Method and apparatus for spatial filtering using difference in propagation delay between electromagnetic signal and acoustic signal

摘要

A method and apparatus related to spatial filtering to select target terminals only located at a predetermined distance among a plurality of target terminals, using a propagation delay between an electromagnetic signal and an acoustic signal are provided. A user terminal transmits the acoustic signal to neighboring terminals to select terminals of which distances from the user terminal correspond to a distance from the user terminal to a target terminal among neighboring terminals. The electromagnetic signal is transmitted to the neighboring terminals in a predetermined transmission delay. Response signals are received from neighboring terminals of which distances from the user terminal are within a predetermined range, among the neighboring terminals that have received the acoustic signal and the electromagnetic signal. The neighboring terminals receive the acoustic signal from the user terminal, and receive the electromagnetic signal transmitted in the transmission delay from the user terminal.