Active_Two_Way_BackScatter_Modulation.pdf

Abstract—Backscatter modulation (BM), usually used for Radio Frequency Identifications (RFID), has the potential to be exploited in wider range of applications such as Internet of Things and wireless sensor networks. In this paper, we leverage BM by increasing its down-link (from reader to tag) and uplink (from tag to reader) range. We propose two active twoway BM tag configurations, named parallel and series. For both configurations, we use active loads in the tag modulators to maximize the BM range and implement the desired backscattered constellation, subject to no data loss in down-link path. Contrary to most existing BM studies, we use Thevenin/Norton\ equivalent
circuit, only to calculate the received power at tag, while we
derive the tag backscattered power using the antenna scatterer theorem. Moreover, we obtain a closed-form expression of the average bit error probability (BEP) at reader in Rician fading channel environment for both tag configurations. We compare the proposed active BM tags with the conventional passive BM tag. The simulation results prove that for an average BEP equals to 10^-4, an SNR improvement of up to 19 dB and 24 dB can be
achieved for parallel and series configurations, respectively.