Wi-Fi Backscatter Communication for Airtime-Varying Carrier Signals

In the Wi-Fi backscatter communication system using temporal combining to enhance communication reliability, we identify an uneven bit reliability problem within a tag packet due to airtime-varying Wi-Fi carrier signals. To address this problem, we propose a position-wise repetition coding framework that assigns different repetition codes to bits based on their positions within a tag packet. We develop three adaptation algorithms to determine the appropriate repetition code for bit blocks according to current channel conditions. Prototyping the framework and algorithms, our testbed experiments with commodity Wi-Fi receivers demonstrate the framework's effectiveness and the throughput gains achieved by the algorithms.