Backscatter Index Modulation for Green Communications

Backscatter communication (BC) is a promising method of providing low-power interconnection for green or Internet of Things applications. To combat the strong interference from the signal in the direct link, it often uses a small constellation size for modulation, leading to a low data rate. In this paper, backscatter index modulation (BIM) is proposed to increase the data rate of BC by employing multiple single-antenna tags and activating one tag a time to carry extra data bits for information delivery. Assuming full channel knowledge available at the reader, both ambient backscatter communication with Gaussian source signals and dedicated backscatter communication with known source signals are considered. The optimal detectors are derived using the maximum likelihood principle. Numerical results are presented to show the performances of the proposed index modulation and to examine the effects of different system parameters on the symbol error rate.