Asynchronous MAC Protocol for Receiver-Less Backscatter Tag

Ryosuke Koizumi, Yohei Konishi, Kazuhiro Kizaki, Takuya Fujihashi, Shunsuke Saruwatari, Takashi Watanabe

Abstract: Backscatter technology reduces power consumption during data transmission to 1/1000 that of existing wireless transmitters. However, backscatter communication faces two challenges related to medium access control (MAC). First, the carrier wave is not always supplied by an external device when the backscatter tag attempts to transmit data. In addition, if multiple backscatter tags communicate simultaneously, their outgoing frames collide with each other. This study proposes an asynchronous MAC protocol for backscatter tags without a receiving function. The proposed MAC protocol consists of a pseudo-synchronization system and a devised transmission interval between the carrier wave and each backscatter tag. The success rate of data transmission is improved by devising a carrier supply interval and backscatter tag operation. In addition, frame collisions decrease when using a pseudo-random number series to set the transmission interval for each backscatter tag. In a pseudo-synchronization system, the receiver feedbacks time information to the carrier transmitter when the receivers receive or detect a frame. The carrier transmitter adjusts the timing of the carrier supply to match the frame transmission from the backscatter tag, based on the information fed back. This improves the success rate of the communication without time synchronization. The simulation evaluation reveals that the proposed method improves the communication success rate by approximately 1.43 times in the assumed environment.