Performance analysis of two-way relay system based on ambient backscatter

Ambient backscatter technology is a newborn communication scheme, where the devices communicate with each other by backscattering the existing ambient radio frequency sources. However, the poor performance of the primitive system is still an issue that strictly limits the development of ambient backscatter system and urgently needs to be figured out. In this paper, in order to promote the transmission performance we propose a three-time-slot two-way decode-and-forward relay system based on ambient backscatter. To verify the performance of this system, we formulate a transmission model with the influencing factors about distance and derive the optimal detection threshold. On account of the high complexity of the optimal threshold, we provide an approximated optimal threshold and the closed-form bit-error rate (BER) expression. Moreover, the BER expression of the integral relay system compared with direct transmission system is derived and the lower bound of the BER is determined to simplify the performance analysis. Simulation results are finally provided to corroborate the theoretical studies, where the three-time-slot relay system can distinctly promote the transmission performance comparing with the direct transmission system.