Dual-Stream Backscatter Transmission Using a Three-Load Tag

Backscatter communication (BackCom) enables low-power wireless transmission by modulating reflected radio-frequency signals rather than actively generating a carrier. Conventional two-load backscatter tag architectures inherently produce strongly coupled upper and lower sidebands, limiting the flexible utilization of sideband spectral resources. Many existing approaches seek to suppress the unwanted mirror sideband, while the potential to use both sidebands as separate communication resources remains less explored.
This seminar presents a 3-load backscatter tag that uses the positive and negative first-order sidebands for dual-stream transmission. By introducing one additional reflection state and jointly controlling the switching sequence and duty allocation, the proposed tag enables more flexible shaping of the two mirror sidebands, allowing them to serve as separately addressable spectral resources for distinct data streams, with the potential to support different modulation schemes and information priorities. Theoretical analysis reveals an enlarged achievable region for the two first-order sidebands compared with conventional 2-load modulation. A cable-based proof-of-concept experiment demonstrates four distinguishable spectral states corresponding to the two dimensions of dual-stream On-Off Keying (OOK). The talk also briefly discusses ongoing work on sideband phase control and higher-order modulation to extend the proposed approach towards practical BackCom applications.