Fractional Delayed Detection For Unstable Subcarrier-Coded Backscatter Link

This paper proposes a carrier recovery method for subcarrier-coded backscatter links using a fractional, less than one-symbol, delayed detection. The fractional delayed detection extends the permissible subcarrier frequency errors but results in an unbalanced distribution of delayed symbols. This paper reveals the contribution of fractional detection in RFID sensing systems, particularly the system with an FDMA backscatter to collect streaming data. The unbalanced symbol distribution problem is resolved using a principal component analysis (PCA) of delayed symbols. The fractional delayed detection was evaluated both with a MATLAB simulation and a combination of a software-defined interrogator and a prototype wireless sensor. Both evaluations showed the effectiveness of the proposal.