Rethinking Channel Coding for Wi-Fi Backscatter Networking

Most Wi-Fi backscatter systems have been proposed with mechanisms that decode the data from backscatter tags based on XOR operations. These XOR-based mechanisms require two receivers listening on the Wi-Fi and backscatter channels and consider the channel coding process as an obstacle to decode the backscatter packets. We focus on channel coding, which is a technique that all Wi-Fi systems use to detect and correct errors from the wireless channels. In our backscatter system, the tag reflects ambient Wi-Fi signals at the symbol level to transmit tag data. When the receiver demodulates and decodes these reflected signals, certain patterns of errors can be observed because of the symbol and subcarrier structures according to the OFDM scheme in Wi-Fi. We propose a method for detecting bit errors caused by backscatter tags and investigate the possibility of utilizing them in decoding.