Equalization for high-bitrate acoustic backscatter communication in metals

Acoustic backscatter communication allows sensors in challenging environments to transmit data with negligible energy cost and is especially useful where electromagnetic waves are infeasible. In acoustic channels, strong inter-symbol interference (ISI) poses a major challenge, which is usually—in conventional communications—mitigated with equalization. Backscatter channels, however, are nonlinear, and standard equalization techniques are not directly applicable. Our work demonstrates that, by mapping the tag’s load to emerging steady-states, the nonlinear channel can be split into a map and a linear channel, enabling standard equalization techniques. Employing our custom reader and tag hardware design in the guided-wave (GW) metal channel, we demonstrate that data rates can be increased more than five-fold compared to no equalization with negligible additional cost. We compare different algorithms for equalization, timing recovery, and interpolation. Moreover, we investigate the time-variability of the GW channel under realistic scenarios, e.g., varying temperatures and physical stress, and present an effective countermeasure to adapt to the time variance.

DDC Class

004: Informatik

600: Technik

620: Ingenieurwissenschaften

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Equalization for high-bitrate acoustic backscatter communication in metals