability of the roadside equipment to obtain the information from the UE in the RF transaction region; and conveying the value of the parameter to the UE to affect transmission of messages from the UE to the roadside equipment.