Cooperative Ambient Backscatter System: A Symbiotic Radio Paradigm for Passive IoT

Cooperative ambient backscatter system is a novel symbiotic radio paradigm, in which the passive backscatter transmission shares not only the same spectrum but also the same radio-frequency source with the active primary transmission. By considering the unique features of the ambient backscatter system, three practical symbiotic transmission schemes are proposed, in which the relationships between the primary and backscatter transmissions are commensal, parasitic, and competitive, respectively. The achievable rates for both primary and backscatter transmissions are derived for particular fading state. Then, optimal power allocation is obtained for each transmission scheme under the average power constraint. Simulation results are provided to corroborate theoretical studies.