Several New and Efficient Backscatter Modulations for Dual-Sided RIS-Enabled Two-Way Backscatter Systems

This paper proposes several novel backscatter modulation schemes for dual-sided RIS-enabled two-way backscatter systems, which are designed based on the rule of a uniquely factorable constellation pair (UFCP). For such, we propose three detection schemes for the considered systems, then derive the exact closed-form expressions of the symbol error rate (SER) and throughput for the proposed detection schemes. Simulations reveal that UFCP-based detection achieves superior throughput over maximum likelihood (ML), and maximal-ratio-combining (MRC) schemes. Furthermore, phase-shifter-based modulation exhibits stronger error resilience than switch-based approaches under MRC detection.